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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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Qi J, Tan F, Zhang L, Zhou Y, Zhang Z, Sun Q, Li N, Fang Y, Chen X, Wu Y, Zhong G, Chai R. Critical role of TPRN rings in the stereocilia for hearing. Mol Ther 2024; 32:204-217. [PMID: 37952086 PMCID: PMC10787140 DOI: 10.1016/j.ymthe.2023.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 09/29/2023] [Accepted: 11/09/2023] [Indexed: 11/14/2023] Open
Abstract
Inner ear hair cells detect sound vibration through the deflection of mechanosensory stereocilia. Cytoplasmic protein TPRN has been shown to localize at the taper region of the stereocilia, and mutations in TPRN cause hereditary hearing loss through an unknown mechanism. Here, using biochemistry and dual stimulated emission depletion microscopy imaging, we show that the TPRN, together with its binding proteins CLIC5 and PTPRQ, forms concentric rings in the taper region of stereocilia. The disruption of TPRN rings, triggered by the competitive inhibition of the interaction of TPRN and CLIC5 or exogenous TPRN overexpression, leads to stereocilia degeneration and severe hearing loss. Most importantly, restoration of the TPRN rings can rescue the damaged auditory function of Tprn knockout mice by exogenously expressing TPRN at an appropriate level in HCs via promoter recombinant adeno-associated virus (AAV). In summary, our results reveal highly structured TPRN rings near the taper region of stereocilia that are crucial for stereocilia function and hearing. Also, TPRN ring restoration in stereocilia by AAV-Tprn effectively repairs damaged hearing, which lays the foundation for the clinical application of AAV-mediated gene therapy in patients with TPRN mutation.
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Affiliation(s)
- Jieyu Qi
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China; School of Life Science, Beijing Institute of Technology, Beijing 100081, China.
| | - Fangzhi Tan
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China.
| | - Liyan Zhang
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Yinyi Zhou
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Ziyu Zhang
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Qiuhan Sun
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Nianci Li
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Yuan Fang
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Xin Chen
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Yunhao Wu
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Guisheng Zhong
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
| | - Renjie Chai
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China; School of Life Science, Beijing Institute of Technology, Beijing 100081, China; Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 610072, China; Southeast University Shenzhen Research Institute, Shenzhen 518063, China.
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3
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García-Solís B, Van Den Rym A, Martinez-Martínez L, Franco T, Pérez-Caraballo JJ, Markle J, Cubillos-Zapata C, Marín AV, Recio MJ, Regueiro JR, Navarro-Zapata A, Mestre-Durán C, Ferreras C, Martín Cotázar C, Mena R, de la Calle-Fabregat C, López-Lera A, Fernández Arquero M, Pérez-Martínez A, López-Collazo E, Sánchez-Ramón S, Casanova JL, Martínez-Barricarte R, de la Calle-Martín O, Pérez de Diego R. Inherited human ezrin deficiency impairs adaptive immunity. J Allergy Clin Immunol 2023; 152:997-1009.e11. [PMID: 37301410 PMCID: PMC11009781 DOI: 10.1016/j.jaci.2023.05.022] [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: 01/13/2023] [Revised: 05/31/2023] [Accepted: 05/31/2023] [Indexed: 06/12/2023]
Abstract
BACKGROUND Inborn errors of immunity (IEI) are a group of monogenic diseases that confer susceptibility to infection, autoimmunity, and cancer. Despite the life-threatening consequences of some IEI, their genetic cause remains unknown in many patients. OBJECTIVE We investigated a patient with an IEI of unknown genetic etiology. METHODS Whole-exome sequencing identified a homozygous missense mutation of the gene encoding ezrin (EZR), substituting a threonine for an alanine at position 129. RESULTS Ezrin is one of the subunits of the ezrin, radixin, and moesin (ERM) complex. The ERM complex links the plasma membrane to the cytoskeleton and is crucial for the assembly of an efficient immune response. The A129T mutation abolishes basal phosphorylation and decreases calcium signaling, leading to complete loss of function. Consistent with the pleiotropic function of ezrin in myriad immune cells, multidimensional immunophenotyping by mass and flow cytometry revealed that in addition to hypogammaglobulinemia, the patient had low frequencies of switched memory B cells, CD4+ and CD8+ T cells, MAIT, γδ T cells, and centralnaive CD4+ cells. CONCLUSIONS Autosomal-recessive human ezrin deficiency is a newly recognized genetic cause of B-cell deficiency affecting cellular and humoral immunity.
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Affiliation(s)
- Blanca García-Solís
- Laboratory of Immunogenetics of Human Diseases, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain; Innate Immunity Group, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain; Interdepartmental Group of Immunodeficiencies, Madrid, Spain
| | - Ana Van Den Rym
- Laboratory of Immunogenetics of Human Diseases, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain; Innate Immunity Group, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain; Interdepartmental Group of Immunodeficiencies, Madrid, Spain
| | | | - Teresa Franco
- Immunology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Jareb J Pérez-Caraballo
- Division of Genetic Medicine, Department of Medicine, Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, Tenn; Division of Molecular Pathogenesis, Department of Pathology, Microbiology, and Immunology, Vanderbilt Center for Immunobiology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tenn
| | - Janet Markle
- Division of Genetic Medicine, Department of Medicine, Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, Tenn; Division of Molecular Pathogenesis, Department of Pathology, Microbiology, and Immunology, Vanderbilt Center for Immunobiology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tenn
| | - Carolina Cubillos-Zapata
- Innate Immunity Group, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain; Centre for Biomedical Research Network, CIBEres, Madrid, Spain
| | - Ana V Marín
- Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine, and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - María J Recio
- Interdepartmental Group of Immunodeficiencies, Madrid, Spain; Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine, and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - José R Regueiro
- Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine, and 12 de Octubre Health Research Institute (imas12), Madrid, Spain
| | - Alfonso Navarro-Zapata
- Translational Research in Paediatric Oncology, Haematopoietic Transplantation and Cell Therapy, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain
| | - Carmen Mestre-Durán
- Translational Research in Paediatric Oncology, Haematopoietic Transplantation and Cell Therapy, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain
| | - Cristina Ferreras
- Translational Research in Paediatric Oncology, Haematopoietic Transplantation and Cell Therapy, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain
| | - Carla Martín Cotázar
- Translational Research in Paediatric Oncology, Haematopoietic Transplantation and Cell Therapy, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain
| | - Roció Mena
- Institute of Medical and Molecular Genetics (INGEMM), Hospital Universitario La Paz, Universidad Autónoma de Madrid, IdiPAZ, Madrid, Spain
| | | | - Alberto López-Lera
- IdiPAZ Institute for Health Research, La Paz University Hospital, CIBERER U-754, Madrid, Spain
| | - Miguel Fernández Arquero
- Interdepartmental Group of Immunodeficiencies, Madrid, Spain; Clinical Immunology Department, San Carlos Clinical Hospital, Madrid, Spain
| | - Antonio Pérez-Martínez
- Translational Research in Paediatric Oncology, Haematopoietic Transplantation and Cell Therapy, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain
| | - Eduardo López-Collazo
- Innate Immunity Group, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain
| | - Silvia Sánchez-Ramón
- Interdepartmental Group of Immunodeficiencies, Madrid, Spain; Clinical Immunology Department, San Carlos Clinical Hospital, Madrid, Spain
| | - Jean-Laurent Casanova
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Institut National de la Santé et de la Recherche Médicale U1163, Paris, France; St Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, NY; Imagine Institute, University Paris Descartes, Paris, France; Howard Hughes Medical Institute, New York, NY
| | - Rubén Martínez-Barricarte
- Division of Genetic Medicine, Department of Medicine, Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, Tenn; Division of Molecular Pathogenesis, Department of Pathology, Microbiology, and Immunology, Vanderbilt Center for Immunobiology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tenn
| | | | - Rebeca Pérez de Diego
- Laboratory of Immunogenetics of Human Diseases, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain; Innate Immunity Group, IdiPAZ Institute for Health Research, La Paz University Hospital, Madrid, Spain; Interdepartmental Group of Immunodeficiencies, Madrid, Spain.
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Sharkova M, Chow E, Erickson T, Hocking JC. The morphological and functional diversity of apical microvilli. J Anat 2023; 242:327-353. [PMID: 36281951 PMCID: PMC9919547 DOI: 10.1111/joa.13781] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/30/2022] Open
Abstract
Sensory neurons use specialized apical processes to perceive external stimuli and monitor internal body conditions. The apical apparatus can include cilia, microvilli, or both, and is adapted for the functions of the particular cell type. Photoreceptors detect light through a large, modified cilium (outer segment), that is supported by a surrounding ring of microvilli-like calyceal processes (CPs). Although first reported 150 years ago, CPs remain poorly understood. As a basis for future study, we therefore conducted a review of existing literature about sensory cell microvilli, which can act either as the primary sensory detector or as support for a cilia-based detector. While all microvilli are finger-like cellular protrusions with an actin core, the processes vary across cell types in size, number, arrangement, dynamics, and function. We summarize the current state of knowledge about CPs and the characteristics of the microvilli found on inner ear hair cells (stereocilia) and cerebral spinal fluid-contacting neurons, with comparisons to the brush border of the intestinal and renal epithelia. The structure, stability, and dynamics of the actin core are regulated by a complement of actin-binding proteins, which includes both common components and unique features when compared across cell types. Further, microvilli are often supported by lateral links, a glycocalyx, and a defined extracellular matrix, each adapted to the function and environment of the cell. Our comparison of microvillar features will inform further research into how CPs support photoreceptor function, and also provide a general basis for investigations into the structure and functions of apical microvilli found on sensory neurons.
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Affiliation(s)
- Maria Sharkova
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Erica Chow
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Timothy Erickson
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Jennifer C Hocking
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Division of Anatomy, Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
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New Insights into the Identity of the DFNA58 Gene. Genes (Basel) 2022; 13:genes13122274. [PMID: 36553541 PMCID: PMC9777997 DOI: 10.3390/genes13122274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/21/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022] Open
Abstract
Hearing loss is the most common sensory deficit, affecting 466 million people worldwide. The vast and diverse genes involved reflect the complexity of auditory physiology, which requires the use of animal models in order to gain a fuller understanding. Among the loci with a yet-to-be validated gene is the DFNA58, in which ~200 Kb genomic duplication, including three protein-coding genes (PLEK, CNRIP1, and PPP3R1's exon1), was found to segregate with autosomal dominant hearing loss. Through whole genome sequencing, the duplication was found to be in tandem and inserted in an intergenic region, without the disruption of the topological domains. Reanalysis of transcriptomes data studies (zebrafish and mouse), and RT-qPCR analysis of adult zebrafish target organs, in order to access their orthologues expression, highlighted promising results with Cnrip1a, corroborated by zebrafish in situ hybridization and immunofluorescence. Mouse data also suggested Cnrip1 as the best candidate for a relevant role in auditory physiology, and its importance in hearing seems to have remained conserved but the cell type exerting its function might have changed, from hair cells to spiral ganglion neurons.
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Hausrat TJ, Vogl C, Neef J, Schweizer M, Yee BK, Strenzke N, Kneussel M. Monoallelic loss of the F-actin-binding protein radixin facilitates startle reactivity and pre-pulse inhibition in mice. Front Cell Dev Biol 2022; 10:987691. [DOI: 10.3389/fcell.2022.987691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 11/11/2022] [Indexed: 11/29/2022] Open
Abstract
Hearing impairment is one of the most common disorders with a global burden and increasing prevalence in an ever-aging population. Previous research has largely focused on peripheral sensory perception, while the brain circuits of auditory processing and integration remain poorly understood. Mutations in the rdx gene, encoding the F-actin binding protein radixin (Rdx), can induce hearing loss in human patients and homozygous depletion of Rdx causes deafness in mice. However, the precise physiological function of Rdx in hearing and auditory information processing is still ill-defined. Here, we investigated consequences of rdx monoallelic loss in the mouse. Unlike the homozygous (−/−) rdx knockout, which is characterized by the degeneration of actin-based stereocilia and subsequent hearing loss, our analysis of heterozygous (+/−) mutants has revealed a different phenotype. Specifically, monoallelic loss of rdx potentiated the startle reflex in response to acoustic stimulation of increasing intensities, suggesting a gain of function relative to wildtype littermates. The monoallelic loss of the rdx gene also facilitated pre-pulse inhibition of the acoustic startle reflex induced by weak auditory pre-pulse stimuli, indicating a modification to the circuit underlying sensorimotor gating of auditory input. However, the auditory brainstem response (ABR)-based hearing thresholds revealed a mild impairment in peripheral sound perception in rdx (+/-) mice, suggesting minor aberration of stereocilia structural integrity. Taken together, our data suggest a critical role of Rdx in the top-down processing and/or integration of auditory signals, and therefore a novel perspective to uncover further Rdx-mediated mechanisms in central auditory information processing.
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Miyoshi T, Belyantseva IA, Kitajiri SI, Miyajima H, Nishio SY, Usami SI, Kim BJ, Choi BY, Omori K, Shroff H, Friedman TB. Human deafness-associated variants alter the dynamics of key molecules in hair cell stereocilia F-actin cores. Hum Genet 2022; 141:363-382. [PMID: 34232383 PMCID: PMC11351816 DOI: 10.1007/s00439-021-02304-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/15/2021] [Indexed: 12/16/2022]
Abstract
Stereocilia protrude up to 100 µm from the apical surface of vertebrate inner ear hair cells and are packed with cross-linked filamentous actin (F-actin). They function as mechanical switches to convert sound vibration into electrochemical neuronal signals transmitted to the brain. Several genes encode molecular components of stereocilia including actin monomers, actin regulatory and bundling proteins, motor proteins and the proteins of the mechanotransduction complex. A stereocilium F-actin core is a dynamic system, which is continuously being remodeled while maintaining an outwardly stable architecture under the regulation of F-actin barbed-end cappers, severing proteins and crosslinkers. The F-actin cores of stereocilia also provide a pathway for motor proteins to transport cargos including components of tip-link densities, scaffolding proteins and actin regulatory proteins. Deficiencies and mutations of stereocilia components that disturb this "dynamic equilibrium" in stereocilia can induce morphological changes and disrupt mechanotransduction causing sensorineural hearing loss, best studied in mouse and zebrafish models. Currently, at least 23 genes, associated with human syndromic and nonsyndromic hearing loss, encode proteins involved in the development and maintenance of stereocilia F-actin cores. However, it is challenging to predict how variants associated with sensorineural hearing loss segregating in families affect protein function. Here, we review the functions of several molecular components of stereocilia F-actin cores and provide new data from our experimental approach to directly evaluate the pathogenicity and functional impact of reported and novel variants of DIAPH1 in autosomal-dominant DFNA1 hearing loss using single-molecule fluorescence microscopy.
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Affiliation(s)
- Takushi Miyoshi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA.
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA
| | - Shin-Ichiro Kitajiri
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Hiroki Miyajima
- Department of Otolaryngology, Shinshu University School of Medicine, Matsumoto, 390-8621, Japan
- Department of Otolaryngology, Aizawa Hospital, Matsumoto, 390-8510, Japan
| | - Shin-Ya Nishio
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Shin-Ichi Usami
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Bong Jik Kim
- Department of Otolaryngology-Head and Neck Surgery, Chungnam National University College of Medicine, Chungnam National University Sejong Hospital, Sejong, 30099, South Korea
- Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, South Korea
| | - Byung Yoon Choi
- Department of Otorhinolaryngology, Seoul National University Bundang Hospital, Seongnam, 13620, South Korea
| | - Koichi Omori
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Hari Shroff
- Laboratory of High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA
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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: 9] [Impact Index Per Article: 4.5] [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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9
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Myosin VI Haploinsufficiency Reduced Hearing Ability in Mice. Neuroscience 2021; 478:100-111. [PMID: 34619316 DOI: 10.1016/j.neuroscience.2021.09.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/10/2021] [Accepted: 09/27/2021] [Indexed: 11/22/2022]
Abstract
In human, myosin VI (MYO6) haploinsufficiency causes postlingual progressive hearing loss. Because the usefulness of mouse models remains unclear, we produced novel Myo6 null (-/-) mutant mice and analyzed the hearing phenotypes of Myo6+/- (+/-) heterozygous mutants. We first recorded and compared the auditory brainstem responses and distortion product otoacoustic emissions in control Myo6+/+ (+/+) wild-type and +/- mice. These hearing phenotypes of +/- mice were mild; however, we confirmed that +/- mice developed progressive hearing loss. In particular, the hearing loss of female +/- mice progressed faster than that of male +/- mice. The stereocilia bundles of +/- mice exhibited progressive taper loss in cochlear inner hair cells (IHCs) and outer hair cells (OHCs). The loss of OHCs in +/- heterozygotes occurred at an earlier age than in +/+ mice. In particular, the OHCs at the basal area of the cochlea were decreased in +/- mice. IHC ribbon synapses from the area at the base of the cochlea were significantly reduced in +/- mice. Thus, our study indicated that MYO6 haploinsufficiency affected the detection of sounds in mice, and we suggest that +/- mice with Myo6 null alleles are useful animal models for gene therapy and drug treatment in patients with progressive hearing loss due to MYO6 haploinsufficiency.
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10
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Ikäheimo K, Herranen A, Iivanainen V, Lankinen T, Aarnisalo AA, Sivonen V, Patel KA, Demir K, Saarma M, Lindahl M, Pirvola U. MANF supports the inner hair cell synapse and the outer hair cell stereocilia bundle in the cochlea. Life Sci Alliance 2021; 5:5/2/e202101068. [PMID: 34815294 PMCID: PMC8616558 DOI: 10.26508/lsa.202101068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 11/08/2021] [Accepted: 11/08/2021] [Indexed: 11/29/2022] Open
Abstract
The authors show in the mouse how the auditory hair cell structural maintenance is perturbed by the inactivation of Manf and the concomitant ER stress, causing early-onset, progressive hearing loss. Failure in the structural maintenance of the hair cell stereocilia bundle and ribbon synapse causes hearing loss. Here, we have studied how ER stress elicits hair cell pathology, using mouse models with inactivation of Manf (mesencephalic astrocyte-derived neurotrophic factor), encoding an ER-homeostasis-promoting protein. From hearing onset, Manf deficiency caused disarray of the outer hair cell stereocilia bundle and reduced cochlear sound amplification capability throughout the tonotopic axis. In high-frequency outer hair cells, the pathology ended in molecular changes in the stereocilia taper region and in strong stereocilia fusion. In high-frequency inner hair cells, Manf deficiency degraded ribbon synapses. The altered phenotype strongly depended on the mouse genetic background. Altogether, the failure in the ER homeostasis maintenance induced early-onset stereociliopathy and synaptopathy and accelerated the effect of genetic causes driving age-related hearing loss. Correspondingly, MANF mutation in a human patient induced severe sensorineural hearing loss from a young age onward. Thus, we present MANF as a novel protein and ER stress as a mechanism that regulate auditory hair cell maintenance in both mice and humans.
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Affiliation(s)
- Kuu Ikäheimo
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, Helsinki, Finland
| | - Anni Herranen
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, Helsinki, Finland
| | - Vilma Iivanainen
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, Helsinki, Finland
| | - Tuuli Lankinen
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, Helsinki, Finland
| | - Antti A Aarnisalo
- Department of Otorhinolaryngology-Head and Neck Surgery, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Ville Sivonen
- Department of Otorhinolaryngology-Head and Neck Surgery, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Kashyap A Patel
- Institute of Biomedical and Clinical Science, College of Medicine and Health, University of Exeter, Exeter, UK
| | - Korcan Demir
- Department of Paediatric Endocrinology, Dokuz Eylul University, Izmir, Turkey
| | - Mart Saarma
- Institute of Biotechnology, HILIFE Unit, University of Helsinki, Helsinki, Finland
| | - Maria Lindahl
- Institute of Biotechnology, HILIFE Unit, University of Helsinki, Helsinki, Finland
| | - Ulla Pirvola
- Molecular and Integrative Biosciences Research Programme, University of Helsinki, Helsinki, Finland
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11
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Disruption of the autism-related gene Pak1 causes stereocilia disorganization, hair cell loss, and deafness in mice. J Genet Genomics 2021; 48:324-332. [PMID: 34049799 DOI: 10.1016/j.jgg.2021.03.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/18/2021] [Accepted: 03/12/2021] [Indexed: 01/06/2023]
Abstract
Several clinical studies have reported that hearing loss is correlated with autism in children. However, little is known about the underlying mechanism between hearing loss and autism. p21-activated kinases (PAKs) are a family of serine/threonine kinases that can be activated by multiple signaling molecules, particularly the Rho family of small GTPases. Previous studies have shown that Pak1 mutations are associated with autism. In the present study, we take advantage of Pak1 knockout (Pak1-/-) mice to investigate the role of PAK1 in hearing function. We find that PAK1 is highly expressed in the postnatal mouse cochlea and that PAK1 deficiency leads to hair cell (HC) apoptosis and severe hearing loss. Further investigation indicates that PAK1 deficiency downregulates the phosphorylation of cofilin and ezrin-radixin-moesin and the expression of βII-spectrin, which further decreases the HC synapse density in the basal turn of cochlea and disorganized the HC stereocilia in all three turns of cochlea in Pak1-/- mice. Overall, our work demonstrates that the autism-related gene Pak1 plays a crucial role in hearing function. As the first candidate gene linking autism and hearing loss, Pak1 may serve as a potential target for the clinical diagnosis of autism-related hearing loss.
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12
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Radixin modulates the function of outer hair cell stereocilia. Commun Biol 2020; 3:792. [PMID: 33361775 PMCID: PMC7758333 DOI: 10.1038/s42003-020-01506-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 11/18/2020] [Indexed: 01/07/2023] Open
Abstract
The stereocilia of the inner ear sensory cells contain the actin-binding protein radixin, encoded by RDX. Radixin is important for hearing but remains functionally obscure. To determine how radixin influences hearing sensitivity, we used a custom rapid imaging technique to visualize stereocilia motion while measuring electrical potential amplitudes during acoustic stimulation. Radixin inhibition decreased sound-evoked electrical potentials. Other functional measures, including electrically induced sensory cell motility and sound-evoked stereocilia deflections, showed a minor amplitude increase. These unique functional alterations demonstrate radixin as necessary for conversion of sound into electrical signals at acoustic rates. We identified patients with RDX variants with normal hearing at birth who showed rapidly deteriorating hearing during the first months of life. This may be overlooked by newborn hearing screening and explained by multiple disturbances in postnatal sensory cells. We conclude radixin is necessary for ensuring normal conversion of sound to electrical signals in the inner ear. Sonal Prasad et al. identify several mutations in the radixin (RDX) gene that are associated with early-life hearing loss. Using a guinea pig model, they propose that radixin helps convert sound into electrical signals in the mature inner ear.
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13
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Lee H, Yu D, Park JS, Lee H, Kim J, Kim HL, Koo S, Lee J, Lee S, Ko Y. Prominin-1-Radixin axis controls hepatic gluconeogenesis by regulating PKA activity. EMBO Rep 2020; 21:e49416. [PMID: 33030802 PMCID: PMC7645247 DOI: 10.15252/embr.201949416] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 08/31/2020] [Accepted: 09/10/2020] [Indexed: 12/18/2022] Open
Abstract
Prominin-1 (Prom1) is a major cell surface marker of cancer stem cells, but its physiological functions in the liver have not been elucidated. We analyzed the levels of mRNA transcripts in serum-starved primary WT (Prom1+/+ ) and KO (Prom1-/- ) mouse hepatocytes using RNA sequencing (RNA-seq) data, and found that CREB target genes were downregulated. This initial observation led us to determine that Prom1 deficiency inhibited cAMP response element-binding protein (CREB) activation and gluconeogenesis, but not cyclic AMP (cAMP) accumulation, in glucagon-, epinephrine-, or forskolin-treated liver tissues and primary hepatocytes, and mitigated glucagon-induced hyperglycemia. Because Prom1 interacted with radixin, Prom1 deficiency prevented radixin from localizing to the plasma membrane. Moreover, systemic adenoviral knockdown of radixin inhibited CREB activation and gluconeogenesis in glucagon-treated liver tissues and primary hepatocytes, and mitigated glucagon-elicited hyperglycemia. Based on these results, we conclude that Prom1 regulates hepatic PKA signaling via radixin functioning as an A kinase-anchored protein (AKAP).
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Affiliation(s)
- Hyun Lee
- Tunneling Nanotube Research CenterKorea UniversitySeoulKorea
- Division of Life SciencesKorea UniversitySeoulKorea
| | - Dong‐Min Yu
- Tunneling Nanotube Research CenterKorea UniversitySeoulKorea
- Division of Life SciencesKorea UniversitySeoulKorea
| | - Jun Sub Park
- Tunneling Nanotube Research CenterKorea UniversitySeoulKorea
- Division of Life SciencesKorea UniversitySeoulKorea
| | - Hwayeon Lee
- Tunneling Nanotube Research CenterKorea UniversitySeoulKorea
- Division of Life SciencesKorea UniversitySeoulKorea
| | - Jun‐Seok Kim
- Tunneling Nanotube Research CenterKorea UniversitySeoulKorea
- Division of Life SciencesKorea UniversitySeoulKorea
| | - Hong Lim Kim
- Laboratory of Electron MicroscopeIntegrative Research Support CenterCollege of MedicineThe Catholic University of KoreaSeoulKorea
| | - Seung‐Hoi Koo
- Tunneling Nanotube Research CenterKorea UniversitySeoulKorea
- Division of Life SciencesKorea UniversitySeoulKorea
| | - Jae‐Seon Lee
- Department of Molecular MedicineInha University College of MedicineIncheonKorea
- Hypoxia‐related Disease Research CenterInha University College of MedicineIncheonKorea
| | - Sungsoo Lee
- Tunneling Nanotube Research CenterKorea UniversitySeoulKorea
- Division of Life SciencesKorea UniversitySeoulKorea
| | - Young‐Gyu Ko
- Tunneling Nanotube Research CenterKorea UniversitySeoulKorea
- Division of Life SciencesKorea UniversitySeoulKorea
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14
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Song J, Patterson R, Metlagel Z, Krey JF, Hao S, Wang L, Ng B, Sazzed S, Kovacs J, Wriggers W, He J, Barr-Gillespie PG, Auer M. A cryo-tomography-based volumetric model of the actin core of mouse vestibular hair cell stereocilia lacking plastin 1. J Struct Biol 2020; 210:107461. [PMID: 31962158 PMCID: PMC7067663 DOI: 10.1016/j.jsb.2020.107461] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/11/2020] [Accepted: 01/14/2020] [Indexed: 12/11/2022]
Abstract
Electron cryo-tomography allows for high-resolution imaging of stereocilia in their native state. Because their actin filaments have a higher degree of order, we imaged stereocilia from mice lacking the actin crosslinker plastin 1 (PLS1). We found that while stereocilia actin filaments run 13 nm apart in parallel for long distances, there were gaps of significant size that were stochastically distributed throughout the actin core. Actin crosslinkers were distributed through the stereocilium, but did not occupy all possible binding sites. At stereocilia tips, protein density extended beyond actin filaments, especially on the side of the tip where a tip link is expected to anchor. Along the shaft, repeating density was observed that corresponds to actin-to-membrane connectors. In the taper region, most actin filaments terminated near the plasma membrane. The remaining filaments twisted together to make a tighter bundle than was present in the shaft region; the spacing between them decreased from 13 nm to 9 nm, and the apparent filament diameter decreased from 6.4 to 4.8 nm. Our models illustrate detailed features of distinct structural domains that are present within the stereocilium.
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Affiliation(s)
- Junha Song
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Roma Patterson
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Zoltan Metlagel
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jocelyn F Krey
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, USA
| | - Samantha Hao
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Linshanshan Wang
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Brian Ng
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Salim Sazzed
- Department of Computer Science, Old Dominion University, Norfolk, VA, USA
| | - Julio Kovacs
- Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, VA, USA
| | - Willy Wriggers
- Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, VA, USA
| | - Jing He
- Department of Computer Science, Old Dominion University, Norfolk, VA, USA
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, USA.
| | - Manfred Auer
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
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15
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Shabardina V, Kashima Y, Suzuki Y, Makalowski W. Emergence and Evolution of ERM Proteins and Merlin in Metazoans. Genome Biol Evol 2020; 12:3710-3724. [PMID: 31851361 PMCID: PMC6978628 DOI: 10.1093/gbe/evz265] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2019] [Indexed: 12/18/2022] Open
Abstract
Ezrin, radixin, moesin, and merlin are cytoskeletal proteins, whose functions are specific to metazoans. They participate in cell cortex rearrangement, including cell-cell contact formation, and play an important role in cancer progression. Here, we have performed a comprehensive phylogenetic analysis of the proteins spanning 87 species. The results describe a possible mechanism for the protein family origin in the root of Metazoa, paralogs diversification in vertebrates, and acquisition of novel functions, including tumor suppression. In addition, a merlin paralog, present in most vertebrates but lost in mammals, has been described here for the first time. We have also highlighted a set of amino acid variations within the conserved motifs as the candidates for determining physiological differences between ERM paralogs.
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Affiliation(s)
| | - Yukie Kashima
- Department of Computational Biology and Medical Sciences, The University of Tokyo, Kashiwa, Japan
| | - Yutaka Suzuki
- Laboratory of Systems Genomics, Department of Computational Biology and Medical Sciences, The University of Tokyo, Kashiwa, Japan
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16
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Richardson GP, Petit C. Hair-Bundle Links: Genetics as the Gateway to Function. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033142. [PMID: 30617060 DOI: 10.1101/cshperspect.a033142] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Up to five distinct cell-surface specializations interconnect the stereocilia and the kinocilium of the mature hair bundle in some species: kinocilial links, tip links, top connectors, shaft connectors, and ankle links. In developing hair bundles, transient lateral links are prominent. Mutations in genes encoding proteins associated with these links cause Usher deafness/blindness syndrome or nonsyndromic (isolated) forms of human hereditary deafness, and mice with constitutive or conditional alleles of these genes have provided considerable insight into the molecular composition and function of the different links. We describe the structure of these links and review evidence showing CDH23 and PCDH15 are components of the tip, kinocilial, and transient-lateral links, that stereocilin (STRC) and protein tyrosine phosphatase (PTPRQ) are associated with top and shaft connectors, respectively, and that USH2A and ADGRV1 are associated with the ankle links. Whereas tip links are required for mechanoelectrical transduction, all link proteins play key roles in the normal development and/or the maintenance of hair bundle structure and function. Recent crystallographic and single-particle analyses of PCDH15 and CDH23 provide insight as to how the structure of tip link may contribute to the elastic element predicted to lie in series with the hair cell's mechanoelectrical transducer channel.
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Affiliation(s)
- Guy P Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
| | - Christine Petit
- Institut Pasteur, 75724 Paris Cedex 15, France.,Collège de France, 75231 Paris Cedex 05, France
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17
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Bullen A, Forge A, Wright A, Richardson GP, Goodyear RJ, Taylor R. Ultrastructural defects in stereocilia and tectorial membrane in aging mouse and human cochleae. J Neurosci Res 2019; 98:1745-1763. [DOI: 10.1002/jnr.24556] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 10/24/2019] [Accepted: 10/28/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Anwen Bullen
- UCL Ear Institute University College London London UK
| | - Andrew Forge
- UCL Ear Institute University College London London UK
| | | | - Guy P. Richardson
- Sussex Neuroscience School of Life Sciences University of Sussex Falmer, Brighton UK
| | - Richard J. Goodyear
- Sussex Neuroscience School of Life Sciences University of Sussex Falmer, Brighton UK
| | - Ruth Taylor
- UCL Ear Institute University College London London UK
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18
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Michie KA, Bermeister A, Robertson NO, Goodchild SC, Curmi PMG. Two Sides of the Coin: Ezrin/Radixin/Moesin and Merlin Control Membrane Structure and Contact Inhibition. Int J Mol Sci 2019; 20:ijms20081996. [PMID: 31018575 PMCID: PMC6515277 DOI: 10.3390/ijms20081996] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/16/2019] [Accepted: 04/19/2019] [Indexed: 12/21/2022] Open
Abstract
The merlin-ERM (ezrin, radixin, moesin) family of proteins plays a central role in linking the cellular membranes to the cortical actin cytoskeleton. Merlin regulates contact inhibition and is an integral part of cell–cell junctions, while ERM proteins, ezrin, radixin and moesin, assist in the formation and maintenance of specialized plasma membrane structures and membrane vesicle structures. These two protein families share a common evolutionary history, having arisen and separated via gene duplication near the origin of metazoa. During approximately 0.5 billion years of evolution, the merlin and ERM family proteins have maintained both sequence and structural conservation to an extraordinary level. Comparing crystal structures of merlin-ERM proteins and their complexes, a picture emerges of the merlin-ERM proteins acting as switchable interaction hubs, assembling protein complexes on cellular membranes and linking them to the actin cytoskeleton. Given the high level of structural conservation between the merlin and ERM family proteins we speculate that they may function together.
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Affiliation(s)
- Katharine A Michie
- School of Physics, University of New South Wales, Sydney 2052, Australia.
| | - Adam Bermeister
- School of Physics, University of New South Wales, Sydney 2052, Australia.
| | - Neil O Robertson
- School of Physics, University of New South Wales, Sydney 2052, Australia.
| | - Sophia C Goodchild
- Department of Molecular Sciences, Macquarie University, Sydney 2109, Australia.
| | - Paul M G Curmi
- School of Physics, University of New South Wales, Sydney 2052, Australia.
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19
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Sphingosine 1-phosphate-mediated activation of ezrin-radixin-moesin proteins contributes to cytoskeletal remodeling and changes of membrane properties in epithelial otic vesicle progenitors. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:554-565. [PMID: 30611767 DOI: 10.1016/j.bbamcr.2018.12.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 11/24/2018] [Accepted: 12/18/2018] [Indexed: 12/20/2022]
Abstract
Hearing loss is among the most prevalent sensory impairments in humans. Cochlear implantable devices represent the current therapies for hearing loss but have various shortcomings. ERM (ezrin- radixin -moesin) are a family of adaptor proteins that link plasma membrane with actin cytoskeleton, playing a crucial role in cell morphology and in the formation of membrane protrusions. Recently, bioactive sphingolipids have emerged as regulators of ERM proteins. Sphingosine 1-phosphate (S1P) is a pleiotropic sphingolipid which regulates fundamental cellular functions such as proliferation, survival, migration as well as processes such as development and inflammation mainly via ligation to its specific receptors S1PR (S1P1-5). Experimental findings demonstrate a key role for S1P signaling axis in the maintenance of auditory function. Preservation of cellular junctions is a fundamental function both for S1P and ERM proteins, crucial for the maintenance of cochlear integrity. In the present work, S1P was found to activate ERM in a S1P2-dependent manner in murine auditory epithelial progenitors US/VOT-E36. S1P-induced ERM activation potently contributed to actin cytoskeletal remodeling and to the appearance of ionic currents and membrane passive properties changes typical of more differentiated cells. Moreover, PKC and Akt activation was found to mediate S1P-induced ERM phosphorylation. The obtained findings contribute to demonstrate the role of S1P signaling pathway in inner ear biology and to disclose potential innovative therapeutical approaches in the field of hearing loss prevention and treatment.
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20
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The microRNA-183/96/182 Cluster is Essential for Stereociliary Bundle Formation and Function of Cochlear Sensory Hair Cells. Sci Rep 2018; 8:18022. [PMID: 30575790 PMCID: PMC6303392 DOI: 10.1038/s41598-018-36894-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 11/22/2018] [Indexed: 12/20/2022] Open
Abstract
The microRNA (miR)-183/96/182 cluster plays important roles in the development and functions of sensory organs, including the inner ear. Point-mutations in the seed sequence of miR-96 result in non-syndromic hearing loss in both mice and humans. However, the lack of a functionally null mutant has hampered the evaluation of the cluster’s physiological functions. Here we have characterized a loss-of-function mutant mouse model (miR-183CGT/GT), in which the miR-183/96/182 cluster gene is inactivated by a gene-trap (GT) construct. The homozygous mutant mice show profound congenital hearing loss with severe defects in cochlear hair cell (HC) maturation, alignment, hair bundle formation and the checkboard-like pattern of the cochlear sensory epithelia. The stereociliary bundles retain an immature appearance throughout the cochlea at postnatal day (P) 3 and degenerate soon after. The organ of Corti of mutant newborn mice has no functional mechanoelectrical transduction. Several predicted target genes of the miR-183/96/182 cluster that are known to play important roles in HC development and function, including Clic5, Rdx, Ezr, Rac1, Myo1c, Pvrl3 and Sox2, are upregulated in the cochlea. These results suggest that the miR-183/96/182 cluster is essential for stereociliary bundle formation, morphogenesis and function of the cochlear HCs.
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21
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Zhai X, Liu C, Zhao B, Wang Y, Xu Z. Inactivation of Cyclin-Dependent Kinase 5 in Hair Cells Causes Hearing Loss in Mice. Front Mol Neurosci 2018; 11:461. [PMID: 30618612 PMCID: PMC6297389 DOI: 10.3389/fnmol.2018.00461] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 11/29/2018] [Indexed: 12/30/2022] Open
Abstract
Cyclin-dependent kinase 5 (CDK5) is abundantly expressed in post-mitotic cells including neurons. It is involved in multiple cellular events, such as cytoskeletal dynamics, signaling cascades, gene expression, and cell survival, et al. Dysfunction of CDK5 has been associated with a number of neurological disorders. Here we show that CDK5 is expressed in mouse cochlear hair cells, and CDK5 inactivation in hair cells causes hearing loss in mice. CDK5 inactivation has no effect on stereocilia development in the cochlear hair cells. However, it affects stereocilia maintenance, resulting in stereocilia disorganization and eventually stereocilia loss. Consistently, hair cell loss was significantly elevated by CDK5 inactivation. Despite that CDK5 has been shown to play important roles in synapse development and/or function, CDK5 inactivation does not affect the formation of ribbon synapses of cochlear hair cells. Further investigation showed that CDK5 inactivation causes reduced phosphorylation of ERM (ezrin, radixin, and moesin) proteins, which might contribute to the stereocilia deficits. Taken together, our data suggest that CDK5 plays pivotal roles in auditory hair cells, and CDK5 inactivation causes hearing loss in mice.
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Affiliation(s)
- Xiaoyan Zhai
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Chengcheng Liu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China.,Department of Otolaryngology-Head and Neck Surgery, The Second Hospital of Shandong University, Jinan, China
| | - Bin Zhao
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China.,Shenzhen Research Institute of Shandong University, Shenzhen, China.,Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, China
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22
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Pelaseyed T, Bretscher A. Regulation of actin-based apical structures on epithelial cells. J Cell Sci 2018; 131:131/20/jcs221853. [PMID: 30333133 DOI: 10.1242/jcs.221853] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Cells of transporting epithelia are characterized by the presence of abundant F-actin-based microvilli on their apical surfaces. Likewise, auditory hair cells have highly reproducible rows of apical stereocilia (giant microvilli) that convert mechanical sound into an electrical signal. Analysis of mutations in deaf patients has highlighted the critical components of tip links between stereocilia, and related structures that contribute to the organization of microvilli on epithelial cells have been found. Ezrin/radixin/moesin (ERM) proteins, which are activated by phosphorylation, provide a critical link between the plasma membrane and underlying actin cytoskeleton in surface structures. Here, we outline recent insights into how microvilli and stereocilia are built, and the roles of tip links. Furthermore, we highlight how ezrin is locally regulated by phosphorylation, and that this is necessary to maintain polarity. Localized phosphorylation is achieved through an intricate coincidence detection mechanism that requires the membrane lipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and the apically localized ezrin kinase, lymphocyte-oriented kinase (LOK, also known as STK10) or Ste20-like kinase (SLK). We also discuss how ezrin-binding scaffolding proteins regulate microvilli and how, despite these significant advances, it remains to be discovered how the cell polarity program ultimately interfaces with these processes.
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Affiliation(s)
- Thaher Pelaseyed
- Institute of Biomedicine, Department of Medical Biochemistry and Cell Biology, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Anthony Bretscher
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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23
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Men Y, Li X, Tu H, Zhang A, Fu X, Wang Z, Jin Y, Hou C, Zhang T, Zhang S, Zhou Y, Li B, Li J, Sun X, Wang H, Gao J. Tprn is essential for the integrity of stereociliary rootlet in cochlear hair cells in mice. Front Med 2018; 13:690-704. [PMID: 30159668 DOI: 10.1007/s11684-018-0638-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Accepted: 01/27/2018] [Indexed: 11/24/2022]
Abstract
Tprn encodes the taperin protein, which is concentrated in the tapered region of hair cell stereocilia in the inner ear. In humans, TPRN mutations cause autosomal recessive nonsyndromic deafness (DFNB79) by an unknown mechanism. To determine the role of Tprn in hearing, we generated Tprn-null mice by clustered regularly interspaced short palindromic repeat/Cas9 genome-editing technology from a CBA/CaJ background. We observed significant hearing loss and progressive degeneration of stereocilia in the outer hair cells of Tprn-null mice starting from postnatal day 30. Transmission electron microscopy images of stereociliary bundles in the mutant mice showed some stereociliary rootlets with curved shafts. The central cores of the stereociliary rootlets possessed hollow structures with surrounding loose peripheral dense rings. Radixin, a protein expressed at stereocilia tapering, was abnormally dispersed along the stereocilia shafts in Tprn-null mice. The expression levels of radixin and β-actin significantly decreased.We propose that Tprn is critical to the retention of the integrity of the stereociliary rootlet. Loss of Tprn in Tprn-null mice caused the disruption of the stereociliary rootlet, which resulted in damage to stereociliary bundles and hearing impairments. The generated Tprn-null mice are ideal models of human hereditary deafness DFNB79.
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Affiliation(s)
- Yuqin Men
- School of Life Science, Shandong University, Jinan, 250100, China
| | - Xiujuan Li
- Rizhao Polytechnic, Rizhao, 276826, China
| | - Hailong Tu
- School of Life Science, Shandong University, Jinan, 250100, China
| | - Aizhen Zhang
- School of Life Science, Shandong University, Jinan, 250100, China
| | - Xiaolong Fu
- School of Life Science, Shandong University, Jinan, 250100, China
| | - Zhishuo Wang
- School of Life Science, Shandong University, Jinan, 250100, China
| | - Yecheng Jin
- School of Life Science, Shandong University, Jinan, 250100, China
| | - Congzhe Hou
- The Second Hospital of Shandong University, Jinan, 250033, China
| | - Tingting Zhang
- School of Life Science, Shandong University, Jinan, 250100, China
| | - Sen Zhang
- School of Life Science, Shandong University, Jinan, 250100, China
| | - Yichen Zhou
- School of Life Science, Shandong University, Jinan, 250100, China
| | - Boqin Li
- Electron Microscopy Laboratory, Shandong Institute of Otolaryngology, Jinan, 250022, China.,Laboratory of Electron Microscopy, Jinan WEI-YA Biotech Company, Jinan, 250100, China
| | - Jianfeng Li
- Department of Otolaryngology-Head and Neck Surgery, Provincial Hospital Affiliated to Shandong University, Jinan, 250021, China
| | - Xiaoyang Sun
- School of Life Science, Shandong University, Jinan, 250100, China.
| | - Haibo Wang
- Department of Otolaryngology-Head and Neck Surgery, Provincial Hospital Affiliated to Shandong University, Jinan, 250021, China.
| | - Jiangang Gao
- School of Life Science, Shandong University, Jinan, 250100, China.
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24
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Wan M, Bennett BD, Pittman GS, Campbell MR, Reynolds LM, Porter DK, Crowl CL, Wang X, Su D, Englert NA, Thompson IJ, Liu Y, Bell DA. Identification of Smoking-Associated Differentially Methylated Regions Using Reduced Representation Bisulfite Sequencing and Cell type-Specific Enhancer Activation and Gene Expression. ENVIRONMENTAL HEALTH PERSPECTIVES 2018; 126:047015. [PMID: 29706059 PMCID: PMC6071796 DOI: 10.1289/ehp2395] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 03/22/2018] [Accepted: 03/22/2018] [Indexed: 05/23/2023]
Abstract
BACKGROUND Cigarette smoke is a causal factor in cancers and cardiovascular disease. Smoking-associated differentially methylated regions (SM-DMRs) have been observed in disease studies, but the causal link between altered DNA methylation and transcriptional change is obscure. OBJECTIVE Our objectives were to finely resolve SM-DMRs and to interrogate the mechanistic link between SM-DMRs and altered transcription of enhancer noncoding RNA (eRNA) and mRNA in human circulating monocytes. METHOD We integrated SM-DMRs identified by reduced representation bisulfite sequencing (RRBS) of circulating CD14+ monocyte DNA collected from two independent human studies [n=38 from Clinical Research Unit (CRU) and n=55 from the Multi-Ethnic Study of Atherosclerosis (MESA), about half of whom were active smokers] with gene expression for protein-coding genes and noncoding RNAs measured by RT-PCR or RNA sequencing. Candidate SM-DMRs were compared with RRBS of purified CD4+ T cells, CD8+ T cells, CD15+ granulocytes, CD19+ B cells, and CD56+ NK cells (n=19 females, CRU). DMRs were validated using pyrosequencing or bisulfite amplicon sequencing in up to 85 CRU volunteers, who also provided saliva DNA. RESULTS RRBS identified monocyte SM-DMRs frequently located in putative gene regulatory regions. The most significant monocyte DMR occurred at a poised enhancer in the aryl-hydrocarbon receptor repressor gene (AHRR) and it was also detected in both granulocytes and saliva DNA. To our knowledge, we identify for the first time that SM-DMRs in or near AHRR, C5orf55-EXOC-AS, and SASH1 were associated with increased noncoding eRNA as well as mRNA in monocytes. Functionally, the AHRR SM-DMR appeared to up-regulate AHRR mRNA through activating the AHRR enhancer, as suggested by increased eRNA in the monocytes, but not granulocytes, from smokers compared with nonsmokers. CONCLUSIONS Our findings suggest that AHRR SM-DMR up-regulates AHRR mRNA in a monocyte-specific manner by activating the AHRR enhancer. Cell type-specific activation of enhancers at SM-DMRs may represent a mechanism driving smoking-related disease. https://doi.org/10.1289/EHP2395.
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Affiliation(s)
- Ma Wan
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Brian D Bennett
- Integrative Bioinformatics Support Group, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina, USA
| | - Gary S Pittman
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Michelle R Campbell
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Lindsay M Reynolds
- Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Devin K Porter
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Christopher L Crowl
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Xuting Wang
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Dan Su
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Neal A Englert
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Isabel J Thompson
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Yongmei Liu
- Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Douglas A Bell
- Environmental Epigenomics and Disease Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
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25
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Abstract
Studies of bioactive lipids in general and sphingolipids in particular have intensified over the past several years, revealing an unprecedented and unanticipated complexity of the lipidome and its many functions, which rivals, if not exceeds, that of the genome or proteome. These results highlight critical roles for bioactive sphingolipids in most, if not all, major cell biological responses, including all major cell signalling pathways, and they link sphingolipid metabolism to key human diseases. Nevertheless, the fairly nascent field of bioactive sphingolipids still faces challenges in its biochemical and molecular underpinnings, including defining the molecular mechanisms of pathway and enzyme regulation, the study of lipid-protein interactions and the development of cellular probes, suitable biomarkers and therapeutic approaches.
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Affiliation(s)
- Yusuf A Hannun
- Stony Brook Cancer Center and Department of Medicine, Stony Brook University, New York 11794, USA
| | - Lina M Obeid
- Stony Brook Cancer Center and Department of Medicine, Stony Brook University, New York 11794, USA
- Northport Veterans Affairs Medical Center, Northport, New York 11768, USA
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26
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Park J, Jang JH, Oh S, Kim M, Shin C, Jeong M, Heo K, Park JB, Kim SR, Oh YS. LPA-induced migration of ovarian cancer cells requires activation of ERM proteins via LPA 1 and LPA 2. Cell Signal 2018; 44:138-147. [PMID: 29329782 DOI: 10.1016/j.cellsig.2018.01.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 01/02/2018] [Accepted: 01/07/2018] [Indexed: 12/22/2022]
Abstract
Lysophosphatidic acid (LPA) has been implicated in the pathology of human ovarian cancer. This phospholipid elicits a wide range of cancer cell responses, such as proliferation, trans-differentiation, migration, and invasion, via various G-protein-coupled LPA receptors (LPARs). Here, we explored the cellular signaling pathway via which LPA induces migration of ovarian cancer cells. LPA induced robust phosphorylation of ezrin/radixin/moesin (ERM) proteins, which are membrane-cytoskeleton linkers, in the ovarian cancer cell line OVCAR-3. Among the LPAR subtypes expressed in these cells, LPA1 and LPA2, but not LPA3, induced phosphorylation of ERM proteins at their C-termini. This phosphorylation was dependent on the Gα12/13/RhoA pathway, but not on the Gαq/Ca2+/PKC or Gαs/adenylate cyclase/PKA pathway. The activated ERM proteins mediated cytoskeletal reorganization and formation of membrane protrusions in OVCAR-3 cells. Importantly, LPA-induced migration of OVCAR-3 cells was completely abolished not only by gene silencing of LPA1 or LPA2, but also by overexpression of a dominant negative ezrin mutant (ezrin-T567A). Taken together, this study demonstrates that the LPA1/LPA2/ERM pathway mediates LPA-induced migration of ovarian cancer cells. These findings may provide a potential therapeutic target to prevent metastatic progression of ovarian cancer.
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Affiliation(s)
- Jeongrak Park
- Department of Brain-Cognitive Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpung-myeon, Dalseong-gun, Daegu, Republic of Korea
| | - Jin-Hyeok Jang
- Department of Brain-Cognitive Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpung-myeon, Dalseong-gun, Daegu, Republic of Korea
| | - Seojin Oh
- Department of Brain-Cognitive Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpung-myeon, Dalseong-gun, Daegu, Republic of Korea
| | - Minhye Kim
- Department of Brain-Cognitive Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpung-myeon, Dalseong-gun, Daegu, Republic of Korea
| | - Changhoon Shin
- Department of Brain-Cognitive Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpung-myeon, Dalseong-gun, Daegu, Republic of Korea
| | - Minseok Jeong
- Department of Brain-Cognitive Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpung-myeon, Dalseong-gun, Daegu, Republic of Korea
| | - Kyun Heo
- Research Institute, National Cancer Center, Goyang, Republic of Korea
| | - Jong Bae Park
- Research Institute, National Cancer Center, Goyang, Republic of Korea; Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Republic of Korea
| | - Sang Ryong Kim
- School of Life Sciences, BK21 plus KNU Creative BioResearch Group, Institute of Life Science & Biotechnology, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Yong-Seok Oh
- Department of Brain-Cognitive Sciences, Daegu-Gyeongbuk Institute of Science and Technology (DGIST), Hyeonpung-myeon, Dalseong-gun, Daegu, Republic of Korea.
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27
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ELMOD1 Stimulates ARF6-GTP Hydrolysis to Stabilize Apical Structures in Developing Vestibular Hair Cells. J Neurosci 2017; 38:843-857. [PMID: 29222402 DOI: 10.1523/jneurosci.2658-17.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/21/2017] [Accepted: 11/30/2017] [Indexed: 11/21/2022] Open
Abstract
Sensory hair cells require control of physical properties of their apical plasma membranes for normal development and function. Members of the ADP-ribosylation factor (ARF) small GTPase family regulate membrane trafficking and cytoskeletal assembly in many cells. We identified ELMO domain-containing protein 1 (ELMOD1), a guanine nucleoside triphosphatase activating protein (GAP) for ARF6, as the most highly enriched ARF regulator in hair cells. To characterize ELMOD1 control of trafficking, we analyzed mice of both sexes from a strain lacking functional ELMOD1 [roundabout (rda)]. In rda/rda mice, cuticular plates of utricle hair cells initially formed normally, then degenerated after postnatal day 5; large numbers of vesicles invaded the compromised cuticular plate. Hair bundles initially developed normally, but the cell's apical membrane lifted away from the cuticular plate, and stereocilia elongated and fused. Membrane trafficking in type I hair cells, measured by FM1-43 dye labeling, was altered in rda/rda mice. Consistent with the proposed GAP role for ELMOD1, the ARF6 GTP/GDP ratio was significantly elevated in rda/rda utricles compared with controls, and the level of ARF6-GTP was correlated with the severity of the rda/rda phenotype. These results suggest that conversion of ARF6 to its GDP-bound form is necessary for final stabilization of the hair bundle.SIGNIFICANCE STATEMENT Assembly of the mechanically sensitive hair bundle of sensory hair cells requires growth and reorganization of apical actin and membrane structures. Hair bundles and apical membranes in mice with mutations in the Elmod1 gene degenerate after formation, suggesting that the ELMOD1 protein stabilizes these structures. We show that ELMOD1 is a GTPase-activating protein in hair cells for the small GTP-binding protein ARF6, known to participate in actin assembly and membrane trafficking. We propose that conversion of ARF6 into the GDP-bound form in the apical domain of hair cells is essential for stabilizing apical actin structures like the hair bundle and ensuring that the apical membrane forms appropriately around the stereocilia.
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28
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Ferreira ÉR, Bonfim-Melo A, Cordero EM, Mortara RA. ERM Proteins Play Distinct Roles in Cell Invasion by Extracellular Amastigotes of Trypanosoma cruzi. Front Microbiol 2017; 8:2230. [PMID: 29209287 PMCID: PMC5702390 DOI: 10.3389/fmicb.2017.02230] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/30/2017] [Indexed: 12/03/2022] Open
Abstract
The protozoan parasite Trypanosoma cruzi is the causative agent of Chagas' disease. In mammalian hosts, T. cruzi alternates between trypomastigote and amastigote forms. Additionally, trypomastigotes can differentiate into amastigotes in the extracellular environment generating infective extracellular amastigotes (EAs). Ezrin-radixin-moesin (ERM) are key proteins linking plasma membrane to actin filaments, the major host cell component responsible for EA internalization. Our results revealed that depletion of host ezrin and radixin but not moesin inhibited EAs invasion in HeLa cells. ERM are recruited and colocalize with F-actin at EA invasion sites as shown by confocal microscopy. Invasion assays performed with cells overexpressing ERM showed increased EAs invasion in ezrin and radixin but not moesin overexpressing cells. Finally, time-lapse experiments have shown altered actin dynamics leading to delayed EA internalization in ezrin and radixin depleted cells when compared to control or moesin depleted cells. Altogether, these findings show distinct roles of ERM during EAs invasion, possibly regulating F-actin dynamics and plasma membrane interplay.
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Affiliation(s)
- Éden R Ferreira
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Alexis Bonfim-Melo
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Esteban M Cordero
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.,Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Renato A Mortara
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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29
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Vogl C, Butola T, Haag N, Hausrat TJ, Leitner MG, Moutschen M, Lefèbvre PP, Speckmann C, Garrett L, Becker L, Fuchs H, Hrabe de Angelis M, Nietzsche S, Kessels MM, Oliver D, Kneussel M, Kilimann MW, Strenzke N. The BEACH protein LRBA is required for hair bundle maintenance in cochlear hair cells and for hearing. EMBO Rep 2017; 18:2015-2029. [PMID: 28893864 DOI: 10.15252/embr.201643689] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 07/27/2017] [Accepted: 08/07/2017] [Indexed: 12/15/2022] Open
Abstract
Lipopolysaccharide-responsive beige-like anchor protein (LRBA) belongs to the enigmatic class of BEACH domain-containing proteins, which have been attributed various cellular functions, typically involving intracellular protein and membrane transport processes. Here, we show that LRBA deficiency in mice leads to progressive sensorineural hearing loss. In LRBA knockout mice, inner and outer hair cell stereociliary bundles initially develop normally, but then partially degenerate during the second postnatal week. LRBA deficiency is associated with a reduced abundance of radixin and Nherf2, two adaptor proteins, which are important for the mechanical stability of the basal taper region of stereocilia. Our data suggest that due to the loss of structural integrity of the central parts of the hair bundle, the hair cell receptor potential is reduced, resulting in a loss of cochlear sensitivity and functional loss of the fraction of spiral ganglion neurons with low spontaneous firing rates. Clinical data obtained from two human patients with protein-truncating nonsense or frameshift mutations suggest that LRBA deficiency may likewise cause syndromic sensorineural hearing impairment in humans, albeit less severe than in our mouse model.
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Affiliation(s)
- Christian Vogl
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Tanvi Butola
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Synaptic Nanophysiology Group, Max-Planck-Institute for Biophysical Chemistry Göttingen, Göttingen, Germany
| | - Natja Haag
- Institute for Biochemistry I, University Hospital Jena, Jena, Germany
| | - Torben J Hausrat
- Department for Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Michael G Leitner
- Department of Physiology, Philipps University Marburg, Marburg, Germany
| | - Michel Moutschen
- Department of Immunology and Infectious Diseases, University of Liège CHU Liège, Liège, Belgium
| | - Philippe P Lefèbvre
- Department of Otorhinolaryngology, University of Liège CHU Liège, Liège, Belgium
| | - Carsten Speckmann
- Division of Pediatric Hematology and Oncology, Center for Chronic Immunodeficiency and Department of Pediatrics and Adolescent Medicine, Medical Centre, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Lillian Garrett
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München German Research Center for Environmental Health, Neuherberg, Germany.,Institute of Developmental Genetics, Helmholtz Zentrum München German Research Center for Environmental Health, Neuherberg, Germany
| | - Lore Becker
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München German Research Center for Environmental Health, Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München German Research Center for Environmental Health, Neuherberg, Germany
| | - Martin Hrabe de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München German Research Center for Environmental Health, Neuherberg, Germany.,Chair of Experimental Genetics, School of Life Science Weihenstephan, Technische Universität München, München, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany
| | | | - Michael M Kessels
- Institute for Biochemistry I, University Hospital Jena, Jena, Germany
| | - Dominik Oliver
- Department of Physiology, Philipps University Marburg, Marburg, Germany
| | - Matthias Kneussel
- Department for Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Manfred W Kilimann
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany.,Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Nicola Strenzke
- Auditory Systems Physiology Group Department of Otolaryngology University Medical Center Göttingen, Göttingen, Germany
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30
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Seki Y, Miyasaka Y, Suzuki S, Wada K, Yasuda SP, Matsuoka K, Ohshiba Y, Endo K, Ishii R, Shitara H, Kitajiri SI, Nakagata N, Takebayashi H, Kikkawa Y. A novel splice site mutation of myosin VI in mice leads to stereociliary fusion caused by disruption of actin networks in the apical region of inner ear hair cells. PLoS One 2017; 12:e0183477. [PMID: 28832620 PMCID: PMC5568226 DOI: 10.1371/journal.pone.0183477] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 08/04/2017] [Indexed: 01/03/2023] Open
Abstract
An unconventional myosin encoded by the myosin VI gene (MYO6) contributes to hearing loss in humans. Homozygous mutations of MYO6 result in nonsyndromic profound congenital hearing loss, DFNB37. Kumamoto shaker/waltzer (ksv) mice harbor spontaneous mutations, and homozygous mutants exhibit congenital defects in balance and hearing caused by fusion of the stereocilia. We identified a Myo6c.1381G>A mutation that was found to be a p.E461K mutation leading to alternative splicing errors in Myo6 mRNA in ksv mutants. An analysis of the mRNA and protein expression in animals harboring this mutation suggested that most of the abnormal alternatively spliced isoforms of MYO6 are degraded in ksv mice. In the hair cells of ksv/ksv homozygotes, the MYO6 protein levels were significantly decreased in the cytoplasm, including in the cuticular plates. MYO6 and stereociliary taper-specific proteins were mislocalized along the entire length of the stereocilia of ksv/ksv mice, thus suggesting that MYO6 attached to taper-specific proteins at the stereociliary base. Histological analysis of the cochlear hair cells showed that the stereociliary fusion in the ksv/ksv mutants, developed through fusion between stereociliary bundles, raised cuticular plate membranes in the cochlear hair cells and resulted in incorporation of the bundles into the sheaths of the cuticular plates. Interestingly, the expression of the stereociliary rootlet-specific TRIO and F-actin binding protein (TRIOBP) was altered in ksv/ksv mice. The abnormal expression of TRIOBP suggested that the rootlets in the hair cells of ksv/ksv mice had excessive growth. Hence, these data indicated that decreased MYO6 levels in ksv/ksv mutants disrupt actin networks in the apical region of hair cells, thereby maintaining the normal structure of the cuticular plates and rootlets, and additionally provided a cellular basis for stereociliary fusion in Myo6 mutants.
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Affiliation(s)
- Yuta Seki
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Yuki Miyasaka
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.,Division of Experimental Animals, Center for Promotion of Medical Research and Education, Graduate School of Medicine, Nagoya University, Nagoya, Aichi, Japan
| | - Sari Suzuki
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Kenta Wada
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.,Laboratory of Animal Biotechnology, Department of Bioproduction, Faculty of Bioindustry, Tokyo University of Agriculture, Abashiri, Hokkaido, Japan
| | - Shumpei P Yasuda
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Kunie Matsuoka
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Yasuhiro Ohshiba
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Kentaro Endo
- Histology Laboratory, Advanced Technical Support Department, Center for Basic Technology Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Rie Ishii
- Laboratory for Transgenic Technology, Animal Research Division, Center for Basic Technology Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Hiroshi Shitara
- Laboratory for Transgenic Technology, Animal Research Division, Center for Basic Technology Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Shin-Ichiro Kitajiri
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Naomi Nakagata
- Division of Reproductive Engineering, Center for Animal Resources and Development (CARD), Kumamoto University, Kumamoto, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Yoshiaki Kikkawa
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
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31
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Argenzio E, Moolenaar WH. Emerging biological roles of Cl- intracellular channel proteins. J Cell Sci 2017; 129:4165-4174. [PMID: 27852828 DOI: 10.1242/jcs.189795] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cl- intracellular channels (CLICs) are a family of six evolutionary conserved cytosolic proteins that exist in both soluble and membrane-associated forms; however, their functions have long been elusive. Soluble CLICs adopt a glutathione S-transferase (GST)-fold, can induce ion currents in artificial membranes and show oxidoreductase activity in vitro, but there is no convincing evidence of CLICs having such activities in vivo. Recent studies have revealed a role for CLIC proteins in Rho-regulated cortical actin dynamics as well as vesicular trafficking and integrin recycling, the latter of which are under the control of Rab GTPases. In this Commentary, we discuss the emerging roles of CLIC proteins in these processes and the lessons learned from gene-targeting studies. We also highlight outstanding questions regarding the molecular function(s) of these important but still poorly understood proteins.
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Affiliation(s)
- Elisabetta Argenzio
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
| | - Wouter H Moolenaar
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
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32
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Kawaguchi K, Yoshida S, Hatano R, Asano S. Pathophysiological Roles of Ezrin/Radixin/Moesin Proteins. Biol Pharm Bull 2017; 40:381-390. [PMID: 28381792 DOI: 10.1248/bpb.b16-01011] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ezrin/radixin/moesin (ERM) proteins function as general cross-linkers between plasma membrane proteins and the actin cytoskeleton and are involved in the functional expression of membrane proteins on the cell surface. They also integrate Rho guanosine 5'-triphosphatase (GTPase) signaling to regulate cytoskeletal organization by sequestering Rho-related proteins. They act as protein kinase A (PKA)-anchoring proteins and sequester PKA close to its target proteins for their effective phosphorylation and functional regulation. Therefore, ERM proteins seem to play important roles in the membrane transport of electrolytes by ion channels and transporters. In this review, we focus on the pathophysiological roles of ERM proteins in in vivo studies and introduce the phenotypes of their knockout and knockdown mice.
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Affiliation(s)
- Kotoku Kawaguchi
- Department of Molecular Physiology, College of Pharmaceutical Sciences, Ritsumeikan University
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Ezrin enhances line tension along transcellular tunnel edges via NMIIa driven actomyosin cable formation. Nat Commun 2017. [PMID: 28643776 PMCID: PMC5490010 DOI: 10.1038/ncomms15839] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Transendothelial cell macroaperture (TEM) tunnels control endothelium barrier function and are triggered by several toxins from pathogenic bacteria that provoke vascular leakage. Cellular dewetting theory predicted that a line tension of uncharacterized origin works at TEM boundaries to limit their widening. Here, by conducting high-resolution microscopy approaches we unveil the presence of an actomyosin cable encircling TEMs. We develop a theoretical cellular dewetting framework to interpret TEM physical parameters that are quantitatively determined by laser ablation experiments. This establishes the critical role of ezrin and non-muscle myosin II (NMII) in the progressive implementation of line tension. Mechanistically, fluorescence-recovery-after-photobleaching experiments point for the upstream role of ezrin in stabilizing actin filaments at the edges of TEMs, thereby favouring their crosslinking by NMIIa. Collectively, our findings ascribe to ezrin and NMIIa a critical function of enhancing line tension at the cell boundary surrounding the TEMs by promoting the formation of an actomyosin ring.
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Global Analysis of Protein Expression of Inner Ear Hair Cells. J Neurosci 2016; 37:1320-1339. [PMID: 28039372 DOI: 10.1523/jneurosci.2267-16.2016] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 11/29/2016] [Accepted: 12/19/2016] [Indexed: 11/21/2022] Open
Abstract
The mammalian inner ear (IE) subserves auditory and vestibular sensations via highly specialized cells and proteins. Sensory receptor hair cells (HCs) are necessary for transducing mechanical inputs and stimulating sensory neurons by using a host of known and as yet unknown protein machinery. To understand the protein composition of these unique postmitotic cells, in which irreversible protein degradation or damage can lead to impaired hearing and balance, we analyzed IE samples by tandem mass spectrometry to generate an unbiased, shotgun-proteomics view of protein identities and abundances. By using Pou4f3/eGFP-transgenic mice in which HCs express GFP driven by Pou4f3, we FACS purified a population of HCs to analyze and compare the HC proteome with other IE subproteomes from sensory epithelia and whole IE. We show that the mammalian HC proteome comprises hundreds of uniquely or highly expressed proteins. Our global proteomic analysis of purified HCs extends the existing HC transcriptome, revealing previously undetected gene products and isoform-specific protein expression. Comparison of our proteomic data with mouse and human databases of genetic auditory/vestibular impairments confirms the critical role of the HC proteome for normal IE function, providing a cell-specific pool of candidates for novel, important HC genes. Several proteins identified exclusively in HCs by proteomics and verified by immunohistochemistry map to human genetic deafness loci, potentially representing new deafness genes. SIGNIFICANCE STATEMENT Hearing and balance rely on specialized sensory hair cells (HCs) in the inner ear (IE) to convey information about sound, acceleration, and orientation to the brain. Genetically and environmentally induced perturbations to HC proteins can result in deafness and severe imbalance. We used transgenic mice with GFP-expressing HCs, coupled with FACS sorting and tandem mass spectrometry, to define the most complete HC and IE proteome to date. We show that hundreds of proteins are uniquely identified or enriched in HCs, extending previous gene expression analyses to reveal novel HC proteins and isoforms. Importantly, deafness-linked proteins were significantly enriched in HCs, suggesting that this in-depth proteomic analysis of IE sensory cells may hold potential for deafness gene discovery.
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Tavasoli M, Al-Momany A, Wang X, Li L, Edwards JC, Ballermann BJ. Both CLIC4 and CLIC5A activate ERM proteins in glomerular endothelium. Am J Physiol Renal Physiol 2016; 311:F945-F957. [PMID: 27582103 DOI: 10.1152/ajprenal.00353.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/25/2016] [Indexed: 01/17/2023] Open
Abstract
The chloride intracellular channel (CLIC) 5A is expressed at very high levels in renal glomeruli, in both endothelial cells (EC) and podocytes. CLIC5A stimulates Rac1- and phosphatidylinositol (4,5)-bisphosphate-dependent ERM (ezrin, radixin, moesin) activation. ERM proteins, in turn, function in lumen formation and in the development of actin-based cellular projections. In mice lacking CLIC5A, ERM phosphorylation is profoundly reduced in podocytes, but preserved in glomerular EC. Since glomerular EC also express CLIC4, we reasoned that, if CLIC4 activates ERM proteins like CLIC5A, then CLIC4 could compensate for the CLIC5A loss in glomerular EC. In glomeruli of CLIC5-deficient mice, CLIC4 expression was upregulated and colocalized with moesin and ezrin in glomerular EC, but not in podocytes. In cultured glomerular EC, CLIC4 silencing reduced ERM phosphorylation and cytoskeletal association, and expression of exogenous CLIC4 or CLIC5A rescued ERM de-phosphorylation due to CLIC4 silencing. In mice lacking either CLIC4 or CLIC5, ERM phosphorylation was retained in glomerular EC, but, in mice lacking both CLIC4 and CLIC5, glomerular EC ERM phosphorylation was profoundly reduced. Although glomerular EC fenestrae developed normally in dual CLIC4/CLIC5-deficient mice, the density of fenestrae declined substantially by 8 mo of age, along with the deposition of subendothelial electron-lucent material. The dual CLIC4/CLIC5-deficient mice developed spontaneous proteinuria, glomerular cell proliferation, and matrix deposition. Thus CLIC4 stimulates ERM activation and can compensate for CLIC5A in glomerular EC. The findings indicate that CLIC4/CLIC5A-mediated ERM activation is required for maintenance of the glomerular capillary architecture.
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Affiliation(s)
- Mahtab Tavasoli
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Abass Al-Momany
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; and
| | - Xin Wang
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Laiji Li
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - John C Edwards
- Department of Internal Medicine, St. Louis University, St. Louis, Missouri
| | - Barbara J Ballermann
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; .,Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; and
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Ohlemiller KK, Kiener AL, Gagnon PM. QTL Mapping of Endocochlear Potential Differences between C57BL/6J and BALB/cJ mice. J Assoc Res Otolaryngol 2016; 17:173-94. [PMID: 26980469 DOI: 10.1007/s10162-016-0558-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 02/25/2016] [Indexed: 12/18/2022] Open
Abstract
We reported earlier that the endocochlear potential (EP) differs between C57BL/6J (B6) and BALB/cJ (BALB) mice, being lower in BALBs by about 10 mV (Ohlemiller et al. Hear Res 220: 10-26, 2006). This difference corresponds to strain differences with respect to the density of marginal cells in cochlear stria vascularis. After about 1 year of age, BALB mice also tend toward EP reduction that correlates with further marginal cell loss. We therefore suggested that early sub-clinical features of the BALB stria vascularis may predispose these mice to a condition modeling Schuknecht's strial presbycusis. We further reported (Ohlemiller et al. J Assoc Res Otolaryngol 12: 45-58, 2011) that the acute effects of a 2-h 110 dB SPL noise exposure differ between B6 and BALB mice, such that the EP remains unchanged in B6 mice, but is reduced by 40-50 mV in BALBs. In about 25 % of BALBs, the EP does not completely recover, so that permanent EP reduction may contribute to noise-induced permanent threshold shifts in BALBs. To identify genes and alleles that may promote natural EP variation as well as noise-related EP reduction in BALB mice, we have mapped related quantitative trait loci (QTLs) using 12 recombinant inbred (RI) strains formed from B6 and BALB (CxB1-CxB12). EP and strial marginal cell density were measured in B6 mice, BALB mice, their F1 hybrids, and RI mice without noise exposure, and 1-3 h after broadband noise (4-45 kHz, 110 dB SPL, 2 h). For unexposed mice, the strain distribution patterns for EP and marginal cell density were used to generate preliminary QTL maps for both EP and marginal cell density. Six QTL regions were at least statistically suggestive, including a significant QTL for marginal cell density on chromosome 12 that overlapped a weak QTL for EP variation. This region, termed Maced (Marginal cell density QTL) supports the notion of marginal cell density as a genetically influenced contributor to natural EP variation. Candidate genes for Maced notably include Foxg1, Foxa1, Akap6, Nkx2-1, and Pax9. Noise exposure produced significant EP reductions in two RI strains as well as significant EP increases in two RI strains. QTL mapping of the EP in noise-exposed RI mice yielded four suggestive regions. Two of these overlapped with QTL regions we previously identified for noise-related EP reduction in CBA/J mice (Ohlemiller et al. Hear Res 260: 47-53, 2010) on chromosomes 5 and 18 (Nirep). The present map may narrow the Nirep interval to a ~10-Mb region of proximal Chr. 18 that includes Zeb1, Arhgap12, Mpp7, and Gjd4. This study marks the first exploration of natural gene variants that modulate the EP. Their orthologs may underlie some human hearing loss that originates in the lateral wall.
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Affiliation(s)
- Kevin K Ohlemiller
- Department of Otolaryngology, Central Institute for the Deaf at Washington University School of Medicine, Fay and Carl Simons Center for Hearing and Deafness, Washington University School of Medicine, 660 S. Euclid, St. Louis, MO, 63110, USA.
| | - Anna L Kiener
- Department of Speech and Hearing Science, Ohio State University, Columbus, OH, USA
| | - Patricia M Gagnon
- Department of Otolaryngology, Central Institute for the Deaf at Washington University School of Medicine, Fay and Carl Simons Center for Hearing and Deafness, Washington University School of Medicine, 660 S. Euclid, St. Louis, MO, 63110, USA
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Tavasoli M, Li L, Al-Momany A, Zhu LF, Adam BA, Wang Z, Ballermann BJ. The chloride intracellular channel 5A stimulates podocyte Rac1, protecting against hypertension-induced glomerular injury. Kidney Int 2016; 89:833-47. [PMID: 26924049 DOI: 10.1016/j.kint.2016.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 07/02/2015] [Accepted: 10/15/2015] [Indexed: 11/16/2022]
Abstract
Glomerular capillary hypertension elicits podocyte remodeling and is a risk factor for the progression of glomerular disease. Ezrin, which links podocalyxin to actin in podocytes, is activated through the chloride intracellular channel 5A (CLIC5A)-dependent phosphatidylinositol 4,5 bisphosphate (PI[4,5]P2) accumulation. Because Rac1 is involved in podocyte actin remodeling and can promote PI[4,5]P2 production we determined whether CLIC5A-dependent PI[4,5]P2 generation and ezrin activation are mediated by Rac1. In COS7 cells, CLIC5A expression stimulated Rac1 but not Cdc42 or Rho activity. CLIC5A also stimulated phosphorylation of the Rac1 effector Pak1 in COS7 cells and in cultured mouse podocytes. CLIC5A-induced PI[4,5]P2 accumulation and Pak1 and ezrin phosphorylation were all Rac1 dependent. In DOCA/Salt hypertension, phosphorylated Pak increased in podocytes of wild-type, but not CLIC5-deficient mice. In DOCA/salt hypertensive mice lacking CLIC5, glomerular capillary microaneurysms were more frequent and albuminuria was greater than in wild-type mice. Thus, augmented hypertension-induced glomerular capillary injury in mice lacking CLIC5 results from abrogation of Rac1-dependent Pak and ezrin activation, perhaps reducing the tensile strength of the podocyte actin cytoskeleton.
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Affiliation(s)
- Mahtab Tavasoli
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Laiji Li
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Abass Al-Momany
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Lin-Fu Zhu
- Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Benjamin A Adam
- Department of Pathology and Laboratory Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Zhixiang Wang
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Barbara J Ballermann
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
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Santos-Cortez RLP, Faridi R, Rehman AU, Lee K, Ansar M, Wang X, Morell RJ, Isaacson R, Belyantseva IA, Dai H, Acharya A, Qaiser TA, Muhammad D, Ali RA, Shams S, Hassan MJ, Shahzad S, Raza SI, Bashir ZEH, Smith JD, Nickerson DA, Bamshad MJ, Riazuddin S, Ahmad W, Friedman TB, Leal SM. Autosomal-Recessive Hearing Impairment Due to Rare Missense Variants within S1PR2. Am J Hum Genet 2016; 98:331-8. [PMID: 26805784 DOI: 10.1016/j.ajhg.2015.12.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/07/2015] [Indexed: 11/17/2022] Open
Abstract
The sphingosine-1-phosphate receptors (S1PRs) are a well-studied class of transmembrane G protein-coupled sphingolipid receptors that mediate multiple cellular processes. However, S1PRs have not been previously reported to be involved in the genetic etiology of human traits. S1PR2 lies within the autosomal-recessive nonsyndromic hearing impairment (ARNSHI) locus DFNB68 on 19p13.2. From exome sequence data we identified two pathogenic S1PR2 variants, c.323G>C (p.Arg108Pro) and c.419A>G (p.Tyr140Cys). Each of these variants co-segregates with congenital profound hearing impairment in consanguineous Pakistani families with maximum LOD scores of 6.4 for family DEM4154 and 3.3 for family PKDF1400. Neither S1PR2 missense variant was reported among ∼120,000 chromosomes in the Exome Aggregation Consortium database, in 76 unrelated Pakistani exomes, or in 720 Pakistani control chromosomes. Both DNA variants affect highly conserved residues of S1PR2 and are predicted to be damaging by multiple bioinformatics tools. Molecular modeling predicts that these variants affect binding of sphingosine-1-phosphate (p.Arg108Pro) and G protein docking (p.Tyr140Cys). In the previously reported S1pr2(-/-) mice, stria vascularis abnormalities, organ of Corti degeneration, and profound hearing loss were observed. Additionally, hair cell defects were seen in both knockout mice and morphant zebrafish. Family PKDF1400 presents with ARNSHI, which is consistent with the lack of gross malformations in S1pr2(-/-) mice, whereas family DEM4154 has lower limb malformations in addition to hearing loss. Our findings suggest the possibility of developing therapies against hair cell damage (e.g., from ototoxic drugs) through targeted stimulation of S1PR2.
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Affiliation(s)
- Regie Lyn P Santos-Cortez
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Rabia Faridi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA; Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54550, Pakistan
| | - Atteeq U Rehman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA
| | - Kwanghyuk Lee
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Muhammad Ansar
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Xin Wang
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Robert J Morell
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA
| | - Rivka Isaacson
- Department of Chemistry, Faculty of Natural and Mathematical Sciences, King's College London, London WC2R 2LS, UK
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA
| | - Hang Dai
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Anushree Acharya
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Tanveer A Qaiser
- Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54550, Pakistan
| | - Dost Muhammad
- Chandka Medical College, Larkana, Sindh 77150, Pakistan
| | | | - Sulaiman Shams
- Department of Biochemistry, Abdul Wali Khan University, Mardan, 23200 Khyber Pakhtunkhwa, Pakistan
| | - Muhammad Jawad Hassan
- Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Science & Technology (NUST), Islamabad 44000, Pakistan
| | - Shaheen Shahzad
- Department of Biotechnology and Bioinformatics, International Islamic University, Islamabad 44000, Pakistan
| | - Syed Irfan Raza
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Zil-E-Huma Bashir
- Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54550, Pakistan
| | - Joshua D Smith
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Deborah A Nickerson
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Michael J Bamshad
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Sheikh Riazuddin
- University of Lahore, Lahore 54550, Pakistan; Allama Iqbal Medical Research Centre, Jinnah Hospital Complex, Lahore 54550, Pakistan; Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad 44000, Pakistan
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA
| | - Suzanne M Leal
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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Sauvanet C, Wayt J, Pelaseyed T, Bretscher A. Structure, Regulation, and Functional Diversity of Microvilli on the Apical Domain of Epithelial Cells. Annu Rev Cell Dev Biol 2015; 31:593-621. [DOI: 10.1146/annurev-cellbio-100814-125234] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Cécile Sauvanet
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
| | - Jessica Wayt
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
| | - Thaher Pelaseyed
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
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Men Y, Zhang A, Li H, Zhang T, Jin Y, Li H, Zhang J, Gao J. LKB1 Is Required for the Development and Maintenance of Stereocilia in Inner Ear Hair Cells in Mice. PLoS One 2015; 10:e0135841. [PMID: 26274331 PMCID: PMC4537123 DOI: 10.1371/journal.pone.0135841] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 07/27/2015] [Indexed: 01/14/2023] Open
Abstract
The LKB1 gene, which encodes a serine/threonine kinase, was discovered to play crucial roles in cell differentiation, proliferation, and the establishment of cell polarity. In our study, LKB1 conditional knockout mice (Atoh1-LKB1-/- mice) were generated to investigate LKB1 function in the inner ear. Tests of auditory brainstem response and distortion product otoacoustic emissions revealed significant decreases in the hearing sensitivities of the Atoh1-LKB1-/- mice. In Atoh1-LKB1-/- mice, malformations of hair cell stereocilliary bundles were present as early as postnatal day 1 (P1), a time long before the maturation of the hair cell bundles. In addition, we also observed outer hair cell (OHC) loss starting at P14. The impaired stereocilliary bundles occurred long before the presence of hair cell loss. Stereociliary cytoskeletal structure depends on the core actin-based cytoskeleton and several actin-binding proteins. By Western blot, we examined actin-binding proteins, specifically ERM (ezrin/radixin/moesin) proteins involved in the regulation of the actin cytoskeleton of hair cell stereocilia. Our results revealed that the phosphorylation of ERM proteins (pERM) was significantly decreased in mutant mice. Thus, we propose that the decreased pERM may be a key factor for the impaired stereocillia function, and the damaged stereocillia may induce hair cell loss and hearing impairments. Taken together, our data indicates that LKB1 is required for the development and maintenance of stereocilia in the inner ear.
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Affiliation(s)
- Yuqin Men
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Aizhen Zhang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Haixiang Li
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Tingting Zhang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Yecheng Jin
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Huashun Li
- SARITEX Center for Stem Cell, Engineering Translational Medicine, Shanghai East Hospital, Advanced Institute of Translational Medicine, Tongji University School of Medicine, Shanghai, China
- Center for Stem Cell&Nano-Medicine, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
- Shenzhen Key Laboratory for Molecular Biology of Neural Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Jian Zhang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
- * E-mail: (JG); (JZ)
| | - Jiangang Gao
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
- * E-mail: (JG); (JZ)
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Adada MM, Canals D, Jeong N, Kelkar AD, Hernandez-Corbacho M, Pulkoski-Gross MJ, Donaldson JC, Hannun YA, Obeid LM. Intracellular sphingosine kinase 2-derived sphingosine-1-phosphate mediates epidermal growth factor-induced ezrin-radixin-moesin phosphorylation and cancer cell invasion. FASEB J 2015. [PMID: 26209696 DOI: 10.1096/fj.15-274340] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The bioactive sphingolipid sphingosine-1-phosphate (S1P) mediates cellular proliferation, mitogenesis, inflammation, and angiogenesis. These biologies are mediated through S1P binding to specific GPCRs [sphingosine-1-phosphate receptor (S1PR)1-5] and some other less well-characterized intracellular targets. Ezrin-radixin-moesin (ERM) proteins, a family of adaptor molecules linking the cortical actin cytoskeleton to the plasma membrane, are emerging as critical regulators of cancer invasion via regulation of cell morphology and motility. Recently, we identified S1P as an acute ERM activator (via phosphorylation) through its action on S1PR2. In this work, we dissect the mechanism of S1P generation downstream of epidermal growth factor (EGF) leading to ERM phosphorylation and cancer invasion. Using pharmacologic inhibitors, small interfering RNA technologies, and genetic approaches, we demonstrate that sphingosine kinase (SK)2, and not SK1, is essential and sufficient in EGF-mediated ERM phosphorylation in HeLa cells. In fact, knocking down SK2 decreased ERM activation 2.5-fold. Furthermore, we provide evidence that SK2 is necessary to mediate EGF-induced invasion. In addition, overexpressing SK2 causes a 2-fold increase in HeLa cell invasion. Surprisingly, and for the first time, we find that this event, although dependent on S1PR2 activation, does not generate and does not require extracellular S1P secretion, therefore introducing a potential novel model of autocrine/intracrine action of S1P that still involves its GPCRs. These results define new mechanistic insights for EGF-mediated invasion and novel actions of SK2, therefore setting the stage for novel targets in the treatment of growth factor-driven malignancies.
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Affiliation(s)
- Mohamad M Adada
- *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA
| | - Daniel Canals
- *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA
| | - Nara Jeong
- *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA
| | - Ashwin D Kelkar
- *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA
| | - Maria Hernandez-Corbacho
- *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA
| | - Michael J Pulkoski-Gross
- *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA
| | - Jane C Donaldson
- *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA
| | - Yusuf A Hannun
- *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA
| | - Lina M Obeid
- *Department of Medicine and the Stony Brook Cancer Center, Stony Brook University, Stony Brook, New York, USA; and Northport Veterans Affairs Medical Center, North Port, New York, USA
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A short splice form of Xin-actin binding repeat containing 2 (XIRP2) lacking the Xin repeats is required for maintenance of stereocilia morphology and hearing function. J Neurosci 2015; 35:1999-2014. [PMID: 25653358 DOI: 10.1523/jneurosci.3449-14.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Approximately one-third of known deafness genes encode proteins located in the hair bundle, the sensory hair cell's mechanoreceptive organelle. In previous studies, we used mass spectrometry to characterize the hair bundle's proteome, resulting in the discovery of novel bundle proteins. One such protein is Xin-actin binding repeat containing 2 (XIRP2), an actin-cross-linking protein previously reported to be specifically expressed in striated muscle. Because mutations in other actin-cross-linkers result in hearing loss, we investigated the role of XIRP2 in hearing function. In the inner ear, XIRP2 is specifically expressed in hair cells, colocalizing with actin-rich structures in bundles, the underlying cuticular plate, and the circumferential actin belt. Analysis using peptide mass spectrometry revealed that the bundle harbors a previously uncharacterized XIRP2 splice variant, suggesting XIRP2's role in the hair cell differs significantly from that reported in myocytes. To determine the role of XIRP2 in hearing, we applied clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-mediated genome-editing technology to induce targeted mutations into the mouse Xirp2 gene, resulting in the elimination of XIRP2 protein expression in the inner ear. Functional analysis of hearing in the resulting Xirp2-null mice revealed high-frequency hearing loss, and ultrastructural scanning electron microscopy analyses of hair cells demonstrated stereocilia degeneration in these mice. We thus conclude that XIRP2 is required for long-term maintenance of hair cell stereocilia, and that its dysfunction causes hearing loss in the mouse.
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Nishio SY, Hattori M, Moteki H, Tsukada K, Miyagawa M, Naito T, Yoshimura H, Iwasa YI, Mori K, Shima Y, Sakuma N, Usami SI. Gene expression profiles of the cochlea and vestibular endorgans: localization and function of genes causing deafness. Ann Otol Rhinol Laryngol 2015; 124 Suppl 1:6S-48S. [PMID: 25814645 DOI: 10.1177/0003489415575549] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES We sought to elucidate the gene expression profiles of the causative genes as well as the localization of the encoded proteins involved in hereditary hearing loss. METHODS Relevant articles (as of September 2014) were searched in PubMed databases, and the gene symbols of the genes reported to be associated with deafness were located on the Hereditary Hearing Loss Homepage using localization, expression, and distribution as keywords. RESULTS Our review of the literature allowed us to systematize the gene expression profiles for genetic deafness in the inner ear, clarifying the unique functions and specific expression patterns of these genes in the cochlea and vestibular endorgans. CONCLUSIONS The coordinated actions of various encoded molecules are essential for the normal development and maintenance of auditory and vestibular function.
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Affiliation(s)
- Shin-Ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Mitsuru Hattori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hideaki Moteki
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Keita Tsukada
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Maiko Miyagawa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Takehiko Naito
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hidekane Yoshimura
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yoh-Ichiro Iwasa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Kentaro Mori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yutaka Shima
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Naoko Sakuma
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Otorhinolaryngology and Head and Neck Surgery, Yokohama City University School of Medicine, Yokohama, Japan
| | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
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Abstract
Epithelial cells from diverse tissues, including the enterocytes that line the intestinal tract, remodel their apical surface during differentiation to form a brush border: an array of actin-supported membrane protrusions known as microvilli that increases the functional capacity of the tissue. Although our understanding of how epithelial cells assemble, stabilize, and organize apical microvilli is still developing, investigations of the biochemical and physical underpinnings of these processes suggest that cells coordinate cytoskeletal remodeling, membrane-cytoskeleton cross-linking, and extracellular adhesion to shape the apical brush border domain.
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Affiliation(s)
- Scott W Crawley
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Mark S Mooseker
- Department of Molecular, Cellular and Developmental Biology, Department of Cell Biology, and Department of Pathology, Yale University, New Haven, CT 06520 Department of Molecular, Cellular and Developmental Biology, Department of Cell Biology, and Department of Pathology, Yale University, New Haven, CT 06520 Department of Molecular, Cellular and Developmental Biology, Department of Cell Biology, and Department of Pathology, Yale University, New Haven, CT 06520
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232
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Han Y, Wang X, Chen J, Sha SH. Noise-induced cochlear F-actin depolymerization is mediated via ROCK2/p-ERM signaling. J Neurochem 2015; 133:617-28. [PMID: 25683353 DOI: 10.1111/jnc.13061] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/26/2015] [Accepted: 02/04/2015] [Indexed: 02/02/2023]
Abstract
Our previous work has suggested that traumatic noise activates Rho-GTPase pathways in cochlear outer hair cells (OHCs), resulting in cell death and noise-induced hearing loss (NIHL). In this study, we investigated Rho effectors, Rho-associated kinases (ROCKs), and the targets of ROCKs, the ezrin-radixin-moesin (ERM) proteins, in the regulation of the cochlear actin cytoskeleton using adult CBA/J mice under conditions of noise-induced temporary threshold shift (TTS) and permanent threshold shift (PTS) hearing loss, which result in changes to the F/G-actin ratio. The levels of cochlear ROCK2 and p-ERM decreased 1 h after either TTS- or PTS-noise exposure. In contrast, ROCK2 and p-ERM in OHCs decreased only after PTS-, not after TTS-noise exposure. Treatment with lysophosphatidic acid, an activator of the Rho pathway, resulted in significant reversal of the F/G-actin ratio changes caused by noise exposure and attenuated OHC death and NIHL. Conversely, the down-regulation of ROCK2 by pretreatment with ROCK2 siRNA reduced the expression of ROCK2 and p-ERM in OHCs, exacerbated TTS to PTS, and worsened OHC loss. Additionally, pretreatment with siRNA against radixin, an ERM protein, aggravated TTS to PTS. Our results indicate that a ROCK2-mediated ERM-phosphorylation signaling cascade modulates noise-induced hair cell loss and NIHL by targeting the cytoskeleton. We propose the following cascade following noise trauma leading to alteration of the F-actin arrangement in the outer hair cell cytoskeleton: Noise exposure reduces the levels of GTP-RhoA and subsequently diminishes levels of RhoA effector ROCK2 (Rho-associated kinase 2). Phosphorylation of ezrin-radixin-moesin (ERM) by ROCK2 normally allows ERM to cross-link actin filaments with the plasma membrane. Noise-decreased levels of ROCK results in reduction of phosphorylation of ERM that leads to depolymerization of actin filaments. Lysophosphatidic acid (LPA), an agonist of RhoA, binds to the G-protein-coupled receptor (GPCR) leading to activation of RhoA through Gα12/13 and RhoGEF. Administration of LPA rescues the noise-diminished F/G-actin ratio.
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Affiliation(s)
- Yu Han
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
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Al-Momany A, Li L, Alexander RT, Ballermann BJ. Clustered PI(4,5)P₂ accumulation and ezrin phosphorylation in response to CLIC5A. J Cell Sci 2014; 127:5164-78. [PMID: 25344252 DOI: 10.1242/jcs.147744] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
CLIC5A (encoded by CLIC5) is a component of the ezrin-NHERF2-podocalyxin complex in renal glomerular podocyte foot processes. We explored the mechanism(s) by which CLIC5A regulates ezrin function. In COS-7 cells, CLIC5A augmented ezrin phosphorylation without changing ezrin abundance, increased the association of ezrin with the cytoskeletal fraction and enhanced actin polymerization and the formation of cell surface projections. CLIC5A caused the phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] reporter RFP-PH-PLC to translocate from the cytosol to discrete plasma membrane clusters at the cell surface, where it colocalized with CLIC5A. Transiently expressed HA-PIP5Kα colocalized with GFP-CLIC5A and was pulled from cell lysates by GST-CLIC5A, and silencing of endogenous PIP5Kα abrogated CLIC5A-dependent ERM phosphorylation. N- and C-terminal deletion mutants of CLIC5A, which failed to associate with the plasma membrane, failed to colocalize with PIP5Kα, did not alter the abundance of PI(4,5)P2 plasma membrane clusters and failed to enhance ezrin phosphorylation. Relative to wild-type mice, in CLIC5-deficient mice, the phosphorylation of glomerular ezrin was diminished and the cytoskeletal association of both ezrin and NHERF2 was reduced. Therefore, the mechanism of CLIC5A action involves clustered plasma membrane PI(4,5)P2 accumulation through an interaction of CLIC5A with PI(4,5)P2-generating kinases, in turn facilitating ezrin activation and actin-dependent cell surface remodeling.
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Affiliation(s)
- Abass Al-Momany
- Department of Physiology, University of Alberta, Edmonton, AL T6G 2V2, Canada
| | - Laiji Li
- Department of Medicine (Nephrology), University of Alberta, Edmonton, AL T6G 2V2, Canada
| | - R Todd Alexander
- Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AL T6G 2V2, Canada
| | - Barbara J Ballermann
- Department of Physiology, University of Alberta, Edmonton, AL T6G 2V2, Canada Department of Medicine (Nephrology), University of Alberta, Edmonton, AL T6G 2V2, Canada
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Kitajiri SI, Katsuno T, Sasaki H, Ito J, Furuse M, Tsukita S. Deafness in occludin-deficient mice with dislocation of tricellulin and progressive apoptosis of the hair cells. Biol Open 2014; 3:759-66. [PMID: 25063198 PMCID: PMC4133728 DOI: 10.1242/bio.20147799] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Occludin is the first identified protein in the tight junction (TJ), but its function has remained for the most part obscure. TJs have been demonstrated to play important roles in the inner ear function, and occludin is expressed in all the epithelial TJs in the inner ear. Thus, we examined the inner ears of occludin-deficient (Occ−/−) mice. Although inner ears initially developed normally in Occ−/− mice, apoptosis occurs in hair cells in the organ of Corti around day 12 after birth, and deafness develops. Since hair cell degeneration was not observed in cochlear explant cultures of Occ−/− mice, environmental changes were considered to be the trigger of cell death. As for the vestibular system, both the morphologies and functions are normal in Occ−/− mice. These phenotypes of Occ−/− mice are very similar with those of claudin-14 or claudin-9 deficient mice, leading us to speculate on the existence of imbalance induced by TJ abnormalities, such as localized ionic components. Moreover, the occludin deficiency led to dislocalization of tricellulin, a gene responsible for human deafness DFNB49. The deafness in Occ−/− mice may be due to this dislocalization of tricellulin.
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Affiliation(s)
- Shin-Ichiro Kitajiri
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan Department of Cell Biology, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Tatsuya Katsuno
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Hiroyuki Sasaki
- Department of Physical Therapy, Faculty of Community Health Care, Teikyo Heisei University, Uruido Minami, Ichihara, Chiba 290-0193, Japan
| | - Juichi Ito
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Mikio Furuse
- Department of Cell Biology, Division of Cell Biology, Kobe University Graduate School of Medicine, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan
| | - Shoichiro Tsukita
- Department of Cell Biology, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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48
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Genetics of auditory mechano-electrical transduction. Pflugers Arch 2014; 467:49-72. [PMID: 24957570 PMCID: PMC4281357 DOI: 10.1007/s00424-014-1552-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 06/04/2014] [Accepted: 06/05/2014] [Indexed: 12/29/2022]
Abstract
The hair bundles of cochlear hair cells play a central role in the auditory mechano-electrical transduction (MET) process. The identification of MET components and of associated molecular complexes by biochemical approaches is impeded by the very small number of hair cells within the cochlea. In contrast, human and mouse genetics have proven to be particularly powerful. The study of inherited forms of deafness led to the discovery of several essential proteins of the MET machinery, which are currently used as entry points to decipher the associated molecular networks. Notably, MET relies not only on the MET machinery but also on several elements ensuring the proper sound-induced oscillation of the hair bundle or the ionic environment necessary to drive the MET current. Here, we review the most significant advances in the molecular bases of the MET process that emerged from the genetics of hearing.
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49
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Seco CZ, Oonk AMM, Domínguez-Ruiz M, Draaisma JMT, Gandía M, Oostrik J, Neveling K, Kunst HPM, Hoefsloot LH, del Castillo I, Pennings RJE, Kremer H, Admiraal RJC, Schraders M. Progressive hearing loss and vestibular dysfunction caused by a homozygous nonsense mutation in CLIC5. Eur J Hum Genet 2014; 23:189-94. [PMID: 24781754 DOI: 10.1038/ejhg.2014.83] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 03/20/2014] [Accepted: 04/04/2014] [Indexed: 11/10/2022] Open
Abstract
In a consanguineous Turkish family diagnosed with autosomal recessive nonsyndromic hearing impairment (arNSHI), a homozygous region of 47.4 Mb was shared by the two affected siblings on chromosome 6p21.1-q15. This region contains 247 genes including the known deafness gene MYO6. No pathogenic variants were found in MYO6, neither with sequence analysis of the coding region and splice sites nor with mRNA analysis. Subsequent candidate gene evaluation revealed CLIC5 as an excellent candidate gene. The orthologous mouse gene is mutated in the jitterbug mutant that exhibits progressive hearing impairment and vestibular dysfunction. Mutation analysis of CLIC5 revealed a homozygous nonsense mutation c.96T>A (p.(Cys32Ter)) that segregated with the hearing loss. Further analysis of CLIC5 in 213 arNSHI patients from mostly Dutch and Spanish origin did not reveal any additional pathogenic variants. CLIC5 mutations are thus not a common cause of arNSHI in these populations. The hearing loss in the present family had an onset in early childhood and progressed from mild to severe or even profound before the second decade. Impaired hearing is accompanied by vestibular areflexia and in one of the patients with mild renal dysfunction. Although we demonstrate that CLIC5 is expressed in many other human tissues, no additional symptoms were observed in these patients. In conclusion, our results show that CLIC5 is a novel arNSHI gene involved in progressive hearing impairment, vestibular and possibly mild renal dysfunction in a family of Turkish origin.
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Affiliation(s)
- Celia Zazo Seco
- 1] Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, The Netherlands [2] Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands [3] Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Anne M M Oonk
- 1] Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, The Netherlands [2] Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - María Domínguez-Ruiz
- 1] Servicio de Genética, Hospital Universitario Ramon y Cajal, IRYCIS, Madrid, Spain [2] Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Jos M T Draaisma
- Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marta Gandía
- 1] Servicio de Genética, Hospital Universitario Ramon y Cajal, IRYCIS, Madrid, Spain [2] Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Jaap Oostrik
- 1] Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, The Netherlands [2] Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands [3] Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kornelia Neveling
- 1] Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands [2] Institute for Genetic and Metabolic Disease, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Henricus P M Kunst
- 1] Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, The Netherlands [2] Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lies H Hoefsloot
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ignacio del Castillo
- Servicio de Genética, Hospital Universitario Ramon y Cajal, IRYCIS, Madrid, Spain
| | - Ronald J E Pennings
- 1] Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, The Netherlands [2] Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hannie Kremer
- 1] Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, The Netherlands [2] Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands [3] Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands [4] Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ronald J C Admiraal
- 1] Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, The Netherlands [2] Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Margit Schraders
- 1] Department of Otorhinolaryngology, Hearing & Genes, Radboud University Medical Center, Nijmegen, The Netherlands [2] Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands [3] Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
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50
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Goodyear RJ, Ratnayaka HSK, Warchol ME, Richardson GP. Staurosporine-induced collapse of cochlear hair bundles. J Comp Neurol 2014; 522:3281-94. [PMID: 24700109 PMCID: PMC4321040 DOI: 10.1002/cne.23597] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 03/26/2014] [Accepted: 03/27/2014] [Indexed: 12/31/2022]
Abstract
Early postnatal mouse cochlear cultures were treated with a small panel of kinase inhibitors to elucidate the mechanisms underlying the maintenance of hair-bundle structure in the developing inner ear. At low concentrations (1–10 nM), staurosporine causes the collapse and loss of hair bundles without provoking hair-cell death, as judged by lack of terminal transferase dUTP nick end labeling (TUNEL) labeling or reactivity to anti-activated caspase-3. Staurosporine exposure results in the fusion of the hair bundle’s stereocilia, a resorption of the parallel actin bundles of the stereocilia into the cytoplasm of the hair cell, a detachment of the apical, non-stereociliary membrane of the hair cell from the underlying cuticular plate, and a severing of the hair-bundle’s rootlets from the actin cores of the stereocilia. It does not block membrane retrieval at the apical pole of the hair cells, nor does it elicit the externalization of phosphatidylserine. Staurosporine treatment causes a reduction in levels of the phosphorylated forms of ezrin, radixin, and moesin in cochlear cultures during the period of hair-bundle loss, indicating the integrity of the hair bundle may be actively maintained by the phosphorylation status of these proteins. J. Comp. Neurol. 522:3281–3294, 2014. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Richard J Goodyear
- Sussex Neuroscience and School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
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