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Ruan K, Bai G, Fang Y, Li D, Li T, Liu X, Lu B, Lu Q, Songyang Z, Sun S, Wang Z, Zhang X, Zhou W, Zhang H. Biomolecular condensates and disease pathogenesis. SCIENCE CHINA. LIFE SCIENCES 2024; 67:1792-1832. [PMID: 39037698 DOI: 10.1007/s11427-024-2661-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 06/21/2024] [Indexed: 07/23/2024]
Abstract
Biomolecular condensates or membraneless organelles (MLOs) formed by liquid-liquid phase separation (LLPS) divide intracellular spaces into discrete compartments for specific functions. Dysregulation of LLPS or aberrant phase transition that disturbs the formation or material states of MLOs is closely correlated with neurodegeneration, tumorigenesis, and many other pathological processes. Herein, we summarize the recent progress in development of methods to monitor phase separation and we discuss the biogenesis and function of MLOs formed through phase separation. We then present emerging proof-of-concept examples regarding the disruption of phase separation homeostasis in a diverse array of clinical conditions including neurodegenerative disorders, hearing loss, cancers, and immunological diseases. Finally, we describe the emerging discovery of chemical modulators of phase separation.
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Affiliation(s)
- Ke Ruan
- The First Affiliated Hospital & School of Life Sciences, Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, China.
| | - Ge Bai
- Nanhu Brain-computer Interface Institute, Hangzhou, 311100, China.
- Department of Neurology of Second Affiliated Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China.
| | - Yanshan Fang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 201210, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Dan Li
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, 200030, China.
| | - Tingting Li
- Department of Biomedical Informatics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China.
| | - Xingguo Liu
- CAS Key Laboratory of Regenerative Biology, Joint School of Life Sciences, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China.
- Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, 510000, China.
| | - Boxun Lu
- Neurology Department at Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, School of Life Sciences, Fudan University, Shanghai, 200433, 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.
| | - Zhou Songyang
- State Key Laboratory of Biocontrol, MOE Key Laboratory of Gene Function and Regulation and Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510275, China.
| | - Shuguo Sun
- Department of Human Anatomy, Histology and Embryology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Zheng Wang
- The Second Affiliated Hospital, School of Basic Medical Sciences, Institute of Biomedical Innovation, Jiangxi Medical College, Nanchang University, Nanchang, 330031, China.
| | - Xin Zhang
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024, China.
| | - Wen Zhou
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Hong Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
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Hoffmann C, Milovanovic D. Dipping contacts - a novel type of contact site at the interface between membraneless organelles and membranes. J Cell Sci 2023; 136:jcs261413. [PMID: 38149872 PMCID: PMC10785658 DOI: 10.1242/jcs.261413] [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] [Indexed: 12/28/2023] Open
Abstract
Liquid-liquid phase separation is a major mechanism for organizing macromolecules, particularly proteins with intrinsically disordered regions, in compartments not limited by a membrane or a scaffold. The cell can therefore be perceived as a complex emulsion containing many of these membraneless organelles, also referred to as biomolecular condensates, together with numerous membrane-bound organelles. It is currently unclear how such a complex concoction operates to allow for intracellular trafficking, signaling and metabolic processes to occur with high spatiotemporal precision. Based on experimental observations of synaptic vesicle condensates - a membraneless organelle that is in fact packed with membranes - we present here the framework of dipping contacts: a novel type of contact site between membraneless organelles and membranes. In this Hypothesis, we propose that our framework of dipping contacts can serve as a foundation to investigate the interface that couples the diffusion and material properties of condensates to biochemical processes occurring in membranes. The identity and regulation of this interface is especially critical in the case of neurodegenerative diseases, where aberrant inclusions of misfolded proteins and damaged organelles underlie cellular pathology.
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Affiliation(s)
- Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA
- National Center for X-ray Tomography, Advanced Light Source, Berkeley, CA 94720, USA
- Einstein Center for Neuroscience, Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität Berlin and Berlin Institute of Health, 10117 Berlin, Germany
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Park J, Bird JE. The actin cytoskeleton in hair bundle development and hearing loss. Hear Res 2023; 436:108817. [PMID: 37300948 PMCID: PMC10408727 DOI: 10.1016/j.heares.2023.108817] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/18/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023]
Abstract
Inner ear hair cells assemble mechanosensitive hair bundles on their apical surface that transduce sounds and accelerations. Each hair bundle is comprised of ∼ 100 individual stereocilia that are arranged into rows of increasing height and width; their specific and precise architecture being necessary for mechanoelectrical transduction (MET). The actin cytoskeleton is fundamental to establishing this architecture, not only by forming the structural scaffold shaping each stereocilium, but also by composing rootlets and the cuticular plate that together provide a stable foundation supporting each stereocilium. In concert with the actin cytoskeleton, a large assortment of actin-binding proteins (ABPs) function to cross-link actin filaments into specific topologies, as well as control actin filament growth, severing, and capping. These processes are individually critical for sensory transduction and are all disrupted in hereditary forms of human hearing loss. In this review, we provide an overview of actin-based structures in the hair bundle and the molecules contributing to their assembly and functional properties. We also highlight recent advances in mechanisms driving stereocilia elongation and how these processes are tuned by MET.
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Affiliation(s)
- Jinho Park
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States.
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Krey JF, Chatterjee P, Halford J, Cunningham CL, Perrin BJ, Barr-Gillespie PG. Control of stereocilia length during development of hair bundles. PLoS Biol 2023; 21:e3001964. [PMID: 37011103 PMCID: PMC10101650 DOI: 10.1371/journal.pbio.3001964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 04/13/2023] [Accepted: 03/14/2023] [Indexed: 04/05/2023] Open
Abstract
Assembly of the hair bundle, the sensory organelle of the inner ear, depends on differential growth of actin-based stereocilia. Separate rows of stereocilia, labeled 1 through 3 from tallest to shortest, lengthen or shorten during discrete time intervals during development. We used lattice structured illumination microscopy and surface rendering to measure dimensions of stereocilia from mouse apical inner hair cells during early postnatal development; these measurements revealed a sharp transition at postnatal day 8 between stage III (row 1 and 2 widening; row 2 shortening) and stage IV (final row 1 lengthening and widening). Tip proteins that determine row 1 lengthening did not accumulate simultaneously during stages III and IV; while the actin-bundling protein EPS8 peaked at the end of stage III, GNAI3 peaked several days later-in early stage IV-and GPSM2 peaked near the end of stage IV. To establish the contributions of key macromolecular assemblies to bundle structure, we examined mouse mutants that eliminated tip links (Cdh23v2J or Pcdh15av3J), transduction channels (TmieKO), or the row 1 tip complex (Myo15ash2). Cdh23v2J/v2J and Pcdh15av3J/av3J bundles had adjacent stereocilia in the same row that were not matched in length, revealing that a major role of these cadherins is to synchronize lengths of side-by-side stereocilia. Use of the tip-link mutants also allowed us to distinguish the role of transduction from effects of transduction proteins themselves. While levels of GNAI3 and GPSM2, which stimulate stereocilia elongation, were greatly attenuated at the tips of TmieKO/KO row 1 stereocilia, they accumulated normally in Cdh23v2J/v2J and Pcdh15av3J/av3J stereocilia. These results reinforced the suggestion that the transduction proteins themselves facilitate localization of proteins in the row 1 complex. By contrast, EPS8 concentrates at tips of all TmieKO/KO, Cdh23v2J/v2J, and Pcdh15av3J/av3J stereocilia, correlating with the less polarized distribution of stereocilia lengths in these bundles. These latter results indicated that in wild-type hair cells, the transduction complex prevents accumulation of EPS8 at the tips of shorter stereocilia, causing them to shrink (rows 2 and 3) or disappear (row 4 and microvilli). Reduced rhodamine-actin labeling at row 2 stereocilia tips of tip-link and transduction mutants suggests that transduction's role is to destabilize actin filaments there. These results suggest that regulation of stereocilia length occurs through EPS8 and that CDH23 and PCDH15 regulate stereocilia lengthening beyond their role in gating mechanotransduction channels.
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Affiliation(s)
- Jocelyn F. Krey
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Paroma Chatterjee
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Julia Halford
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Christopher L. Cunningham
- Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Benjamin J. Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Peter G. Barr-Gillespie
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
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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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Morales EA, Gaeta I, Tyska MJ. Building the brush border, one microvillus at a time. Curr Opin Cell Biol 2023; 80:102153. [PMID: 36827850 PMCID: PMC10033394 DOI: 10.1016/j.ceb.2023.102153] [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: 08/22/2022] [Revised: 01/11/2023] [Accepted: 01/19/2023] [Indexed: 02/24/2023]
Abstract
Microvilli are actin bundle-supported surface protrusions assembled by diverse cell types to mediate biochemical and physical interactions with the external environment. Found on the surface of some of the earliest animal cells, primordial microvilli likely contributed to bacterial entrapment and feeding. Although millions of years of evolution have repurposed these protrusions to fulfill diverse roles such as detection of mechanical or visual stimuli in inner ear hair cells or retinal pigmented epithelial cells, respectively, solute uptake remains a key essential function linked to these structures. In this mini review, we offer a brief overview of the composition and structure of epithelial microvilli, highlight recent discoveries on the growth of these protrusions early in differentiation, and point to fundamental questions surrounding microvilli biogenesis that remain open for future studies.
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Affiliation(s)
- E Angelo Morales
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Isabella Gaeta
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA.
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Wu X, Qiu H, Zhang M. Interactions between Membraneless Condensates and Membranous Organelles at the Presynapse: A Phase Separation View of Synaptic Vesicle Cycle. J Mol Biol 2023; 435:167629. [PMID: 35595170 DOI: 10.1016/j.jmb.2022.167629] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 02/04/2023]
Abstract
Action potential-induced neurotransmitter release in presynaptic boutons involves coordinated actions of a large list of proteins that are associated directly or indirectly with membrane structures including synaptic vesicles and plasma membranes. These proteins are often highly abundant in different synaptic bouton sub-compartments, and they rarely act alone. Instead, these proteins interact with each other forming intricate and distinct molecular complexes. Many of these complexes form condensed clusters on membrane surfaces. This review summarizes findings in recent years showing that many of presynaptic protein complex assemblies are formed via phase separation. These protein condensates extensively interact with lipid membranes via distinct modes, forming various mesoscale structures by different mode of organizations between membraneless condensates and membranous organelles. We discuss that such mesoscale interactions could have deep implications on mobilization, exocytosis, and retrieval of synaptic vesicles.
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Affiliation(s)
- Xiandeng Wu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Hua Qiu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518036, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
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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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9
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Moreland ZG, Bird JE. Myosin motors in sensory hair bundle assembly. Curr Opin Cell Biol 2022; 79:102132. [PMID: 36257241 DOI: 10.1016/j.ceb.2022.102132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 09/02/2022] [Accepted: 09/07/2022] [Indexed: 01/31/2023]
Abstract
Mechanosensory hair bundles are assembled from actin-based stereocilia that project from the apical surface of hair cells in the inner ear. Stereocilia architecture is critical for the transduction of sound and accelerations, and structural defects in these mechano-sensors are a clinical cause of hearing and balance disorders in humans. Unconventional myosin motors are central to the assembly and shaping of stereocilia architecture. A sub-group of myosin motors with MyTH4-FERM domains (MYO7A, MYO15A) are particularly important in these processes, and hypothesized to act as transporters delivering structural and actin-regulatory cargos, in addition to generating force and tension. In this review, we summarize existing evidence for how MYO7A and MYO15A operate and how their dysfunction leads to stereocilia pathology. We further highlight emerging properties of the MyTH4/FERM myosin family and speculate how these new functions might contribute towards the acquisition and maintenance of mechano-sensitivity.
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Affiliation(s)
- Zane G Moreland
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, 32610, USA; Myology Institute, University of Florida, Gainesville, FL, 32610, USA; Graduate Program in Biomedical Sciences, University of Florida, Gainesville, FL, 32610, USA
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, 32610, USA; Myology Institute, University of Florida, Gainesville, FL, 32610, USA.
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Wang L, Zhang Y, Xue Q, Huang P, Liu X. Identification of novel compound heterozygous mutations of the MYO15A gene with autosomal recessive non-syndromic hearing loss. J Clin Lab Anal 2022; 36:e24653. [PMID: 36217262 PMCID: PMC9551133 DOI: 10.1002/jcla.24653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The most common inheritance pattern responsible for congenital deafness belongs to autosomal recessive non-syndromic hearing loss (ARNSHL) and mutations of the highly heterogeneous MYO15A locus are present in a large proportion of cases. METHODS One Chinese family with ARNSHL was subjected to clinical evaluation and genetic analysis. We used targeted and whole exome sequencing with Sanger sequencing to identify and characterize mutations. Bioinformatics analysis was conducted to evaluate molecular functions. RESULTS Three compound heterozygous MYO15A gene variants, including two novel variants, c.6804G > A (p.M2268I), and c.6188_6190delinsGTCA (p.F2063Cfs*60), responsible for deafness were identified. Pathogenicity was assessed by multiple bioinformatics analyses. CONCLUSION We identified novel mutations of the MYO15A locus associated with ARNSHL in a Chinese family. The current findings expand the MYO15A pathogenic mutation spectrum to assist with genetic counseling and prenatal diagnosis.
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Affiliation(s)
- Luming Wang
- Prenatal Diagnosis CenterJiaxing Maternity and Child Health Care HospitalJiaxingChina
| | - Yue Zhang
- Prenatal Diagnosis CenterJiaxing Maternity and Child Health Care HospitalJiaxingChina
| | - Qiuxia Xue
- Prenatal Diagnosis CenterJiaxing Maternity and Child Health Care HospitalJiaxingChina
| | - Pinghua Huang
- Prenatal Diagnosis CenterJiaxing Maternity and Child Health Care HospitalJiaxingChina
| | - Xiaodan Liu
- Prenatal Diagnosis CenterJiaxing Maternity and Child Health Care HospitalJiaxingChina
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Shi Y, Lin L, Wang C, Zhu J. Polarized condensates confer row identity of hair cell stereocilia. J Mol Cell Biol 2022; 14:6650222. [PMID: 35881491 PMCID: PMC9514030 DOI: 10.1093/jmcb/mjac045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 07/24/2022] [Indexed: 11/12/2022] Open
Affiliation(s)
- Yingdong Shi
- Department of Neurology, the First Affiliated Hospital of USTC, Ministry of Education Key Laboratory for Cellular Dynamics, Biomedical Sciences and Health Laboratory of Anhui Province, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Lin Lin
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chao Wang
- Department of Neurology, the First Affiliated Hospital of USTC, Ministry of Education Key Laboratory for Cellular Dynamics, Biomedical Sciences and Health Laboratory of Anhui Province, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Jinwei Zhu
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China
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12
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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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Shi Y, Lin L, Wang C, Zhu J. Promotion of row 1-specific tip complex condensates by Gpsm2-Gαi provides insights into row identity of the tallest stereocilia. SCIENCE ADVANCES 2022; 8:eabn4556. [PMID: 35687681 PMCID: PMC9187228 DOI: 10.1126/sciadv.abn4556] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 04/26/2022] [Indexed: 06/12/2023]
Abstract
The mechanosensory stereocilia in hair cells are organized into rows of graded height, a property crucial for auditory perception. Gpsm2-Gαi-Whirlin-Myo15-Eps8 complex at tips of the tallest stereocilia is proposed to define hair bundle row identity, although the underlying mechanism remains elusive. Here, we find that Gpsm2 could undergo phase separation. Moreover, row 1-specific Gpsm2-Gαi complex significantly promotes the formation of the five-component tip complex density (5xTCD) condensates. The 5xTCD condensates display much stronger actin-bundling ability than those without Gpsm2-Gαi, which may provide critical insights into how Gpsm2-Gαi specifies the tallest stereocilia. A deafness-associated mutation of Gpsm2 leads to impaired formation of the 5xTCD condensates and consequently reduced actin bundling, providing possible clues for etiology of hearing loss in patients with Chudley-McCullough syndrome.
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Affiliation(s)
- Yingdong Shi
- Department of Neurology, the First Affiliated Hospital of USTC, Ministry of Education Key Laboratory for Cellular Dynamics, Biomedical Sciences and Health Laboratory of Anhui Province, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Lin Lin
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chao Wang
- Department of Neurology, the First Affiliated Hospital of USTC, Ministry of Education Key Laboratory for Cellular Dynamics, Biomedical Sciences and Health Laboratory of Anhui Province, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Jinwei Zhu
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China
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Halford J, Bateschell M, Barr-Gillespie PG. Ca 2+ entry through mechanotransduction channels localizes BAIAP2L2 to stereocilia tips. Mol Biol Cell 2022; 33:br6. [PMID: 35044843 PMCID: PMC9250357 DOI: 10.1091/mbc.e21-10-0491] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Brain-specific angiogenesis inhibitor 1-associated protein 2-like protein 2 (BAIAP2L2), a membrane-binding protein required for the maintenance of mechanotransduction in hair cells, is selectively retained at the tips of transducing stereocilia. BAIAP2L2 trafficked to stereocilia tips in the absence of EPS8, but EPS8 increased the efficiency of localization. A tripartite complex of BAIAP2L2, EPS8, and MYO15A formed efficiently in vitro, and these three proteins robustly targeted to filopodia tips when coexpressed in cultured cells. Mice lacking functional transduction channels no longer concentrated BAIAP2L2 at row 2 stereocilia tips, a result that was phenocopied by blocking channels with tubocurarine in cochlear explants. Transduction channels permit Ca2+ entry into stereocilia, and we found that membrane localization of BAIAP2L2 was enhanced in the presence of Ca2+. Finally, reduction of intracellular Ca2+ in hair cells using BAPTA-AM led to a loss of BAIAP2L2 at stereocilia tips. Taken together, our results show that a MYO15A-EPS8 complex transports BAIAP2L2 to stereocilia tips, and Ca2+ entry through open channels at row 2 tips retains BAIAP2L2 there.
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Affiliation(s)
- Julia Halford
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Michael Bateschell
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
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Abstract
Usher syndrome (USH) is the most common genetic condition responsible for combined loss of hearing and vision. Balance disorders and bilateral vestibular areflexia are also observed in some cases. The syndrome was first described by Albrecht von Graefe in 1858, but later named by Charles Usher, who presented a large number of cases with hearing loss and retinopathy in 1914. USH has been grouped into three main clinical types: 1, 2, and 3, which are caused by mutations in different genes and are further divided into different subtypes. To date, nine causative genes have been identified and confirmed as responsible for the syndrome when mutated: MYO7A, USH1C, CDH23, PCDH15, and USH1G (SANS) for Usher type 1; USH2A, ADGRV1, and WHRN for Usher type 2; CLRN1 for Usher type 3. USH is inherited in an autosomal recessive pattern. Digenic, bi-allelic, and polygenic forms have also been reported, in addition to dominant or nonsyndromic forms of genetic mutations. This narrative review reports the causative forms, diagnosis, prognosis, epidemiology, rehabilitation, research, and new treatments of USH.
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Abstract
Filopodia, microvilli and stereocilia represent an important group of plasma membrane protrusions. These specialized projections are supported by parallel bundles of actin filaments and have critical roles in sensing the external environment, increasing cell surface area, and acting as mechanosensors. While actin-associated proteins are essential for actin-filament elongation and bundling in these protrusions, myosin motors have a surprising role in the formation and extension of filopodia and stereocilia and in the organization of microvilli. Actin regulators and specific myosins collaborate in controlling the length of these structures. Myosins can transport cargoes along the length of these protrusions, and, in the case of stereocilia and microvilli, interactions with adaptors and cargoes can also serve to anchor adhesion receptors to the actin-rich core via functionally conserved motor-adaptor complexes. This review highlights recent progress in understanding the diverse roles myosins play in filopodia, microvilli and stereocilia.
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Affiliation(s)
- Anne Houdusse
- Structural Motility, Institut Curie, Paris Université Sciences et Lettres, Sorbonne Université, CNRS UMR144, 75005 Paris, France.
| | - Margaret A Titus
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA.
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