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Watanabe K, Nishio SY, Usami SI. The prevalence and clinical features of MYO7A-related hearing loss including DFNA11, DFNB2 and USH1B. Sci Rep 2024; 14:8326. [PMID: 38594301 PMCID: PMC11003999 DOI: 10.1038/s41598-024-57415-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/18/2024] [Indexed: 04/11/2024] Open
Abstract
The MYO7A gene is known to be responsible for both syndromic hearing loss (Usher syndrome type1B:USH1B) and non-syndromic hearing loss including autosomal dominant and autosomal recessive inheritance (DFNA11, DFNB2). However, the prevalence and detailed clinical features of MYO7A-associated hearing loss across a large population remain unclear. In this study, we conducted next-generation sequencing analysis for a large cohort of 10,042 Japanese hearing loss patients. As a result, 137 patients were identified with MYO7A-associated hearing loss so that the prevalence among Japanese hearing loss patients was 1.36%. We identified 70 disease-causing candidate variants in this study, with 36 of them being novel variants. All variants identified in autosomal dominant cases were missense or in-frame deletion variants. Among the autosomal recessive cases, all patients had at least one missense variant. On the other hand, in patients with Usher syndrome, almost half of the patients carried biallelic null variants (nonsense, splicing, and frameshift variants). Most of the autosomal dominant cases showed late-onset progressive hearing loss. On the other hand, cases with autosomal recessive inheritance or Usher syndrome showed congenital or early-onset hearing loss. The visual symptoms in the Usher syndrome cases developed between age 5-15, and the condition was diagnosed at about 6-15 years of age.
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Affiliation(s)
- Kizuki Watanabe
- Department of Otorhinolaryngology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Japan
| | - Shin-Ya Nishio
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan
| | - Shin-Ichi Usami
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
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2
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Melrose J. Keratan sulfate, an electrosensory neurosentient bioresponsive cell instructive glycosaminoglycan. Glycobiology 2024; 34:cwae014. [PMID: 38376199 PMCID: PMC10987296 DOI: 10.1093/glycob/cwae014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 02/21/2024] Open
Abstract
The roles of keratan sulfate (KS) as a proton detection glycosaminoglycan in neurosensory processes in the central and peripheral nervous systems is reviewed. The functional properties of the KS-proteoglycans aggrecan, phosphacan, podocalyxcin as components of perineuronal nets in neurosensory processes in neuronal plasticity, cognitive learning and memory are also discussed. KS-glycoconjugate neurosensory gels used in electrolocation in elasmobranch fish species and KS substituted mucin like conjugates in some tissue contexts in mammals need to be considered in sensory signalling. Parallels are drawn between KS's roles in elasmobranch fish neurosensory processes and its roles in mammalian electro mechanical transduction of acoustic liquid displacement signals in the cochlea by the tectorial membrane and stereocilia of sensory inner and outer hair cells into neural signals for sound interpretation. The sophisticated structural and functional proteins which maintain the unique high precision physical properties of stereocilia in the detection, transmittance and interpretation of acoustic signals in the hearing process are important. The maintenance of the material properties of stereocilia are essential in sound transmission processes. Specific, emerging roles for low sulfation KS in sensory bioregulation are contrasted with the properties of high charge density KS isoforms. Some speculations are made on how the molecular and electrical properties of KS may be of potential application in futuristic nanoelectronic, memristor technology in advanced ultrafast computing devices with low energy requirements in nanomachines, nanobots or molecular switches which could be potentially useful in artificial synapse development. Application of KS in such innovative areas in bioregulation are eagerly awaited.
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Affiliation(s)
- James Melrose
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW 2052, Australia
- Raymond Purves Laboratory, Institute of Bone and Joint Research, Kolling Institute of Medical Research, Northern Sydney Local Health District, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia
- Sydney Medical School, Northern, University of Sydney at Royal North Shore Hospital, St. Leonards, NSW 2065, Australia
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Li N, Liu S, Zhao D, Du H, Xi Y, Wei X, Liu Q, Müller U, Lu Q, Xiong W, Xu Z. Disruption of Cdh23 exon 68 splicing leads to progressive hearing loss in mice by affecting tip-link stability. Proc Natl Acad Sci U S A 2024; 121:e2309656121. [PMID: 38408254 PMCID: PMC10927504 DOI: 10.1073/pnas.2309656121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 12/21/2023] [Indexed: 02/28/2024] Open
Abstract
Inner ear hair cells are characterized by the F-actin-based stereocilia that are arranged into a staircase-like pattern on the apical surface of each hair cell. The tips of shorter-row stereocilia are connected with the shafts of their neighboring taller-row stereocilia through extracellular links named tip links, which gate mechano-electrical transduction (MET) channels in hair cells. Cadherin 23 (CDH23) forms the upper part of tip links, and its cytoplasmic tail is inserted into the so-called upper tip-link density (UTLD) that contains other proteins such as harmonin. The Cdh23 gene is composed of 69 exons, and we show here that exon 68 is subjected to hair cell-specific alternative splicing. Tip-link formation is not affected in genetically modified mutant mice lacking Cdh23 exon 68. Instead, the stability of tip links is compromised in the mutants, which also suffer from progressive and noise-induced hearing loss. Moreover, we show that the cytoplasmic tail of CDH23(+68) but not CDH23(-68) cooperates with harmonin in phase separation-mediated condensate formation. In conclusion, our work provides evidence that inclusion of Cdh23 exon 68 is critical for the stability of tip links through regulating condensate formation of UTLD components.
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Affiliation(s)
- Nana Li
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong266237, China
| | - Shuang Liu
- Chinese Institute for Brain Research, Beijing102206, China
| | - Dange Zhao
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai200030, China
| | - Haibo Du
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong266237, China
| | - Yuehui Xi
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong266237, China
| | - Xiaoxi Wei
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai200030, China
| | - Qingling Liu
- Chinese Institute for Brain Research, Beijing102206, China
| | - Ulrich Müller
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD21205
| | - Qing Lu
- Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Bio-X Institutes, Shanghai Jiao Tong University, Shanghai200030, China
| | - Wei Xiong
- Chinese Institute for Brain Research, Beijing102206, China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong266237, China
- Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, Shandong250014, China
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Wang Y, Zhang C, Peng W, Du H, Xi Y, Xu Z. RBM24 is required for mouse hair cell development through regulating pre-mRNA alternative splicing and mRNA stability. J Cell Physiol 2023; 238:1095-1110. [PMID: 36947695 DOI: 10.1002/jcp.31003] [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: 12/30/2022] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 03/24/2023]
Abstract
As the sensory receptor cells in vertebrate inner ear and lateral lines, hair cells are characterized by the hair bundle that consists of one tubulin-based kinocilium and dozens of actin-based stereocilia on the apical surface of each hair cell. Hair cell development is tightly regulated, and deficits in this process usually lead to hearing loss and/or balance dysfunctions. RNA-binding motif protein 24 (RBM24) is an RNA-binding protein that is specifically expressed in the hair cells in the inner ear. Previously, we showed that RBM24 affects hair cell development in zebrafish by regulating messenger RNA (mRNA) stability. In the present work, we further investigate the role of RBM24 in hearing and balance using conditional knockout mice. Our results show that Rbm24 knockout results in severe hearing and balance deficits. Hair cell development is significantly affected in Rbm24 knockout cochlea, as the hair bundles are poorly developed and eventually degenerated. Hair bundle disorganization is also observed in Rbm24 knockout vestibular hair cells, although to a lesser extent. Consistently, significant hair cell loss is observed in the cochlea but not vestibule. RNAseq analysis identified several genes whose mRNA stability or pre-mRNA alternative splicing is affected by Rbm24 knockout. Among them are Cdh23, Pcdh15, and Myo7a, which have been shown to play important roles in stereocilia development as well as mechano-electrical transduction. Taken together, our present work suggests that RBM24 is required for mouse hair cell development through regulating pre-mRNA alternative splicing as well as mRNA stability.
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Affiliation(s)
- Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Cuiqiao Zhang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Wu Peng
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Haibo Du
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Yuehui Xi
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
- Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, Shandong, China
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Nagel-Wolfrum K, Fadl BR, Becker MM, Wunderlich KA, Schäfer J, Sturm D, Fritze J, Gür B, Kaplan L, Andreani T, Goldmann T, Brooks M, Starostik MR, Lokhande A, Apel M, Fath KR, Stingl K, Kohl S, DeAngelis MM, Schlötzer-Schrehardt U, Kim IK, Owen LA, Vetter JM, Pfeiffer N, Andrade-Navarro MA, Grosche A, Swaroop A, Wolfrum U. Expression and subcellular localization of USH1C/harmonin in human retina provides insights into pathomechanisms and therapy. Hum Mol Genet 2023; 32:431-449. [PMID: 35997788 PMCID: PMC9851744 DOI: 10.1093/hmg/ddac211] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/18/2022] [Accepted: 08/19/2022] [Indexed: 01/24/2023] Open
Abstract
Usher syndrome (USH) is the most common form of hereditary deaf-blindness in humans. USH is a complex genetic disorder, assigned to three clinical subtypes differing in onset, course and severity, with USH1 being the most severe. Rodent USH1 models do not reflect the ocular phenotype observed in human patients to date; hence, little is known about the pathophysiology of USH1 in the human eye. One of the USH1 genes, USH1C, exhibits extensive alternative splicing and encodes numerous harmonin protein isoforms that function as scaffolds for organizing the USH interactome. RNA-seq analysis of human retinae uncovered harmonin_a1 as the most abundant transcript of USH1C. Bulk RNA-seq analysis and immunoblotting showed abundant expression of harmonin in Müller glia cells (MGCs) and retinal neurons. Furthermore, harmonin was localized in the terminal endfeet and apical microvilli of MGCs, presynaptic region (pedicle) of cones and outer segments (OS) of rods as well as at adhesive junctions between MGCs and photoreceptor cells (PRCs) in the outer limiting membrane (OLM). Our data provide evidence for the interaction of harmonin with OLM molecules in PRCs and MGCs and rhodopsin in PRCs. Subcellular expression and colocalization of harmonin correlate with the clinical phenotype observed in USH1C patients. We also demonstrate that primary cilia defects in USH1C patient-derived fibroblasts could be reverted by the delivery of harmonin_a1 transcript isoform. Our studies thus provide novel insights into PRC cell biology, USH1C pathophysiology and development of gene therapy treatment(s).
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Affiliation(s)
- Kerstin Nagel-Wolfrum
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Benjamin R Fadl
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mirjana M Becker
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Kirsten A Wunderlich
- Department of Physiological Genomics, BioMedical Center, Ludwig-Maximilian University Munich, 82152 Planegg-Martinsried, Germany
| | - Jessica Schäfer
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Daniel Sturm
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Jacques Fritze
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Burcu Gür
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Lew Kaplan
- Department of Physiological Genomics, BioMedical Center, Ludwig-Maximilian University Munich, 82152 Planegg-Martinsried, Germany
| | - Tommaso Andreani
- Computational Biology and Data Mining, Institute of Organismic & Molecular Evolution Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Tobias Goldmann
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Matthew Brooks
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Margaret R Starostik
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anagha Lokhande
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Melissa Apel
- Department of Ophthalmology, University Medical Centre Mainz, 55131 Mainz, Germany
| | - Karl R Fath
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
- Department of Biology, Queens College of CUNY, Kissena Blvd, Flushing, NY 11367, USA
| | - Katarina Stingl
- University Eye Hospital, Centre for Ophthalmology, University of Tubingen, 72076 Tubingen, Germany
| | - Susanne Kohl
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tubingen, 72076 Tubingen, Germany
| | - Margaret M DeAngelis
- Department of Ophthalmology and Ira G. Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University of Buffalo, NY 14209, USA
| | | | - Ivana K Kim
- Retina Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
| | - Leah A Owen
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT 84132, USA
| | - Jan M Vetter
- Department of Ophthalmology, University Medical Centre Mainz, 55131 Mainz, Germany
| | - Norbert Pfeiffer
- Department of Ophthalmology, University Medical Centre Mainz, 55131 Mainz, Germany
| | - Miguel A Andrade-Navarro
- Computational Biology and Data Mining, Institute of Organismic & Molecular Evolution Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Antje Grosche
- Department of Physiological Genomics, BioMedical Center, Ludwig-Maximilian University Munich, 82152 Planegg-Martinsried, Germany
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Uwe Wolfrum
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
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6
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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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Li J. Liquid-liquid phase separation in hair cell stereocilia development and maintenance. Comput Struct Biotechnol J 2023; 21:1738-1745. [PMID: 36890881 PMCID: PMC9986246 DOI: 10.1016/j.csbj.2023.02.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/22/2023] [Accepted: 02/22/2023] [Indexed: 03/03/2023] Open
Abstract
As an emerging concept, liquid-liquid phase separation (LLPS) in biological systems has shed light on the formation mechanisms of membrane-less compartments in cells. The process is driven by multivalent interactions of biomolecules such as proteins and/or nucleic acids, allowing them to form condensed structures. In the inner ear hair cells, LLPS-based biomolecular condensate assembly plays a vital role in the development and maintenance of stereocilia, the mechanosensing organelles located at the apical surface of hair cells. This review aims to summarize recent findings on the molecular basis governing the LLPS of Usher syndrome-related gene-encoding proteins and their binding partners, which may ultimately result in the formation of upper tip-link density and tip complex density in hair cell stereocilia, offering a better understanding of this severe inherited disease that causes deaf-blindness.
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Affiliation(s)
- Jianchao Li
- Department of Otorhinolaryngology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou 510180, China.,Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, China
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Qiu X, Müller U. Sensing sound: Cellular specializations and molecular force sensors. Neuron 2022; 110:3667-3687. [PMID: 36223766 PMCID: PMC9671866 DOI: 10.1016/j.neuron.2022.09.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/03/2022] [Accepted: 09/14/2022] [Indexed: 11/08/2022]
Abstract
Organisms of all phyla express mechanosensitive ion channels with a wide range of physiological functions. In recent years, several classes of mechanically gated ion channels have been identified. Some of these ion channels are intrinsically mechanosensitive. Others depend on accessory proteins to regulate their response to mechanical force. The mechanotransduction machinery of cochlear hair cells provides a particularly striking example of a complex force-sensing machine. This molecular ensemble is embedded into a specialized cellular compartment that is crucial for its function. Notably, mechanotransduction channels of cochlear hair cells are not only critical for auditory perception. They also shape their cellular environment and regulate the development of auditory circuitry. Here, we summarize recent discoveries that have shed light on the composition of the mechanotransduction machinery of cochlear hair cells and how this machinery contributes to the development and function of the auditory system.
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Affiliation(s)
- Xufeng Qiu
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ulrich Müller
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Colcombet-Cazenave B, Druart K, Bonnet C, Petit C, Spérandio O, Guglielmini J, Wolff N. Phylogenetic analysis of Harmonin homology domains. BMC Bioinformatics 2021; 22:190. [PMID: 33853521 PMCID: PMC8048344 DOI: 10.1186/s12859-021-04116-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/24/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Harmonin Homogy Domains (HHD) are recently identified orphan domains of about 70 residues folded in a compact five alpha-helix bundle that proved to be versatile in terms of function, allowing for direct binding to a partner as well as regulating the affinity and specificity of adjacent domains for their own targets. Adding their small size and rather simple fold, HHDs appear as convenient modules to regulate protein-protein interactions in various biological contexts. Surprisingly, only nine HHDs have been detected in six proteins, mainly expressed in sensory neurons. RESULTS Here, we built a profile Hidden Markov Model to screen the entire UniProtKB for new HHD-containing proteins. Every hit was manually annotated, using a clustering approach, confirming that only a few proteins contain HHDs. We report the phylogenetic coverage of each protein and build a phylogenetic tree to trace the evolution of HHDs. We suggest that a HHD ancestor is shared with Paired Amphipathic Helices (PAH) domains, a four-helix bundle partially sharing fold and functional properties. We characterized amino-acid sequences of the various HHDs using pairwise BLASTP scoring coupled with community clustering and manually assessed sequence features among each individual family. These sequence features were analyzed using reported structures as well as homology models to highlight structural motifs underlying HHDs fold. We show that functional divergence is carried out by subtle differences in sequences that automatized approaches failed to detect. CONCLUSIONS We provide the first HHD databases, including sequences and conservation, phylogenic trees and a list of HHD variants found in the auditory system, which are available for the community. This case study highlights surprising phylogenetic properties found in orphan domains and will assist further studies of HHDs. We unveil the implication of HHDs in their various binding interfaces using conservation across families and a new protein-protein surface predictor. Finally, we discussed the functional consequences of three identified pathogenic HHD variants involved in Hoyeraal-Hreidarsson syndrome and of three newly reported pathogenic variants identified in patients suffering from Usher Syndrome.
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Affiliation(s)
- Baptiste Colcombet-Cazenave
- Unité Récepteurs-Canaux, Institut Pasteur, 75015, Paris, France
- Collège Doctoral, Sorbonne Université, 75005, Paris, France
| | - Karen Druart
- Unité de Bio-Informatique Structurale, Institut Pasteur, 75015, Paris, France
| | - Crystel Bonnet
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015, Paris, France
- INSERM, Institut de l'Audition, Institut Pasteur, 75012, Paris, France
| | - Christine Petit
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015, Paris, France
- INSERM, Institut de l'Audition, Institut Pasteur, 75012, Paris, France
| | - Olivier Spérandio
- Unité de Bio-Informatique Structurale, Institut Pasteur, 75015, Paris, France
| | - Julien Guglielmini
- Hub de Bioinformatique et Biostatistique - Département Biologie Computationnelle, USR 3756 CNRS, Institut Pasteur, Paris, France
| | - Nicolas Wolff
- Unité Récepteurs-Canaux, Institut Pasteur, 75015, Paris, France.
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Spectrum of MYO7A Mutations in an Indigenous South African Population Further Elucidates the Nonsyndromic Autosomal Recessive Phenotype of DFNB2 to Include Both Homozygous and Compound Heterozygous Mutations. Genes (Basel) 2021; 12:genes12020274. [PMID: 33671976 PMCID: PMC7919343 DOI: 10.3390/genes12020274] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/20/2021] [Accepted: 01/21/2021] [Indexed: 11/17/2022] Open
Abstract
MYO7A gene encodes unconventional myosin VIIA, which, when mutated, causes a phenotypic spectrum ranging from recessive hearing loss DFNB2 to deaf-blindness, Usher Type 1B (USH1B). MYO7A mutations are reported in nine DFNB2 families to date, none from sub-Saharan Africa.In DNA, from a cohort of 94 individuals representing 92 families from the Limpopo province of South Africa, eight MYO7A variations were detected among 10 individuals. Family studies identified homozygous and compound heterozygous mutations in 17 individuals out of 32 available family members. Four mutations were novel, p.Gly329Asp, p.Arg373His, p.Tyr1780Ser, and p.Pro2126Leufs*5. Two variations, p.Ser617Pro and p.Thr381Met, previously listed as of uncertain significance (ClinVar), were confirmed to be pathogenic. The identified mutations are predicted to interfere with the conformational properties of myosin VIIA through interruption or abrogation of multiple interactions between the mutant and neighbouring residues. Specifically, p.Pro2126Leufs*5, is predicted to abolish the critical site for the interactions between the tail and the motor domain essential for the autoregulation, leaving a non-functional, unregulated protein that causes hearing loss. We have identified MYO7A as a possible key deafness gene among indigenous sub-Saharan Africans. The spectrum of MYO7A mutations in this South African population points to DFNB2 as a specific entity that may occur in a homozygous or in a compound heterozygous state.
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Bugge K, Staby L, Salladini E, Falbe-Hansen RG, Kragelund BB, Skriver K. αα-Hub domains and intrinsically disordered proteins: A decisive combo. J Biol Chem 2021; 296:100226. [PMID: 33361159 PMCID: PMC7948954 DOI: 10.1074/jbc.rev120.012928] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/22/2020] [Accepted: 12/22/2020] [Indexed: 01/02/2023] Open
Abstract
Hub proteins are central nodes in protein-protein interaction networks with critical importance to all living organisms. Recently, a new group of folded hub domains, the αα-hubs, was defined based on a shared αα-hairpin supersecondary structural foundation. The members PAH, RST, TAFH, NCBD, and HHD are found in large proteins such as Sin3, RCD1, TAF4, CBP, and harmonin, which organize disordered transcriptional regulators and membrane scaffolds in interactomes of importance to human diseases and plant quality. In this review, studies of structures, functions, and complexes across the αα-hubs are described and compared to provide a unified description of the group. This analysis expands the associated molecular concepts of "one domain-one binding site", motif-based ligand binding, and coupled folding and binding of intrinsically disordered ligands to additional concepts of importance to signal fidelity. These include context, motif reversibility, multivalency, complex heterogeneity, synergistic αα-hub:ligand folding, accessory binding sites, and supramodules. We propose that these multifaceted protein-protein interaction properties are made possible by the characteristics of the αα-hub fold, including supersite properties, dynamics, variable topologies, accessory helices, and malleability and abetted by adaptability of the disordered ligands. Critically, these features provide additional filters for specificity. With the presentations of new concepts, this review opens for new research questions addressing properties across the group, which are driven from concepts discovered in studies of the individual members. Combined, the members of the αα-hubs are ideal models for deconvoluting signal fidelity maintained by folded hubs and their interactions with intrinsically disordered ligands.
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Affiliation(s)
- Katrine Bugge
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark; Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lasse Staby
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark; Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Edoardo Salladini
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus G Falbe-Hansen
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Birthe B Kragelund
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark; Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
| | - Karen Skriver
- REPIN and The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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12
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Noman M, Bukhari SA, Rehman S, Qasim M, Ali M, Riazuddin S, Ahmed ZM. Identification and computational analysis of USH1C, and SLC26A4 variants in Pakistani families with prelingual hearing loss. Mol Biol Rep 2020; 47:9987-9993. [PMID: 33231815 PMCID: PMC10680121 DOI: 10.1007/s11033-020-06016-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 11/16/2020] [Indexed: 12/16/2022]
Abstract
Hearing loss (HL) is clinically and genetically heterogeneous disorder and is the most frequent occurring sensory deficit in humans. This study was conducted to decipher the genetic cause of HL occurring in two large consanguineous Pakistani families (GCNF-01, GCNF-03). Family history and pure tone audiometry of both families suggested prelingual HL, while the affected individuals of GCNF-01 also had low vision and balance problems, consistent with cardinal features of Usher syndrome type I (USH1). Exome sequencing followed by segregating analysis revealed a novel splice site variant (c.877-1G > A) of USH1C occurring with USH1 phenotype in family GCNF01. While the affected individual of family GCNF-03 were homozygous for the c.716 T > A, p.(Val239Asp) previously reported pathogenic variant of SLC26A4. Both variants have very low frequencies in control database. In silico mutagenesis and 3-dimensional simulation analyses revealed that both variants have deleterious impact on the proteins folding and secondary structures. Our study expands the mutation spectrum of the HL genes and emphasizes the utility of exome sequencing coupled with bioinformatics tools for clinical genetic diagnosis, prognosis, and family counseling.
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Affiliation(s)
- Muhammad Noman
- Department of Biochemistry, Government College University, Faisalabad, 38000, Pakistan
| | - Shazia A Bukhari
- Department of Biochemistry, Government College University, Faisalabad, 38000, Pakistan.
| | - Sakina Rehman
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Muhammad Qasim
- Department of Biotechnology, Government College University, Faisalabad, 38000, Pakistan
| | - Muhammad Ali
- Department of Animal Sciences, Quaid Azam University, Islamabad, 46000, Pakistan
| | - Saima Riazuddin
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Zubair M Ahmed
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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13
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He Y, Li J, Zhang M. Myosin VII, USH1C, and ANKS4B or USH1G Together Form Condensed Molecular Assembly via Liquid-Liquid Phase Separation. Cell Rep 2020; 29:974-986.e4. [PMID: 31644917 DOI: 10.1016/j.celrep.2019.09.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/18/2019] [Accepted: 09/11/2019] [Indexed: 01/01/2023] Open
Abstract
Hair cell stereocilia tip-links function to sense mechanical forces generated by sound waves and maintain the structure of stereocilia by rooting the tail of cadherins to highly dense structures known as tip-link densities. Although the molecular components are largely known, the mechanisms underlying the tip-link density formation are unknown. Here, we show that Myosin VIIB (MYO7B), USH1C, and ANKS4B, which form a specific complex stabilizing tip-links in intestine microvilli, could form dense condensates via liquid-liquid phase separation in vitro and in cells. The MYO7A, USH1C, and USH1G complex also undergoes phase separation in cells. Formation of the MYO7A/USH1C/USH1G and MYO7B/USH1C/ANKS4B condensates requires strong and multivalent interactions between proteins in both tripartite complexes. Point mutations of MYO7A found in Usher syndrome patients weaken or even disrupt the multivalent interactions of the MYO7A/USH1C/USH1G complex and impair its phase separation. Thus, the stereocilia tip-link densities may form via phase separation of the MYO7A/USH1C/USH1G complex.
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Affiliation(s)
- Yunyun He
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jianchao Li
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou 510006, China.
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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14
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Alternative Splicing of Cdh23 Exon 68 Is Regulated by RBM24, RBM38, and PTBP1. Neural Plast 2020; 2020:8898811. [PMID: 32774357 PMCID: PMC7397384 DOI: 10.1155/2020/8898811] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/19/2020] [Accepted: 07/01/2020] [Indexed: 01/08/2023] Open
Abstract
Alternative splicing plays a pivotal role in modulating the function of eukaryotic proteins. In the inner ear, many genes undergo alternative splicing, and errors in this process lead to hearing loss. Cadherin 23 (CDH23) forms part of the so-called tip links, which are indispensable for mechanoelectrical transduction (MET) in the hair cells. Cdh23 gene contains 69 exons, and exon 68 is subjected to alternative splicing. Exon 68 of the Cdh23 gene is spliced into its mRNA only in a few cell types including hair cells. The mechanism responsible for the alternative splicing of Cdh23 exon 68 remains elusive. In the present work, we performed a cell-based screening to look for splicing factors that regulate the splicing of Cdh23 exon 68. RBM24 and RBM38 were identified to enhance the inclusion of Cdh23 exon 68. The splicing of Cdh23 exon 68 is affected in Rbm24 knockdown or knockout cells. Moreover, we also found that PTBP1 inhibits the inclusion of Cdh23 exon 68. Taken together, we show here that alternative splicing of Cdh23 exon 68 is regulated by RBM24, RBM38, and PTBP1.
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15
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Song JS, Bahloul A, Petit C, Kim SJ, Moon IJ, Lee J, Ki CS. A Novel Heterozygous Missense Variant (c.667G>T;p.Gly223Cys) in USH1C That Interferes With Cadherin-Related 23 and Harmonin Interaction Causes Autosomal Dominant Nonsyndromic Hearing Loss. Ann Lab Med 2020; 40:224-231. [PMID: 31858762 PMCID: PMC6933062 DOI: 10.3343/alm.2020.40.3.224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/23/2019] [Accepted: 11/26/2019] [Indexed: 01/28/2023] Open
Abstract
Background Pathogenic variants of USH1C, encoding a PDZ-domain-containing protein called harmonin, have been known to cause autosomal recessive syndromic or nonsyndromic hearing loss (NSHL). We identified a causative gene in a large Korean family with NSHL showing a typical pattern of autosomal dominant (AD) inheritance. Methods Exome sequencing was performed for five affected and three unaffected individuals in this family. Following identification of a candidate gene variant, segregation analysis and functional studies, including circular dichroism and biolayer interferometry experiments, were performed. Results A novel USH1C heterozygous missense variant (c.667G>T;p.Gly223Cys) was shown to segregate with the NSHL phenotype in this family. This variant affects an amino acid residue located in the highly conserved carboxylate-binding loop of the harmonin PDZ2 domain and is predicted to disturb the interaction with cadherin-related 23 (cdh23). The affinity of the variant PDZ2 domain for a biotinylated synthetic peptide containing the PDZ-binding motif of cdh23 was approximately 16-fold lower than that of the wild-type PDZ2 domain and that this inaccessibility of the binding site was caused by a conformational change in the variant PDZ2 domain. Conclusions A heterozygous variant of USH1C that interferes with the interaction between cdh23 and harmonin causes novel AD-NSHL.
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Affiliation(s)
| | - Amel Bahloul
- Unité de génétique et physiologie de l'audition, Institut Pasteur, Paris, France.,UMRS 1120, Inserm, Paris, France.,Sorbonne Universités, Paris, France.,Department of Otolaryngology - Head and Neck Surgery, Stanford University, Stanford, California, USA
| | - Christine Petit
- Unité de génétique et physiologie de l'audition, Institut Pasteur, Paris, France.,UMRS 1120, Inserm, Paris, France.,Sorbonne Universités, Paris, France.,College de France and Institut Pasteur, Paris, France
| | - Sang Jin Kim
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Il Joon Moon
- Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jinhyuk Lee
- Korean Bioinformation Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea.,Department of Bioinformatics, University of Sciences and Technology, Daejeon, Korea
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16
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Kim S, Kalappurakkal JM, Mayor S, Rosen MK. Phosphorylation of nephrin induces phase separated domains that move through actomyosin contraction. Mol Biol Cell 2019; 30:2996-3012. [PMID: 31599693 PMCID: PMC6857567 DOI: 10.1091/mbc.e18-12-0823] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 09/03/2019] [Accepted: 10/03/2019] [Indexed: 01/12/2023] Open
Abstract
The plasma membrane of eukaryotic cells is organized into lipid and protein microdomains, whose assembly mechanisms and functions are incompletely understood. We demonstrate that proteins in the nephrin/Nck/N-WASP actin-regulatory pathway cluster into micron-scale domains at the basal plasma membrane upon triggered phosphorylation of transmembrane protein nephrin. The domains are persistent but readily exchange components with their surroundings, and their formation is dependent on the number of Nck SH3 domains, suggesting they are phase separated polymers assembled through multivalent interactions among the three proteins. The domains form independent of the actin cytoskeleton, but acto-myosin contractility induces their rapid lateral movement. Nephrin phosphorylation induces larger clusters at the cell periphery, which are associated with extensive actin assembly and dense filopodia. Our studies illustrate how multivalent interactions between proteins at the plasma membrane can produce micron-scale organization of signaling molecules, and how the resulting clusters can both respond to and control the actin cytoskeleton.
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Affiliation(s)
- Soyeon Kim
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
- The HHMI/MBL Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543
| | - Joseph M. Kalappurakkal
- The HHMI/MBL Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543
- National Centre for Biological Sciences, Bangalore 560065, India
| | - Satyajit Mayor
- The HHMI/MBL Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543
- National Centre for Biological Sciences, Bangalore 560065, India
| | - Michael K. Rosen
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
- The HHMI/MBL Summer Institute, Marine Biological Laboratory, Woods Hole, MA 02543
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17
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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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18
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Jaiganesh A, Narui Y, Araya-Secchi R, Sotomayor M. Beyond Cell-Cell Adhesion: Sensational Cadherins for Hearing and Balance. Cold Spring Harb Perspect Biol 2018; 10:a029280. [PMID: 28847902 PMCID: PMC6008173 DOI: 10.1101/cshperspect.a029280] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cadherins form a large family of proteins often involved in calcium-dependent cellular adhesion. Although classical members of the family can provide a physical bond between cells, a subset of special cadherins use their extracellular domains to interlink apical specializations of single epithelial sensory cells. Two of these cadherins, cadherin-23 (CDH23) and protocadherin-15 (PCDH15), form extracellular "tip link" filaments that connect apical bundles of stereocilia on hair cells essential for inner-ear mechanotransduction. As these bundles deflect in response to mechanical stimuli from sound or head movements, tip links gate hair-cell mechanosensitive channels to initiate sensory perception. Here, we review the unusual and diverse structural properties of these tip-link cadherins and the functional significance of their deafness-related missense mutations. Based on the structural features of CDH23 and PCDH15, we discuss the elasticity of tip links and models that bridge the gap between the nanomechanics of cadherins and the micromechanics of hair-cell bundles during inner-ear mechanotransduction.
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Affiliation(s)
- Avinash Jaiganesh
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Yoshie Narui
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Raul Araya-Secchi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
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19
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Jaiganesh A, De-la-Torre P, Patel AA, Termine DJ, Velez-Cortes F, Chen C, Sotomayor M. Zooming in on Cadherin-23: Structural Diversity and Potential Mechanisms of Inherited Deafness. Structure 2018; 26:1210-1225.e4. [PMID: 30033219 DOI: 10.1016/j.str.2018.06.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 03/22/2018] [Accepted: 06/08/2018] [Indexed: 12/18/2022]
Abstract
Cadherin-23 (CDH23) is an essential component of hair-cell tip links, fine filaments that mediate inner-ear mechanotransduction. The extracellular domain of CDH23 forms about three-fourths of the tip link with 27 extracellular cadherin (EC) repeats that are structurally similar but not identical to each other. Calcium (Ca2+) coordination at the EC linker regions is key for tip-link elasticity and function. There are ∼116 sites in CDH23 affected by deafness-causing mutations, many of which alter conserved Ca2+-binding residues. Here we present crystal structures showing 18 CDH23 EC repeats, including the most and least conserved, a fragment carrying disease mutations, and EC repeats with non-canonical Ca2+-binding motif sequences and unusual secondary structure. Complementary experiments show deafness mutations' effects on stability and affinity for Ca2+. Additionally, a model of nine contiguous CDH23 EC repeats reveals helicity and potential parallel dimerization faces. Overall, our studies provide detailed structural insight into CDH23 function in mechanotransduction.
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Affiliation(s)
- Avinash Jaiganesh
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA; Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Pedro De-la-Torre
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Aniket A Patel
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Domenic J Termine
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Florencia Velez-Cortes
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Conghui Chen
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA; Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA.
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20
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Bahloul A, Pepermans E, Raynal B, Wolff N, Cordier F, England P, Nouaille S, Baron B, El-Amraoui A, Hardelin JP, Durand D, Petit C. Conformational switch of harmonin, a submembrane scaffold protein of the hair cell mechanoelectrical transduction machinery. FEBS Lett 2017; 591:2299-2310. [PMID: 28653419 PMCID: PMC5599985 DOI: 10.1002/1873-3468.12729] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 05/15/2017] [Accepted: 06/08/2017] [Indexed: 11/25/2022]
Abstract
Mutations in the gene encoding harmonin, a multi‐PDZ domain‐containing submembrane protein, cause Usher syndrome type 1 (congenital deafness and balance disorder, and early‐onset sight loss). The structure of the protein and biological activities of its three different classes of splice isoforms (a, b, and c) remain poorly understood. Combining biochemical and biophysical analyses, we show that harmonin‐a1 can switch between open and closed conformations through intramolecular binding of its C‐terminal PDZ‐binding motif to its N‐terminal supramodule NTD‐PDZ1 and through a flexible PDZ2‐PDZ3 linker. This conformational switch presumably extends to most harmonin isoforms, and it is expected to have an impact on the interaction with some binding partners, as shown here for cadherin‐related 23, another component of the hair cell mechanoelectrical transduction machinery.
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Affiliation(s)
- Amel Bahloul
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France.,UMRS1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France.,Sorbonne Universités, UPMC Université Paris 6, Paris, France
| | - Elise Pepermans
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France.,UMRS1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France.,Sorbonne Universités, UPMC Université Paris 6, Paris, France
| | - Bertrand Raynal
- Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France
| | - Nicolas Wolff
- Unité de RMN des Biomolécules, Institut Pasteur, Paris, France
| | | | - Patrick England
- Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France
| | - Sylvie Nouaille
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France.,UMRS1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France.,Sorbonne Universités, UPMC Université Paris 6, Paris, France
| | - Bruno Baron
- Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France
| | - Aziz El-Amraoui
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France.,UMRS1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France.,Sorbonne Universités, UPMC Université Paris 6, Paris, France
| | - Jean-Pierre Hardelin
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France.,UMRS1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France.,Sorbonne Universités, UPMC Université Paris 6, Paris, France
| | - Dominique Durand
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Christine Petit
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France.,UMRS1120, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France.,Sorbonne Universités, UPMC Université Paris 6, Paris, France.,Collège de France, Paris, France
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21
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Myosin 7 and its adaptors link cadherins to actin. Nat Commun 2017; 8:15864. [PMID: 28660889 PMCID: PMC5493754 DOI: 10.1038/ncomms15864] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 05/03/2017] [Indexed: 12/17/2022] Open
Abstract
Cadherin linkages between adjacent stereocilia and microvilli are essential for mechanotransduction and maintaining their organization. They are anchored to actin through interaction of their cytoplasmic domains with related tripartite complexes consisting of a class VII myosin and adaptor proteins: Myo7a/SANS/Harmonin in stereocilia and Myo7b/ANKS4B/Harmonin in microvilli. Here, we determine high-resolution structures of Myo7a and Myo7b C-terminal MyTH4-FERM domain (MF2) and unveil how they recognize harmonin using a novel binding mode. Systematic definition of interactions between domains of the tripartite complex elucidates how the complex assembles and prevents possible self-association of harmonin-a. Several Myo7a deafness mutants that map to the surface of MF2 disrupt harmonin binding, revealing the molecular basis for how they impact the formation of the tripartite complex and disrupt mechanotransduction. Our results also suggest how switching between different harmonin isoforms can regulate the formation of networks with Myo7a motors and coordinate force sensing in stereocilia. Cadherin is essential for mechanotransduction and myosin-adaptor-harmonin complexes anchor it to actin. Here the authors present the structures of myosin 7 MF2 domains bound to the harmonin PDZ3c domain and give insights into myosin-adaptor-harmonin complex assembly.
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22
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Blanco-Sánchez B, Clément A, Phillips JB, Westerfield M. Zebrafish models of human eye and inner ear diseases. Methods Cell Biol 2016; 138:415-467. [PMID: 28129854 DOI: 10.1016/bs.mcb.2016.10.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Eye and inner ear diseases are the most common sensory impairments that greatly impact quality of life. Zebrafish have been intensively employed to understand the fundamental mechanisms underlying eye and inner ear development. The zebrafish visual and vestibulo-acoustic systems are very similar to these in humans, and although not yet mature, they are functional by 5days post-fertilization (dpf). In this chapter, we show how the zebrafish has significantly contributed to the field of biomedical research and how researchers, by establishing disease models and meticulously characterizing their phenotypes, have taken the first steps toward therapies. We review here models for (1) eye diseases, (2) ear diseases, and (3) syndromes affecting eye and/or ear. The use of new genome editing technologies and high-throughput screening systems should increase considerably the speed at which knowledge from zebrafish disease models is acquired, opening avenues for better diagnostics, treatments, and therapies.
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Affiliation(s)
| | - A Clément
- University of Oregon, Eugene, OR, United States
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23
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Weck ML, Grega-Larson NE, Tyska MJ. MyTH4-FERM myosins in the assembly and maintenance of actin-based protrusions. Curr Opin Cell Biol 2016; 44:68-78. [PMID: 27836411 DOI: 10.1016/j.ceb.2016.10.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 10/12/2016] [Indexed: 12/13/2022]
Abstract
Unconventional myosins are actin-based molecular motors that serve a multitude of roles within the cell. One group of myosin motors, the MyTH4-FERM myosins, play an integral part in building and maintaining finger-like protrusions, which allow cells to interact with their external environment. Suggested to act primarily as transporters, these motor proteins enrich adhesion molecules, actin-regulatory proteins and other factors at the tips of filopodia, microvilli, and stereocilia. Below we review data from biophysical, biochemical, and cell biological studies, which implicate these myosins as central players in the assembly, maintenance and function of actin-based protrusions.
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Affiliation(s)
- Meredith L Weck
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 3154 MRB III, PMB 407935, 465 21st Avenue South, Nashville, TN 37240-7935, United States
| | - Nathan E Grega-Larson
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 3154 MRB III, PMB 407935, 465 21st Avenue South, Nashville, TN 37240-7935, United States
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 3154 MRB III, PMB 407935, 465 21st Avenue South, Nashville, TN 37240-7935, United States.
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24
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Tyska MJ. Listen to your gut: Using adhesion to shape the surface of functionally diverse epithelia. Rare Dis 2016. [DOI: 10.1080/21675511.2016.1220469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Affiliation(s)
- Matthew J. Tyska
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
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25
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Takahashi S, Mui VJ, Rosenberg SK, Homma K, Cheatham MA, Zheng J. Cadherin 23-C Regulates Microtubule Networks by Modifying CAMSAP3's Function. Sci Rep 2016; 6:28706. [PMID: 27349180 PMCID: PMC4923861 DOI: 10.1038/srep28706] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/08/2016] [Indexed: 02/05/2023] Open
Abstract
Cadherin-related 23 (CDH23) is an adhesive protein important for hearing and vision, while CAMSAP3/Marshalin is a microtubule (MT) minus-end binding protein that regulates MT networks. Although both CDH23 and CAMSAP3/Marshalin are expressed in the organ of Corti, and carry several protein-protein interaction domains, no functional connection between these two proteins has been proposed. In this report, we demonstrate that the C isoform of CDH23 (CDH23-C) directly binds to CAMSAP3/Marshalin and modifies its function by inhibiting CAMSAP3/Marshalin-induced bundle formation, a process that requires a tubulin-binding domain called CKK. We further identified a conserved N-terminal region of CDH23-C that binds to the CKK domain. This CKK binding motif (CBM) is adjacent to the domain that interacts with harmonin, a binding partner of CDH23 implicated in deafness. Because the human Usher Syndrome 1D-associated mutation, CDH23 R3175H, maps to the CBM, we created a matched mutation in mouse CDH23-C at R55H. Both in vivo and in vitro assays decreased the ability of CDH23-C to interact with CAMSAP3/Marshalin, indicating that the interaction between CDH23 and CAMSAP3/Marshalin plays a vital role in hearing and vision. Together, our data suggest that CDH23-C is a CAMSAP3/Marshalin-binding protein that can modify MT networks indirectly through its interaction with CAMSAP3/Marshalin.
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Affiliation(s)
- Satoe Takahashi
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
| | - Vincent J Mui
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
| | - Samuel K Rosenberg
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
| | - Kazuaki Homma
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA.,Knowles Hearing Center, Northwestern University, Evanston, IL 60208, USA
| | - Mary Ann Cheatham
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.,Knowles Hearing Center, Northwestern University, Evanston, IL 60208, USA
| | - Jing Zheng
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA.,Knowles Hearing Center, Northwestern University, Evanston, IL 60208, USA
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26
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Mechanistic Basis of Organization of the Harmonin/USH1C-Mediated Brush Border Microvilli Tip-Link Complex. Dev Cell 2016; 36:179-89. [PMID: 26812017 DOI: 10.1016/j.devcel.2015.12.020] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/08/2015] [Accepted: 12/21/2015] [Indexed: 11/23/2022]
Abstract
Brush border microvilli are actin-based protrusions lining the apical surface of epithelial cells in intestines and proximal tubules of kidneys. While brush border microvilli resemble the relatively well-characterized stereocilia of hair cells, the mechanistic basis of tip-link complex organization in microvilli is poorly understood. Here, we have biochemically and structurally characterized the following pairs of interactions: protocadherin 24 and Harmonin (also known as USH1C or AIE-75), Harmonin and myosin VIIb (MYO7B), Harmonin and ANKS4B, and ANKS4B and MYO7B. We show that Harmonin, ANKS4B, and MYO7B form a stable ternary complex for anchoring microvilli tip-link cadherins. Despite having only Harmonin in common, the microvilli and the stereocilia tip-link complexes are formed via strikingly similar interaction modes. These results not only provide insight into the mechanistic bases of brush border microvilli formation and maintenance but may also be valuable for understanding some gut and/or kidney diseases caused by perturbations of brush border microvilli structures.
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Hu J, Xu M, Yuan J, Li B, Entenman S, Yu H, Zheng QY. Tauroursodeoxycholic acid prevents hearing loss and hair cell death in Cdh23(erl/erl) mice. Neuroscience 2015; 316:311-20. [PMID: 26748055 DOI: 10.1016/j.neuroscience.2015.12.050] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/24/2015] [Accepted: 12/28/2015] [Indexed: 12/13/2022]
Abstract
Sensorineural hearing loss has long been the subject of experimental and clinical research for many years. The recently identified novel mutation of the Cadherin23 (Cdh23) gene, Cdh23(erl/erl), was proven to be a mouse model of human autosomal recessive nonsyndromic deafness (DFNB12). Tauroursodeoxycholic acid (TUDCA), a taurine-conjugated bile acid, has been used in experimental research and clinical applications related to liver disease, diabetes, neurodegenerative diseases, and other diseases associated with apoptosis. Because hair cell apoptosis was implied to be the cellular mechanism leading to hearing loss in Cdh23(erl/erl) mice (erl mice), this study investigated TUDCA's otoprotective effects in erl mice: preventing hearing impairment and protecting against hair cell death. Our results showed that systemic treatment with TUDCA significantly alleviated hearing loss and suppressed hair cell death in erl mice. Additionally, TUDCA inhibited apoptotic genes and caspase-3 activation in erl mouse cochleae. The data suggest that TUDCA could be a potential therapeutic agent for human DFNB12.
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Affiliation(s)
- J Hu
- Department of Otorhinolaryngology-Head & Neck Surgery, Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, 157 Xiwu Road, Xi'an 710014, Shaanxi, PR China; Department of Otolaryngology-Head & Neck Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - M Xu
- Department of Otorhinolaryngology-Head & Neck Surgery, Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, 157 Xiwu Road, Xi'an 710014, Shaanxi, PR China
| | - J Yuan
- Department of Otolaryngology-Head & Neck Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - B Li
- Transformative Otology and Neuroscience Center, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China
| | - S Entenman
- Department of Otolaryngology-Head & Neck Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - H Yu
- Department of Otolaryngology-Head & Neck Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
| | - Q Y Zheng
- Department of Otorhinolaryngology-Head & Neck Surgery, Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, 157 Xiwu Road, Xi'an 710014, Shaanxi, PR China; Department of Otolaryngology-Head & Neck Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA; Transformative Otology and Neuroscience Center, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, PR China.
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28
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Latysheva NS, Flock T, Weatheritt RJ, Chavali S, Babu MM. How do disordered regions achieve comparable functions to structured domains? Protein Sci 2015; 24:909-22. [PMID: 25752799 PMCID: PMC4456105 DOI: 10.1002/pro.2674] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 02/25/2015] [Accepted: 03/03/2015] [Indexed: 12/19/2022]
Abstract
The traditional structure to function paradigm conceives of a protein's function as emerging from its structure. In recent years, it has been established that unstructured, intrinsically disordered regions (IDRs) in proteins are equally crucial elements for protein function, regulation and homeostasis. In this review, we provide a brief overview of how IDRs can perform similar functions to structured proteins, focusing especially on the formation of protein complexes and assemblies and the mediation of regulated conformational changes. In addition to highlighting instances of such functional equivalence, we explain how differences in the biological and physicochemical properties of IDRs allow them to expand the functional and regulatory repertoire of proteins. We also discuss studies that provide insights into how mutations within functional regions of IDRs can lead to human diseases.
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Affiliation(s)
| | - Tilman Flock
- MRC Laboratory of Molecular BiologyCambridge, CB2 0QH, United Kingdom
| | | | - Sreenivas Chavali
- MRC Laboratory of Molecular BiologyCambridge, CB2 0QH, United Kingdom
| | - M Madan Babu
- MRC Laboratory of Molecular BiologyCambridge, CB2 0QH, United Kingdom
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29
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Chen Q, Zou J, Shen Z, Zhang W, Yang J. Whirlin and PDZ domain-containing 7 (PDZD7) proteins are both required to form the quaternary protein complex associated with Usher syndrome type 2. J Biol Chem 2014; 289:36070-88. [PMID: 25406310 DOI: 10.1074/jbc.m114.610535] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Usher syndrome (USH) is the leading genetic cause of combined hearing and vision loss. Among the three USH clinical types, type 2 (USH2) occurs most commonly. USH2A, GPR98, and WHRN are three known causative genes of USH2, whereas PDZD7 is a modifier gene found in USH2 patients. The proteins encoded by these four USH genes have been proposed to form a multiprotein complex, the USH2 complex, due to interactions found among some of these proteins in vitro, their colocalization in vivo, and mutual dependence of some of these proteins for their normal in vivo localizations. However, evidence showing the formation of the USH2 complex is missing, and details on how this complex is formed remain elusive. Here, we systematically investigated interactions among the intracellular regions of the four USH proteins using colocalization, yeast two-hybrid, and pull-down assays. We show that multiple domains of the four USH proteins interact among one another. Importantly, both WHRN and PDZD7 are required for the complex formation with USH2A and GPR98. In this USH2 quaternary complex, WHRN prefers to bind to USH2A, whereas PDZD7 prefers to bind to GPR98. Interaction between WHRN and PDZD7 is the bridge between USH2A and GPR98. Additionally, the USH2 quaternary complex has a variable stoichiometry. These findings suggest that a non-obligate, short term, and dynamic USH2 quaternary protein complex may exist in vivo. Our work provides valuable insight into the physiological role of the USH2 complex in vivo and informs possible reconstruction of the USH2 complex for future therapy.
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Affiliation(s)
- Qian Chen
- From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center
| | - Junhuang Zou
- From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center
| | - Zuolian Shen
- From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center
| | - Weiping Zhang
- From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center
| | - Jun Yang
- From the Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, the Department of Neurobiology and Anatomy, and the Department of Otolaryngology Head and Neck Surgery, University of Utah, Salt Lake City, Utah 84132
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