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Pedro De-la-Torre, Wen H, Brower J, Martínez-Pérez K, Narui Y, Yeh F, Hale E, Ivanchenko MV, Corey DP, Sotomayor M, Indzhykulian AA. Elasticity and Thermal Stability are Key Determinants of Hearing Rescue by Mini-Protocadherin-15 Proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.16.599132. [PMID: 38948700 PMCID: PMC11212938 DOI: 10.1101/2024.06.16.599132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Protocadherin-15 is a core protein component of inner-ear hair-cell tip links pulling on transduction channels essential for hearing and balance. Protocadherin-15 defects can result in non-syndromic deafness or Usher syndrome type 1F (USH1F) with hearing loss, balance deficits, and progressive blindness. Three rationally engineered shortened versions of protocadherin-15 (mini-PCDH15s) amenable for gene therapy have been used to rescue function in USH1F mouse models. Two can successfully or partially rescue hearing, while another one fails. Here we show that despite varying levels of hearing rescue, all three mini-PCDH15 versions can rescue hair-cell mechanotransduction. Negative-stain electron microscopy shows that all three versions form dimers like the wild-type protein, while crystal structures of some engineered fragments show that these can properly fold and bind calcium ions essential for function. In contrast, simulations predict distinct elasticities and nano differential scanning fluorimetry shows differences in melting temperature measurements. Our data suggest that elasticity and thermal stability are key determinants of sustained hearing rescue by mini-PCDH15s.
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Affiliation(s)
- Pedro De-la-Torre
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School and Massachusetts Eye and Ear, 243 Charles St, Boston, MA, USA
| | - Haosheng Wen
- Department of Chemistry and Biochemistry, The Ohio State University, 484 W. 12th Avenue, Columbus, OH, USA
- Biophysics Program, The Ohio State University, 484 W. 12th Avenue, Columbus, OH, USA
| | - Joseph Brower
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School and Massachusetts Eye and Ear, 243 Charles St, Boston, MA, USA
| | - Karina Martínez-Pérez
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School and Massachusetts Eye and Ear, 243 Charles St, Boston, MA, USA
- Biology Program, Department of Basic Sciences, Universidad del Atlántico, Cra 30 # 8-49, Puerto Colombia, 081007, Colombia
| | - Yoshie Narui
- Center for Electron Microscopy and Analysis, The Ohio State University, 1275-1305 Kinnear Road, Columbus, OH, USA
| | - Frank Yeh
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School and Massachusetts Eye and Ear, 243 Charles St, Boston, MA, USA
| | - Evan Hale
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School and Massachusetts Eye and Ear, 243 Charles St, Boston, MA, USA
- Speech and Hearing Biosciences and Technology graduate program, Harvard University, Cambridge, MA, USA
| | - Maryna V. Ivanchenko
- Department of Neurobiology, Harvard Medical School, 200 Longwood Ave, Boston, MA, USA
| | - David P. Corey
- Department of Neurobiology, Harvard Medical School, 200 Longwood Ave, Boston, MA, USA
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, 484 W. 12th Avenue, Columbus, OH, USA
- Biophysics Program, The Ohio State University, 484 W. 12th Avenue, Columbus, OH, USA
| | - Artur A. Indzhykulian
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School and Massachusetts Eye and Ear, 243 Charles St, Boston, MA, USA
- Speech and Hearing Biosciences and Technology graduate program, Harvard University, Cambridge, MA, USA
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2
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Mesbah I, Habermann B, Rico F. MechanoProDB: a web-based database for exploring the mechanical properties of proteins. Database (Oxford) 2024; 2024:baae047. [PMID: 38837788 DOI: 10.1093/database/baae047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/19/2024] [Accepted: 05/17/2024] [Indexed: 06/07/2024]
Abstract
The mechanical stability of proteins is crucial for biological processes. To understand the mechanical functions of proteins, it is important to know the protein structure and mechanical properties. Protein mechanics is usually investigated through force spectroscopy experiments and simulations that probe the forces required to unfold the protein of interest. While there is a wealth of data in the literature on force spectroscopy experiments and steered molecular dynamics simulations of forced protein unfolding, this information is spread and difficult to access by non-experts. Here, we introduce MechanoProDB, a novel web-based database resource for collecting and mining data obtained from experimental and computational works. MechanoProDB provides a curated repository for a wide range of proteins, including muscle proteins, adhesion molecules and membrane proteins. The database incorporates relevant parameters that provide insights into the mechanical stability of proteins and their conformational stability such as the unfolding forces, energy landscape parameters and contour lengths of unfolding steps. Additionally, it provides intuitive annotations of the unfolding pathways of each protein, allowing users to explore the individual steps during mechanical unfolding. The user-friendly interface of MechanoProDB allows researchers to efficiently navigate, search and download data pertaining to specific protein folds or experimental conditions. Users can visualize protein structures using interactive tools integrated within the database, such as Mol*, and plot available data through integrated plotting tools. To ensure data quality and reliability, we have carefully manually verified and curated the data currently available on MechanoProDB. Furthermore, the database also features an interface that enables users to contribute new data and annotations, promoting community-driven comprehensiveness. The freely available MechanoProDB aims to streamline and accelerate research in the field of mechanobiology and biophysics by offering a unique platform for data sharing and analysis. MechanoProDB is freely available at https://mechanoprodb.ibdm.univ-amu.fr.
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Affiliation(s)
- Ismahene Mesbah
- Aix Marseille Univ, INSERM, DyNaMo, Turing Center of Living Systems (CENTURI), Marseille 13009, France
| | - Bianca Habermann
- Aix Marseille Univ, CNRS, IBDM UMR7288, Turing Center of Living Systems (CENTURI), Marseille 13009, France
| | - Felix Rico
- Aix Marseille Univ, INSERM, DyNaMo, Turing Center of Living Systems (CENTURI), Marseille 13009, France
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3
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Tamilselvan E, Sotomayor M. CELSR1, a core planar cell polarity protein, features a weakly adhesive and flexible cadherin ectodomain. Structure 2024; 32:476-491.e5. [PMID: 38307021 DOI: 10.1016/j.str.2024.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 09/30/2023] [Accepted: 01/08/2024] [Indexed: 02/04/2024]
Abstract
Planar cell polarity (PCP), essential to multicellular developmental processes, arises when cells polarize and align across tissues. Central to PCP is CELSR1, an atypical cadherin featuring a long ectodomain with nine extracellular cadherin (EC) repeats, a membrane adjacent domain (MAD10), and several characteristic adhesion GPCR domains. Cell-based aggregation assays have demonstrated CELSR1's homophilic adhesive nature, but mechanistic details are missing. Here, we investigate the possible adhesive properties and structures of CELSR1 EC repeats. Our bead aggregation assays do not support strong adhesion by EC repeats alone. Consistently, EC1-4 only dimerizes at high concentration in solution. Crystal structures of human CELSR1 EC1-4 and EC4-7 reveal typical folds and a non-canonical linker between EC5 and EC6. Simulations and experiments using EC4-7 indicate flexibility at EC5-6, and solution experiments show EC7-MAD10-mediated dimerization. Our results suggest weak homophilic adhesion by CELSR1 cadherin repeats and provide mechanistic insights into the structural determinants of CELSR1 function.
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Affiliation(s)
- Elakkiya Tamilselvan
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Biophysics Program, The Ohio State University, Columbus, OH 43210, USA
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Biophysics Program, The Ohio State University, Columbus, OH 43210, USA.
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4
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Arora N, Hazra JP, Roy S, Bhati GK, Gupta S, Yogendran KP, Chaudhuri A, Sagar A, Rakshit S. Emergence of slip-ideal-slip behavior in tip-links serve as force filters of sound in hearing. Nat Commun 2024; 15:1595. [PMID: 38383683 PMCID: PMC10881517 DOI: 10.1038/s41467-024-45423-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 01/23/2024] [Indexed: 02/23/2024] Open
Abstract
Tip-links in the inner ear convey force from sound and trigger mechanotransduction. Here, we present evidence that tip-links (collectively as heterotetrameric complexes of cadherins) function as force filters during mechanotransduction. Our force-clamp experiments reveal that the tip-link complexes show slip-ideal-slip bond dynamics. At low forces, the lifetime of the tip-link complex drops monotonically, indicating slip-bond dynamics. The ideal bond, rare in nature, is seen in an intermediate force regime where the survival of the complex remains constant over a wide range. At large forces, tip-links follow a slip bond and dissociate entirely to cut-off force transmission. In contrast, the individual tip-links (heterodimers) display slip-catch-slip bonds to the applied forces. While with a phenotypic mutant, we showed the importance of the slip-catch-slip bonds in uninterrupted hearing, our coarse-grained Langevin dynamics simulations demonstrated that the slip-ideal-slip bonds emerge as a collective feature from the slip-catch-slip bonds of individual tip-links.
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Affiliation(s)
- Nisha Arora
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Jagadish P Hazra
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Sandip Roy
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Gaurav K Bhati
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Sarika Gupta
- National Institute of Immunology, New Delhi, India
| | - K P Yogendran
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Abhishek Chaudhuri
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India.
| | - Amin Sagar
- Centre de Biologie Structurale, INSERM, CNRS, Université de Montpellier, Montpellier, France.
| | - Sabyasachi Rakshit
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India.
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Ali A, Tabouni M, Kizhakkedath P, Baydoun I, Allam M, John A, Busafared F, Alnuaimi A, Al-Jasmi F, Alblooshi H. Spectrum of genetic variants in bilateral sensorineural hearing loss. Front Genet 2024; 15:1314535. [PMID: 38410152 PMCID: PMC10894970 DOI: 10.3389/fgene.2024.1314535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/22/2024] [Indexed: 02/28/2024] Open
Abstract
Background: Hearing loss (HL) is an impairment of auditory function with identified genetic forms that can be syndromic (30%) or non-syndromic (70%). HL is genetically heterogeneous, with more than 1,000 variants across 150 causative genes identified to date. The genetic diagnostic rate varies significantly depending on the population being tested. Countries with a considerably high rate of consanguinity provide a unique resource for studying rare forms of recessive HL. In this study, we identified genetic variants associated with bilateral sensorineural HL (SNHL) using whole-exome sequencing (WES) in 11 families residing in the United Arab Emirates (UAE). Results: We established the molecular diagnosis in six probands, with six different pathogenic or likely pathogenic variants in the genes MYO15A, SLC26A4, and GJB2. One novel nonsense variant, MYO15A:p.Tyr1962Ter*, was identified in a homozygous state in one family, which has not been reported in any public database. SLC26A4 and GJB2 were found to be the most frequently associated genes in this study. In addition, six variants of uncertain significance (VUS) were detected in five probands in the genes CDH23, COL11A1, ADGRV1, NLRP3, and GDF6. In total, 12 variants were observed in eight genes. Among these variants, eight missense variants (66.7%), three nonsense variants (25.0%), and one frameshift (8.3%) were identified. The overall diagnostic rate of this study was 54.5%. Approximately 45.5% of the patients in this study came from consanguineous families. Conclusion: Understanding the genetic basis of HL provides insight for the clinical diagnosis of hearing impairment cases through the utilization of next-generation sequencing (NGS). Our findings contribute to the knowledge of the heterogeneous genetic profile of HL, especially in a population with a high rate of consanguineous marriage in the Arab population.
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Affiliation(s)
- Amanat Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Mohammed Tabouni
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Praseetha Kizhakkedath
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Ibrahim Baydoun
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Mushal Allam
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Anne John
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Faiza Busafared
- Department of Otolaryngology, Al Kuwait Hospital, Dubai, United Arab Emirates
| | - Ayesha Alnuaimi
- Department of Otolaryngology, Al Kuwait Hospital, Dubai, United Arab Emirates
| | - Fatma Al-Jasmi
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
- Department of Pediatrics, Tawam Hospital, Al Ain, United Arab Emirates
| | - Hiba Alblooshi
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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Lee JH, Perez-Flores MC, Park S, Kim HJ, Chen Y, Kang M, Kersigo J, Choi J, Thai PN, Woltz RL, Perez-Flores DC, Perkins G, Sihn CR, Trinh P, Zhang XD, Sirish P, Dong Y, Feng WW, Pessah IN, Dixon RE, Sokolowski B, Fritzsch B, Chiamvimonvat N, Yamoah EN. The Piezo channel is a mechano-sensitive complex component in the mammalian inner ear hair cell. Nat Commun 2024; 15:526. [PMID: 38228630 PMCID: PMC10791687 DOI: 10.1038/s41467-023-44230-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 12/04/2023] [Indexed: 01/18/2024] Open
Abstract
The inner ear is the hub where hair cells (HCs) transduce sound, gravity, and head acceleration stimuli to the brain. Hearing and balance rely on mechanosensation, the fastest sensory signals transmitted to the brain. The mechanoelectrical transducer (MET) channel is the entryway for the sound-balance-brain interface, but the channel-complex composition is not entirely known. Here, we report that the mouse utilizes Piezo1 (Pz1) and Piezo2 (Pz2) isoforms as MET-complex components. The Pz channels, expressed in HC stereocilia, and cell lines are co-localized and co-assembled with MET complex partners. Mice expressing non-functional Pz1 and Pz2 at the ROSA26 locus have impaired auditory and vestibular traits that can only be explained if the Pzs are integral to the MET complex. We suggest that Pz subunits constitute part of the MET complex and that interactions with other MET complex components yield functional MET units to generate HC MET currents.
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Affiliation(s)
- Jeong Han Lee
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Maria C Perez-Flores
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Seojin Park
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, 89557, USA
- Prestige Biopharma, 11-12F, 44, Myongjigukje7-ro, Gangseo-gu, Busan, 67264, South Korea
| | - Hyo Jeong Kim
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Yingying Chen
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Mincheol Kang
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, 89557, USA
- Prestige Biopharma, 11-12F, 44, Myongjigukje7-ro, Gangseo-gu, Busan, 67264, South Korea
| | | | - Jinsil Choi
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Phung N Thai
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Ryan L Woltz
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | | | - Guy Perkins
- National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA, 92093, USA
| | - Choong-Ryoul Sihn
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, 89557, USA
| | - Pauline Trinh
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Xiao-Dong Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Padmini Sirish
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Yao Dong
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 1089 VM3B, Davis, CA, 95616, USA
| | - Wayne Wei Feng
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 1089 VM3B, Davis, CA, 95616, USA
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 1089 VM3B, Davis, CA, 95616, USA
| | - Rose E Dixon
- Department of Physiology & Membrane Biology, Tupper Hall, One Shields Avenue, Davis, CA, 95616, USA
| | - Bernd Sokolowski
- Department of Otolaryngology-Head and Neck Surgery, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
- VA Northern California Healthcare System, Sacramento, USA
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, 89557, USA.
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7
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Pressé MT, Malgrange B, Delacroix L. The cochlear matrisome: Importance in hearing and deafness. Matrix Biol 2024; 125:40-58. [PMID: 38070832 DOI: 10.1016/j.matbio.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/20/2023] [Accepted: 12/06/2023] [Indexed: 02/12/2024]
Abstract
The extracellular matrix (ECM) consists in a complex meshwork of collagens, glycoproteins, and proteoglycans, which serves a scaffolding function and provides viscoelastic properties to the tissues. ECM acts as a biomechanical support, and actively participates in cell signaling to induce tissular changes in response to environmental forces and soluble cues. Given the remarkable complexity of the inner ear architecture, its exquisite structure-function relationship, and the importance of vibration-induced stimulation of its sensory cells, ECM is instrumental to hearing. Many factors of the matrisome are involved in cochlea development, function and maintenance, as evidenced by the variety of ECM proteins associated with hereditary deafness. This review describes the structural and functional ECM components in the auditory organ and how they are modulated over time and following injury.
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Affiliation(s)
- Mary T Pressé
- Developmental Neurobiology Unit, GIGA-Neurosciences, University of Liège, 15 avenue Hippocrate - CHU - B36 (1st floor), Liège B-4000, Belgium
| | - Brigitte Malgrange
- Developmental Neurobiology Unit, GIGA-Neurosciences, University of Liège, 15 avenue Hippocrate - CHU - B36 (1st floor), Liège B-4000, Belgium
| | - Laurence Delacroix
- Developmental Neurobiology Unit, GIGA-Neurosciences, University of Liège, 15 avenue Hippocrate - CHU - B36 (1st floor), Liège B-4000, Belgium.
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8
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Lan Y, Hou T, Peng L, Li Y, Yin S. The association of genetic polymorphisms in protocadherin 15 with sudden sensorineural hearing loss in a Chinese population. J Clin Lab Anal 2023:e24896. [PMID: 37198144 DOI: 10.1002/jcla.24896] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 04/27/2023] [Accepted: 05/04/2023] [Indexed: 05/19/2023] Open
Abstract
BACKGROUND Sudden sensorineural hearing loss (SSNHL) is a multifactorial disease, and its etiology is still unknown. SSNHL may be caused by environmental factors and genetic changes. PCDH15 is associated with susceptibility to hearing loss. The relationship between PCDH15 and SSNHL remains unknown. METHODS In this study, the potential association between PCDH15 polymorphism and SSNHL in Chinese population was evaluated. Two single nucleotide polymorphisms PCDH15-rs7095441 and rs11004085 in 195 SSNHL patients and 182 healthy controls were determined by TaqMan technology. RESULTS In Chinese population, the TT genotype and T allele of rs7095441 are associated with increased susceptibility to SSNHL. The relationships between rs7095441 and the degree of hearing loss were analyzed, and TT genotype increased the risk of hearing loss. Among SSNHL patients, patients with TT genotype of rs7095441 have an increased risk of vertigo. CONCLUSION This study found that the TT genotype of SNP rs7095441 can increase the risk of SSNHL in Chinese population.
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Affiliation(s)
- Ying Lan
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
- Department of Otolaryngology Head and Neck Surgery, The Third Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Tao Hou
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Lu Peng
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Yongpeng Li
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Shihua Yin
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
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9
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Srinivas CS, Singaraju GS, Kaur V, Das S, Ghosh SK, Sagar A, Kumar A, Bhatia T, Rakshit S. Transient interactions drive the lateral clustering of cadherin-23 on membrane. Commun Biol 2023; 6:293. [PMID: 36934176 PMCID: PMC10024700 DOI: 10.1038/s42003-023-04677-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 03/07/2023] [Indexed: 03/20/2023] Open
Abstract
Cis and trans-interactions among cadherins secure multicellularity. While the molecular structure of trans-interactions of cadherins is well understood, work to identify the molecular cues that spread the cis-interactions two-dimensionally is still ongoing. Here, we report that transient, weak, yet multivalent, and spatially distributed hydrophobic interactions that are involved in liquid-liquid phase separations of biomolecules in solution, alone can drive the lateral-clustering of cadherin-23 on a membrane. No specific cis-dimer interactions are required for the lateral clustering. In cells, the cis-clustering accelerates cell-cell adhesion and, thus, contributes to cell-adhesion kinetics along with strengthening the junction. Although the physiological connection of cis-clustering with rapid adhesion is yet to be explored, we speculate that the over-expression of cadherin-23 in M2-macrophages may facilitate faster attachments to circulatory tumor cells during metastasis.
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Affiliation(s)
- Cheerneni S Srinivas
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Gayathri S Singaraju
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Veerpal Kaur
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Sayan Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Sanat K Ghosh
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Amin Sagar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Anuj Kumar
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
- Centre for Protein Science Design and Engineering, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Tripta Bhatia
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Sabyasachi Rakshit
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
- Centre for Protein Science Design and Engineering, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
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10
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Kang B, Lu X, Xiong J, Li Y, Zhu J, Cai T. Identification of four novel variants in the CDH23 gene from four affected families with hearing loss. Front Genet 2022; 13:1027396. [DOI: 10.3389/fgene.2022.1027396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 11/04/2022] [Indexed: 11/18/2022] Open
Abstract
Background: Hearing loss (HL) is the most common form of sensory disorder in humans. Molecular diagnosis of HL is important for genetic counseling for the affected individuals and their families.Methods: To identify potential genetic causes, we performed whole-exome sequencing and related biomedical informatics for 351 non-syndromic HL patients and their family members.Results: In the present study, we report the identification of four compound heterozygous variants in the CDH23 gene from four affected families, including four novel variants (c.995C>A, p.T332K; c.2159G>A, p.R720Q; c.5534A>G, p.N1845S, and c.7055-1G>C) and two frequently reported variants (c.719C>T, p.P240L and c.4762C>T, p.R1588W).Conclusion: Our findings significantly expanded the mutation spectrum of CDH23-associated autosomal recessive hearing loss.
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11
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Qiu X, Müller U. Sensing sound: Cellular specializations and molecular force sensors. Neuron 2022; 110:3667-3687. [PMID: 36223766 PMCID: PMC9671866 DOI: 10.1016/j.neuron.2022.09.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/03/2022] [Accepted: 09/14/2022] [Indexed: 11/08/2022]
Abstract
Organisms of all phyla express mechanosensitive ion channels with a wide range of physiological functions. In recent years, several classes of mechanically gated ion channels have been identified. Some of these ion channels are intrinsically mechanosensitive. Others depend on accessory proteins to regulate their response to mechanical force. The mechanotransduction machinery of cochlear hair cells provides a particularly striking example of a complex force-sensing machine. This molecular ensemble is embedded into a specialized cellular compartment that is crucial for its function. Notably, mechanotransduction channels of cochlear hair cells are not only critical for auditory perception. They also shape their cellular environment and regulate the development of auditory circuitry. Here, we summarize recent discoveries that have shed light on the composition of the mechanotransduction machinery of cochlear hair cells and how this machinery contributes to the development and function of the auditory system.
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Affiliation(s)
- Xufeng Qiu
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ulrich Müller
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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12
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cAMP and voltage modulate rat auditory mechanotransduction by decreasing the stiffness of gating springs. Proc Natl Acad Sci U S A 2022; 119:e2107567119. [PMID: 35858439 PMCID: PMC9335186 DOI: 10.1073/pnas.2107567119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Regulation of auditory sensitivity contributes to the precision, dynamic range, and protection of the auditory system. Regulation of the hair cell mechanotransduction channel is a major contributor to controlling the sensitivity of the auditory transduction process. The gating spring is a critical piece of the mechanotransduction machinery because it opens and closes the mechanotransduction channel, and its stiffness regulates the sensitivity of the mechanotransduction process. In the present work, we characterize the effect of the second-messenger signaling molecule cyclic adenosine monophosphate (cAMP) and identify that it reduces gating spring stiffness likely through an exchange protein directly activated by cAMP (EPAC)-mediated pathway. This is a unique physiologic mechanism to regulate gating spring stiffness. Hair cells of the auditory and vestibular systems transform mechanical input into electrical potentials through the mechanoelectrical transduction process (MET). Deflection of the mechanosensory hair bundle increases tension in the gating springs that open MET channels. Regulation of MET channel sensitivity contributes to the auditory system’s precision, wide dynamic range and, potentially, protection from overexcitation. Modulating the stiffness of the gating spring modulates the sensitivity of the MET process. Here, we investigated the role of cyclic adenosine monophosphate (cAMP) in rat outer hair cell MET and found that cAMP up-regulation lowers the sensitivity of the channel in a manner consistent with decreasing gating spring stiffness. Direct measurements of the mechanical properties of the hair bundle confirmed a decrease in gating spring stiffness with cAMP up-regulation. In parallel, we found that prolonged depolarization mirrored the effects of cAMP. Finally, a limited number of experiments implicate that cAMP activates the exchange protein directly activated by cAMP to mediate the changes in MET sensitivity. These results reveal that cAMP signaling modulates gating spring stiffness to affect auditory sensitivity.
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13
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Thulasiram MR, Ogier JM, Dabdoub A. Hearing Function, Degeneration, and Disease: Spotlight on the Stria Vascularis. Front Cell Dev Biol 2022; 10:841708. [PMID: 35309932 PMCID: PMC8931286 DOI: 10.3389/fcell.2022.841708] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 01/20/2022] [Indexed: 11/21/2022] Open
Abstract
The stria vascularis (SV) is a highly vascularized tissue lining the lateral wall of the cochlea. The SV maintains cochlear fluid homeostasis, generating the endocochlear potential that is required for sound transduction. In addition, the SV acts as an important blood-labyrinth barrier, tightly regulating the passage of molecules from the blood into the cochlea. A healthy SV is therefore vital for hearing function. Degeneration of the SV is a leading cause of age-related hearing loss, and has been associated with several hearing disorders, including Norrie disease, Meniere's disease, Alport syndrome, Waardenburg syndrome, and Cytomegalovirus-induced hearing loss. Despite the SV's important role in hearing, there is still much that remains to be discovered, including cell-specific function within the SV, mechanisms of SV degeneration, and potential protective or regenerative therapies. In this review, we discuss recent discoveries elucidating the molecular regulatory networks of SV function, mechanisms underlying degeneration of the SV, and otoprotective strategies for preventing drug-induced SV damage. We also highlight recent clinical developments for treating SV-related hearing loss and discuss future research trajectories in the field.
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Affiliation(s)
- Matsya R Thulasiram
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Jacqueline M Ogier
- Biological Sciences, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Alain Dabdoub
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Biological Sciences, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
- Department of Otolaryngology–Head and Neck Surgery, University of Toronto, Toronto, ON, Canada
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14
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Gray ME, Johnson ZR, Modak D, Tamilselvan E, Tyska MJ, Sotomayor M. Heterophilic and homophilic cadherin interactions in intestinal intermicrovillar links are species dependent. PLoS Biol 2021; 19:e3001463. [PMID: 34871294 PMCID: PMC8691648 DOI: 10.1371/journal.pbio.3001463] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 12/21/2021] [Accepted: 10/30/2021] [Indexed: 11/19/2022] Open
Abstract
Enterocytes are specialized epithelial cells lining the luminal surface of the small intestine that build densely packed arrays of microvilli known as brush borders. These microvilli drive nutrient absorption and are arranged in a hexagonal pattern maintained by intermicrovillar links formed by 2 nonclassical members of the cadherin superfamily of calcium-dependent cell adhesion proteins: protocadherin-24 (PCDH24, also known as CDHR2) and the mucin-like protocadherin (CDHR5). The extracellular domains of these proteins are involved in heterophilic and homophilic interactions important for intermicrovillar function, yet the structural determinants of these interactions remain unresolved. Here, we present X-ray crystal structures of the PCDH24 and CDHR5 extracellular tips and analyze their species-specific features relevant for adhesive interactions. In parallel, we use binding assays to identify the PCDH24 and CDHR5 domains involved in both heterophilic and homophilic adhesion for human and mouse proteins. Our results suggest that homophilic and heterophilic interactions involving PCDH24 and CDHR5 are species dependent with unique and distinct minimal adhesive units.
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Affiliation(s)
- Michelle E. Gray
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, United States of America
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Zachary R. Johnson
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Debadrita Modak
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Elakkiya Tamilselvan
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
- Biophysics Program, The Ohio State University, Columbus, Ohio, United States of America
| | - Matthew J. Tyska
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Marcos Sotomayor
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, United States of America
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
- Biophysics Program, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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15
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Arora N, Hazra JP, Rakshit S. Anisotropy in mechanical unfolding of protein upon partner-assisted pulling and handle-assisted pulling. Commun Biol 2021; 4:925. [PMID: 34326473 PMCID: PMC8322310 DOI: 10.1038/s42003-021-02445-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 07/07/2021] [Indexed: 02/07/2023] Open
Abstract
Proteins as force-sensors respond to mechanical cues and regulate signaling in physiology. Proteins commonly connect the source and response points of mechanical cues in two conformations, independent proteins in end-to-end geometry and protein complexes in handshake geometry. The force-responsive property of independent proteins in end-to-end geometry is studied extensively using single-molecule force spectroscopy (SMFS). The physiological significance of the complex conformations in force-sensing is often disregarded as mere surge protectors. However, with the potential of force-steering, protein complexes possess a distinct mechano-responsive property over individual force-sensors. To decipher, we choose a force-sensing protein, cadherin-23, from tip-link complex and perform SMFS using end-to-end geometry and handshake complex geometry. We measure higher force-resilience of cadherin-23 with preferential shorter extensions in handshake mode of pulling over the direct mode. The handshake geometry drives the force-response of cadherin-23 through different potential-energy landscapes than direct pulling. Analysis of the dynamic network structure of cadherin-23 under tension indicates narrow force-distributions among residues in cadherin-23 in direct pulling, resulting in low force-dissipation paths and low resilience to force. Overall, the distinct and superior mechanical responses of cadherin-23 in handshake geometry than single protein geometry highlight a probable evolutionary drive of protein-protein complexes as force-conveyors over independent ones.
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Affiliation(s)
- Nisha Arora
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Jagadish Prasad Hazra
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
| | - Sabyasachi Rakshit
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
- Centre for Protein Science Design and Engineering, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
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16
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Liu S, Wang S, Zou L, Xiong W. Mechanisms in cochlear hair cell mechano-electrical transduction for acquisition of sound frequency and intensity. Cell Mol Life Sci 2021; 78:5083-5094. [PMID: 33871677 PMCID: PMC11072359 DOI: 10.1007/s00018-021-03840-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 03/30/2021] [Accepted: 04/09/2021] [Indexed: 10/21/2022]
Abstract
Sound signals are acquired and digitized in the cochlea by the hair cells that further transmit the coded information to the central auditory pathways. Any defect in hair cell function may induce problems in the auditory system and hearing-based brain function. In the past 2 decades, our understanding of auditory transduction has been substantially deepened because of advances in molecular, structural, and functional studies. Results from these experiments can be perfectly embedded in the previously established profile from anatomical, histological, genetic, and biophysical research. This review aims to summarize the progress on the molecular and cellular mechanisms of the mechano-electrical transduction (MET) channel in the cochlear hair cells, which is involved in the acquisition of sound frequency and intensity-the two major parameters of an acoustic cue. We also discuss recent studies on TMC1, the molecule likely to form the MET channel pore.
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Affiliation(s)
- Shuang Liu
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
| | - Shufeng Wang
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
| | - Linzhi Zou
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
| | - Wei Xiong
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China.
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China.
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17
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Abstract
Sound-induced mechanical stimuli are detected by elaborate mechanosensory transduction (MT) machinery in highly specialized hair cells of the inner ear. Genetic studies of inherited deafness in the past decades have uncovered several molecular constituents of the MT complex, and intense debate has surrounded the molecular identity of the pore-forming subunits. How the MT components function in concert in response to physical stimulation is not fully understood. In this review, we summarize and discuss multiple lines of evidence supporting the hypothesis that transmembrane channel-like 1 is a long-sought MT channel subunit. We also review specific roles of other components of the MT complex, including protocadherin 15, cadherin 23, lipoma HMGIC fusion partner-like 5, transmembrane inner ear, calcium and integrin-binding family member 2, and ankyrins. Based on these recent advances, we propose a unifying theory of hair cell MT that may reconcile most of the functional discoveries obtained to date. Finally, we discuss key questions that need to be addressed for a comprehensive understanding of hair cell MT at molecular and atomic levels.
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Affiliation(s)
- Wang Zheng
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA;
| | - Jeffrey R Holt
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA;
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18
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Mulhall EM, Ward A, Yang D, Koussa MA, Corey DP, Wong WP. Single-molecule force spectroscopy reveals the dynamic strength of the hair-cell tip-link connection. Nat Commun 2021; 12:849. [PMID: 33558532 PMCID: PMC7870652 DOI: 10.1038/s41467-021-21033-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 01/08/2021] [Indexed: 01/11/2023] Open
Abstract
The conversion of auditory and vestibular stimuli into electrical signals is initiated by force transmitted to a mechanotransduction channel through the tip link, a double stranded protein filament held together by two adhesion bonds in the middle. Although thought to form a relatively static structure, the dynamics of the tip-link connection has not been measured. Here, we biophysically characterize the strength of the tip-link connection at single-molecule resolution. We show that a single tip-link bond is more mechanically stable relative to classic cadherins, and our data indicate that the double stranded tip-link connection is stabilized by single strand rebinding facilitated by strong cis-dimerization domains. The measured lifetime of seconds suggests the tip-link is far more dynamic than previously thought. We also show how Ca2+ alters tip-link lifetime through elastic modulation and reveal the mechanical phenotype of a hereditary deafness mutation. Together, these data show how the tip link is likely to function during mechanical stimuli.
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Affiliation(s)
- Eric M Mulhall
- Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Program in Neuroscience, Harvard University, Cambridge, MA, USA
| | - Andrew Ward
- Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Darren Yang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Mounir A Koussa
- Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Program in Neuroscience, Harvard University, Cambridge, MA, USA
| | - David P Corey
- Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
| | - Wesley P Wong
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.
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19
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Structural determinants of protocadherin-15 mechanics and function in hearing and balance perception. Proc Natl Acad Sci U S A 2020; 117:24837-24848. [PMID: 32963095 PMCID: PMC7547225 DOI: 10.1073/pnas.1920444117] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
When sound vibrations reach the inner ear, fine protein filaments called “tip links” stretch and open cochlear hair-cell mechanosensitive channels that trigger sensory perception. Similarly, vestibular hair cells use tip links to sense mechanical stimuli produced by head motions. Tip links are formed by cadherin-23 and protocadherin-15, two large proteins involved in hearing loss and balance disorders. Here we present multiple structures, models, and simulations that depict the lower end of the tip link, including the complete protocadherin-15 ectodomain. These models show an essential connection between cadherin-23 and protocadherin-15 with dual molecular “handshakes” and various protein sites that are mutated in inherited deafness. The simulations also reveal how the tip link responds to force to mediate hearing and balance sensing. The vertebrate inner ear, responsible for hearing and balance, is able to sense minute mechanical stimuli originating from an extraordinarily broad range of sound frequencies and intensities or from head movements. Integral to these processes is the tip-link protein complex, which conveys force to open the inner-ear transduction channels that mediate sensory perception. Protocadherin-15 and cadherin-23, two atypically large cadherins with 11 and 27 extracellular cadherin (EC) repeats, are involved in deafness and balance disorders and assemble as parallel homodimers that interact to form the tip link. Here we report the X-ray crystal structure of a protocadherin-15 + cadherin-23 heterotetrameric complex at 2.9-Å resolution, depicting a parallel homodimer of protocadherin-15 EC1-3 molecules forming an antiparallel complex with two cadherin-23 EC1-2 molecules. In addition, we report structures for 10 protocadherin-15 fragments used to build complete high-resolution models of the monomeric protocadherin-15 ectodomain. Molecular dynamics simulations and validated crystal contacts are used to propose models for the complete extracellular protocadherin-15 parallel homodimer and the tip-link bond. Steered molecular dynamics simulations of these models suggest conditions in which a structurally diverse and multimodal protocadherin-15 ectodomain can act as a stiff or soft gating spring. These results reveal the structural determinants of tip-link–mediated inner-ear sensory perception and elucidate protocadherin-15’s structural and adhesive properties relevant in disease.
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20
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Sharma S, Subramani S, Popa I. Does protein unfolding play a functional role in vivo? FEBS J 2020; 288:1742-1758. [PMID: 32761965 DOI: 10.1111/febs.15508] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/09/2020] [Accepted: 08/03/2020] [Indexed: 12/21/2022]
Abstract
Unfolding and refolding of multidomain proteins under force have yet to be recognized as a major mechanism of function for proteins in vivo. In this review, we discuss the inherent properties of multidomain proteins under a force vector from a structural and functional perspective. We then characterize three main systems where multidomain proteins could play major roles through mechanical unfolding: muscular contraction, cellular mechanotransduction, and bacterial adhesion. We analyze how key multidomain proteins for each system can produce a gain-of-function from the perspective of a fine-tuned quantized response, a molecular battery, delivery of mechanical work through refolding, elasticity tuning, protection and exposure of cryptic sites, and binding-induced mechanical changes. Understanding how mechanical unfolding and refolding affect function will have important implications in designing mechano-active drugs against conditions such as muscular dystrophy, cancer, or novel antibiotics.
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Affiliation(s)
- Sabita Sharma
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Smrithika Subramani
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Ionel Popa
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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21
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Nadar-Ponniah PT, Taiber S, Caspi M, Koffler-Brill T, Dror AA, Siman-Tov R, Rubinstein M, Padmanabhan K, Luxenburg C, Lang RA, Avraham KB, Rosin-Arbesfeld R. Striatin Is Required for Hearing and Affects Inner Hair Cells and Ribbon Synapses. Front Cell Dev Biol 2020; 8:615. [PMID: 32766247 PMCID: PMC7381154 DOI: 10.3389/fcell.2020.00615] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 06/22/2020] [Indexed: 12/22/2022] Open
Abstract
Striatin, a subunit of the serine/threonine phosphatase PP2A, is a core member of the conserved striatin-interacting phosphatase and kinase (STRIPAK) complexes. The protein is expressed in the cell junctions between epithelial cells, which play a role in maintaining cell-cell adhesion. Since the cell junctions are crucial for the function of the mammalian inner ear, we examined the localization and function of striatin in the mouse cochlea. Our results show that in neonatal mice, striatin is specifically expressed in the cell-cell junctions of the inner hair cells, the receptor cells in the mammalian cochlea. Auditory brainstem response measurements of striatin-deficient mice indicated a progressive, high-frequency hearing loss, suggesting that striatin is essential for normal hearing. Moreover, scanning electron micrographs of the organ of Corti revealed a moderate degeneration of the outer hair cells in the middle and basal regions, concordant with the high-frequency hearing loss. Additionally, striatin-deficient mice show aberrant ribbon synapse maturation. Loss of the outer hair cells, combined with the aberrant ribbon synapse distribution, may lead to the observed auditory impairment. Together, these results suggest a novel function for striatin in the mammalian auditory system.
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Affiliation(s)
- Prathamesh T. Nadar-Ponniah
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Shahar Taiber
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Michal Caspi
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Tal Koffler-Brill
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Amiel A. Dror
- Department of Otolaryngology, Head and Neck Surgery, Galilee Medical Center, Nahariya, Israel
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Ronen Siman-Tov
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Moran Rubinstein
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Goldschleger Eye Research Institute, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Krishnanand Padmanabhan
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Chen Luxenburg
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Richard A. Lang
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
| | - Karen B. Avraham
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Rina Rosin-Arbesfeld
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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22
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Richardson GP, Petit C. Hair-Bundle Links: Genetics as the Gateway to Function. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033142. [PMID: 30617060 DOI: 10.1101/cshperspect.a033142] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Up to five distinct cell-surface specializations interconnect the stereocilia and the kinocilium of the mature hair bundle in some species: kinocilial links, tip links, top connectors, shaft connectors, and ankle links. In developing hair bundles, transient lateral links are prominent. Mutations in genes encoding proteins associated with these links cause Usher deafness/blindness syndrome or nonsyndromic (isolated) forms of human hereditary deafness, and mice with constitutive or conditional alleles of these genes have provided considerable insight into the molecular composition and function of the different links. We describe the structure of these links and review evidence showing CDH23 and PCDH15 are components of the tip, kinocilial, and transient-lateral links, that stereocilin (STRC) and protein tyrosine phosphatase (PTPRQ) are associated with top and shaft connectors, respectively, and that USH2A and ADGRV1 are associated with the ankle links. Whereas tip links are required for mechanoelectrical transduction, all link proteins play key roles in the normal development and/or the maintenance of hair bundle structure and function. Recent crystallographic and single-particle analyses of PCDH15 and CDH23 provide insight as to how the structure of tip link may contribute to the elastic element predicted to lie in series with the hair cell's mechanoelectrical transducer channel.
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Affiliation(s)
- Guy P Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
| | - Christine Petit
- Institut Pasteur, 75724 Paris Cedex 15, France.,Collège de France, 75231 Paris Cedex 05, France
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23
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Singaraju GS, Sagar A, Kumar A, Samuel JS, Hazra JP, Sannigrahi MK, Yennamalli RM, Ashish , Rakshit S. Structural basis of the strong cell-cell junction formed by cadherin-23. FEBS J 2019; 287:2328-2347. [PMID: 31729176 PMCID: PMC7317872 DOI: 10.1111/febs.15141] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 08/13/2019] [Accepted: 11/13/2019] [Indexed: 12/03/2022]
Abstract
Cadherin-23, a giant atypical cadherin, forms homophilic interactions at the cell-cell junction of epithelial cells and heterophilic interactions with protocadherin-15 at the tip-links of neuroepithelial cells. While the molecular structure of the heterodimer is solved, the homodimer structure is yet to be resolved. The homodimers play an essential role in cell-cell adhesion as the downregulation of cadherin-23 in cancers loosen the intercellular junction resulting in faster-migration of cancer cells and a significant drop in patient survival. In vitro studies have measured a stronger aggregation-propensity of cadherin-23 compared to typical E-cadherin. Here, we deciphered the unique trans-homodimer structure of cadherin-23 in solution, and show that it consists of two electrostatic-based interfaces extended up to two terminal domains. The interface is robust, with a low off-rate of ~8x10-4 s-1 that supports its strong aggregation-propensity. We identified a point-mutation, E78K, that disrupts this binding. Interestingly, a mutation at the interface was reported in skin cancer. Overall, the structural basis of the strong cadherin-23 adhesion may have far-reaching applications in the fields of mechanobiology and cancer.
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Affiliation(s)
- Gayathri S. Singaraju
- Department of Chemical SciencesIndian Institute of Science Education and Research MohaliPunjabIndia
| | - Amin Sagar
- Department of Chemical SciencesIndian Institute of Science Education and Research MohaliPunjabIndia
| | - Anuj Kumar
- Department of Physical SciencesIndian Institute of Science Education and Research MohaliPunjabIndia
| | - Jesse S. Samuel
- Department of Chemical SciencesIndian Institute of Science Education and Research MohaliPunjabIndia
| | - Jagadish P. Hazra
- Department of Chemical SciencesIndian Institute of Science Education and Research MohaliPunjabIndia
| | - Malay K. Sannigrahi
- Department of Chemical SciencesIndian Institute of Science Education and Research MohaliPunjabIndia
| | - Ragothaman M. Yennamalli
- Department of Biotechnology and BioinformaticsJaypee University of Information TechnologyWaknaghatIndia
| | - Ashish
- Institute of Microbial Technology (CSIR)ChandigarhIndia
| | - Sabyasachi Rakshit
- Department of Chemical SciencesIndian Institute of Science Education and Research MohaliPunjabIndia
- Centre for Protein Science Design and EngineeringIndian Institute of Science Education and Research MohaliPunjabIndia
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24
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Abstract
During the detection of sound, hair bundles perform a crucial step by responding to mechanical deflections and converting them into changes in electrical potential that subsequently lead to the release of neurotransmitter. The sensory hair bundle response is characterized by an essential nonlinearity and an energy-consuming amplification of the incoming sound. The active response has been shown to enhance the hair bundle's sensitivity and frequency selectivity of detection. The biological phenomena shown by the bundle have been extensively studied in vitro, allowing comparisons to behaviors observed in vivo. The experimental observations have been well explained by numerical simulations, which describe the cellular mechanisms operant within the bundle, as well as by more sparse theoretical models, based on dynamical systems theory.
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Affiliation(s)
- Dolores Bozovic
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547.,California NanoSystems Institute, University of California, Los Angeles, California 90095-1547
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25
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Abstract
Hearing and balance rely on the transduction of mechanical stimuli arising from sound waves or head movements into electrochemical signals. This archetypal mechanoelectrical transduction process occurs in the hair-cell stereocilia of the inner ear, which experience continuous oscillations driven by undulations in the endolymph in which they are immersed. The filamentous structures called tip links, formed by an intertwined thread composed of an heterotypic complex of cadherin 23 and protocadherin 15 ectodomain dimers, connect each stereocilium to the tip of the lower sterocilium, and must maintain their integrity against continuous stimulatory deflections. By using single molecule force spectroscopy, here we demonstrate that in contrast to the case of classical cadherins, tip-link cadherins are mechanoresilient structures even at the exceptionally low Ca2+ concentration of the endolymph. We also show that the D101G deafness point mutation in cadherin 23, which affects a Ca2+ coordination site, exhibits an altered mechanical phenotype at the physiological Ca2+ concentration. Our results show a remarkable case of functional adaptation of a protein’s nanomechanics to extremely low Ca2+ concentrations and pave the way to a full understanding of the mechanotransduction mechanism mediated by auditory cadherins.
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26
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Broken force dispersal network in tip-links by the mutations at the Ca 2+-binding residues induces hearing-loss. Biochem J 2019; 476:2411-2425. [PMID: 31399498 PMCID: PMC6717114 DOI: 10.1042/bcj20190453] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 08/07/2019] [Accepted: 08/09/2019] [Indexed: 12/26/2022]
Abstract
Tip-link as force-sensor in hearing conveys the mechanical force originating from sound to ion-channels while maintaining the integrity of the entire sensory assembly in the inner ear. This delicate balance between structure and function of tip-links is regulated by Ca2+-ions present in endolymph. Mutations at the Ca2+-binding sites of tip-links often lead to congenital deafness, sometimes syndromic defects impairing vision along with hearing. Although such mutations are already identified, it is still not clear how the mutants alter the structure-function properties of the force-sensors associated with diseases. With an aim to decipher the differences in force-conveying properties of the force-sensors in molecular details, we identified the conformational variability of mutant and wild-type tip-links at the single-molecule level using FRET at the endolymphatic Ca2+ concentrations and subsequently measured the force-responsive behavior using single-molecule force spectroscopy with an Atomic Force Microscope (AFM). AFM allowed us to mimic the high and wide range of force ramps (103-106 pN s-1) as experienced in the inner ear. We performed in silico network analysis to learn that alterations in the conformations of the mutants interrupt the natural force-propagation paths through the sensors and make the mutant tip-links vulnerable to input forces from sound stimuli. We also demonstrated that a Ca2+ rich environment can restore the force-response of the mutant tip-links which may eventually facilitate the designing of better therapeutic strategies to the hearing loss.
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27
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Cuoco JA, Esposito AW, Moriarty S, Tang Y, Seth S, Toia AR, Kampton EB, Mayr Y, Khan M, Khan MB, Mullen BR, Ackman JB, Siddiqi F, Wolfe JH, Savinova OV, Ramos RL. Malformation of the Posterior Cerebellar Vermis Is a Common Neuroanatomical Phenotype of Genetically Engineered Mice on the C57BL/6 Background. THE CEREBELLUM 2019; 17:173-190. [PMID: 29043563 DOI: 10.1007/s12311-017-0892-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
C57BL/6 mice exhibit spontaneous cerebellar malformations consisting of heterotopic neurons and glia in the molecular layer of the posterior vermis, indicative of neuronal migration defect during cerebellar development. Recognizing that many genetically engineered (GE) mouse lines are produced from C57BL/6 ES cells or backcrossed to this strain, we performed histological analyses and found that cerebellar heterotopia were a common feature present in the majority of GE lines on this background. Furthermore, we identify GE mouse lines that will be valuable in the study of cerebellar malformations including diverse driver, reporter, and optogenetic lines. Finally, we discuss the implications that these data have on the use of C57BL/6 mice and GE mice on this background in studies of cerebellar development or as models of disease.
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Affiliation(s)
- Joshua A Cuoco
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Anthony W Esposito
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Shannon Moriarty
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Ying Tang
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Sonika Seth
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Alyssa R Toia
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Elias B Kampton
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Yevgeniy Mayr
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Mussarah Khan
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Mohammad B Khan
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Brian R Mullen
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, 95064, USA
| | - James B Ackman
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Faez Siddiqi
- Division of Neurology and Research Institute of Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - John H Wolfe
- Division of Neurology and Research Institute of Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Pediatrics, Perelman School of Medicine and W.F. Goodman Center for Comparative Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Olga V Savinova
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA
| | - Raddy L Ramos
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Northern Boulevard, PO Box 8000, Old Westbury, NY, 11568-8000, USA.
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28
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Elasticity of individual protocadherin 15 molecules implicates tip links as the gating springs for hearing. Proc Natl Acad Sci U S A 2019; 116:11048-11056. [PMID: 31072932 PMCID: PMC6561218 DOI: 10.1073/pnas.1902163116] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Our hearing depends on mechanosensitive channels in hair cells of the inner ear. Experiments suggest that each channel is opened by a “gating spring,” an elastic element that conveys displacement of a hair bundle to the channel. Appropriate stiffness of the gating spring permits the discrimination of different sound amplitudes; if the spring is too stiff, then a faint sound will elicit the same response as a loud sound, opening all of a cell’s channels. Although the tip link—a fine molecular filament—might be the gating spring, its properties have remained controversial. Using high-precision optical tweezers, we demonstrate that the mechanical properties of a tip link protein correlate with those of a gating spring in vivo. Hair cells, the sensory receptors of the inner ear, respond to mechanical forces originating from sounds and accelerations. An essential feature of each hair cell is an array of filamentous tip links, consisting of the proteins protocadherin 15 (PCDH15) and cadherin 23 (CDH23), whose tension is thought to directly gate the cell’s transduction channels. These links are considered far too stiff to represent the gating springs that convert hair bundle displacement into forces capable of opening the channels, and no mechanism has been suggested through which tip-link stiffness could be varied to accommodate hair cells of distinct frequency sensitivity in different receptor organs and animals. Consequently, the gating spring’s identity and mechanism of operation remain central questions in sensory neuroscience. Using a high-precision optical trap, we show that an individual monomer of PCDH15 acts as an entropic spring that is much softer than its enthalpic stiffness alone would suggest. This low stiffness implies that the protein is a significant part of the gating spring that controls a hair cell’s transduction channels. The tip link’s entropic nature then allows for stiffness control through modulation of its tension. We find that a PCDH15 molecule is unstable under tension and exhibits a rich variety of reversible unfolding events that are augmented when the Ca2+ concentration is reduced to physiological levels. Therefore, tip link tension and Ca2+ concentration are likely parameters through which nature tunes a gating spring’s mechanical properties.
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29
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Tobin M, Chaiyasitdhi A, Michel V, Michalski N, Martin P. Stiffness and tension gradients of the hair cell's tip-link complex in the mammalian cochlea. eLife 2019; 8:e43473. [PMID: 30932811 PMCID: PMC6464607 DOI: 10.7554/elife.43473] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 03/27/2019] [Indexed: 11/23/2022] Open
Abstract
Sound analysis by the cochlea relies on frequency tuning of mechanosensory hair cells along a tonotopic axis. To clarify the underlying biophysical mechanism, we have investigated the micromechanical properties of the hair cell's mechanoreceptive hair bundle within the apical half of the rat cochlea. We studied both inner and outer hair cells, which send nervous signals to the brain and amplify cochlear vibrations, respectively. We find that tonotopy is associated with gradients of stiffness and resting mechanical tension, with steeper gradients for outer hair cells, emphasizing the division of labor between the two hair-cell types. We demonstrate that tension in the tip links that convey force to the mechano-electrical transduction channels increases at reduced Ca2+. Finally, we reveal gradients in stiffness and tension at the level of a single tip link. We conclude that mechanical gradients of the tip-link complex may help specify the characteristic frequency of the hair cell.
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Affiliation(s)
- Mélanie Tobin
- Laboratoire Physico-Chimie CurieInstitut Curie, PSL Research University, CNRS UMR168ParisFrance
- Sorbonne UniversitéParisFrance
| | - Atitheb Chaiyasitdhi
- Laboratoire Physico-Chimie CurieInstitut Curie, PSL Research University, CNRS UMR168ParisFrance
- Sorbonne UniversitéParisFrance
| | - Vincent Michel
- Sorbonne UniversitéParisFrance
- Laboratoire de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM)ParisFrance
| | - Nicolas Michalski
- Sorbonne UniversitéParisFrance
- Laboratoire de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM)ParisFrance
| | - Pascal Martin
- Laboratoire Physico-Chimie CurieInstitut Curie, PSL Research University, CNRS UMR168ParisFrance
- Sorbonne UniversitéParisFrance
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30
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De-la-Torre P, Choudhary D, Araya-Secchi R, Narui Y, Sotomayor M. A Mechanically Weak Extracellular Membrane-Adjacent Domain Induces Dimerization of Protocadherin-15. Biophys J 2018; 115:2368-2385. [PMID: 30527337 PMCID: PMC6302040 DOI: 10.1016/j.bpj.2018.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 11/01/2018] [Accepted: 11/05/2018] [Indexed: 10/27/2022] Open
Abstract
The cadherin superfamily of proteins is defined by the presence of extracellular cadherin (EC) "repeats" that engage in protein-protein interactions to mediate cell-cell adhesion, cell signaling, and mechanotransduction. The extracellular domains of nonclassical cadherins often have a large number of EC repeats along with other subdomains of various folds. Protocadherin-15 (PCDH15), a protein component of the inner-ear tip link filament essential for mechanotransduction, has 11 EC repeats and a membrane adjacent domain (MAD12) of atypical fold. Here we report the crystal structure of a pig PCDH15 fragment including EC10, EC11, and MAD12 in a parallel dimeric arrangement. MAD12 has a unique molecular architecture and folds as a ferredoxin-like domain similar to that found in the nucleoporin protein Nup54. Analytical ultracentrifugation experiments along with size-exclusion chromatography coupled to multiangle laser light scattering and small-angle x-ray scattering corroborate the crystallographic dimer and show that MAD12 induces parallel dimerization of PCDH15 near its membrane insertion point. In addition, steered molecular dynamics simulations suggest that MAD12 is mechanically weak and may unfold before tip-link rupture. Sequence analyses and structural modeling predict the existence of similar domains in cadherin-23, protocadherin-24, and the "giant" FAT and CELSR cadherins, indicating that some of them may also exhibit MAD-induced parallel dimerization.
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Affiliation(s)
- Pedro De-la-Torre
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Deepanshu Choudhary
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Raul Araya-Secchi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio; Structural Biophysics, Section for Neutron and X-ray Science, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Yoshie Narui
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio.
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31
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Jaiganesh A, Narui Y, Araya-Secchi R, Sotomayor M. Beyond Cell-Cell Adhesion: Sensational Cadherins for Hearing and Balance. Cold Spring Harb Perspect Biol 2018; 10:a029280. [PMID: 28847902 PMCID: PMC6008173 DOI: 10.1101/cshperspect.a029280] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cadherins form a large family of proteins often involved in calcium-dependent cellular adhesion. Although classical members of the family can provide a physical bond between cells, a subset of special cadherins use their extracellular domains to interlink apical specializations of single epithelial sensory cells. Two of these cadherins, cadherin-23 (CDH23) and protocadherin-15 (PCDH15), form extracellular "tip link" filaments that connect apical bundles of stereocilia on hair cells essential for inner-ear mechanotransduction. As these bundles deflect in response to mechanical stimuli from sound or head movements, tip links gate hair-cell mechanosensitive channels to initiate sensory perception. Here, we review the unusual and diverse structural properties of these tip-link cadherins and the functional significance of their deafness-related missense mutations. Based on the structural features of CDH23 and PCDH15, we discuss the elasticity of tip links and models that bridge the gap between the nanomechanics of cadherins and the micromechanics of hair-cell bundles during inner-ear mechanotransduction.
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Affiliation(s)
- Avinash Jaiganesh
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Yoshie Narui
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Raul Araya-Secchi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
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32
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Dionne G, Qiu X, Rapp M, Liang X, Zhao B, Peng G, Katsamba PS, Ahlsen G, Rubinstein R, Potter CS, Carragher B, Honig B, Müller U, Shapiro L. Mechanotransduction by PCDH15 Relies on a Novel cis-Dimeric Architecture. Neuron 2018; 99:480-492.e5. [PMID: 30057206 PMCID: PMC6168201 DOI: 10.1016/j.neuron.2018.07.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 06/06/2018] [Accepted: 06/29/2018] [Indexed: 10/28/2022]
Abstract
The tip link, a filament formed by protocadherin 15 (PCDH15) and cadherin 23, conveys mechanical force from sound waves and head movement to open hair-cell mechanotransduction channels. Tip-link cadherins are thought to have acquired structural features critical for their role in mechanotransduction. Here, we biophysically and structurally characterize the unusual cis-homodimeric architecture of PCDH15. We show that PCDH15 molecules form double-helical assemblies through cis-dimerization interfaces in the extracellular cadherin EC2-EC3 domain region and in a unique membrane-proximal domain. Electron microscopy studies visualize the cis-dimeric PCDH15 assembly and reveal the PCDH15 extracellular domain as a parallel double helix with cis cross-bridges at the two locations we defined. The helical configuration suggests the potential for elasticity through helix winding and unwinding. Functional studies in hair cells show that mutations that perturb PCDH15 dimerization contacts affect mechanotransduction. Together, these data reveal the cis-dimeric architecture of PCDH15 and show that dimerization is critical for sensing mechanical stimuli.
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Affiliation(s)
- Gilman Dionne
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Xufeng Qiu
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Micah Rapp
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10027, USA
| | - Xiaoping Liang
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Bo Zhao
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Guihong Peng
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Phinikoula S Katsamba
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Goran Ahlsen
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Rotem Rubinstein
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Systems Biology, Columbia University, New York, NY 10032, USA
| | - Clinton S Potter
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10027, USA
| | - Bridget Carragher
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY 10027, USA
| | - Barry Honig
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Systems Biology, Columbia University, New York, NY 10032, USA.
| | - Ulrich Müller
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Department of Systems Biology, Columbia University, New York, NY 10032, USA.
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33
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Jaiganesh A, De-la-Torre P, Patel AA, Termine DJ, Velez-Cortes F, Chen C, Sotomayor M. Zooming in on Cadherin-23: Structural Diversity and Potential Mechanisms of Inherited Deafness. Structure 2018; 26:1210-1225.e4. [PMID: 30033219 DOI: 10.1016/j.str.2018.06.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 03/22/2018] [Accepted: 06/08/2018] [Indexed: 12/18/2022]
Abstract
Cadherin-23 (CDH23) is an essential component of hair-cell tip links, fine filaments that mediate inner-ear mechanotransduction. The extracellular domain of CDH23 forms about three-fourths of the tip link with 27 extracellular cadherin (EC) repeats that are structurally similar but not identical to each other. Calcium (Ca2+) coordination at the EC linker regions is key for tip-link elasticity and function. There are ∼116 sites in CDH23 affected by deafness-causing mutations, many of which alter conserved Ca2+-binding residues. Here we present crystal structures showing 18 CDH23 EC repeats, including the most and least conserved, a fragment carrying disease mutations, and EC repeats with non-canonical Ca2+-binding motif sequences and unusual secondary structure. Complementary experiments show deafness mutations' effects on stability and affinity for Ca2+. Additionally, a model of nine contiguous CDH23 EC repeats reveals helicity and potential parallel dimerization faces. Overall, our studies provide detailed structural insight into CDH23 function in mechanotransduction.
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Affiliation(s)
- Avinash Jaiganesh
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA; Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Pedro De-la-Torre
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Aniket A Patel
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Domenic J Termine
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Florencia Velez-Cortes
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Conghui Chen
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA; Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA.
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34
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Zhao M, Li P, Xie Y, Liu X, Cheng L, Liu T, Kong L, Wang O, Han F. Recombinant protein of the first two ectodomains of cadherin 23 from erl mice shows impairment in Ca 2+-dependent proteolysis protection. Protein Expr Purif 2018; 147:55-60. [PMID: 29486248 DOI: 10.1016/j.pep.2018.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 02/23/2018] [Accepted: 02/23/2018] [Indexed: 10/18/2022]
Abstract
The erl mouse is a mouse model of nonsyndromic autosomal recessive deafness (DFNB12) on the C57BL/6J background. This project was carried out to express the first two ectodomains of cadherin 23 (CDH23 EC1+2) of erl mice in Escherichia coli and identify the Ca2+-binding ability of the recombinant protein. DNA sequences of CDH23 EC1+2 from wild type and erl mice were synthesized and cloned into pBV220 plasmids. Recombinant plasmids were transformed into Escherichia coli and expression of CDH23 EC1+2 was induced by increasing the temperature from 30 °C to 42 °C. The proteins were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and antigenicity of proteins was identified by Western Blotting. Inclusion bodies were denatured in 8 M urea, purified by ion-exchange and gel filtration chromatography and refolded with dialysis in buffer containing 0.1% sarkosyl. The Ca2+-binding ability of CDH23 EC1+2 was determined by Ca2+-dependent proteolysis protection. The results showed that the sizes and sequences of inserts in recombinant plasmids were consistent with expectation and that the recombinant proteins were found mainly in the form of inclusion bodies which maintain antigenicity. After refolding, the secondary structures of recombinant proteins were measured by circular dichroism (CD) spectra. Moreover, CDH23 EC1+2 from the erl mice showed less Ca2+-dependent proteolysis protection comparing with that of the wild type control. We therefore concluded that impairment of Ca2+-dependent protein interaction was likely involved in the progressive hearing loss in erl mice. The results may aid in understanding the mechanism of hearing loss in DFNB12.
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Affiliation(s)
- Mengmeng Zhao
- Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China; Department of Biochemistry and Molecular Biology, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China
| | - Ping Li
- Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China
| | - Yi Xie
- Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China; Department of Biochemistry and Molecular Biology, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China
| | - Xiang Liu
- Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China
| | - Lin Cheng
- Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China
| | - Tingyan Liu
- Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China
| | - Lijun Kong
- Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China; Department of Biochemistry and Molecular Biology, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China
| | - Oumei Wang
- Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China.
| | - Fengchan Han
- Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China; Department of Biochemistry and Molecular Biology, Binzhou Medical University, 346 Guanhai Road, Yantai, Shandong, 264003, PR China.
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Vanniya S P, Srisailapathy CRS, Kunka Mohanram R. The tip link protein Cadherin-23: From Hearing Loss to Cancer. Pharmacol Res 2018; 130:25-35. [PMID: 29421162 DOI: 10.1016/j.phrs.2018.01.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 01/24/2018] [Accepted: 01/26/2018] [Indexed: 11/26/2022]
Abstract
Cadherin-23 is an atypical member of the cadherin superfamily, with a distinctly long extracellular domain. It has been known to be a part of the tip links of the inner ear mechanosensory hair cells. Several studies have been carried out to understand the role of Cadherin-23 in the hearing mechanism and defects in the CDH23 have been associated with hearing impairment resulting from defective or absence of tip links. Recent studies have highlighted the role of Cadherin-23 in several pathological conditions, including cancer, suggesting the presence of several unknown functions. Initially, it was proposed that Cadherin-23 represents a yet unspecified subtype of Cadherins; however, no other proteins with similar characteristics have been identified, till date. It has a unique cytoplasmic domain that does not bear a β-catenin binding region, but has been demonstrated to mediate cell-cell adhesions. Several protein interacting partners have been identified for Cadherin-23 and the roles of their interactions in various cellular mechanisms are yet to be explored. This review summarizes the characteristics of Cadherin-23 and its roles in several pathologies including cancer.
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Affiliation(s)
- Paridhy Vanniya S
- Department of Genetics, Dr. ALM PG Institute of Basic Medical Science, University of Madras, Taramani campus, Chennai, Tamilnadu, India
| | - C R Srikumari Srisailapathy
- Department of Genetics, Dr. ALM PG Institute of Basic Medical Science, University of Madras, Taramani campus, Chennai, Tamilnadu, India
| | - Ramkumar Kunka Mohanram
- SRM Research Institute, SRM Institute of Science and Technology, Kattankulathur, Tamilnadu, India.
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Jain RK, Pingle SK, Tumane RG, Thakkar LR, Jawade AA, Barapatre A, Trivedi M. Cochlear Proteins Associated with Noise-induced Hearing Loss: An Update. Indian J Occup Environ Med 2018; 22:60-73. [PMID: 30319226 PMCID: PMC6176698 DOI: 10.4103/ijoem.ijoem_43_18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Noise-induced hearing loss (NIHL) is one of the major occupational disease that has influence on the quality of life of mining workers. Several reports suggest NIHL is attributed to noise exposure at workplace and approximately 16% of hearing loss is due to it. NIHL occurs as a result of exposure to high-level noise (>85 dB) in the workplace. Noise disrupts proteins present in the micromachinery of the ear that is required for mechano-electric transduction of sound waves. High-level noise exposure can lead to hearing impairment owing to mechanical and metabolic exhaustion in cochlea, the major organ responsible for resilience of sound. Several key proteins of cochlea include tectorial membrane, inner hair cells, outer hair cells, and stereocilia are damaged due to high-level noise exposure. Numerous studies conducted in animals have shown cochlear proteins involvement in NIHL, but the pertinent literature remains limited in humans. Detection of proteins and pathways perturbed within the micromachinery of the ear after excessive sound induction leads toward the early identification of hearing loss. The situation insisted to present this review as an update on cochlear proteins associated with NIHL after an extensive literature search using several electronic databases which help to understand the pathophysiology of NIHL.
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Affiliation(s)
- Ruchika K Jain
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Shubhangi K Pingle
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Rajani G Tumane
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Lucky R Thakkar
- National Centre for Microbial Resources, National Centre for Cell Science, University of Pune Campus, Pune, Maharashtra, India
| | - Aruna A Jawade
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Anand Barapatre
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Minal Trivedi
- B. K. Birla College of Science, Arts & Commerce (Autonomous), Kalyan, Maharashtra, India
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Choudhary D, Kumar A, Magliery TJ, Sotomayor M. Using thermal scanning assays to test protein-protein interactions of inner-ear cadherins. PLoS One 2017; 12:e0189546. [PMID: 29261728 PMCID: PMC5736220 DOI: 10.1371/journal.pone.0189546] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/27/2017] [Indexed: 12/15/2022] Open
Abstract
Protein-protein interactions play a crucial role in biological processes such as cell-cell adhesion, immune system-pathogen interactions, and sensory perception. Understanding the structural determinants of protein-protein complex formation and obtaining quantitative estimates of their dissociation constant (KD) are essential for the study of these interactions and for the discovery of new therapeutics. At the same time, it is equally important to characterize protein-protein interactions in a high-throughput fashion. Here, we use a modified thermal scanning assay to test interactions of wild type (WT) and mutant variants of N-terminal fragments (EC1+2) of cadherin-23 and protocadherin-15, two proteins essential for inner-ear mechanotransduction. An environmentally sensitive fluorescent dye (SYPRO orange) is used to monitor melting temperature (Tm) shifts of protocadherin-15 EC1+2 (pcdh15) in the presence of increasing concentrations of cadherin-23 EC1+2 (cdh23). These Tm shifts are absent when we use proteins containing deafness-related missense mutations known to disrupt cdh23 binding to pcdh15, and are increased for some rationally designed mutants expected to enhance binding. In addition, surface plasmon resonance binding experiments were used to test if the Tm shifts correlated with changes in binding affinity. We used this approach to find a double mutation (cdh23(T15E)- pcdh15(G16D)) that enhances binding affinity of the cadherin complex by 1.98 kJ/mol, roughly two-fold that of the WT complex. We suggest that the thermal scanning methodology can be used in high-throughput format to quickly compare binding affinities (KD from nM up to 100 μM) for some heterodimeric protein complexes and to screen small molecule libraries to find protein-protein interaction inhibitors and enhancers.
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Affiliation(s)
- Deepanshu Choudhary
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Anusha Kumar
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Thomas J. Magliery
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
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Corey DP, Ó Maoiléidigh D, Ashmore JF. Mechanical Transduction Processes in the Hair Cell. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/978-3-319-52073-5_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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Powers RE, Gaudet R, Sotomayor M. A Partial Calcium-Free Linker Confers Flexibility to Inner-Ear Protocadherin-15. Structure 2017; 25:482-495. [PMID: 28238533 DOI: 10.1016/j.str.2017.01.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 01/16/2017] [Accepted: 01/30/2017] [Indexed: 12/30/2022]
Abstract
Tip links of the inner ear are protein filaments essential for hearing and balance. Two atypical cadherins, cadherin-23 and protocadherin-15, interact in a Ca2+-dependent manner to form tip links. The largely unknown structure and mechanics of these proteins are integral to understanding how tip links pull on ion channels to initiate sensory perception. Protocadherin-15 has 11 extracellular cadherin (EC) repeats. Its EC3-4 linker lacks several of the canonical Ca2+-binding residues, and contains an aspartate-to-alanine polymorphism (D414A) under positive selection in East Asian populations. We present structures of protocadherin-15 EC3-5 featuring two Ca2+-binding linker regions: canonical EC4-5 linker binding three Ca2+ ions, and non-canonical EC3-4 linker binding only two Ca2+ ions. Our structures and biochemical assays reveal little difference between the D414 and D414A variants. Simulations predict that the partial Ca2+-free EC3-4 linker exhibits increased flexural flexibility without compromised mechanical strength, providing insight into the dynamics of tip links and other atypical cadherins.
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Affiliation(s)
- Robert E Powers
- Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA; Biophysics Graduate Program, Harvard University, Boston, MA 02115, USA
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA.
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210, USA.
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Lebeko K, Manyisa N, Chimusa ER, Mulder N, Dandara C, Wonkam A. A Genomic and Protein-Protein Interaction Analyses of Nonsyndromic Hearing Impairment in Cameroon Using Targeted Genomic Enrichment and Massively Parallel Sequencing. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2017; 21:90-99. [PMID: 28075205 DOI: 10.1089/omi.2016.0171] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hearing impairment (HI) is one of the leading causes of disability in the world, impacting the social, economic, and psychological well-being of the affected individual. This is particularly true in sub-Saharan Africa, which carries one of the highest burdens of this condition. Despite this, there are limited data on the most prevalent genes or mutations that cause HI among sub-Saharan Africans. Next-generation technologies, such as targeted genomic enrichment and massively parallel sequencing, offer new promise in this context. This study reports, for the first time to the best of our knowledge, on the prevalence of novel mutations identified through a platform of 116 HI genes (OtoSCOPE®), among 82 African probands with HI. Only variants OTOF NM_194248.2:c.766-2A>G and MYO7A NM_000260.3:c.1996C>T, p.Arg666Stop were found in 3 (3.7%) and 5 (6.1%) patients, respectively. In addition and uniquely, the analysis of protein-protein interactions (PPI), through interrogation of gene subnetworks, using a custom script and two databases (Enrichr and PANTHER), and an algorithm in the igraph package of R, identified the enrichment of sensory perception and mechanical stimulus biological processes, and the most significant molecular functions of these variants pertained to binding or structural activity. Furthermore, 10 genes (MYO7A, MYO6, KCTD3, NUMA1, MYH9, KCNQ1, UBC, DIAPH1, PSMC2, and RDX) were identified as significant hubs within the subnetworks. Results reveal that the novel variants identified among familial cases of HI in Cameroon are not common, and PPI analysis has highlighted the role of 10 genes, potentially important in understanding HI genomics among Africans.
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Affiliation(s)
- Kamogelo Lebeko
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Noluthando Manyisa
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Emile R Chimusa
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Nicola Mulder
- 2 Division of Computational Biology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Collet Dandara
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
| | - Ambroise Wonkam
- 1 Division of Human Genetics, Department of Pathology, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa .,3 Department of Medicine, Faculty of Health Sciences - University of Cape Town , Cap Town, South Africa
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Araya-Secchi R, Neel BL, Sotomayor M. An elastic element in the protocadherin-15 tip link of the inner ear. Nat Commun 2016; 7:13458. [PMID: 27857071 PMCID: PMC5120219 DOI: 10.1038/ncomms13458] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 10/03/2016] [Indexed: 01/16/2023] Open
Abstract
Tip link filaments convey force and gate inner-ear hair-cell transduction channels to mediate perception of sound and head movements. Cadherin-23 and protocadherin-15 form tip links through a calcium-dependent interaction of their extracellular domains made of multiple extracellular cadherin (EC) repeats. These repeats are structurally similar, but not identical in sequence, often featuring linkers with conserved calcium-binding sites that confer mechanical strength to them. Here we present the X-ray crystal structures of human protocadherin-15 EC8-EC10 and mouse EC9-EC10, which show an EC8-9 canonical-like calcium-binding linker, and an EC9-10 calcium-free linker that alters the linear arrangement of EC repeats. Molecular dynamics simulations and small-angle X-ray scattering experiments support this non-linear conformation. Simulations also suggest that unbending of EC9-10 confers some elasticity to otherwise rigid tip links. The new structure provides a first view of protocadherin-15's non-canonical EC linkers and suggests how they may function in inner-ear mechanotransduction, with implications for other cadherins.
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Affiliation(s)
- Raul Araya-Secchi
- Department of Chemistry and Biochemistry, The Ohio State University, 484 W 12th Avenue, Columbus, Ohio 43210, USA
| | - Brandon L. Neel
- Department of Chemistry and Biochemistry, The Ohio State University, 484 W 12th Avenue, Columbus, Ohio 43210, USA
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, 484 W 12th Avenue, Columbus, Ohio 43210, USA
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Cooper SR, Jontes JD, Sotomayor M. Structural determinants of adhesion by Protocadherin-19 and implications for its role in epilepsy. eLife 2016; 5. [PMID: 27787195 PMCID: PMC5115871 DOI: 10.7554/elife.18529] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 10/25/2016] [Indexed: 01/27/2023] Open
Abstract
Non-clustered δ-protocadherins are homophilic cell adhesion molecules essential for the development of the vertebrate nervous system, as several are closely linked to neurodevelopmental disorders. Mutations in protocadherin-19 (PCDH19) result in a female-limited, infant-onset form of epilepsy (PCDH19-FE). Over 100 mutations in PCDH19 have been identified in patients with PCDH19-FE, about half of which are missense mutations in the adhesive extracellular domain. Neither the mechanism of homophilic adhesion by PCDH19, nor the biochemical effects of missense mutations are understood. Here we present a crystallographic structure of the minimal adhesive fragment of the zebrafish Pcdh19 extracellular domain. This structure reveals the adhesive interface for Pcdh19, which is broadly relevant to both non-clustered δ and clustered protocadherin subfamilies. In addition, we show that several PCDH19-FE missense mutations localize to the adhesive interface and abolish Pcdh19 adhesion in in vitro assays, thus revealing the biochemical basis of their pathogenic effects during brain development. DOI:http://dx.doi.org/10.7554/eLife.18529.001 As the brain develops, its basic building blocks – cells called neurons – need to form the correct connections with one another in order to give rise to neural circuits. A mistake that leads to the formation of incorrect connections can result in a number of disorders or brain abnormalities. Proteins called cadherins that are present on the surface of neurons enable them to stick to their correct partners like Velcro. One of these proteins is called Protocadherin-19. However, it was not fully understood how this protein forms an adhesive bond with other Protocadherin-19 molecules, or how some of the proteins within the cadherin family are able to distinguish between one another. Cooper et al. used X-ray crystallography to visualize the molecular structure of Protocadherin-19 taken from zebrafish in order to better understand the adhesive bond that these proteins form with each other. In addition, the new structure showed the sites of the mutations that cause a form of epilepsy in infant females. From this, Cooper et al. could predict how the mutations would disrupt Protocadherin-19’s shape and function. The structures revealed that Protocadherin-19 molecules from adjacent cells engage in a “forearm handshake” to form the bond that connects neurons. Some of the mutations that cause epilepsy occur in the region responsible for this Protocadherin-19 forearm handshake. Laboratory experiments confirmed that these mutations impair the formation of the adhesive bond, revealing the molecular basis for some of the mutations that underlie Protocadherin-19-female-limited epilepsy. Other cadherin molecules may interact via a similar forearm handshake; this could be investigated in future experiments. It also remains to be discovered how brain wiring depends on Protocadherin-19 adhesion in animal development, and how altering these proteins can rewire developing brain circuits. DOI:http://dx.doi.org/10.7554/eLife.18529.002
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Affiliation(s)
- Sharon R Cooper
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, United States.,Department of Neuroscience, The Ohio State University, Columbus, United States
| | - James D Jontes
- Department of Neuroscience, The Ohio State University, Columbus, United States
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, United States
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43
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Bavi N, Bavi O, Vossoughi M, Naghdabadi R, Hill AP, Martinac B, Jamali Y. Nanomechanical properties of MscL α helices: A steered molecular dynamics study. Channels (Austin) 2016; 11:209-223. [PMID: 27753526 DOI: 10.1080/19336950.2016.1249077] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Gating of mechanosensitive (MS) channels is driven by a hierarchical cascade of movements and deformations of transmembrane helices in response to bilayer tension. Determining the intrinsic mechanical properties of the individual transmembrane helices is therefore central to understanding the intricacies of the gating mechanism of MS channels. We used a constant-force steered molecular dynamics (SMD) approach to perform unidirectional pulling tests on all the helices of MscL in M. tuberculosis and E. coli homologs. Using this method, we could overcome the issues encountered with the commonly used constant-velocity SMD simulations, such as low mechanical stability of the helix during stretching and high dependency of the elastic properties on the pulling rate. We estimated Young's moduli of the α-helices of MscL to vary between 0.2 and 12.5 GPa with TM2 helix being the stiffest. We also studied the effect of water on the properties of the pore-lining TM1 helix. In the absence of water, this helix exhibited a much stiffer response. By monitoring the number of hydrogen bonds, it appears that water acts like a 'lubricant' (softener) during TM1 helix elongation. These data shed light on another physical aspect underlying hydrophobic gating of MS channels, in particular MscL.
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Affiliation(s)
- N Bavi
- a Division of Molecular Cardiology and Biophysics , Victor Chang Cardiac Research Institute , Darlinghurst , NSW , Australia.,b St Vincent's Clinical School, Faculty of Medicine , University of New South Wales , Darlinghurst , NSW , Australia
| | - O Bavi
- c Institute for Nanoscience and Nanotechnology, Sharif University of Technology , Tehran , Iran
| | - M Vossoughi
- c Institute for Nanoscience and Nanotechnology, Sharif University of Technology , Tehran , Iran.,d Biochemical & Bioenvironmental Research Center (BBRC) , Tehran , Iran
| | - R Naghdabadi
- c Institute for Nanoscience and Nanotechnology, Sharif University of Technology , Tehran , Iran.,e Department of Mechanical Engineering , Sharif University of Technology , Tehran , Iran
| | - A P Hill
- a Division of Molecular Cardiology and Biophysics , Victor Chang Cardiac Research Institute , Darlinghurst , NSW , Australia
| | - B Martinac
- a Division of Molecular Cardiology and Biophysics , Victor Chang Cardiac Research Institute , Darlinghurst , NSW , Australia.,b St Vincent's Clinical School, Faculty of Medicine , University of New South Wales , Darlinghurst , NSW , Australia
| | - Y Jamali
- f Department of Mathematics , Tarbiat Modares University , Tehran , Iran.,g Computational Physical Sciences Research Laboratory , School of Nanoscience, Institute for Research in Fundamental Sciences (IPM) , Tehran , Iran
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Nicoludis JM, Lau SY, Schärfe CPI, Marks DS, Weihofen WA, Gaudet R. Structure and Sequence Analyses of Clustered Protocadherins Reveal Antiparallel Interactions that Mediate Homophilic Specificity. Structure 2015; 23:2087-98. [PMID: 26481813 PMCID: PMC4635037 DOI: 10.1016/j.str.2015.09.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 09/14/2015] [Accepted: 09/15/2015] [Indexed: 01/07/2023]
Abstract
Clustered protocadherin (Pcdh) proteins mediate dendritic self-avoidance in neurons via specific homophilic interactions in their extracellular cadherin (EC) domains. We determined crystal structures of EC1-EC3, containing the homophilic specificity-determining region, of two mouse clustered Pcdh isoforms (PcdhγA1 and PcdhγC3) to investigate the nature of the homophilic interaction. Within the crystal lattices, we observe antiparallel interfaces consistent with a role in trans cell-cell contact. Antiparallel dimerization is supported by evolutionary correlations. Two interfaces, located primarily on EC2-EC3, involve distinctive clustered Pcdh structure and sequence motifs, lack predicted glycosylation sites, and contain residues highly conserved in orthologs but not paralogs, pointing toward their biological significance as homophilic interaction interfaces. These two interfaces are similar yet distinct, reflecting a possible difference in interaction architecture between clustered Pcdh subfamilies. These structures initiate a molecular understanding of clustered Pcdh assemblies that are required to produce functional neuronal networks.
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Affiliation(s)
- John M. Nicoludis
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA
| | - Sze-Yi Lau
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA, 02138, USA
| | - Charlotta P. I. Schärfe
- Department of Systems Biology, Harvard Medical School, Boston, MA, 02115, USA,Applied Bioinformatics, Department of Computer Science, University of Tübingen, Tübingen, Germany
| | - Debora S. Marks
- Department of Systems Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Wilhelm A. Weihofen
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA, 02138, USA,Correspondence: (R. G.), (W. A.W.)
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA, 02138, USA,Correspondence: (R. G.), (W. A.W.)
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45
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Zhao B, Müller U. The elusive mechanotransduction machinery of hair cells. Curr Opin Neurobiol 2015; 34:172-9. [PMID: 26342686 DOI: 10.1016/j.conb.2015.08.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 08/06/2015] [Accepted: 08/18/2015] [Indexed: 11/18/2022]
Abstract
Hair cells in the mammalian cochlea are specialized sensory cells that convert mechanical signals evoked by sound waves into electrochemical signals. Several integral membrane proteins have recently been identified that are closely linked to the mechanotransduction process. Efforts are under way to determine the extent to which they are subunits of the long thought-after mechanotransduction channel. Recent findings also suggest that mechanotransduction may have a role in fine tuning the length of the stereocilia and thus in the regulation of morphological features of hair cells that are inherently linked to the mechanotransduction process.
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Affiliation(s)
- Bo Zhao
- Department of Molecular and Cellular Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Ulrich Müller
- Department of Molecular and Cellular Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, United States.
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46
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Pan B, Holt JR. The molecules that mediate sensory transduction in the mammalian inner ear. Curr Opin Neurobiol 2015. [PMID: 26218316 DOI: 10.1016/j.conb.2015.06.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Years of searching and researching have finally yielded a few leads in the quest to identify molecules required for mechanosensory transduction in the mammalian inner ear. Studies of human and mouse genetics have raised the profile of several molecules that are crucial for the function sensory hair cells. Follow up studies have begun to define the molecular function and biochemical interactions of several key proteins. These studies have exposed a sensory transduction apparatus that is more complex than originally envisioned and have reinvigorated the search for additional molecular components required for normal inner ear function.
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Affiliation(s)
- Bifeng Pan
- Department of Otolaryngology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, United States
| | - Jeffrey R Holt
- Department of Otolaryngology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, United States.
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47
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Tang PC, Watson GM. Proteomic identification of hair cell repair proteins in the model sea anemone Nematostella vectensis. Hear Res 2015; 327:245-56. [PMID: 26183436 DOI: 10.1016/j.heares.2015.07.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 06/15/2015] [Accepted: 07/09/2015] [Indexed: 12/26/2022]
Abstract
Sea anemones have an extraordinary capability to repair damaged hair bundles, even after severe trauma. A group of secreted proteins, named repair proteins (RPs), found in mucus covering sea anemones significantly assists the repair of damaged hair bundle mechanoreceptors both in the sea anemone Haliplanella luciae and the blind cavefish Astyanax hubbsi. The polypeptide constituents of RPs must be identified in order to gain insight into the molecular mechanisms by which repair of hair bundles is accomplished. In this study, several polypeptides of RPs were isolated from mucus using blue native PAGE and then sequenced using LC-MS/MS. Thirty-seven known polypeptides were identified, including Hsp70s, as well as many polypeptide subunits of the 20S proteasome. Other identified polypeptides included those involved in cellular stress responses, protein folding, and protein degradation. Specific inhibitors of Hsp70s and the 20S proteasome were employed in experiments to test their involvement in hair bundle repair. The results of those experiments suggested that repair requires biologically active Hsp70s and 20S proteasomes. A model is proposed that considers the function of extracellular Hsp70s and 20S proteasomes in the repair of damaged hair cells.
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Affiliation(s)
- Pei-Ciao Tang
- Department of Biology, University of Louisiana Lafayette, USA
| | - Glen M Watson
- Department of Biology, University of Louisiana Lafayette, USA.
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48
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Study of protein structural deformations under external mechanical perturbations by a coarse-grained simulation method. Biomech Model Mechanobiol 2015; 15:317-29. [DOI: 10.1007/s10237-015-0690-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 05/30/2015] [Indexed: 01/14/2023]
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49
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Toms M, Bitner-Glindzicz M, Webster A, Moosajee M. Usher syndrome: a review of the clinical phenotype, genes and therapeutic strategies. EXPERT REVIEW OF OPHTHALMOLOGY 2015. [DOI: 10.1586/17469899.2015.1033403] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Powers RJ, Kulason S, Atilgan E, Brownell WE, Sun SX, Barr-Gillespie PG, Spector AA. The local forces acting on the mechanotransduction channel in hair cell stereocilia. Biophys J 2015; 106:2519-28. [PMID: 24896132 DOI: 10.1016/j.bpj.2014.03.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 03/12/2014] [Accepted: 03/13/2014] [Indexed: 01/18/2023] Open
Abstract
In hair cells, mechanotransduction channels are located in the membrane of stereocilia tips, where the base of the tip link is attached. The tip-link force determines the system of other forces in the immediate channel environment, which change the channel open probability. This system of forces includes components that are out of plane and in plane relative to the membrane; the magnitude and direction of these components depend on the channel environment and arrangement. Using a computational model, we obtained the major forces involved as functions of the force applied via the tip link at the center of the membrane. We simulated factors related to channels and the membrane, including finite-sized channels located centrally or acentrally, stiffness of the hypothesized channel-cytoskeleton tether, and bending modulus of the membrane. Membrane forces are perpendicular to the directions of the principal curvatures of the deformed membrane. Our approach allows for a fine vectorial picture of the local forces gating the channel; membrane forces change with the membrane curvature and are themselves sufficient to affect the open probability of the channel.
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Affiliation(s)
- Richard J Powers
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Sue Kulason
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Erdinc Atilgan
- Department of Microbiology, Columbia University, New York, New York
| | - William E Brownell
- Bobby R. Alford Department of Otolaryngology-Head & Neck Surgery, Baylor College of Medicine, Houston, Texas
| | - Sean X Sun
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland; Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon
| | - Alexander A Spector
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland; Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland.
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