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Liu H, Liu H, Wang L, Song L, Jiang G, Lu Q, Yang T, Peng H, Cai R, Zhao X, Zhao T, Wu H. Cochlear transcript diversity and its role in auditory functions implied by an otoferlin short isoform. Nat Commun 2023; 14:3085. [PMID: 37248244 DOI: 10.1038/s41467-023-38621-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 05/10/2023] [Indexed: 05/31/2023] Open
Abstract
Isoforms of a gene may contribute to diverse biological functions. In the cochlea, the repertoire of alternative isoforms remains unexplored. We integrated single-cell short-read and long-read RNA sequencing techniques and identified 236,012 transcripts, 126,612 of which were unannotated in the GENCODE database. Then we analyzed and verified the unannotated transcripts using RNA-seq, RT-PCR, Sanger sequencing, and MS-based proteomics approaches. To illustrate the importance of identifying spliced isoforms, we investigated otoferlin, a key protein involved in synaptic transmission in inner hair cells (IHCs). Upon deletion of the canonical otoferlin isoform, the identified short isoform is able to support normal hearing thresholds but with reduced sustained exocytosis of IHCs, and further revealed otoferlin functions in endocytic membrane retrieval that was not well-addressed previously. Furthermore, we found that otoferlin isoforms are associated with IHC functions and auditory phenotypes. This work expands our mechanistic understanding of auditory functions at the level of isoform resolution.
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Affiliation(s)
- Huihui Liu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Hongchao Liu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Longhao Wang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Lei Song
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Guixian Jiang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Qing Lu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Tao Yang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Hu Peng
- Department of Otolaryngology-Head and Neck Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, China
| | - Ruijie Cai
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Xingle Zhao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Ting Zhao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China.
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China.
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200011, China.
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Wang H, Du H, Ren R, Du T, Lin L, Feng Z, Zhao D, Wei X, Zhai X, Wang H, Dong T, Sun JP, Wu H, Xu Z, Lu Q. Temporal and spatial assembly of inner ear hair cell ankle link condensate through phase separation. Nat Commun 2023; 14:1657. [PMID: 36964137 PMCID: PMC10039067 DOI: 10.1038/s41467-023-37267-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 03/09/2023] [Indexed: 03/26/2023] Open
Abstract
Stereocilia are actin-based cell protrusions of inner ear hair cells and are indispensable for mechanotransduction. Ankle links connect the ankle region of developing stereocilia, playing an essential role in stereocilia development. WHRN, PDZD7, ADGRV1 and USH2A have been identified to form the so-called ankle link complex (ALC); however, the detailed mechanism underlying the temporal emergence and degeneration of ankle links remains elusive. Here we show that WHRN and PDZD7 orchestrate ADGRV1 and USH2A to assemble the ALC through liquid-liquid phase separation (LLPS). Disruption of the ALC multivalency for LLPS largely abolishes the distribution of WHRN at the ankle region of stereocilia. Interestingly, high concentration of ADGRV1 inhibits LLPS, providing a potential mechanism for ALC disassembly. Moreover, certain deafness mutations of ALC genes weaken the multivalent interactions of ALC and impair LLPS. In conclusion, our study demonstrates that LLPS mediates ALC formation, providing essential clues for understanding the pathogenesis of deafness.
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Affiliation(s)
- Huang Wang
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Haibo Du
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong, 266237, China
- Air Force Medical Center, PLA, Beijing, 100074, China
| | - Rui Ren
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong, 266237, China
| | - Tingting Du
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Lin Lin
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Zhe Feng
- School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Dange Zhao
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Xiaoxi Wei
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Xiaoyan Zhai
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong, 266237, China
| | - Hongyang Wang
- College of Otolaryngology, Head and Neck Surgery, Department of Audiology and Vestibular Medicine, Chinese PLA Institute of Otolaryngology, Chinese PLA General Hospital, Medical School of Chinese PLA, 28 Fuxing Road, 100853, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Chinese PLA General Hospital, Medical School of Chinese PLA, 28 Fuxing Road, 100853, Beijing, China
| | - Tingting Dong
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Jin-Peng Sun
- Key Laboratory Experimental Teratology of the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong, 266237, China.
- Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, Shandong, 250014, China.
| | - Qing Lu
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200030, China.
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
- Bio-X-Renji Hospital Research Center, School of Medicine, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China.
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Kim KS, Koo HY, Bok J. Alternative splicing in shaping the molecular landscape of the cochlea. Front Cell Dev Biol 2023; 11:1143428. [PMID: 36936679 PMCID: PMC10018040 DOI: 10.3389/fcell.2023.1143428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/16/2023] [Indexed: 03/06/2023] Open
Abstract
The cochlea is a complex organ comprising diverse cell types with highly specialized morphology and function. Until now, the molecular underpinnings of its specializations have mostly been studied from a transcriptional perspective, but accumulating evidence points to post-transcriptional regulation as a major source of molecular diversity. Alternative splicing is one of the most prevalent and well-characterized post-transcriptional regulatory mechanisms. Many molecules important for hearing, such as cadherin 23 or harmonin, undergo alternative splicing to produce functionally distinct isoforms. Some isoforms are expressed specifically in the cochlea, while some show differential expression across the various cochlear cell types and anatomical regions. Clinical phenotypes that arise from mutations affecting specific splice variants testify to the functional relevance of these isoforms. All these clues point to an essential role for alternative splicing in shaping the unique molecular landscape of the cochlea. Although the regulatory mechanisms controlling alternative splicing in the cochlea are poorly characterized, there are animal models with defective splicing regulators that demonstrate the importance of RNA-binding proteins in maintaining cochlear function and cell survival. Recent technological breakthroughs offer exciting prospects for overcoming some of the long-standing hurdles that have complicated the analysis of alternative splicing in the cochlea. Efforts toward this end will help clarify how the remarkable diversity of the cochlear transcriptome is both established and maintained.
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Affiliation(s)
- Kwan Soo Kim
- Department of Anatomy, Yonsei University College of Medicine, Seoul, Republic of Korea
- Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Hei Yeun Koo
- Department of Anatomy, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jinwoong Bok
- Department of Anatomy, Yonsei University College of Medicine, Seoul, Republic of Korea
- Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Republic of Korea
- *Correspondence: Jinwoong Bok,
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Deafness-related protein PDZD7 forms complex with the C-terminal tail of FCHSD2. Biochem J 2022; 479:1393-1405. [PMID: 35695292 PMCID: PMC9317961 DOI: 10.1042/bcj20220147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 06/09/2022] [Accepted: 06/13/2022] [Indexed: 11/24/2022]
Abstract
In cochlea, deafness-related protein PDZD7 is an indispensable component of the ankle link complex, which is critical for the maturation of inner-ear hair cell for sound perception. Ankle links, connecting the different rows of cochlear stereocilia, are essential for the staircase-like development of stereocilia. However, the molecular mechanism of how PDZD7 governs stereociliary development remains unknown. Here, we reported a novel PDZD7-binding partner, FCHSD2, identified by yeast two-hybrid screening. FCHSD2 was reported to be expressed in hair cell, where it co-operated with CDC42 and N-WASP to regulate the formation of cell protrusion. The association between FCHSD2 and PDZD7 was further confirmed in COS-7 cells. More importantly, we solved the complex structure of FCHSD2 tail with PDZD7 PDZ3 domain at 2.0 Å resolution. The crystal structure shows that PDZD7 PDZ3 adopts a typical PDZ domain topology, comprising five β strands and two α helixes. The PDZ-binding motif of FCHSD2 tail stretches through the αB/βB groove of PDZD7 PDZ3. Our study not only uncovers the interaction between FCHSD2 tail and PDZD7 PDZ3 at the atomic level, but also provides clues of connecting the ankle link complex with cytoskeleton dynamics for exploiting the molecular mechanism of stereociliary development.
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Poncet AF, Grunewald O, Vaclavik V, Meunier I, Drumare I, Pelletier V, Bocquet B, Todorova MG, Le Moing AG, Devos A, Schorderet DF, Jobic F, Defoort-Dhellemmes S, Dollfus H, Smirnov VM, Dhaenens CM. Contribution of Whole-Genome Sequencing and Transcript Analysis to Decipher Retinal Diseases Associated with MFSD8 Variants. Int J Mol Sci 2022; 23:ijms23084294. [PMID: 35457110 PMCID: PMC9032189 DOI: 10.3390/ijms23084294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/25/2022] [Accepted: 04/11/2022] [Indexed: 01/01/2023] Open
Abstract
Biallelic gene defects in MFSD8 are not only a cause of the late-infantile form of neuronal ceroid lipofuscinosis, but also of rare isolated retinal degeneration. We report clinical and genetic data of seven patients compound heterozygous or homozygous for variants in MFSD8, issued from a French cohort with inherited retinal degeneration, and two additional patients retrieved from a Swiss cohort. Next-generation sequencing of large panels combined with whole-genome sequencing allowed for the identification of twelve variants from which seven were novel. Among them were one deep intronic variant c.998+1669A>G, one large deletion encompassing exon 9 and 10, and a silent change c.750A>G. Transcript analysis performed on patients’ lymphoblastoid cell lines revealed the creation of a donor splice site by c.998+1669A>G, resulting in a 140 bp pseudoexon insertion in intron 10. Variant c.750A>G produced exon 8 skipping. In silico and in cellulo studies of these variants allowed us to assign the pathogenic effect, and showed that the combination of at least one severe variant with a moderate one leads to isolated retinal dystrophy, whereas the combination in trans of two severe variants is responsible for early onset severe retinal dystrophy in the context of late-infantile neuronal ceroid lipofuscinosis.
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Affiliation(s)
- Anaïs F. Poncet
- Univ. Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience & Cognition, F-59000 Lille, France; (A.F.P.); (O.G.); (A.D.)
| | - Olivier Grunewald
- Univ. Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience & Cognition, F-59000 Lille, France; (A.F.P.); (O.G.); (A.D.)
| | - Veronika Vaclavik
- University of Lausanne, Jules-Gonin Eye Hospital, 1004 Lausanne, Switzerland;
- Cantonal Hospital, Department of Ophthalmology, 1700 Fribourg, Switzerland
| | - Isabelle Meunier
- National Reference Centre for Inherited Sensory Diseases, University of Montpellier, Montpellier University Hospital, Sensgene Care Network, ERN-EYE Network, F-34000 Montpellier, France; (I.M.); (B.B.)
- Institute for Neurosciences of Montpellier (INM), University of Montpellier, INSERM, F-34000 Montpellier, France
| | - Isabelle Drumare
- Exploration de la Vision et Neuro-Ophtalmology, CHU de Lille, F-59000 Lille, France; (I.D.); (S.D.-D.); (V.M.S.)
| | - Valérie Pelletier
- Centre de Référence pour les Affections Rares en Génétique Ophtalmologiques, Hopitaux Universitaires de Strasbourg, F-67000 Strasbourg, France; (V.P.); (H.D.)
| | - Béatrice Bocquet
- National Reference Centre for Inherited Sensory Diseases, University of Montpellier, Montpellier University Hospital, Sensgene Care Network, ERN-EYE Network, F-34000 Montpellier, France; (I.M.); (B.B.)
- Institute for Neurosciences of Montpellier (INM), University of Montpellier, INSERM, F-34000 Montpellier, France
| | - Margarita G. Todorova
- Department of Ophthalmology, Cantonal Hospital, 9007 St. Gallen, Switzerland;
- Department of Ophthalmology, University of Zürich, 8091 Zürich, Switzerland
- Department of Ophthalmology, University of Basel, 4056 Basel, Switzerland
| | - Anne-Gaëlle Le Moing
- Department of Child Neurology, Amiens-Picardy University Hospital, F-80000 Amiens, France;
| | - Aurore Devos
- Univ. Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience & Cognition, F-59000 Lille, France; (A.F.P.); (O.G.); (A.D.)
| | - Daniel F. Schorderet
- Faculty of Biology and Medicine, University of Lausanne and Faculty of Life Sciences, Ecole Polytechnique Fédérale of Lausanne, 1004 Lausanne, Switzerland;
| | - Florence Jobic
- Unité de Génétique Médicale et Oncogénétique, Centre Hospitalier Universitaire Amiens Picardie, F-80000 Amiens, France;
| | - Sabine Defoort-Dhellemmes
- Exploration de la Vision et Neuro-Ophtalmology, CHU de Lille, F-59000 Lille, France; (I.D.); (S.D.-D.); (V.M.S.)
| | - Hélène Dollfus
- Centre de Référence pour les Affections Rares en Génétique Ophtalmologiques, Hopitaux Universitaires de Strasbourg, F-67000 Strasbourg, France; (V.P.); (H.D.)
| | - Vasily M. Smirnov
- Exploration de la Vision et Neuro-Ophtalmology, CHU de Lille, F-59000 Lille, France; (I.D.); (S.D.-D.); (V.M.S.)
- Université de Lille, Faculté de Médecine, F-59000 Lille, France
| | - Claire-Marie Dhaenens
- Univ. Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience & Cognition, F-59000 Lille, France; (A.F.P.); (O.G.); (A.D.)
- Correspondence: ; Tel.: +33-320444953
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Zheng L, Adam SA, García‐Anoveros J, Mitchell BJ, Bartles JR. Espin overexpression causes stereocilia defects and provides an anti-capping effect on actin polymerization. Cytoskeleton (Hoboken) 2022; 79:64-74. [PMID: 35844198 PMCID: PMC9796729 DOI: 10.1002/cm.21719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 07/01/2022] [Accepted: 07/12/2022] [Indexed: 01/30/2023]
Abstract
Stereocilia are actin-based projections of hair cells that are arranged in a step like array, in rows of increasing height, and that constitute the mechanosensory organelle used for the senses of hearing and balance. In order to function properly, stereocilia must attain precise sizes in different hair cell types and must coordinately form distinct rows with varying lengths. Espins are actin-bundling proteins that have a well-characterized role in stereocilia formation; loss of function mutations in Espin result in shorter stereocilia and deafness in the jerker mouse. Here we describe the generation of an Espin overexpressing transgenic mouse line that results in longer first row stereocilia and discoordination of second-row stereocilia length. Furthermore, Espin overexpression results in the misregulation of other stereocilia factors including GNAI3, GPSM2, EPS8, WHRN, and MYO15A, revealing that GNAI3 and GPSM2 are dispensable for stereocilia overgrowth. Finally, using an in vitro actin polymerization assay we show that espin provides an anti-capping function that requires both the G-actin binding WH2 domain as well as either the C-terminal F-actin binding domain or the internal xAB actin-binding domain. Our results provide a novel function for Espins at the barbed ends of actin filaments distinct from its previous known function of actin bundling that may account for their effects on stereocilia growth.
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Affiliation(s)
- Lili Zheng
- Department of Cell and Developmental BiologyNorthwestern University, Feinberg School of MedicineChicagoIllinoisUSA
| | - Stephen A. Adam
- Department of Cell and Developmental BiologyNorthwestern University, Feinberg School of MedicineChicagoIllinoisUSA
| | - Jaime García‐Anoveros
- Department of Anesthesiology Neurology and NeuroscienceNorthwestern University, Feinberg School of MedicineChicagoIllinoisUSA,Hugh Knowles Center for Clinical and Basic Science in Hearing and its DisordersNorthwestern University, Feinberg School of MedicineChicagoIllinoisUSA
| | - Brian J. Mitchell
- Department of Cell and Developmental BiologyNorthwestern University, Feinberg School of MedicineChicagoIllinoisUSA
| | - James R. Bartles
- Department of Cell and Developmental BiologyNorthwestern University, Feinberg School of MedicineChicagoIllinoisUSA,Hugh Knowles Center for Clinical and Basic Science in Hearing and its DisordersNorthwestern University, Feinberg School of MedicineChicagoIllinoisUSA
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Abstract
Usher syndrome (USH) encompasses a group of clinically and genetically heterogenous disorders defined by the triad of sensorineural hearing loss (SNHL), vestibular dysfunction, and vision loss. USH is the most common cause of deaf blindness. USH is divided clinically into three subtypes-USH1, USH2, and USH3-based on symptom severity, progression, and age of onset. The underlying genetics of these USH forms are, however, significantly more complex, with over a dozen genes linked to the three primary clinical subtypes and other atypical USH phenotypes. Several of these genes are associated with other deaf-blindness syndromes that share significant clinical overlap with USH, pointing to the limits of a clinically based classification system. The genotype-phenotype relationships among USH forms also may vary significantly based on the location and type of mutation in the gene of interest. Understanding these genotype-phenotype relationships and associated natural disease histories is necessary for the successful development and application of gene-based therapies and precision medicine approaches to USH. Currently, the state of knowledge varies widely depending on the gene of interest. Recent studies utilizing next-generation sequencing technology have expanded the list of known pathogenic mutations in USH genes, identified new genes associated with USH-like phenotypes, and proposed algorithms to predict the phenotypic effects of specific categories of allelic variants. Further work is required to validate USH gene causality, and better define USH genotype-phenotype relationships and disease natural histories-particularly for rare mutations-to lay the groundwork for the future of USH treatment.
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Abstract
Vestibular hair cells are mechanosensory receptors that are capable of detecting changes in head position and thereby allow animals to maintain their posture and coordinate their movement. Vestibular hair cells are susceptible to ototoxic drugs, aging, and genetic factors that can lead to permanent vestibular dysfunction. Vestibular dysfunction mainly results from the injury of hair cells, which are located in the vestibular sensory epithelium. This review summarizes the mechanisms of different factors causing vestibular hair cell damage and therapeutic strategies to protect vestibular hair cells.
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Affiliation(s)
- Luoying Jiang
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Zhiwei Zheng
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Yingzi He
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China.
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Visconti L, Malagrinò F, Troilo F, Pagano L, Toto A, Gianni S. Folding and Misfolding of a PDZ Tandem Repeat. J Mol Biol 2021; 433:166862. [PMID: 33539879 DOI: 10.1016/j.jmb.2021.166862] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/22/2021] [Accepted: 01/27/2021] [Indexed: 01/29/2023]
Abstract
Although the vast majority of the human proteome is represented by multi-domain proteins, the study of multi-domain folding and misfolding is a relatively poorly explored field. The protein Whirlin is a multi-domain scaffolding protein expressed in the inner ear. It is characterized by the presence of tandem repeats of PDZ domains. The first two PDZ domains of Whirlin (PDZ1 and PDZ2 - namely P1P2) are structurally close and separated by a disordered short linker. We recently described the folding mechanism of the P1P2 tandem. The difference in thermodynamic stability of the two domains allowed us to selectively unfold one or both PDZ domains and to pinpoint the accumulation of a misfolded intermediate, which we demonstrated to retain physiological binding activity. In this work, we provide an extensive characterization of the folding and unfolding of P1P2. Based on the observed data, we describe an integrated kinetic analysis that satisfactorily fits the experiments and provides a valuable model to interpret multi-domain folding. The experimental and analytical approaches described in this study may be of general interest for the interpretation of complex multi-domain protein folding kinetics.
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Affiliation(s)
- Lorenzo Visconti
- Istituto Pasteur - Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Francesca Malagrinò
- Istituto Pasteur - Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Francesca Troilo
- Istituto Pasteur - Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Livia Pagano
- Istituto Pasteur - Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Angelo Toto
- Istituto Pasteur - Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy.
| | - Stefano Gianni
- Istituto Pasteur - Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy.
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10
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Zhu Y, Delhommel F, Cordier F, Lüchow S, Mechaly A, Colcombet-Cazenave B, Girault V, Pepermans E, Bahloul A, Gautier C, Brûlé S, Raynal B, Hoos S, Haouz A, Caillet-Saguy C, Ivarsson Y, Wolff N. Deciphering the Unexpected Binding Capacity of the Third PDZ Domain of Whirlin to Various Cochlear Hair Cell Partners. J Mol Biol 2020; 432:5920-5937. [PMID: 32971111 DOI: 10.1016/j.jmb.2020.09.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/11/2020] [Accepted: 09/15/2020] [Indexed: 10/23/2022]
Abstract
Hearing is a mechanical and neurochemical process, which occurs in the hair cells of inner ear that converts the sound vibrations into electrical signals transmitted to the brain. The multi-PDZ scaffolding protein whirlin plays a critical role in the formation and function of stereocilia exposed at the surface of hair cells. In this article, we reported seven stereociliary proteins that encode PDZ binding motifs (PBM) and interact with whirlin PDZ3, where four of them are first reported. We solved the atomic resolution structures of complexes between whirlin PDZ3 and the PBMs of myosin 15a, CASK, harmonin a1 and taperin. Interestingly, the PBM of CASK and taperin are rare non-canonical PBM, which are not localized at the extreme C terminus. This large capacity to accommodate various partners could be related to the distinct functions of whirlin at different stages of the hair cell development.
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Affiliation(s)
- Yanlei Zhu
- Unité Récepteurs-Canaux, Institut Pasteur, 75015 Paris, France; Complexité du Vivant, Sorbonne Université, 75005 Paris, France
| | - Florent Delhommel
- Unité Récepteurs-Canaux, Institut Pasteur, 75015 Paris, France; Complexité du Vivant, Sorbonne Université, 75005 Paris, France
| | | | | | - Ariel Mechaly
- Plateforme de Cristallographie, Institut Pasteur, Paris, France
| | - Baptiste Colcombet-Cazenave
- Unité Récepteurs-Canaux, Institut Pasteur, 75015 Paris, France; Complexité du Vivant, Sorbonne Université, 75005 Paris, France
| | | | - Elise Pepermans
- Complexité du Vivant, Sorbonne Université, 75005 Paris, France; Unité de génétique et physiologie de l'audition, Institut Pasteur, 75015 Paris, France
| | - Amel Bahloul
- Unité de génétique et physiologie de l'audition, Institut Pasteur, 75015 Paris, France
| | - Candice Gautier
- Istituto Pasteur - Fondazione C. Bolognetti, Sapienza Università di Roma, Rome, Italy
| | - Sébastien Brûlé
- Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France
| | - Bertrand Raynal
- Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France
| | - Sylviane Hoos
- Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France
| | - Ahmed Haouz
- Plateforme de Cristallographie, Institut Pasteur, Paris, France
| | | | - Ylva Ivarsson
- Department of Chemistry-BMC, Uppsala University, Sweden
| | - Nicolas Wolff
- Unité Récepteurs-Canaux, Institut Pasteur, 75015 Paris, France.
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11
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Interaction of protocadherin-15 with the scaffold protein whirlin supports its anchoring of hair-bundle lateral links in cochlear hair cells. Sci Rep 2020; 10:16430. [PMID: 33009420 PMCID: PMC7532178 DOI: 10.1038/s41598-020-73158-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 09/07/2020] [Indexed: 11/26/2022] Open
Abstract
The hair bundle of cochlear hair cells is the site of auditory mechanoelectrical transduction. It is formed by three rows of stiff microvilli-like protrusions of graduated heights, the short, middle-sized, and tall stereocilia. In developing and mature sensory hair cells, stereocilia are connected to each other by various types of fibrous links. Two unconventional cadherins, protocadherin-15 (PCDH15) and cadherin-23 (CDH23), form the tip-links, whose tension gates the hair cell mechanoelectrical transduction channels. These proteins also form transient lateral links connecting neighboring stereocilia during hair bundle morphogenesis. The proteins involved in anchoring these diverse links to the stereocilia dense actin cytoskeleton remain largely unknown. We show that the long isoform of whirlin (L-whirlin), a PDZ domain-containing submembrane scaffold protein, is present at the tips of the tall stereocilia in mature hair cells, together with PCDH15 isoforms CD1 and CD2; L-whirlin localization to the ankle-link region in developing hair bundles moreover depends on the presence of PCDH15-CD1 also localizing there. We further demonstrate that L-whirlin binds to PCDH15 and CDH23 with moderate-to-high affinities in vitro. From these results, we suggest that L-whirlin is part of the molecular complexes bridging PCDH15-, and possibly CDH23-containing lateral links to the cytoskeleton in immature and mature stereocilia.
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12
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Molecular characterization of a whirlin-like protein with biomineralization-related functions from the shell of Mytilus coruscus. PLoS One 2020; 15:e0231414. [PMID: 32267882 PMCID: PMC7141649 DOI: 10.1371/journal.pone.0231414] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 03/23/2020] [Indexed: 11/19/2022] Open
Abstract
Mollusc shells are produced from calcified skeletons and have excellent mechanical properties. Shell matrix proteins (SMPs) have important functions in shell formation. A 16.6 kDa whirlin-like protein (WLP) with a PDZ domain was identified in the shell of Mytilus coruscus as a novel SMP. In this study, the expression, function, and location of WLP were analysed. The WLP gene was highly expressed and specifically located in the adductor muscle and mantle. The expression of recombinant WLP (rWLP) was associated with morphological change, polymorphic change, binding ability, and crystallization rate inhibition of the calcium carbonate crystals in vitro. In addition, an anti-rWLP antibody was prepared, and the results from immunohistochemistry and immunofluorescence analyses revealed the specific location of the WLP in the mantle, adductor muscle, and myostracum layer of the shell, suggesting multiple functions for WLP in biomineralization, muscle-shell attachment, and muscle attraction. Furthermore, results from a pull-down analysis revealed 10 protein partners of WLP in the shell matrices and a possible network of interacting WLPs in the shell. In addition, in this study, one of the WLP partners, actin, was confirmed to have the ability to bind WLP. These results expand the understanding of the functions of PDZ-domain-containing proteins in biomineralization and provide clues for determining the mechanisms of myostracum formation and muscle-shell attachment.
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13
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Géléoc GGS, El-Amraoui A. Disease mechanisms and gene therapy for Usher syndrome. Hear Res 2020; 394:107932. [PMID: 32199721 DOI: 10.1016/j.heares.2020.107932] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/03/2020] [Accepted: 02/26/2020] [Indexed: 12/11/2022]
Abstract
Usher syndrome (USH) is a major cause of deaf-blindness in humans, affecting ∼400 000 patients worldwide. Three clinical subtypes, USH1-3, have been defined, with 10 USH genes identified so far. In recent years, in addition to identification of new Usher genes and diagnostic tools, major progress has been made in understanding the role of Usher proteins and how they cooperate through interaction networks to ensure proper development, architecture and function of the stereociliary bundle at the apex of sensory hair cells in the inner ear. Several Usher mouse models of known human Usher genes have been characterized. These mice faithfully reproduce the auditory phenotype associated with Usher syndrome and the vestibular phenotype associated with some mutations in USH genes, particularly USH1. Interestingly, very few mouse models of Usher syndrome recapitulate the retinal phenotype associated with the disease in human. Usher patients can benefit from hearing aids or cochlear implants, which partially alleviate auditory sensory deprivation. However, there are currently no biological treatments available for auditory or visual dysfunction in Usher patients. Development of novel therapies for Usher syndrome has sprouted over the past decade, building on recent progress in gene transfer and new gene editing tools. Promising success demonstrating recovery of hearing and balance functions have been obtained via distinct therapeutic strategies in animal models. Clinical translation to Usher patients, however, calls for further improvements and concerted efforts to overcome the challenges ahead.
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Affiliation(s)
- Gwenaelle G S Géléoc
- Boston Children's Hospital and Harvard Medical School, 3, Blackfan circle, Center for Life Science, 03001, Boston, MA, 02115, United States.
| | - Aziz El-Amraoui
- Unit Progressive Sensory Disorders, Institut Pasteur, INSERM-UMRS1120, Sorbonne Université, 25 rue du Dr. Roux, 75015, Paris, France.
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14
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Mechanotransduction-Dependent Control of Stereocilia Dimensions and Row Identity in Inner Hair Cells. Curr Biol 2020; 30:442-454.e7. [PMID: 31902726 DOI: 10.1016/j.cub.2019.11.076] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 11/08/2019] [Accepted: 11/26/2019] [Indexed: 02/07/2023]
Abstract
Actin-rich structures, like stereocilia and microvilli, are assembled with precise control of length, diameter, and relative spacing. By quantifying actin-core dimensions of stereocilia from phalloidin-labeled mouse cochleas, we demonstrated that inner hair cell stereocilia developed in specific stages, where a widening phase is sandwiched between two lengthening phases. Moreover, widening of the second-tallest stereocilia rank (row 2) occurred simultaneously with the appearance of mechanotransduction. Correspondingly, Tmc1KO/KO;Tmc2KO/KO or TmieKO/KO hair cells, which lack transduction, have significantly altered stereocilia lengths and diameters, including a narrowed row 2. EPS8 and the short splice isoform of MYO15A, identity markers for mature row 1 (the tallest row), lost their row exclusivity in transduction mutants. GNAI3, another member of the mature row 1 complex, accumulated at mutant row 1 tips at considerably lower levels than in wild-type bundles. Alterations in stereocilia dimensions and in EPS8 distribution seen in transduction mutants were mimicked by block of transduction channels of cochlear explants in culture. In addition, proteins normally concentrated at mature row 2 tips were also distributed differently in transduction mutants; the heterodimeric capping protein subunit CAPZB and its partner TWF2 never concentrated at row 2 tips like they do in wild-type bundles. The altered distribution of marker proteins in transduction mutants was accompanied by increased variability in stereocilia length. Transduction channels thus specify and maintain row identity, control addition of new actin filaments to increase stereocilia diameter, and coordinate stereocilia height within rows.
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15
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Du H, Zou L, Ren R, Li N, Li J, Wang Y, Sun J, Yang J, Xiong W, Xu Z. Lack of PDZD7 long isoform disrupts ankle-link complex and causes hearing loss in mice. FASEB J 2019; 34:1136-1149. [PMID: 31914662 DOI: 10.1096/fj.201901657rr] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 09/28/2019] [Accepted: 11/14/2019] [Indexed: 12/12/2022]
Abstract
Usher syndrome (USH) is the most frequent form of combined hereditary deafness-blindness, characterized by hearing loss and retinitis pigmentosa, with or without vestibular dysfunction. PDZD7 is a PDZ domain-containing scaffold protein that was suggested to be a USH modifier and a contributor to digenic USH. In the inner ear hair cells, PDZD7 localizes at the ankle region of the stereocilia and constitutes the so-called ankle-link complex together with three other USH proteins Usherin, WHRN, and ADGRV1. PDZD7 gene is subjected to alternative splicing, which gives rise to two types of PDZD7 isoforms, namely the long and short isoforms. At present, little is known which specific isoform is involved in ankle-link formation and stereocilia development. In this work, we showed that PDZD7 long isoform, but not short isoforms, localizes at the ankle region of the stereocilia. Moreover, we established Pdzd7 mutant mice by introducing deletions into exon 14 of the Pdzd7 gene, which causes potential premature translational stop in the long isoform but leaves short isoforms unaffected. We found that lack of PDZD7 long isoform affects the localization of other ankle-link complex components in the stereocilia. Consequently, Pdzd7 mutant mice showed stereocilia development deficits and hearing loss as well as reduced mechanotransduction (MET) currents, suggesting that PDZD7 long isoform is indispensable for hair cells. Furthermore, by performing yeast two-hybrid screening, we identified a PDZD7 long isoform-specific binding partner PIP5K1C, which has been shown to play important roles in hearing and might participate in the function and/or transportation of PDZD7.
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Affiliation(s)
- Haibo Du
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Linzhi Zou
- School of Life Sciences, IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing, China
| | - Rui Ren
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Nana Li
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Jie Li
- School of Life Sciences, IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing, China
| | - Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Jinpeng Sun
- Key Laboratory Experimental Teratology of the Ministry of Education, Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, China
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, Utah
| | - Wei Xiong
- School of Life Sciences, IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing, China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China.,Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, China
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16
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Wang L, Wei B, Fu X, Wang Y, Sui Y, Ma J, Gong X, Hao J, Xing S. Identification of whirlin domains interacting with espin: A study of the mechanism of Usher syndrome type II. Mol Med Rep 2019; 20:5111-5117. [PMID: 31638198 PMCID: PMC6854525 DOI: 10.3892/mmr.2019.10728] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 08/19/2019] [Indexed: 11/23/2022] Open
Abstract
Usher syndrome is the most common condition of combined blindness and deafness and is classified into three types (USH1-USH3). USH2 is the most commonly diagnosed of all Usher syndrome cases. There are three identified proteins (usherin, GPR98 and whirlin) that form the USH2 complex. Defects in any of these proteins may cause failure in the formation of the USH2 complex, which is the primary cause of USH2. Whirlin is a scaffold protein and is essential for the assembly of the USH2 protein complex. It has been reported that espin is an interacting partner protein for whirlin. However, which fragment of whirlin interacts with espin remains unclear. In the present study, whirlin N- and C-terminal fragments in the pEGFP-C2 vectors were constructed. The recombinant plasmids were transfected into COS-7 cells to observe the co-localization by confocal laser scanning microscopy. The interactions between whirlin and espin were investigated by co-immunoprecipitation using the 293 cell line. It was demonstated that only the whirlin N-terminal fragment was able to interact with espin and the PR (proline-rich) region in whirlin may be important for the interaction. However, the present study did not investigate the interaction between whirlin and espin without the PR domain which warrants future research. Our findings elucidated a primary mechanism of interaction between whirlin and espin, which are crucial for further study on the USH2 complex and USH2 pathogenesis.
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Affiliation(s)
- Le Wang
- Department of Ophthalmology, First Hospital, Jilin University, Changchun, Jilin 130021, P.R. China
| | - Bo Wei
- Department of Neurosurgery, China‑Japan Union Hospital, Jilin University, Changchun, Jilin 130033, P.R. China
| | - Xueqi Fu
- Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Yuchen Wang
- Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Yuan Sui
- Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Junfeng Ma
- Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Xianhui Gong
- Department of Opthalmology, Eye Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027, P.R. China
| | - Jilong Hao
- Department of Ophthalmology, First Hospital, Jilin University, Changchun, Jilin 130021, P.R. China
| | - Shu Xing
- Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
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17
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Tadenev ALD, Akturk A, Devanney N, Mathur PD, Clark AM, Yang J, Tarchini B. GPSM2-GNAI Specifies the Tallest Stereocilia and Defines Hair Bundle Row Identity. Curr Biol 2019; 29:921-934.e4. [PMID: 30827920 DOI: 10.1016/j.cub.2019.01.051] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 12/12/2018] [Accepted: 01/21/2019] [Indexed: 12/12/2022]
Abstract
The transduction compartment of inner ear hair cells, the hair bundle, is composed of stereocilia rows of graded height, a property essential for sensory function that remains poorly understood at the molecular level. We previously showed that GPSM2-GNAI is enriched at stereocilia distal tips and required for their postnatal elongation and bundle morphogenesis-two characteristics shared with MYO15A (short isoform), WHRN, and EPS8 proteins. Here we first performed a comprehensive genetic analysis of the mouse auditory epithelium to show that GPSM2, GNAI, MYO15A, and WHRN operate in series within the same pathway. To understand how these functionally disparate proteins act as an obligate complex, we then systematically analyzed their distribution in normal and mutant bundles over time. We discovered that WHRN-GPSM2-GNAI is an extra module recruited by and added to a pre-existing MYO15A-EPS8 stereocilia tip complex. This extended complex is only present in the first, tallest row, and is required to stabilize larger amounts of MYO15A-EPS8 than in shorter rows, which at tips harbor only MYO15A-EPS8. In the absence of GPSM2 or GNAI function, including in the epistatic Myo15a and Whrn mutants, bundles retain an embryonic-like organization that coincides with generic stereocilia at the molecular level. We propose that GPSM2-GNAI confers on the first row its unique tallest identity and participates in generating differential row identity across the hair bundle.
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Affiliation(s)
| | - Anil Akturk
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | | | - Pranav Dinesh Mathur
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | - Anna M Clark
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA; Department of Neurobiology and Anatomy, University of Utah, 20 North 1900 East, Salt Lake City, UT 84132, USA; Division of Otolaryngology, Department of Surgery, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA
| | - Basile Tarchini
- The Jackson Laboratory, Bar Harbor, ME 04609, USA; Department of Medicine, Tufts University, Boston, MA 02111, USA; Graduate School of Biomedical Science and Engineering (GSBSE), University of Maine, Orono, ME 04469, USA.
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18
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Mathur PD, Yang J. Usher syndrome and non-syndromic deafness: Functions of different whirlin isoforms in the cochlea, vestibular organs, and retina. Hear Res 2019; 375:14-24. [PMID: 30831381 DOI: 10.1016/j.heares.2019.02.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 01/30/2019] [Accepted: 02/20/2019] [Indexed: 12/15/2022]
Abstract
Usher syndrome (USH) is the leading cause of inherited combined vision and hearing loss. However, mutations in most USH causative genes lead to other diseases, such as hearing loss only or vision loss only. The molecular mechanisms underlying the variable disease manifestations associated with USH gene mutations are unclear. This review focuses on an USH type 2 (USH2) gene encoding whirlin (WHRN; previously known as DFNB31), mutations in which have been found to cause either USH2 subtype USH2D or autosomal recessive non-syndromic deafness type 31 (DFNB31). This review summarizes the current knowledge about different whirlin isoforms encoded by WHRN orthologs in animal models, the interactions of different whirlin isoforms with their partners, and the function of whirlin isoforms in different cellular and subcellular locations. The recent findings regarding the function of whirlin isoforms suggest that disruption of different isoforms may be one of the mechanisms underlying the variable disease manifestations caused by USH gene mutations. This review also presents recent findings about the vestibular defects in Whrn mutant mouse models, which suggests that previous assumptions about the normal vestibular function of USH2 patients need to be re-evaluated. Finally, this review describes recent progress in developing therapeutics for diseases caused by WHRN mutations.
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Affiliation(s)
- Pranav Dinesh Mathur
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, 84132, USA; Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT, 84132, USA
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, 84132, USA; Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT, 84132, USA; Department of Otolaryngology Head and Neck Surgery, University of Utah, Salt Lake City, UT, 84132, USA.
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19
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Photoreceptor actin dysregulation in syndromic and non-syndromic retinitis pigmentosa. Biochem Soc Trans 2018; 46:1463-1473. [PMID: 30464047 DOI: 10.1042/bst20180138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 09/26/2018] [Accepted: 10/12/2018] [Indexed: 01/11/2023]
Abstract
Retinitis pigmentosa (RP) is the leading cause of inherited blindness. RP is a genetically heterogeneous disorder, with more than 100 different causal genes identified in patients. Central to disease pathogenesis is the progressive loss of retinal photoreceptors. Photoreceptors are specialised sensory neurons that exhibit a complex and highly dynamic morphology. The highly polarised and elaborated architecture of photoreceptors requires precise regulation of numerous cytoskeletal elements. In recent years, significant work has been placed on investigating the role of microtubules (specifically, the acetylated microtubular axoneme of the photoreceptor connecting cilium) and their role in normal photoreceptor function. This has been driven by the emerging field of ciliopathies, human diseases arising from mutations in genes required for cilia formation or function, of which RP is a frequently reported phenotype. Recent studies have highlighted an intimate relationship between cilia and the actin cystoskeleton. This review will focus on the role of actin in photoreceptors, examining the connection between actin dysregulation in RP.
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20
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Delhommel F, Cordier F, Saul F, Chataigner L, Haouz A, Wolff N. Structural plasticity of the HHD2 domain of whirlin. FEBS J 2018; 285:3738-3752. [PMID: 30053338 DOI: 10.1111/febs.14614] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/04/2018] [Accepted: 07/25/2018] [Indexed: 01/10/2023]
Abstract
Whirlin is a protein essential to sensory neurons. Its defects are responsible for nonsyndromic deafness or for the Usher syndrome, a condition associating congenital deafness and progressive blindness. This large multidomain scaffolding protein is expressed in three isoforms with different functions and localizations in stereocilia bundles of hearing hair cells or in the connecting cilia of photoreceptor cells. The HHD2 domain of whirlin is the only domain shared by all isoforms, but its function remains unknown. In this article, we report its crystal structure in two distinct conformations, a monomeric five-helix bundle, similar to the known structure of other HHD domains, and a three-helix bundle organized as a swapped dimer. Most of the hydrophobic contacts and electrostatic interactions that maintain the globular monomeric form are conserved at the protomer interface of the dimer. NMR experiments revealed that the five-helix conformation is predominant in solution, but exhibits increased dynamics on one face encompassing the hinge loops. Using NMR and SAXS, we also show that HHD2 does not interact with its preceding domains. Our findings suggest that structural plasticity might play a role in the function of the HHD2 domain.
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Affiliation(s)
- Florent Delhommel
- Unité Récepteurs-Canaux, Institut Pasteur, Paris, France.,CNRS, UMR3571, Paris, France.,Collège Doctoral, Sorbonne Université, Paris, France
| | - Florence Cordier
- Unité de Bioinformatique Structurale, Institut Pasteur, Paris, France.,CNRS, UMR3528, Paris, France
| | - Frederick Saul
- CNRS, UMR3528, Paris, France.,Plateforme de Cristallographie, Institut Pasteur, Paris, France
| | - Lucas Chataigner
- Unité Récepteurs-Canaux, Institut Pasteur, Paris, France.,CNRS, UMR3571, Paris, France.,Collège Doctoral, Sorbonne Université, Paris, France
| | - Ahmed Haouz
- CNRS, UMR3528, Paris, France.,Plateforme de Cristallographie, Institut Pasteur, Paris, France
| | - Nicolas Wolff
- Unité Récepteurs-Canaux, Institut Pasteur, Paris, France.,CNRS, UMR3571, Paris, France
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21
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DiStefano MT, Hemphill SE, Cushman BJ, Bowser MJ, Hynes E, Grant AR, Siegert RK, Oza AM, Gonzalez MA, Amr SS, Rehm HL, Abou Tayoun AN. Curating Clinically Relevant Transcripts for the Interpretation of Sequence Variants. J Mol Diagn 2018; 20:789-801. [PMID: 30096381 DOI: 10.1016/j.jmoldx.2018.06.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 05/20/2018] [Accepted: 06/19/2018] [Indexed: 10/28/2022] Open
Abstract
Variant interpretation depends on accurate annotations using biologically relevant transcripts. We have developed a systematic strategy for designating primary transcripts and have applied it to 109 hearing loss-associated genes that were divided into three categories. Category 1 genes (n = 38) had a single transcript; category 2 genes (n = 33) had multiple transcripts, but a single transcript was sufficient to represent all exons; and category 3 genes (n = 38) had multiple transcripts with unique exons. Transcripts were curated with respect to gene expression reported in the literature and the Genotype-Tissue Expression Project. In addition, high-frequency loss-of-function variants in the Genome Aggregation Database and disease-causing variants in ClinVar and the Human Gene Mutation Database across the 109 genes were queried. These data were used to classify exons as clinically significant, insignificant, or of uncertain significance. Interestingly, 6% of all exons, containing 124 reportedly disease-causing variants, were of uncertain significance. Finally, we used exon-level next-generation sequencing quality metrics generated at two clinical laboratories and identified a total of 43 technically challenging exons in 20 different genes that had inadequate coverage and/or homology issues that might lead to false-variant calls. We have demonstrated that transcript analysis plays a critical role in accurate clinical variant interpretation.
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Affiliation(s)
- Marina T DiStefano
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Sarah E Hemphill
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Brandon J Cushman
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Mark J Bowser
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Elizabeth Hynes
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Andrew R Grant
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Rebecca K Siegert
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Andrea M Oza
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts
| | - Michael A Gonzalez
- Division of Genomic Diagnostics, The Children's Hospital of Philadelphia, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Sami S Amr
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts; Center for Genomic Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Heidi L Rehm
- Laboratory for Molecular Medicine, Partners Healthcare Personalized Medicine, Cambridge, Massachusetts; Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Medical and Population Genetics, The Broad Institute of the Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Ahmad N Abou Tayoun
- Division of Genomic Diagnostics, The Children's Hospital of Philadelphia, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania; Genetics Department, Al Jalila Children's Specialty Hospital, Dubai, United Arab Emirates.
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22
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Khowal S, Naqvi SH, Monga S, Jain SK, Wajid S. Assessment of cellular and serum proteome from tongue squamous cell carcinoma patient lacking addictive proclivities for tobacco, betel nut, and alcohol: Case study. J Cell Biochem 2018; 119:5186-5221. [PMID: 29236289 DOI: 10.1002/jcb.26554] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 11/30/2017] [Indexed: 02/06/2023]
Abstract
The intriguing molecular pathways involved in oral carcinogenesis are still ambiguous. The oral squamous cell carcinoma (OSCC) ranks as the most common type constituting more than 90% of the globally diagnosed oral cancers cases. The elevation in the OSCC incidence rate during past 10 years has an alarming impression on human healthcare. The major challenges associated with OSCC include delayed diagnosis, high metastatic rates, and low 5-year survival rates. The present work foundations on reverse genetic strategy and involves the identification of genes showing expressional variability in an OSCC case lacking addictive proclivities for tobacco, betel nut, and/or alcohol, major etiologies. The expression modulations in the identified genes were analyzed in 16 patients comprising oral pre-cancer and cancer histo-pathologies. The genes SCCA1 and KRT1 were found to down regulate while DNAJC13, GIPC2, MRPL17, IG-Vreg, SSFA2, and UPF0415 upregulated in the oral pre-cancer and cancer pathologies, implicating the genes as crucial players in oral carcinogenesis.
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Affiliation(s)
- Sapna Khowal
- Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi, India
| | - Samar H Naqvi
- Molecular Diagnostics, Genetix Biotech Asia (P) Ltd., New Delhi, India
| | - Seema Monga
- Department of ENT, Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi, India
| | - Swatantra K Jain
- Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi, India
- Department of Biochemistry, Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi, India
| | - Saima Wajid
- Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi, India
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23
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Wei C, Yang L, Cheng J, Imani S, Fu S, Lv H, Li Y, Chen R, Leung ELH, Fu J. A novel homozygous variant of GPR98 causes usher syndrome type IIC in a consanguineous Chinese family by next generation sequencing. BMC MEDICAL GENETICS 2018; 19:99. [PMID: 29890953 PMCID: PMC5996530 DOI: 10.1186/s12881-018-0602-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/01/2018] [Indexed: 11/10/2022]
Abstract
BACKGROUND Usher syndrome (USH) is a common heterogeneous retinopathy and a hearing loss (HL) syndrome. However, the gene causing Usher syndrome type IIC (USH2C) in a consanguineous Chinese pedigree is unknown. METHODS We performed targeted next-generation sequencing analysis and Sanger sequencing to explore the GPR98 mutations in a USH2C pedigree that included a 32-year-old male patient from a consanguineous marriage family. Western blot verified the nonsense mutation. RESULTS To identify disease-causing gene variants in a consanguineous Chinese pedigree with USH2C, DNA from proband was analyzed using targeted next generation sequencing (NGS). The patient was clinically documented as a possible USH2 by a comprehensive auditory and ophthalmology evaluation. We succeeded in identifying the deleterious, novel, and homologous variant, c.6912dupG (p.Leu2305Valfs*4), in the GPR98 gene (NM_032119.3) that contributes to the progression of USH2C. Variant detected by targeted NGS was then confirmed and co-segregation was conducted by direct Sanger sequencing. Western blot verified losing almost two-thirds of its amino acid residues, including partial Calx-beta, whole EPTP and 7TM-GPCRs at the C-terminus of GPR98. Furthermore, our results highlighted that this p.Leu2305Valfs*4 variant is most likely pathogenic due to a large deletion at the seven-transmembrane G protein-coupled receptors (7TM-GPCRs) domain in GPR98 protein, leading to significantly decreased functionality and complex stability. CONCLUSIONS These findings characterized the novel disease causativeness variant in GPR98 and broaden mutation spectrums, which could predict the pathogenic progression of patient with USH2C, guide diagnosis and treatment of this disease; and provide genetic counseling and family planning for consanguineous marriage pedigree in developing countries, including China.
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Affiliation(s)
- Chunli Wei
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute For Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macao, Special Administrative Region of China.,Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Lisha Yang
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Jingliang Cheng
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Saber Imani
- Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China.,Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Shangyi Fu
- The Honors College, University of Houston, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Hongbin Lv
- Department of Ophthalmology, Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Elaine Lai-Han Leung
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute For Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macao, Special Administrative Region of China. .,Guangzhou Institute of Respiratory Disease, State Key Laboratory of Respiratory Disease, The 1st Affiliated Hospital of Guangzhou Medical College, Guangzhou, China. .,Respiratoire Medicine Department, Taihe Hospital, Hubei University of Medicine, Hubei, China.
| | - Junjiang Fu
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute For Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macao, Special Administrative Region of China. .,Key Laboratory of Epigenetics and Oncology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China.
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24
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Delhommel F, Cordier F, Bardiaux B, Bouvier G, Colcombet-Cazenave B, Brier S, Raynal B, Nouaille S, Bahloul A, Chamot-Rooke J, Nilges M, Petit C, Wolff N. Structural Characterization of Whirlin Reveals an Unexpected and Dynamic Supramodule Conformation of Its PDZ Tandem. Structure 2017; 25:1645-1656.e5. [PMID: 28966015 DOI: 10.1016/j.str.2017.08.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/26/2017] [Accepted: 08/18/2017] [Indexed: 10/18/2022]
Abstract
Hearing relies on the transduction of sound-evoked vibrations into electric signals, occurring in the stereocilia bundle of hair cells. The bundle is organized in a staircase pattern formed by rows of packed stereocilia. This architecture is pivotal to transduction and involves a network of scaffolding proteins with hitherto uncharacterized features. Key interactions in this network are mediated by PDZ domains. Here, we describe the architecture of the first two PDZ domains of whirlin, a protein involved in these assemblies and associated with congenital deaf-blindness. C-terminal hairpin extensions of the PDZ domains mediate the transient supramodular assembly, which improves the binding capacity of the first domain. We determined a detailed structural model of the closed conformation of the PDZ tandem and characterized its equilibrium with an ensemble of open conformations. The structural and dynamic behavior of this PDZ tandem provides key insights into the regulatory mechanisms involved in the hearing machinery.
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Affiliation(s)
- Florent Delhommel
- Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, 75005 Paris, France; CNRS, UMR 3528, 75015 Paris, France; Unité de Résonance Magnétique Nucléaire des Biomolécules, Institut Pasteur, 75015 Paris, France
| | - Florence Cordier
- CNRS, UMR 3528, 75015 Paris, France; Unité de Résonance Magnétique Nucléaire des Biomolécules, Institut Pasteur, 75015 Paris, France
| | - Benjamin Bardiaux
- CNRS, UMR 3528, 75015 Paris, France; Unité de Bio-Informatique Structurale, Institut Pasteur, 75015 Paris, France
| | - Guillaume Bouvier
- CNRS, UMR 3528, 75015 Paris, France; Unité de Bio-Informatique Structurale, Institut Pasteur, 75015 Paris, France
| | - Baptiste Colcombet-Cazenave
- CNRS, UMR 3528, 75015 Paris, France; Unité de Résonance Magnétique Nucléaire des Biomolécules, Institut Pasteur, 75015 Paris, France
| | - Sébastien Brier
- CNRS, UMR 3528, 75015 Paris, France; Unité de Spectrométrie de Masse Structurale et Protéomique, Institut Pasteur, 75015 Paris, France
| | - Bertrand Raynal
- CNRS, UMR 3528, 75015 Paris, France; Plateforme de Biophysique Moléculaire, Institut Pasteur, 75015 Paris, France
| | - Sylvie Nouaille
- Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, 75005 Paris, France; Unité de Génétique et physiologie de l'audition, Institut Pasteur, 75015 Paris, France; Unité Mixte de Recherche, UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), 75015 Paris, France
| | - Amel Bahloul
- Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, 75005 Paris, France; Unité de Génétique et physiologie de l'audition, Institut Pasteur, 75015 Paris, France; Unité Mixte de Recherche, UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), 75015 Paris, France
| | - Julia Chamot-Rooke
- CNRS, UMR 3528, 75015 Paris, France; Unité de Spectrométrie de Masse Structurale et Protéomique, Institut Pasteur, 75015 Paris, France
| | - Michael Nilges
- CNRS, UMR 3528, 75015 Paris, France; Unité de Bio-Informatique Structurale, Institut Pasteur, 75015 Paris, France
| | - Christine Petit
- Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, 75005 Paris, France; Unité de Génétique et physiologie de l'audition, Institut Pasteur, 75015 Paris, France; Unité Mixte de Recherche, UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), 75015 Paris, France; Collège de France, 75005 Paris, France
| | - Nicolas Wolff
- CNRS, UMR 3528, 75015 Paris, France; Unité de Résonance Magnétique Nucléaire des Biomolécules, Institut Pasteur, 75015 Paris, France.
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25
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Zou J, Chen Q, Almishaal A, Mathur PD, Zheng T, Tian C, Zheng QY, Yang J. The roles of USH1 proteins and PDZ domain-containing USH proteins in USH2 complex integrity in cochlear hair cells. Hum Mol Genet 2017; 26:624-636. [PMID: 28031293 DOI: 10.1093/hmg/ddw421] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 12/07/2016] [Indexed: 11/14/2022] Open
Abstract
Usher syndrome (USH) is the most common cause of inherited deaf-blindness, manifested as USH1, USH2 and USH3 clinical types. The protein products of USH2 causative and modifier genes, USH2A, ADGRV1, WHRN and PDZD7, interact to assemble a multiprotein complex at the ankle link region of the mechanosensitive stereociliary bundle in hair cells. Defects in this complex cause stereociliary bundle disorganization and hearing loss. The four USH2 proteins also interact in vitro with USH1 proteins including myosin VIIa, USH1G (SANS), CIB2 and harmonin. However, it is unclear whether the interactions between USH1 and USH2 proteins occur in vivo and whether USH1 proteins play a role in USH2 complex assembly in hair cells. In this study, we identified a novel interaction between myosin VIIa and PDZD7 by FLAG pull-down assay. We further investigated the role of the above-mentioned four USH1 proteins in the cochlear USH2 complex assembly using USH1 mutant mice. We showed that only myosin VIIa is indispensable for USH2 complex assembly at ankle links, indicating the potential transport and/or anchoring role of myosin VIIa for USH2 proteins in hair cells. However, myosin VIIa is not required for USH2 complex assembly in photoreceptors. We further showed that, while PDZ protein harmonin is not involved, its paralogous USH2 proteins, PDZD7 and whirlin, function synergistically in USH2 complex assembly in cochlear hair cells. In summary, our studies provide novel insight into the functional relationship between USH1 and USH2 proteins in the cochlea and the retina as well as the disease mechanisms underlying USH1 and USH2.
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Affiliation(s)
- Junhuang Zou
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | - Qian Chen
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | - Ali Almishaal
- Department of Communication Sciences and Disorders, University of Utah, 390 South 1530 East, Salt Lake City, UT 84112, USA
| | - Pranav Dinesh Mathur
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA.,Department of Neurobiology and Anatomy, University of Utah, 20 North 1900 East, Salt Lake City, UT 84132, USA
| | - Tihua Zheng
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | - Cong Tian
- Department of Otolaryngology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Qing Y Zheng
- Department of Otolaryngology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA.,Department of Neurobiology and Anatomy, University of Utah, 20 North 1900 East, Salt Lake City, UT 84132, USA.,Division of Otolaryngology, Department of Surgery, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA
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26
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Almishaal AA, Mathur PD, Hillas E, Chen L, Zhang A, Yang J, Wang Y, Yokoyama WM, Firpo MA, Park AH. Natural killer cells attenuate cytomegalovirus-induced hearing loss in mice. PLoS Pathog 2017; 13:e1006599. [PMID: 28859161 PMCID: PMC5597263 DOI: 10.1371/journal.ppat.1006599] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 09/13/2017] [Accepted: 08/22/2017] [Indexed: 11/25/2022] Open
Abstract
Congenital cytomegalovirus (CMV) infection is the most common non-hereditary cause of sensorineural hearing loss (SNHL) yet the mechanisms of hearing loss remain obscure. Natural Killer (NK) cells play a critical role in regulating murine CMV infection via NK cell recognition of the Ly49H cell surface receptor of the viral-encoded m157 ligand expressed at the infected cell surface. This Ly49H NK receptor/m157 ligand interaction has been found to mediate host resistance to CMV in the spleen, and lung, but is much less effective in the liver, so it is not known if this interaction is important in the context of SNHL. Using a murine model for CMV-induced labyrinthitis, we have demonstrated that the Ly49H/m157 interaction mediates host resistance in the temporal bone. BALB/c mice, which lack functional Ly49H, inoculated with mCMV at post-natal day 3 developed profound hearing loss and significant outer hair cell loss by 28 days of life. In contrast, C57BL/6 mice, competent for the Ly49H/m157 interaction, had minimal hearing loss and attenuated outer hair cell loss with the same mCMV dose. Administration of Ly49H blocking antibody or inoculation with a mCMV viral strain deleted for the m157 gene rendered the previously resistant C57BL/6 mouse strain susceptible to hearing loss to a similar extent as the BALB/c mouse strain indicating a direct role of the Ly49H/m157 interaction in mCMV-dependent hearing loss. Additionally, NK cell recruitment to sites of infection was evident in the temporal bone of inoculated susceptible mouse strains. These results demonstrate participation of NK cells in protection from CMV-induced labyrinthitis and SNHL in mice. Cytomegalovirus (CMV) transmission from an infected mother to her fetus is a leading cause of permanent hearing loss in children, but the contributing processes are not clear. In this report, we utilized a mouse model, which recapitulates many features of congenital CMV mediated childhood hearing loss, to demonstrate that natural killer cells (NK), a component of early host immune response to infection, play a critical protective role in CMV-induced hearing loss. Specifically, we determined that NK cells interact with CMV infected cells through binding of the NK cell receptor, Ly49H, with a virally-encoded protein, m157, expressed on the cell surface of CMV infected inner ear cells, to mediate the protective effect. Findings from this study provide insight into the host immune response during CMV-induced hearing loss in mice.
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Affiliation(s)
- Ali A. Almishaal
- Department of Communication Sciences and Disorders, University of Utah College of Health, Salt Lake City, Utah, United States of America
| | - Pranav D. Mathur
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Elaine Hillas
- Department of Surgery, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Liting Chen
- Division of Otolaryngology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Anne Zhang
- Division of Otolaryngology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Yong Wang
- Division of Otolaryngology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Wayne M. Yokoyama
- Division of Rheumatology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Matthew A. Firpo
- Department of Surgery, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- * E-mail:
| | - Albert H. Park
- Division of Otolaryngology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
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27
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Lee C, Holt JC, Jones TA. Effect of M-current modulation on mammalian vestibular responses to transient head motion. J Neurophysiol 2017; 118:2991-3006. [PMID: 28855291 DOI: 10.1152/jn.00384.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/25/2017] [Accepted: 08/25/2017] [Indexed: 12/26/2022] Open
Abstract
The precise role and mechanisms underlying efferent modulation of peripheral vestibular afferent function are not well understood in mammals. Clarifying the details of efferent action may lead to new strategies for clinical management of debilitating disturbances in vestibular and balance function. Recent evidence in turtle indicates that efferent modulation of M-currents is likely one mechanism for modifying afferent discharge. M-currents depend in part on KCNQ potassium conductances (Kv7), which can be adjusted through efferent activation of M1, M3, and/or M5 muscarinic acetylcholine receptors (mAChRs). How KCNQ channels and altered M-currents affect vestibular afferent function in vivo is unclear, and whether such a mechanism operates in mammals is unknown. In this study we used the KCNQ antagonist XE991 and the KCNQ activator retigabine in anesthetized mice to evaluate the effects of M-current modulation on peripheral vestibular responses to transient head motion. At low doses of XE991, responses were modestly enhanced, becoming larger in amplitude and shorter in latency. Higher doses of XE991 produced transient response enhancement, followed by steady-state suppression where latencies and thresholds increased and amplitudes decreased. Retigabine produced opposite effects. Auditory function was also impacted, based on results of companion auditory brain stem response testing. We propose that closure of KCNQ channels transforms vestibular afferent behavior by suppressing responses to transient high-frequency stimuli while simultaneously enhancing responses to sustained low-frequency stimulation. Our results clearly demonstrate that KCNQ channels are critical for normal mammalian vestibular function and suggest that efferent action may utilize these mechanisms to modulate the dynamic characteristics and gain of vestibular afferent responses.NEW & NOTEWORTHY The role of calyceal KCNQ channels and associated M-current in normal mammalian vestibular function is unknown. Our results show that calyceal KCNQ channels are critical for normal vestibular function in the intact mammal. The findings provide evidence that efferent modulation of M-currents may act normally to differentially adjust the sensitivity of vestibular neurons to transient and tonic stimulation and that such mechanisms may be targeted to achieve effective clinical management of vestibular disorders.
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Affiliation(s)
- Choongheon Lee
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska; and
| | - J Chris Holt
- Department of Otolaryngology, Department of Neuroscience, and Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York
| | - Timothy A Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska; and
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28
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Gene Therapy Restores Balance and Auditory Functions in a Mouse Model of Usher Syndrome. Mol Ther 2017; 25:780-791. [PMID: 28254438 DOI: 10.1016/j.ymthe.2017.01.007] [Citation(s) in RCA: 120] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 01/03/2017] [Accepted: 01/06/2017] [Indexed: 12/15/2022] Open
Abstract
Dizziness and hearing loss are among the most common disabilities. Many forms of hereditary balance and hearing disorders are caused by abnormal development of stereocilia, mechanosensory organelles on the apical surface of hair cells in the inner ear. The deaf whirler mouse, a model of human Usher syndrome (manifested by hearing loss, dizziness, and blindness), has a recessive mutation in the whirlin gene, which renders hair cell stereocilia short and dysfunctional. In this study, wild-type whirlin cDNA was delivered to the inner ears of neonatal whirler mice using adeno-associated virus serotype 2/8 (AAV8-whirlin) by injection into the posterior semicircular canal. Unilateral whirlin gene therapy injection was able to restore balance function as well as improve hearing in whirler mice for at least 4 months. Our data indicate that gene therapy is likely to become a treatment option for hereditary disorders of balance and hearing.
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29
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Alternative Splice Forms Influence Functions of Whirlin in Mechanosensory Hair Cell Stereocilia. Cell Rep 2016; 15:935-943. [PMID: 27117407 PMCID: PMC4859837 DOI: 10.1016/j.celrep.2016.03.081] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 02/18/2016] [Accepted: 03/22/2016] [Indexed: 11/23/2022] Open
Abstract
WHRN (DFNB31) mutations cause diverse hearing disorders: profound deafness (DFNB31) or variable hearing loss in Usher syndrome type II. The known role of WHRN in stereocilia elongation does not explain these different pathophysiologies. Using spontaneous and targeted Whrn mutants, we show that the major long (WHRN-L) and short (WHRN-S) isoforms of WHRN have distinct localizations within stereocilia and also across hair cell types. Lack of both isoforms causes abnormally short stereocilia and profound deafness and vestibular dysfunction. WHRN-S expression, however, is sufficient to maintain stereocilia bundle morphology and function in a subset of hair cells, resulting in some auditory response and no overt vestibular dysfunction. WHRN-S interacts with EPS8, and both are required at stereocilia tips for normal length regulation. WHRN-L localizes midway along the shorter stereocilia, at the level of inter-stereociliary links. We propose that differential isoform expression underlies the variable auditory and vestibular phenotypes associated with WHRN mutations. Major WHRN isoforms WHRN-S and WHRN-L have distinct localizations within stereocilia Lack of WHRN-S and WHRN-L causes short stereocilia bundles and profound deafness In absence of WHRN-L, WHRN-S can preserve stereocilia length in certain hair cells Differential isoform expression underlies distinct phenotypes of known Whrn mutations
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30
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Miyasaka Y, Shitara H, Suzuki S, Yoshimoto S, Seki Y, Ohshiba Y, Okumura K, Taya C, Tokano H, Kitamura K, Takada T, Hibino H, Shiroishi T, Kominami R, Yonekawa H, Kikkawa Y. Heterozygous mutation of Ush1g/Sans in mice causes early-onset progressive hearing loss, which is recovered by reconstituting the strain-specific mutation in Cdh23. Hum Mol Genet 2016; 25:2045-2059. [PMID: 26936824 DOI: 10.1093/hmg/ddw078] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 02/29/2016] [Indexed: 12/21/2022] Open
Abstract
Most clinical reports have suggested that patients with congenital profound hearing loss have recessive mutations in deafness genes, whereas dominant alleles are associated with progressive hearing loss (PHL). Jackson shaker (Ush1gjs) is a mouse model of recessive deafness that exhibits congenital profound deafness caused by the homozygous mutation of Ush1g/Sans on chromosome 11. We found that C57BL/6J-Ush1gjs/+ heterozygous mice exhibited early-onset PHL (ePHL) accompanied by progressive degeneration of stereocilia in the cochlear outer hair cells. Interestingly, ePHL did not develop in mutant mice with the C3H/HeN background, thus suggesting that other genetic factors are required for ePHL development. Therefore, we performed classical genetic analyses and found that the occurrence of ePHL in Ush1gjs/+ mice was associated with an interval in chromosome 10 that contains the cadherin 23 gene (Cdh23), which is also responsible for human deafness. To confirm this mutation effect, we generated C57BL/6J-Ush1gjs/+, Cdh23c.753A/G double-heterozygous mice by using the CRISPR/Cas9-mediated Cdh23c.753A>G knock-in method. The Cdh23c.753A/G mice harbored a one-base substitution (A for G), and the homozygous A allele caused moderate hearing loss with aging. Analyses revealed the complete recovery of ePHL and stereocilia degeneration in C57BL/6J-Ush1gjs/+ mice. These results clearly show that the development of ePHL requires at least two mutant alleles of the Ush1g and Cdh23 genes. Our results also suggest that because the SANS and CDH23 proteins form a complex in the stereocilia, the interaction between these proteins may play key roles in the maintenance of stereocilia and the prevention of ePHL.
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Affiliation(s)
- Yuki Miyasaka
- Mammalian Genetics Project, Graduate School of Medical and Dental Sciences
| | - Hiroshi Shitara
- Laboratory for Transgenic Technology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | | | - Sachi Yoshimoto
- Laboratory for Transgenic Technology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | | | - Yasuhiro Ohshiba
- Mammalian Genetics Project, Graduate School of Medical and Dental Sciences
| | - Kazuhiro Okumura
- Division of Oncogenomics, Cancer Genome Center, Chiba Cancer Center Research Institute, Chiba 260-0801, Japan
| | - Choji Taya
- Laboratory for Transgenic Technology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Hisashi Tokano
- Department of Otolaryngology, Tokyo Medical and Dental University, Tokyo 113-0034, Japan and
| | - Ken Kitamura
- Department of Otolaryngology, Tokyo Medical and Dental University, Tokyo 113-0034, Japan and
| | - Toyoyuki Takada
- Mammalian Genetics Laboratory, National Institute of Genetics, Mishima 411-8540, Japan
| | - Hiroshi Hibino
- Department of Molecular Physiology, Niigata University School of Medicine, Niigata 951-8510, Japan
| | - Toshihiko Shiroishi
- Mammalian Genetics Laboratory, National Institute of Genetics, Mishima 411-8540, Japan
| | | | - Hiromichi Yonekawa
- Laboratory for Transgenic Technology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Yoshiaki Kikkawa
- Mammalian Genetics Project, Graduate School of Medical and Dental Sciences,
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Mathur PD, Vijayakumar S, Vashist D, Jones SM, Jones TA, Yang J. A study of whirlin isoforms in the mouse vestibular system suggests potential vestibular dysfunction in DFNB31-deficient patients. Hum Mol Genet 2015; 24:7017-30. [PMID: 26420843 DOI: 10.1093/hmg/ddv403] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 09/21/2015] [Indexed: 11/12/2022] Open
Abstract
The DFNB31 gene plays an indispensable role in the cochlea and retina. Mutations in this gene disrupt its various isoforms and lead to non-syndromic deafness, blindness and deaf-blindness. However, the known expression of Dfnb31, the mouse ortholog of DFNB31, in vestibular organs and the potential vestibular-deficient phenotype observed in one Dfnb31 mutant mouse (Dfnb31(wi/wi)) suggest that DFNB31 may also be important for vestibular function. In this study, we find that full-length (FL-) and C-terminal (C-) whirlin isoforms are expressed in the vestibular organs, where their stereociliary localizations are similar to those of developing cochlear inner hair cells. No whirlin is detected in Dfnb31(wi/wi) vestibular organs, while only C-whirlin is expressed in Dfnb31(neo/neo) vestibular organs. Both FL- and C-whirlin isoforms are required for normal vestibular stereociliary growth, although they may play slightly different roles in the central and peripheral zones of the crista ampullaris. Vestibular sensory-evoked potentials demonstrate severe to profound vestibular deficits in Dfnb31(neo/neo) and Dfnb31(wi/wi) mice. Swimming and rotarod tests demonstrate that the two Dfnb31 mutants have balance problems, with Dfnb31(wi/wi) mice being more affected than Dfnb31(neo/neo) mice. Because Dfnb31(wi/wi) and Dfnb31(neo/neo) mice faithfully recapitulate hearing and vision symptoms in patients, our findings of vestibular dysfunction in these Dfnb31 mutants raise the question of whether DFNB31-deficient patients may acquire vestibular as well as hearing and vision loss.
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Affiliation(s)
- Pranav Dinesh Mathur
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA, Department of Neurobiology and Anatomy, University of Utah, 20 North 1900 East, Salt Lake City, UT 84132, USA
| | - Sarath Vijayakumar
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, 304 Barkley Memorial Center, Lincoln, NE 68583, USA and
| | - Deepti Vashist
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA
| | - Sherri M Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, 304 Barkley Memorial Center, Lincoln, NE 68583, USA and
| | - Timothy A Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, 304 Barkley Memorial Center, Lincoln, NE 68583, USA and
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA, Department of Neurobiology and Anatomy, University of Utah, 20 North 1900 East, Salt Lake City, UT 84132, USA, Division of Otolaryngology, Department of Surgery, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA
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32
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Zou J, Mathur PD, Zheng T, Wang Y, Almishaal A, Park AH, Yang J. Individual USH2 proteins make distinct contributions to the ankle link complex during development of the mouse cochlear stereociliary bundle. Hum Mol Genet 2015; 24:6944-57. [PMID: 26401052 DOI: 10.1093/hmg/ddv398] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 09/21/2015] [Indexed: 11/14/2022] Open
Abstract
Usher syndrome (USH) is the leading cause of inherited deaf-blindness, with type 2 (USH2) being the most common clinical form. Studies suggest that proteins encoded by USH2 causative genes assemble into the ankle link complex (ALC) at the hair cell stereociliary bundle; however, little is known about the in vivo assembly and function of this complex. Using various USH2 mutant mice, we showed by immunofluorescence that USH2 proteins play different roles in cochlear ALC assembly, with G protein-coupled receptor 98 being the most important protein. Complex assembly likely occurs at the stereociliary bundle but not along the protein transport route in the cell body. Stereociliary morphological defects in USH2 mutant mice suggest roles for the ALC in regulating inner hair cell stereociliary growth and differentiation as well as outer hair cell stereociliary rigidity and organization during development. These roles are unique from the bundle cohesion role of Usher syndrome type 1 protein complexes. Loss of individual USH2 gene expressions leads to variable morphological and functional consequences, correlating with the severity of ALC disruption. This finding suggests a potential genotype-phenotype correlation in USH2 patients. In summary, this study provides novel insights into the molecular mechanism underlying cochlear stereociliary bundle development and hearing loss pathogenesis of various USH2 subtypes. Our thorough phenotypical characterization of USH2 mouse models is essential for future use of these animal models in therapeutic development.
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Affiliation(s)
- Junhuang Zou
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA
| | - Pranav D Mathur
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA, Department of Neurobiology and Anatomy, University of Utah, 20 North 1900 East, Salt Lake City, UT 84132, USA
| | - Tihua Zheng
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA
| | - Yong Wang
- Division of Otolaryngology, Department of Surgery, University of Utah, 30 North 1900 East, Salt Lake City, UT 84132, USA and
| | - Ali Almishaal
- Department of Communication Sciences and Disorders, University of Utah, 390 South 1530 East, Salt Lake City, UT 84112, USA
| | - Albert H Park
- Division of Otolaryngology, Department of Surgery, University of Utah, 30 North 1900 East, Salt Lake City, UT 84132, USA and
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA, Department of Neurobiology and Anatomy, University of Utah, 20 North 1900 East, Salt Lake City, UT 84132, USA, Division of Otolaryngology, Department of Surgery, University of Utah, 30 North 1900 East, Salt Lake City, UT 84132, USA and
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