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Ghiselli S, Parmeggiani G, Zambonini G, Cuda D. Hearing Loss in Baraitser-Winter Syndrome: Case Reports and Review of the Literature. J Clin Med 2024; 13:1500. [PMID: 38592426 PMCID: PMC10935159 DOI: 10.3390/jcm13051500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 03/01/2024] [Accepted: 03/02/2024] [Indexed: 04/10/2024] Open
Abstract
Background: Baraitser-Winter Syndrome (BRWS) is a rare autosomal dominant condition associated with hearing loss (HL). In the literature, two types of this condition are reported, Baraitser-Winter type 1 (BRWS1) and type 2 (BRWS2) produced by specific pathogenetic variants of two different genes, ACTB for BRWS1 and ACTG1 for BRWS2. In addition to syndromic BRWS2, some pathogenic variants in ACTG1 are associated also to another pathologic entity, the "Autosomal dominant non-syndromic hearing loss 20/26". In these syndromes, typical craniofacial features, sensory impairment (vision and hearing) and intellectual disabilities are frequently present. Heart anomalies, renal and gastrointestinal involvement and seizure are also common. Wide inter- and intra-familial variety in the phenotypic spectrum is reported. Some phenotypic aspects of these syndromes are not yet fully described, such as the degree and progression of HL, and better knowledge of them could be useful for correct follow-up and treatment. Methods and Results: In this study, we report two cases of children with HL and diagnosis of BRWS and a review of the current literature on HL in these syndromes.
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Affiliation(s)
- Sara Ghiselli
- Department of Otorhinolaryngology, AUSL Piacenza, 29121 Piacenza, Italy; (G.Z.); (D.C.)
| | | | - Giulia Zambonini
- Department of Otorhinolaryngology, AUSL Piacenza, 29121 Piacenza, Italy; (G.Z.); (D.C.)
| | - Domenico Cuda
- Department of Otorhinolaryngology, AUSL Piacenza, 29121 Piacenza, Italy; (G.Z.); (D.C.)
- Department of Medicine and Surgery, University of Parma, 43121 Parma, Italy
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2
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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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Zhou LY, Jin CX, Wang WX, Song L, Shin JB, Du TT, Wu H. Differential regulation of hair cell actin cytoskeleton mediated by SRF and MRTFB. eLife 2023; 12:e90155. [PMID: 37982489 PMCID: PMC10703445 DOI: 10.7554/elife.90155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 11/17/2023] [Indexed: 11/21/2023] Open
Abstract
The MRTF-SRF pathway has been extensively studied for its crucial role in driving the expression of a large number of genes involved in actin cytoskeleton of various cell types. However, the specific contribution of MRTF-SRF in hair cells remains unknown. In this study, we showed that hair cell-specific deletion of Srf or Mrtfb, but not Mrtfa, leads to similar defects in the development of stereocilia dimensions and the maintenance of cuticular plate integrity. We used fluorescence-activated cell sorting-based hair cell RNA-Seq analysis to investigate the mechanistic underpinnings of the changes observed in Srf and Mrtfb mutants, respectively. Interestingly, the transcriptome analysis revealed distinct profiles of genes regulated by Srf and Mrtfb, suggesting different transcriptional regulation mechanisms of actin cytoskeleton activities mediated by Srf and Mrtfb. Exogenous delivery of calponin 2 using Adeno-associated virus transduction in Srf mutants partially rescued the impairments of stereocilia dimensions and the F-actin intensity of cuticular plate, suggesting the involvement of Cnn2, as an Srf downstream target, in regulating the hair bundle morphology and cuticular plate actin cytoskeleton organization. Our study uncovers, for the first time, the unexpected differential transcriptional regulation of actin cytoskeleton mediated by Srf and Mrtfb in hair cells, and also demonstrates the critical role of SRF-CNN2 in modulating actin dynamics of the stereocilia and cuticular plate, providing new insights into the molecular mechanism underlying hair cell development and maintenance.
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Affiliation(s)
- Ling-Yun Zhou
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Ear Institute, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghaiChina
| | - Chen-Xi Jin
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Ear Institute, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghaiChina
| | - Wen-Xiao Wang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Ear Institute, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghaiChina
| | - Lei Song
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Ear Institute, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghaiChina
| | - Jung-Bum Shin
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
| | - Ting-Ting Du
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Ear Institute, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghaiChina
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Ear Institute, Shanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghaiChina
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4
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Zhu G, Huang Y, Zhang L, Yan K, Qiu C, He Y, Liu Q, Zhu C, Morín M, Moreno‐Pelayo MÁ, Zhu M, Cao X, Zhou H, Qian X, Xu Z, Chen J, Gao X, Wan G. Cingulin regulates hair cell cuticular plate morphology and is required for hearing in human and mouse. EMBO Mol Med 2023; 15:e17611. [PMID: 37691516 PMCID: PMC10630877 DOI: 10.15252/emmm.202317611] [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: 02/21/2023] [Revised: 08/17/2023] [Accepted: 08/22/2023] [Indexed: 09/12/2023] Open
Abstract
Cingulin (CGN) is a cytoskeleton-associated protein localized at the apical junctions of epithelial cells. CGN interacts with major cytoskeletal filaments and regulates RhoA activity. However, physiological roles of CGN in development and human diseases are currently unknown. Here, we report a multi-generation family presenting with autosomal dominant non-syndromic hearing loss (ADNSHL) that co-segregates with a CGN heterozygous truncating variant, c.3330delG (p.Leu1110Leufs*17). CGN is normally expressed at the apical cell junctions of the organ of Corti, with enriched localization at hair cell cuticular plates and circumferential belts. In mice, the putative disease-causing mutation results in reduced expression and abnormal subcellular localization of the CGN protein, abolishes its actin polymerization activity, and impairs the normal morphology of hair cell cuticular plates and hair bundles. Hair cell-specific Cgn knockout leads to high-frequency hearing loss. Importantly, Cgn mutation knockin mice display noise-sensitive, progressive hearing loss and outer hair cell degeneration. In summary, we identify CGN c.3330delG as a pathogenic variant for ADNSHL and reveal essential roles of CGN in the maintenance of cochlear hair cell structures and auditory function.
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Affiliation(s)
- Guang‐Jie Zhu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- MOE Key Laboratory of Model Animal for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, National Resource Center for Mutant Mice of ChinaNanjing UniversityNanjingChina
- Research Institute of OtolaryngologyNanjingChina
| | - Yuhang Huang
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- MOE Key Laboratory of Model Animal for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, National Resource Center for Mutant Mice of ChinaNanjing UniversityNanjingChina
| | - Linqing Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- MOE Key Laboratory of Model Animal for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, National Resource Center for Mutant Mice of ChinaNanjing UniversityNanjingChina
| | - Keji Yan
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life SciencesShandong UniversityQingdaoChina
| | - Cui Qiu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- MOE Key Laboratory of Model Animal for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, National Resource Center for Mutant Mice of ChinaNanjing UniversityNanjingChina
| | - Yihan He
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- MOE Key Laboratory of Model Animal for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, National Resource Center for Mutant Mice of ChinaNanjing UniversityNanjingChina
| | - Qing Liu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- MOE Key Laboratory of Model Animal for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, National Resource Center for Mutant Mice of ChinaNanjing UniversityNanjingChina
- Research Institute of OtolaryngologyNanjingChina
| | - Chengwen Zhu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- MOE Key Laboratory of Model Animal for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, National Resource Center for Mutant Mice of ChinaNanjing UniversityNanjingChina
- Research Institute of OtolaryngologyNanjingChina
| | - Matías Morín
- Servicio de GenéticaHospital Universitario Ramón y Cajal, IRYCISMadridSpain
- Centro de Investigación Biomédica en Red de Enfermedades RarasInstituto de Salud Carlos III (CB06/07/0048; CIBERER‐ISCIII)MadridSpain
| | - Miguel Ángel Moreno‐Pelayo
- Servicio de GenéticaHospital Universitario Ramón y Cajal, IRYCISMadridSpain
- Centro de Investigación Biomédica en Red de Enfermedades RarasInstituto de Salud Carlos III (CB06/07/0048; CIBERER‐ISCIII)MadridSpain
| | - Min‐Sheng Zhu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- MOE Key Laboratory of Model Animal for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, National Resource Center for Mutant Mice of ChinaNanjing UniversityNanjingChina
- Research Institute of OtolaryngologyNanjingChina
| | - Xin Cao
- Department of Medical Genetics, School of Basic Medical ScienceNanjing Medical UniversityNanjingChina
| | - Han Zhou
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- Research Institute of OtolaryngologyNanjingChina
| | - Xiaoyun Qian
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- Research Institute of OtolaryngologyNanjingChina
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life SciencesShandong UniversityQingdaoChina
| | - Jie Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- Research Institute of OtolaryngologyNanjingChina
| | - Xia Gao
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- Research Institute of OtolaryngologyNanjingChina
| | - Guoqiang Wan
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical SchoolNanjing UniversityNanjingChina
- MOE Key Laboratory of Model Animal for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, National Resource Center for Mutant Mice of ChinaNanjing UniversityNanjingChina
- Research Institute of OtolaryngologyNanjingChina
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Cortada M, Levano S, Hall MN, Bodmer D. mTORC2 regulates auditory hair cell structure and function. iScience 2023; 26:107687. [PMID: 37694145 PMCID: PMC10484995 DOI: 10.1016/j.isci.2023.107687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/14/2023] [Accepted: 08/17/2023] [Indexed: 09/12/2023] Open
Abstract
mTOR broadly controls cell growth, but little is known about the role of mTOR complex 2 (mTORC2) in the inner ear. To investigate the role of mTORC2 in sensory hair cells (HCs), we generated HC-specific Rictor knockout (HC-RicKO) mice. HC-RicKO mice exhibited early-onset, progressive, and profound hearing loss. Increased DPOAE thresholds indicated outer HC dysfunction. HCs are lost, but this occurs after hearing loss. Ultrastructural analysis revealed stunted and absent stereocilia in outer HCs. In inner HCs, the number of synapses was significantly decreased and the remaining synapses displayed a disrupted actin cytoskeleton and disorganized Ca2+ channels. Thus, the mTORC2 signaling pathway plays an important role in regulating auditory HC structure and function via regulation of the actin cytoskeleton. These results provide molecular insights on a central regulator of cochlear HCs and thus hearing.
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Affiliation(s)
- Maurizio Cortada
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
| | - Soledad Levano
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
| | | | - Daniel Bodmer
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
- Clinic for Otorhinolaryngology, Head and Neck Surgery, University of Basel Hospital, CH-4031 Basel, Switzerland
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6
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Baxi AB, Nemes P, Moody SA. Time-resolved quantitative proteomic analysis of the developing Xenopus otic vesicle reveals putative congenital hearing loss candidates. iScience 2023; 26:107665. [PMID: 37670778 PMCID: PMC10475516 DOI: 10.1016/j.isci.2023.107665] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/16/2023] [Accepted: 08/14/2023] [Indexed: 09/07/2023] Open
Abstract
Over 200 genes are known to underlie human congenital hearing loss (CHL). Although transcriptomic approaches have identified candidate regulators of otic development, little is known about the abundance of their protein products. We used a multiplexed quantitative mass spectrometry-based proteomic approach to determine protein abundances over key stages of Xenopus otic morphogenesis to reveal a dynamic expression of cytoskeletal, integrin signaling, and extracellular matrix proteins. We correlated these dynamically expressed proteins to previously published lists of putative downstream targets of human syndromic hearing loss genes: SIX1 (BOR syndrome), CHD7 (CHARGE syndrome), and SOX10 (Waardenburg syndrome). We identified transforming growth factor beta-induced (Tgfbi), an extracellular integrin-interacting protein, as a putative target of Six1 that is required for normal otic vesicle formation. Our findings demonstrate the application of this Xenopus dataset to understanding the dynamic regulation of proteins during otic development and to discovery of additional candidates for human CHL.
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Affiliation(s)
- Aparna B. Baxi
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20052, USA
| | - Peter Nemes
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Sally A. Moody
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20052, USA
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7
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Park J, Bird JE. The actin cytoskeleton in hair bundle development and hearing loss. Hear Res 2023; 436:108817. [PMID: 37300948 PMCID: PMC10408727 DOI: 10.1016/j.heares.2023.108817] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/18/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023]
Abstract
Inner ear hair cells assemble mechanosensitive hair bundles on their apical surface that transduce sounds and accelerations. Each hair bundle is comprised of ∼ 100 individual stereocilia that are arranged into rows of increasing height and width; their specific and precise architecture being necessary for mechanoelectrical transduction (MET). The actin cytoskeleton is fundamental to establishing this architecture, not only by forming the structural scaffold shaping each stereocilium, but also by composing rootlets and the cuticular plate that together provide a stable foundation supporting each stereocilium. In concert with the actin cytoskeleton, a large assortment of actin-binding proteins (ABPs) function to cross-link actin filaments into specific topologies, as well as control actin filament growth, severing, and capping. These processes are individually critical for sensory transduction and are all disrupted in hereditary forms of human hearing loss. In this review, we provide an overview of actin-based structures in the hair bundle and the molecules contributing to their assembly and functional properties. We also highlight recent advances in mechanisms driving stereocilia elongation and how these processes are tuned by MET.
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Affiliation(s)
- Jinho Park
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States.
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8
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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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9
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Arambula AM, Gu S, Warnecke A, Schmitt HA, Staecker H, Hoa M. In Silico Localization of Perilymph Proteins Enriched in Meńier̀e Disease Using Mammalian Cochlear Single-cell Transcriptomics. OTOLOGY & NEUROTOLOGY OPEN 2023; 3:e027. [PMID: 38516320 PMCID: PMC10950140 DOI: 10.1097/ono.0000000000000027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 12/01/2022] [Indexed: 03/23/2024]
Abstract
Hypothesis Proteins enriched in the perilymph proteome of Meńier̀e disease (MD) patients may identify affected cell types. Utilizing single-cell transcriptome datasets from the mammalian cochlea, we hypothesize that these enriched perilymph proteins can be localized to specific cochlear cell types. Background The limited understanding of human inner ear pathologies and their associated biomolecular variations hinder efforts to develop disease-specific diagnostics and therapeutics. Perilymph sampling and analysis is now enabling further characterization of the cochlear microenvironment. Recently, enriched inner ear protein expression has been demonstrated in patients with MD compared to patients with other inner ear diseases. Localizing expression of these proteins to cochlear cell types can further our knowledge of potential disease pathways and subsequent development of targeted therapeutics. Methods We compiled previously published data regarding differential perilymph proteome profiles amongst patients with MD, otosclerosis, enlarged vestibular aqueduct, sudden hearing loss, and hearing loss of undefined etiology (controls). Enriched proteins in MD were cross-referenced against published single-cell/single-nucleus RNA-sequencing datasets to localize gene expression to specific cochlear cell types. Results In silico analysis of single-cell transcriptomic datasets demonstrates enrichment of a unique group of perilymph proteins associated with MD in a variety of intracochlear cells, and some exogeneous hematologic and immune effector cells. This suggests that these cell types may play an important role in the pathology associated with late MD, suggesting potential future areas of investigation for MD pathophysiology and treatment. Conclusions Perilymph proteins enriched in MD are expressed by specific cochlear cell types based on in silico localization, potentially facilitating development of disease-specific diagnostic markers and therapeutics.
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Affiliation(s)
- Alexandra M. Arambula
- Department of Otolaryngology-Head & Neck Surgery, University of Kansas Medical Center, Kansas City, KS
| | - Shoujun Gu
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, Bethesda, MD
| | - Athanasia Warnecke
- Department of Otolaryngology and Cluster of Excellence of the German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”) “Hearing4all,” Hannover Medical School, Hannover, Germany
| | - Heike A. Schmitt
- Department of Otolaryngology and Cluster of Excellence of the German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”) “Hearing4all,” Hannover Medical School, Hannover, Germany
| | - Hinrich Staecker
- Department of Otolaryngology-Head & Neck Surgery, University of Kansas Medical Center, Kansas City, KS
| | - Michael Hoa
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, Bethesda, MD
- Department of Otolaryngology–Head and Neck Surgery, Georgetown University Medical Center, Washington, DC
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10
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Sundby LJ, Southern WM, Hawbaker KM, Trujillo JM, Perrin BJ, Ervasti JM. Nucleotide- and Protein-Dependent Functions of Actg1. Mol Biol Cell 2022; 33:ar77. [PMID: 35594181 PMCID: PMC9582642 DOI: 10.1091/mbc.e22-02-0054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/10/2022] [Accepted: 05/11/2022] [Indexed: 11/11/2022] Open
Abstract
Cytoplasmic β- and γ-actin proteins are 99% identical but support unique organismal functions. The cytoplasmic actin nucleotide sequences Actb and Actg1, respectively, are more divergent but still 89% similar. Actb-/- mice are embryonic lethal and Actb-/- cells fail to proliferate, but editing the Actb gene to express γ-actin (Actbc-g) resulted in none of the overt phenotypes of the knockout revealing protein-independent functions for Actb. To determine if Actg1 has a protein-independent function, we crossed Actbc-g and Actg1-/- mice to generate the bG/0 line, where the only cytoplasmic actin expressed is γ-actin from Actbc-g. The bG/0 mice were viable but showed a survival defect despite expressing γ-actin protein at levels no different from bG/gG with normal survival. A unique myopathy phenotype was also observed in bG/0 mice. We conclude that impaired survival and myopathy in bG/0 mice are due to loss of Actg1 nucleotide-dependent function(s). On the other hand, the bG/0 genotype rescued functions impaired by Actg1-/-, including cell proliferation and auditory function, suggesting a role for γ-actin protein in both fibroblasts and hearing. Together, these results identify nucleotide-dependent functions for Actg1 while implicating γ-actin protein in more cell-/tissue-specific functions.
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Affiliation(s)
- Lauren J. Sundby
- Program in Molecular, Cellular, Developmental Biology, and Genetics, and
| | - William M. Southern
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455
| | - Katelin M. Hawbaker
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46022
| | - Jesús M. Trujillo
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455
| | - Benjamin J. Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46022
| | - James M. Ervasti
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455
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11
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Nie K, Huang J, Liu L, Lv H, Chen D, Fan W. Identification of a De Novo Heterozygous Missense ACTB Variant in Baraitser–Winter Cerebrofrontofacial Syndrome. Front Genet 2022; 13:828120. [PMID: 35401677 PMCID: PMC8989421 DOI: 10.3389/fgene.2022.828120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/23/2022] [Indexed: 11/21/2022] Open
Abstract
Baraitser–Winter cerebrofrontofacial syndrome (BWCFF, OMIM: 243310) is a rare autosomal-dominant developmental disorder associated with variants in the genes ACTB or ACTG1. It is characterized by brain malformations, a distinctive facial appearance, ocular coloboma, and intellectual disability. However, the phenotypes of BWCFF are heterogenous, and its molecular pathogenesis has not been fully elucidated. In the present study, we conducted detailed clinical examinations on a Chinese patient with BWCFF and found novel ocular manifestations including pseudoduplication of the optic disc and nystagmus. Targeted gene panel sequencing and Sanger sequencing identified a de novo heterozygous missense c.478A > G (p.Thr160Ala) variant in ACTB. The mRNA and protein expression of ACTB was assessed by quantitative reverse transcription PCR and Western blots. Furthermore, the functional effects of the pathogenic variant were analyzed by protein structure analysis, which indicated that the variant may affect the active site for ATP hydrolysis by the actin ATPase, resulting in abnormal filamentous actin organization in peripheral blood mononuclear cells. This discovery extends the ACTB variant spectrum, which will improve genetic counseling and diagnosis, and may contribute to understanding the pathogenic mechanisms of actin-related diseases.
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Affiliation(s)
- Kailai Nie
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
- Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Junting Huang
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Longqian Liu
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Hongbin Lv
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Danian Chen
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
- Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
- *Correspondence: Wei Fan, ; Danian Chen,
| | - Wei Fan
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
- *Correspondence: Wei Fan, ; Danian Chen,
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12
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Stoner ZA, Ketchum EM, Sheltz-Kempf S, Blinkiewicz PV, Elliott KL, Duncan JS. Fzd3 Expression Within Inner Ear Afferent Neurons Is Necessary for Central Pathfinding. Front Neurosci 2022; 15:779871. [PMID: 35153658 PMCID: PMC8828977 DOI: 10.3389/fnins.2021.779871] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 12/29/2021] [Indexed: 11/29/2022] Open
Abstract
During development the afferent neurons of the inner ear make precise wiring decisions in the hindbrain reflective of their topographic distribution in the periphery. This is critical for the formation of sensory maps capable of faithfully processing both auditory and vestibular input. Disorganized central projections of inner ear afferents in Fzd3 null mice indicate Wnt/PCP signaling is involved in this process and ear transplantation in Xenopus indicates that Fzd3 is necessary in the ear but not the hindbrain for proper afferent navigation. However, it remains unclear in which cell type of the inner ear Fzd3 expression is influencing the guidance of inner ear afferents to their proper synaptic targets in the hindbrain. We utilized Atoh1-cre and Neurod1-cre mouse lines to conditionally knockout Fzd3 within the mechanosensory hair cells of the organ of Corti and within the inner ear afferents, respectively. Following conditional deletion of Fzd3 within the hair cells, the central topographic distribution of inner ear afferents was maintained with no gross morphological defects. In contrast, conditional deletion of Fzd3 within inner ear afferents leads to central pathfinding defects of both cochlear and vestibular afferents. Here, we show that Fzd3 is acting in a cell autonomous manner within inner ear afferents to regulate central pathfinding within the hindbrain.
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Affiliation(s)
- Zachary A. Stoner
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, United States
| | - Elizabeth M. Ketchum
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, United States
| | - Sydney Sheltz-Kempf
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, United States
| | - Paige V. Blinkiewicz
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, United States
| | - Karen L. Elliott
- Department of Biology, University of Iowa, Iowa City, IA, United States
- *Correspondence: Karen L. Elliott,
| | - Jeremy S. Duncan
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, United States
- Department of Biomedical Sciences, Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, MI, United States
- Jeremy S. Duncan,
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13
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Essential Role of Sptan1 in Cochlear Hair Cell Morphology and Function Via Focal Adhesion Signaling. Mol Neurobiol 2021; 59:386-404. [PMID: 34708331 PMCID: PMC8786805 DOI: 10.1007/s12035-021-02551-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 08/31/2021] [Indexed: 12/05/2022]
Abstract
Hearing loss is the most common human sensory deficit. Hearing relies on stereocilia, inserted into the cuticular plate of hair cells (HCs), where they play an important role in the perception of sound and its transmission. Although numerous genes have been associated with hearing loss, the function of many hair cell genes has yet to be elucidated. Herein, we focused on nonerythroid spectrin αII (SPTAN1), abundant in the cuticular plate, surrounding the rootlets of stereocilia and along the plasma membrane. Interestingly, mice with HC-specific Sptan1 knockout exhibited rapid deafness, abnormal formation of stereocilia and cuticular plates, and loss of HCs from middle and apical turns of the cochlea during early postnatal stages. Additionally, Sptan1 deficiency led to the decreased spreading of House Ear Institute-Organ of Corti 1 cells, and induced abnormal formation of focal adhesions and integrin signaling in mouse HCs. Altogether, our findings highlight SPTAN1 as a critical molecule for HC stereocilia morphology and auditory function via regulation of focal adhesion signaling.
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14
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DFNA20/26 and Other ACTG1-Associated Phenotypes: A Case Report and Review of the Literature. Audiol Res 2021; 11:582-593. [PMID: 34698053 PMCID: PMC8544197 DOI: 10.3390/audiolres11040052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/10/2021] [Accepted: 10/13/2021] [Indexed: 02/08/2023] Open
Abstract
Since the early 2000s, an ever-increasing subset of missense pathogenic variants in the ACTG1 gene has been associated with an autosomal-dominant, progressive, typically post-lingual non-syndromic hearing loss (NSHL) condition designed as DFNA20/26. ACTG1 gene encodes gamma actin, the predominant actin protein in the cytoskeleton of auditory hair cells; its normal expression and function are essential for the stereocilia maintenance. Different gain-of-function pathogenic variants of ACTG1 have been associated with two major phenotypes: DFNA20/26 and Baraitser-Winter syndrome, a multiple congenital anomaly disorder. Here, we report a novel ACTG1 variant [c.625G>A (p. Val209Met)] in an adult patient with moderate-severe NSHL characterized by a downsloping audiogram. The patient, who had a clinical history of slowly progressive NSHL and tinnitus, was referred to our laboratory for the analysis of a large panel of NSHL-associated genes by next generation sequencing. An extensive review of previously reported ACTG1 variants and their associated phenotypes was also performed.
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15
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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 2021; 141:363-382. [PMID: 34232383 DOI: 10.1007/s00439-021-02304-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [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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16
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McGrath J, Tung CY, Liao X, Belyantseva IA, Roy P, Chakraborty O, Li J, Berbari NF, Faaborg-Andersen CC, Barzik M, Bird JE, Zhao B, Balakrishnan L, Friedman TB, Perrin BJ. Actin at stereocilia tips is regulated by mechanotransduction and ADF/cofilin. Curr Biol 2021; 31:1141-1153.e7. [PMID: 33400922 PMCID: PMC8793668 DOI: 10.1016/j.cub.2020.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 10/21/2020] [Accepted: 12/07/2020] [Indexed: 11/30/2022]
Abstract
Stereocilia on auditory sensory cells are actin-based protrusions that mechanotransduce sound into an electrical signal. These stereocilia are arranged into a bundle with three rows of increasing length to form a staircase-like morphology that is required for hearing. Stereocilia in the shorter rows, but not the tallest row, are mechanotransducing because they have force-sensitive channels localized at their tips. The onset of mechanotransduction during mouse postnatal development refines stereocilia length and width. However, it is unclear how actin is differentially regulated between stereocilia in the tallest row of the bundle and the shorter, mechanotransducing rows. Here, we show actin turnover is increased at the tips of mechanotransducing stereocilia during bundle maturation. Correspondingly, from birth to postnatal day 6, these stereocilia had increasing amounts of available actin barbed ends, where monomers can be added or lost readily, as compared with the non-mechanotransducing stereocilia in the tallest row. The increase in available barbed ends depended on both mechanotransduction and MYO15 or EPS8, which are required for the normal specification and elongation of the tallest row of stereocilia. We also found that loss of the F-actin-severing proteins ADF and cofilin-1 decreased barbed end availability at stereocilia tips. These proteins enriched at mechanotransducing stereocilia tips, and their localization was perturbed by the loss of mechanotransduction, MYO15, or EPS8. Finally, stereocilia lengths and widths were dysregulated in Adf and Cfl1 mutants. Together, these data show that actin is remodeled, likely by a severing mechanism, in response to mechanotransduction.
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Affiliation(s)
- Jamis McGrath
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Chun-Yu Tung
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Xiayi Liao
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, 35A Convent Drive, Bethesda, MD 20892, USA
| | - Pallabi Roy
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Oisorjo Chakraborty
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Jinan Li
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, IN 46202, USA
| | - Nicolas F Berbari
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Christian C Faaborg-Andersen
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, 35A Convent Drive, Bethesda, MD 20892, USA
| | - Melanie Barzik
- Section on Sensory Cell Biology, National Institute on Deafness and Other Communication Disorders, NIH, 35A Convent Drive, Bethesda, MD 20892, USA
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, 1200 Newell Drive, Gainesville, FL 32610, USA
| | - Bo Zhao
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, IN 46202, USA
| | - Lata Balakrishnan
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, 35A Convent Drive, Bethesda, MD 20892, USA
| | - Benjamin J Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA.
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17
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Vanslembrouck B, Ampe C, Hengel J. Time for rethinking the different β‐actin transgenic mouse models? Cytoskeleton (Hoboken) 2020; 77:527-543. [DOI: 10.1002/cm.21647] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 11/19/2020] [Accepted: 11/24/2020] [Indexed: 01/23/2023]
Affiliation(s)
- Bieke Vanslembrouck
- Medical Cell Biology Research Group, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences Ghent University Ghent Belgium
| | - Christophe Ampe
- Department of Biomolecular Medicine, Faculty of Medicine and Health Sciences Ghent University Ghent Belgium
| | - Jolanda Hengel
- Medical Cell Biology Research Group, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences Ghent University Ghent Belgium
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18
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Lechuga S, Naydenov NG, Feygin A, Cruise M, Ervasti JM, Ivanov AI. Loss of β-Cytoplasmic Actin in the Intestinal Epithelium Increases Gut Barrier Permeability in vivo and Exaggerates the Severity of Experimental Colitis. Front Cell Dev Biol 2020; 8:588836. [PMID: 33195251 PMCID: PMC7644907 DOI: 10.3389/fcell.2020.588836] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/06/2020] [Indexed: 12/21/2022] Open
Abstract
Intestinal epithelial barrier is critical for the maintenance of normal gut homeostasis and disruption of this barrier may trigger or exaggerate mucosal inflammation. The actin cytoskeleton is a key regulator of barrier structure and function, controlling the assembly and permeability of epithelial adherens and tight junctions. Epithelial cells express two actin isoforms: a β-cytoplasmic actin and γ-cytoplasmic actin. Our previous in vitro studies demonstrated that these actin isoforms play distinctive roles in establishing the intestinal epithelial barrier, by controlling the organization of different junctional complexes. It remains unknown, whether β-actin and γ-actin have unique or redundant functions in regulating the gut barrier in vivo. To address this question, we selectively knocked out β-actin expression in mouse intestinal epithelium. Mice with intestinal epithelial knockout of β-actin do not display gastrointestinal abnormalities or gross alterations of colonic mucosal architecture. This could be due to compensatory upregulation of γ-actin expression. Despite such compensation, β-actin knockout mice demonstrate increased intestinal permeability. Furthermore, these animals show more severe clinical symptoms during dextran sodium sulfate induced colitis, compared to control littermates. Such exaggerated colitis is associated with the higher expression of inflammatory cytokines, increased macrophage infiltration in the gut, and accelerated mucosal cell death. Consistently, intestinal organoids generated from β-actin knockout mice are more sensitive to tumor necrosis factor induced cell death, ex vivo. Overall, our data suggests that β-actin functions as an essential regulator of gut barrier integrity in vivo, and plays a tissue protective role during mucosal injury and inflammation.
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Affiliation(s)
- Susana Lechuga
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, United States
| | - Nayden G Naydenov
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, United States
| | - Alex Feygin
- School of Nursing, Virginia Commonwealth University School of Nursing, Richmond, VA, United States
| | - Michael Cruise
- Department of Pathology, Cleveland Clinic Foundation, Cleveland, OH, United States
| | - James M Ervasti
- Department of Biochemistry and Molecular Biology, University of Minnesota Medical School, Minneapolis, MN, United States
| | - Andrei I Ivanov
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, United States
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Kashina AS. Regulation of actin isoforms in cellular and developmental processes. Semin Cell Dev Biol 2020; 102:113-121. [PMID: 32001148 DOI: 10.1016/j.semcdb.2019.12.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 12/02/2019] [Accepted: 12/02/2019] [Indexed: 12/18/2022]
Abstract
Actin is one of the most abundant and essential intracellular proteins that mediates nearly every form of cellular movement and underlies such key processes as embryogenesis, tissue integrity, cell division and contractility of all types of muscle and non-muscle cells. In mammals, actin is represented by six isoforms, which are encoded by different genes but produce proteins that are 95-99 % identical to each other. The six actin genes have vastly different functions in vivo, and the small amino acid differences between the proteins they encode are rigorously maintained through evolution, but the underlying differences behind this distinction, as well as the importance of specific amino acid sequences for each actin isoform, are not well understood. This review summarizes different levels of actin isoform-specific regulation in cellular and developmental processes, starting with the nuclear actin's role in transcription, and covering the gene-level, mRNA-level, and protein-level regulation, with a special focus on mammalian actins in non-muscle cells.
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Affiliation(s)
- Anna S Kashina
- University of Pennsylvania, Philadelphia, PA, 19104, United States.
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20
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Mechanotransduction-Dependent Control of Stereocilia Dimensions and Row Identity in Inner Hair Cells. Curr Biol 2020; 30:442-454.e7. [PMID: 31902726 DOI: 10.1016/j.cub.2019.11.076] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 11/08/2019] [Accepted: 11/26/2019] [Indexed: 02/07/2023]
Abstract
Actin-rich structures, like stereocilia and microvilli, are assembled with precise control of length, diameter, and relative spacing. By quantifying actin-core dimensions of stereocilia from phalloidin-labeled mouse cochleas, we demonstrated that inner hair cell stereocilia developed in specific stages, where a widening phase is sandwiched between two lengthening phases. Moreover, widening of the second-tallest stereocilia rank (row 2) occurred simultaneously with the appearance of mechanotransduction. Correspondingly, Tmc1KO/KO;Tmc2KO/KO or TmieKO/KO hair cells, which lack transduction, have significantly altered stereocilia lengths and diameters, including a narrowed row 2. EPS8 and the short splice isoform of MYO15A, identity markers for mature row 1 (the tallest row), lost their row exclusivity in transduction mutants. GNAI3, another member of the mature row 1 complex, accumulated at mutant row 1 tips at considerably lower levels than in wild-type bundles. Alterations in stereocilia dimensions and in EPS8 distribution seen in transduction mutants were mimicked by block of transduction channels of cochlear explants in culture. In addition, proteins normally concentrated at mature row 2 tips were also distributed differently in transduction mutants; the heterodimeric capping protein subunit CAPZB and its partner TWF2 never concentrated at row 2 tips like they do in wild-type bundles. The altered distribution of marker proteins in transduction mutants was accompanied by increased variability in stereocilia length. Transduction channels thus specify and maintain row identity, control addition of new actin filaments to increase stereocilia diameter, and coordinate stereocilia height within rows.
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21
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Zhu Y, Scheibinger M, Ellwanger DC, Krey JF, Choi D, Kelly RT, Heller S, Barr-Gillespie PG. Single-cell proteomics reveals changes in expression during hair-cell development. eLife 2019; 8:50777. [PMID: 31682227 PMCID: PMC6855842 DOI: 10.7554/elife.50777] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 11/01/2019] [Indexed: 12/12/2022] Open
Abstract
Hearing and balance rely on small sensory hair cells that reside in the inner ear. To explore dynamic changes in the abundant proteins present in differentiating hair cells, we used nanoliter-scale shotgun mass spectrometry of single cells, each ~1 picoliter, from utricles of embryonic day 15 chickens. We identified unique constellations of proteins or protein groups from presumptive hair cells and from progenitor cells. The single-cell proteomes enabled the de novo reconstruction of a developmental trajectory using protein expression levels, revealing proteins that greatly increased in expression during differentiation of hair cells (e.g., OCM, CRABP1, GPX2, AK1, GSTO1) and those that decreased during differentiation (e.g., TMSB4X, AGR3). Complementary single-cell transcriptome profiling showed corresponding changes in mRNA during maturation of hair cells. Single-cell proteomics data thus can be mined to reveal features of cellular development that may be missed with transcriptomics.
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Affiliation(s)
- Ying Zhu
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, United States
| | - Mirko Scheibinger
- Department of Otolaryngology Head and Neck Surgery, Stanford University, Stanford, United States
| | - Daniel Christian Ellwanger
- Department of Otolaryngology Head and Neck Surgery, Stanford University, Stanford, United States.,Genome Analysis Unit, Amgen Research, Amgen Inc, South San Francisco, United States
| | - Jocelyn F Krey
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, United States.,Vollum Institute, Oregon Health & Science University, Portland, United States
| | - Dongseok Choi
- OHSU-PSU School of Public Health, Oregon Health & Science University, Portland, United States.,Graduate School of Dentistry, Kyung Hee University, Seoul, Republic of Korea
| | - Ryan T Kelly
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, United States.,Department of Chemistry and Biochemistry, Brigham Young University, Provo, United States
| | - Stefan Heller
- Department of Otolaryngology Head and Neck Surgery, Stanford University, Stanford, United States
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, United States.,Vollum Institute, Oregon Health & Science University, Portland, United States
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22
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Protein Kinase C and Calmodulin Serve As Calcium Sensors for Calcium-Stimulated Endocytosis at Synapses. J Neurosci 2019; 39:9478-9490. [PMID: 31628181 DOI: 10.1523/jneurosci.0182-19.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 08/27/2019] [Accepted: 10/07/2019] [Indexed: 02/04/2023] Open
Abstract
Calcium influx triggers and facilitates endocytosis, which recycles vesicles and thus sustains synaptic transmission. Despite decades of studies, the underlying calcium sensor remained not well understood. Here, we examined two calcium binding proteins, protein kinase C (PKC) and calmodulin. Whether PKC is involved in endocytosis was unclear; whether calmodulin acts as a calcium sensor for endocytosis was neither clear, although calmodulin involvement in endocytosis had been suggested. We generated PKC (α or β-isoform) and calmodulin (calmodulin 2 gene) knock-out mice of either sex and measured endocytosis with capacitance measurements, pHluorin imaging and electron microscopy. We found that these knock-outs inhibited slow (∼10-30 s) and rapid (<∼3 s) endocytosis at large calyx-type calyces, and inhibited slow endocytosis and bulk endocytosis (forming large endosome-like structures) at small conventional hippocampal synapses, suggesting the involvement of PKC and calmodulin in three most common forms of endocytosis-the slow, rapid and bulk endocytosis. Inhibition of slow endocytosis in PKC or calmodulin 2 knock-out hippocampal synapses was rescued by overexpressing wild-type PKC or calmodulin, but not calcium-binding-deficient PKC or calmodulin mutant, respectively, suggesting that calcium stimulates endocytosis by binding with its calcium sensor PKC and calmodulin. PKC and calmodulin 2 knock-out inhibited calcium-dependent vesicle mobilization to the readily releasable pool, suggesting that PKC and calmodulin may mediate calcium-dependent facilitation of vesicle mobilization. These findings shed light on the molecular signaling link among calcium, endocytosis and vesicle mobilization that are crucial in maintaining synaptic transmission and neuronal network activity.SIGNIFICANCE STATEMENT Vesicle fusion releases neurotransmitters to mediate synaptic transmission. To sustain synaptic transmission, fused vesicles must be retrieved via endocytosis. Accumulating evidence suggests that calcium influx triggers synaptic vesicle endocytosis. However, how calcium triggers endocytosis is not well understood. Using genetic tools together with capacitance measurements, optical imaging and electron microscopy, we identified two calcium sensors, including protein kinase C (α and β isoforms) and calmodulin, for the most commonly observed forms of endocytosis: slow, rapid, and bulk. We also found that these two proteins are involved in calcium-dependent vesicle mobilization to the readily releasable pool. These results provide the molecular signaling link among calcium, endocytosis, and vesicle mobilization that are essential in sustaining synaptic transmission and neuronal network activity.
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23
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Huang J, Liu F, Wang B, Tang H, Teng Z, Li L, Qiu Y, Wu H, Chen J. Central and Peripheral Changes in FOS Expression in Schizophrenia Based on Genome-Wide Gene Expression. Front Genet 2019; 10:232. [PMID: 30967896 PMCID: PMC6439315 DOI: 10.3389/fgene.2019.00232] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 03/04/2019] [Indexed: 01/19/2023] Open
Abstract
Schizophrenia is a chronic, debilitating neuropsychiatric disorder. Multiple transcriptomic gene expression profiling analysis has been used to identify schizophrenia-associated genes, unravel disease-associated biomarkers, and predict clinical outcomes. We aimed to identify gene expression regulation, underlying pathways, and their roles in schizophrenia pathogenesis. We searched the Gene Expression Omnibus (GEO) database for microarray studies of fibroblasts, lymphoblasts, and post-mortem brains of schizophrenia patients. Our analysis demonstrated high FOS expression in non-neural peripheral samples and low FOS expression in brain tissues of schizophrenia patients compared with healthy controls. FOS exhibited predictive value for schizophrenia patients in these datasets. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that “amphetamine addiction” was among the top 10 significantly enriched KEGG pathways. FOS and FOSB, which are implicated in the amphetamine addiction pathway, were up-regulated in schizophrenia fibroblast samples. Protein–protein interaction (PPI) network analysis revealed that proteins closely interacting with FOS-encoded protein were also involved in the amphetamine addiction pathway. Pearson correlation test indicated that FOS showed positive correlation with genes in the amphetamine pathway. The results revealed that FOS was acceptable as a biomarker for schizophrenia and may be involved in schizophrenia pathogenesis.
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Affiliation(s)
- Jing Huang
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,Mental Health Institute of the Second Xiangya Hospital, Central South University, Chinese National Clinical Research Center for Mental Disorders (Xiangya), Chinese National Technology Institute on Mental Disorders, Hunan Key Laboratory of Psychiatry and Mental Health, Changsha, China
| | - Fangkun Liu
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
| | - Bolun Wang
- Department of Orthopedics, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Hui Tang
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,Mental Health Institute of the Second Xiangya Hospital, Central South University, Chinese National Clinical Research Center for Mental Disorders (Xiangya), Chinese National Technology Institute on Mental Disorders, Hunan Key Laboratory of Psychiatry and Mental Health, Changsha, China
| | - Ziwei Teng
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,Mental Health Institute of the Second Xiangya Hospital, Central South University, Chinese National Clinical Research Center for Mental Disorders (Xiangya), Chinese National Technology Institute on Mental Disorders, Hunan Key Laboratory of Psychiatry and Mental Health, Changsha, China
| | - Lehua Li
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,Mental Health Institute of the Second Xiangya Hospital, Central South University, Chinese National Clinical Research Center for Mental Disorders (Xiangya), Chinese National Technology Institute on Mental Disorders, Hunan Key Laboratory of Psychiatry and Mental Health, Changsha, China
| | - Yan Qiu
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,Mental Health Institute of the Second Xiangya Hospital, Central South University, Chinese National Clinical Research Center for Mental Disorders (Xiangya), Chinese National Technology Institute on Mental Disorders, Hunan Key Laboratory of Psychiatry and Mental Health, Changsha, China
| | - Haishan Wu
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,Mental Health Institute of the Second Xiangya Hospital, Central South University, Chinese National Clinical Research Center for Mental Disorders (Xiangya), Chinese National Technology Institute on Mental Disorders, Hunan Key Laboratory of Psychiatry and Mental Health, Changsha, China
| | - Jindong Chen
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, China.,Mental Health Institute of the Second Xiangya Hospital, Central South University, Chinese National Clinical Research Center for Mental Disorders (Xiangya), Chinese National Technology Institute on Mental Disorders, Hunan Key Laboratory of Psychiatry and Mental Health, Changsha, China
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24
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Vélez-Ortega AC, Frolenkov GI. Building and repairing the stereocilia cytoskeleton in mammalian auditory hair cells. Hear Res 2019; 376:47-57. [PMID: 30638948 DOI: 10.1016/j.heares.2018.12.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/19/2018] [Accepted: 12/28/2018] [Indexed: 10/27/2022]
Abstract
Despite all recent achievements in identification of the molecules that are essential for the structure and mechanosensory function of stereocilia bundles in the auditory hair cells of mammalian species, we still have only a rudimentary understanding of the mechanisms of stereocilia formation, maintenance, and repair. Important molecular differences distinguishing mammalian auditory hair cells from hair cells of other types and species have been recently revealed. In addition, we are beginning to solve the puzzle of the apparent life-long stability of the stereocilia bundles in these cells. New data link the stability of the cytoskeleton in the mammalian auditory stereocilia with the normal activity of mechanotransduction channels. These data suggest new ideas on how a terminally-differentiated non-regenerating hair cell in the mammalian cochlea may repair and tune its stereocilia bundle throughout the life span of the organism.
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Affiliation(s)
- A Catalina Vélez-Ortega
- Department of Physiology, University of Kentucky, 800 Rose St., Lexington, KY, 40536-0298, USA.
| | - Gregory I Frolenkov
- Department of Physiology, University of Kentucky, 800 Rose St., Lexington, KY, 40536-0298, USA.
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25
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Haag N, Schüler S, Nietzsche S, Hübner CA, Strenzke N, Qualmann B, Kessels MM. The Actin Nucleator Cobl Is Critical for Centriolar Positioning, Postnatal Planar Cell Polarity Refinement, and Function of the Cochlea. Cell Rep 2018; 24:2418-2431.e6. [DOI: 10.1016/j.celrep.2018.07.087] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/18/2018] [Accepted: 07/26/2018] [Indexed: 11/26/2022] Open
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26
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Shimada E, Ahsan FM, Nili M, Huang D, Atamdede S, TeSlaa T, Case D, Yu X, Gregory BD, Perrin BJ, Koehler CM, Teitell MA. PNPase knockout results in mtDNA loss and an altered metabolic gene expression program. PLoS One 2018; 13:e0200925. [PMID: 30024931 PMCID: PMC6053217 DOI: 10.1371/journal.pone.0200925] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 07/05/2018] [Indexed: 01/10/2023] Open
Abstract
Polynucleotide phosphorylase (PNPase) is an essential mitochondria-localized exoribonuclease implicated in multiple biological processes and human disorders. To reveal role(s) for PNPase in mitochondria, we established PNPase knockout (PKO) systems by first shifting culture conditions to enable cell growth with defective respiration. Interestingly, PKO established in mouse embryonic fibroblasts (MEFs) resulted in the loss of mitochondrial DNA (mtDNA). The transcriptional profile of PKO cells was similar to rho0 mtDNA deleted cells, with perturbations in cholesterol (FDR = 6.35 x 10-13), lipid (FDR = 3.21 x 10-11), and secondary alcohol (FDR = 1.04x10-12) metabolic pathway gene expression compared to wild type parental (TM6) MEFs. Transcriptome analysis indicates processes related to axonogenesis (FDR = 4.49 x 10-3), axon development (FDR = 4.74 x 10-3), and axonal guidance (FDR = 4.74 x 10-3) were overrepresented in PKO cells, consistent with previous studies detailing causative PNPase mutations in delayed myelination, hearing loss, encephalomyopathy, and chorioretinal defects in humans. Overrepresentation analysis revealed alterations in metabolic pathways in both PKO and rho0 cells. Therefore, we assessed the correlation of genes implicated in cell cycle progression and total metabolism and observed a strong positive correlation between PKO cells and rho0 MEFs compared to TM6 MEFs. We quantified the normalized biomass accumulation rate of PKO clones at 1.7% (SD ± 2.0%) and 2.4% (SD ± 1.6%) per hour, which was lower than TM6 cells at 3.3% (SD ± 3.5%) per hour. Furthermore, PKO in mouse inner ear hair cells caused progressive hearing loss that parallels human familial hearing loss previously linked to mutations in PNPase. Combined, our study reports that knockout of a mitochondrial nuclease results in mtDNA loss and suggests that mtDNA maintenance could provide a unifying connection for the large number of biological activities reported for PNPase.
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Affiliation(s)
- Eriko Shimada
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
| | - Fasih M. Ahsan
- Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Mahta Nili
- Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Dian Huang
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California, United States of America
| | - Sean Atamdede
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
| | - Tara TeSlaa
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
| | - Dana Case
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
| | - Xiang Yu
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Brian D. Gregory
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Benjamin J. Perrin
- Department of Biology, Indiana University–Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Carla M. Koehler
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
- Jonsson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (CMK); (MAT)
| | - Michael A. Teitell
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California, United States of America
- Jonsson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, California, United States of America
- Broad Center for Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Pediatrics, University of California Los Angeles, Los Angeles, California, United States of America
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (CMK); (MAT)
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Abstract
The highly similar cytoplasmic β- and γ-actins differ by only four functionally similar amino acids, yet previous in vitro and in vivo data suggest that they support unique functions due to striking phenotypic differences between Actb and Actg1 null mouse and cell models. To determine whether the four amino acid variances were responsible for the functional differences between cytoplasmic actins, we gene edited the endogenous mouse Actb locus to translate γ-actin protein. The resulting mice and primary embryonic fibroblasts completely lacked β-actin protein, but were viable and did not present with the most overt and severe cell and organismal phenotypes observed with gene knockout. Nonetheless, the edited mice exhibited progressive high-frequency hearing loss and degeneration of actin-based stereocilia as previously reported for hair cell-specific Actb knockout mice. Thus, β-actin protein is not required for general cellular functions, but is necessary to maintain auditory stereocilia.
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28
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Madsen AB, Knudsen JR, Henriquez-Olguin C, Angin Y, Zaal KJ, Sylow L, Schjerling P, Ralston E, Jensen TE. β-Actin shows limited mobility and is required only for supraphysiological insulin-stimulated glucose transport in young adult soleus muscle. Am J Physiol Endocrinol Metab 2018; 315. [PMID: 29533739 PMCID: PMC6087721 DOI: 10.1152/ajpendo.00392.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Studies in skeletal muscle cell cultures suggest that the cortical actin cytoskeleton is a major requirement for insulin-stimulated glucose transport, implicating the β-actin isoform, which in many cell types is the main actin isoform. However, it is not clear that β-actin plays such a role in mature skeletal muscle. Neither dependency of glucose transport on β-actin nor actin reorganization upon glucose transport have been tested in mature muscle. To investigate the role of β-actin in fully differentiated muscle, we performed a detailed characterization of wild type and muscle-specific β-actin knockout (KO) mice. The effects of the β-actin KO were subtle; however, we confirmed the previously reported decline in running performance of β-actin KO mice compared with wild type during repeated maximal running tests. We also found insulin-stimulated glucose transport into incubated muscles reduced in soleus but not in extensor digitorum longus muscle of young adult mice. Contraction-stimulated glucose transport trended toward the same pattern, but the glucose transport phenotype disappeared in soleus muscles from mature adult mice. No genotype-related differences were found in body composition or glucose tolerance or by indirect calorimetry measurements. To evaluate β-actin mobility in mature muscle, we electroporated green fluorescent protein (GFP)-β-actin into flexor digitorum brevis muscle fibers and measured fluorescence recovery after photobleaching. GFP-β-actin showed limited unstimulated mobility and no changes after insulin stimulation. In conclusion, β-actin is not required for glucose transport regulation in mature mouse muscle under the majority of the tested conditions. Thus, our work reveals fundamental differences in the role of the cortical β-actin cytoskeleton in mature muscle compared with cell culture.
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Affiliation(s)
- Agnete B Madsen
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Jonas R Knudsen
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Carlos Henriquez-Olguin
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
- Centro de Estudios Moleculares de la Célula, Instituto de Ciencias Biomédicas, Universidad de Chile ; Laboratory of Exercise Sciences, Clínica MEDS, Santiago , Chile
| | - Yeliz Angin
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Kristien J Zaal
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health , Bethesda, Maryland
| | - Lykke Sylow
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Peter Schjerling
- Institute of Sports Medicine, Department of Orthopedic Surgery, Bispebjerg Hospital , Copenhagen , Denmark
- Center of Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Evelyn Ralston
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health , Bethesda, Maryland
| | - Thomas E Jensen
- Department of Nutrition, Exercise and Sports, University of Copenhagen , Copenhagen , Denmark
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29
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Roy P, Perrin BJ. The stable actin core of mechanosensory stereocilia features continuous turnover of actin cross-linkers. Mol Biol Cell 2018; 29:1856-1865. [PMID: 29874122 PMCID: PMC6085822 DOI: 10.1091/mbc.e18-03-0196] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Stereocilia are mechanosensitive protrusions on the surfaces of sensory hair cells in the inner ear that detect sound, gravity, and head movement. Their cores are composed of parallel actin filaments that are cross-linked and stabilized by several actin-binding proteins, including fascin-2, plastin-1, espin, and XIRP2. The actin filaments are the most stable known, with actin turnover primarily occurring at the stereocilia tips. While stereocilia actin dynamics has been well studied, little is known about the behavior of the actin cross-linking proteins, which are the most abundant type of protein in stereocilia after actin and are critical for stereocilia morphogenesis and maintenance. Here, we developed a novel transgenic mouse to monitor EGFP-fascin-2 incorporation. In contrast to actin, EGFP-fascin-2 readily enters the stereocilia core. We also compared the effect of EGFP-fascin-2 expression on developing and mature stereocilia. When it was induced during hair cell development, we observed increases in both stereocilia length and width. Interestingly, stereocilia size was not affected when EGFP-fascin-2 was induced in adult stereocilia. Regardless of the time of induction, EGFP-fascin-2 displaced both espin and plastin-1 from stereocilia. Altering the actin cross-linker composition, even as the actin filaments exhibit little to no turnover, provides a mechanism for ongoing remodeling and repair important for stereocilia homeostasis.
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Affiliation(s)
- Pallabi Roy
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202
| | - Benjamin J Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202
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30
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Skogseid IM, Røsby O, Konglund A, Connelly JP, Nedregaard B, Jablonski GE, Kvernmo N, Stray-Pedersen A, Glover JC. Dystonia-deafness syndrome caused by ACTB p.Arg183Trp heterozygosity shows striatal dopaminergic dysfunction and response to pallidal stimulation. J Neurodev Disord 2018; 10:17. [PMID: 29788902 PMCID: PMC5964724 DOI: 10.1186/s11689-018-9235-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 05/10/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dystonia-deafness syndrome is a well-known clinical entity, with sensorineural deafness typically manifesting earlier than dystonia. ACTB p.Arg183Trp heterozygosity has been reported in six patients to cause combined infant-onset deafness and dystonia manifesting in adolescence or young adulthood. Three of these have received beneficial pallidal stimulation. Brain imaging to assess striatal function has not been reported previously, however. Nor has a comprehensive hypothesis been presented for how the pleiotropic manifestations of this specific beta-actin gene mutation originate developmentally. CASE PRESENTATION A 19-year-old girl with congenital mild dysmorphic facial features, cochlear implants for infant-onset deafness, and mild cognitive and emotional disability, presented with an adolescent-onset, severe generalized dystonia. Brain MRI and multiple single gene sequencing were inconclusive. Due to life-threatening dystonia, we implanted a neurostimulation device, targeting the postero-ventral internal pallidum bilaterally. The Burke-Fahn-Marsden Dystonia Rating Scale motor/disability scores improved from 87/25 to 21/13 at 2.5 months postoperatively, 26/14 at 3 years, and 30/14 at 4 years. Subsequent whole exome sequencing identified heterozygosity for the ACTB p.Arg183Trp variant. Brain imaging included 123I-ioflupane single photon emission computed tomography (Dopamine Transporter-SPECT), SPECT with 123I-epidepride (binds to dopamine type 2-receptors) and 18 Fluoro-Deoxy-Glucose (FDG)-PET. Both Epidepride-SPECT and FDG-PET showed reduced tracer uptake in the striatum bilaterally, particularly in the putamen. DaT-SPECT was slightly abnormal. CONCLUSIONS In this patient with dystonia-deafness syndrome caused by ACTB p.Arg183Trp heterozygosity, unprecedented brain imaging findings strongly indicate striatal neuronal/dopaminergic dysfunction as the underlying cause of the dystonia. Pallidal stimulation provided a substantial improvement of the severe generalized dystonia, which is largely sustained at 4-year follow-up, and we advise this treatment to be considered in such patients. We hypothesize that the pleiotropic manifestations of the dystonia-deafness syndrome caused by this mutation derive from diverse developmental functions of beta-actin in neural crest migration and proliferation (facial dysmorphogenesis), hair cell stereocilia function (infant-onset deafness), and altered synaptic activity patterns associated with pubertal changes in striatal function (adolescent-onset dystonia). The temporal differences in developmental onset are likely due to varying degrees of susceptibility and of compensatory upregulation of other actin variants in the affected structures.
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Affiliation(s)
- Inger Marie Skogseid
- Department of Neurology, Division of Clinical Neuroscience, Oslo University Hospital, Po.box. 4950, Nydalen, 0424, Oslo, Norway.
| | - Oddveig Røsby
- Department of Medical Genetics, Division of Laboratory Medicine, Oslo University Hospital, Oslo, Norway
| | - Ane Konglund
- Department of Neurosurgery, Division of Clinical Neuroscience, Oslo University Hospital, Oslo, Norway
| | - James P Connelly
- Department of Nuclear Medicine, Division of Radiology & Nuclear Medicine, Oslo University Hospital, Oslo, Norway
| | - Bård Nedregaard
- Department of Radiology, Division of Radiology & Nuclear Medicine, Oslo University Hospital, Oslo, Norway
| | - Greg Eigner Jablonski
- Department of Otorhinolaryngology, Division of Head, Neck & Reconstructive Surgery, Oslo University Hospital, Oslo, Norway.,Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Nadja Kvernmo
- Department of Neurology, Division of Clinical Neuroscience, Oslo University Hospital, Po.box. 4950, Nydalen, 0424, Oslo, Norway
| | - Asbjørg Stray-Pedersen
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Baylor-Hopkins Center for Mendelian Genomics, Baylor College of Medicine, Houston, TX, 77030, USA.,Norwegian National Unit for Newborn Screening, Division of Pediatric and Adolescent Medicine, Oslo University Hospital, Oslo, Norway
| | - Joel C Glover
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Norwegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway
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31
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Wang L, Yan D, Qin L, Li T, Liu H, Li W, Mittal R, Yong F, Chapagain P, Liao S, Liu X. Amino acid 118 in the Deafness Causing (DFNA20/26) ACTG1 gene is a Mutational Hot Spot. GENE REPORTS 2018; 11:264-269. [PMID: 30599039 DOI: 10.1016/j.genrep.2018.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Background Hearing loss is an economically and socially important cause of human morbidity, affecting 360 million people (over 5% of the world's population), of whom 32 million are children. Of the estimated minimum of 50% of hereditary hearing loss, non-syndromic hearing loss (NSHL) accounts for more than 70%. The autosomal dominant non-syndromic hearing loss (ADNSHL) is highly heterogeneous. To date, 67 ADNSHL loci (DFNA1-67) have been mapped; however, only 35 causative genes have been cloned since 1997 (http://hereditaryhearingloss.org/). Methods To identify the genetic basis of hereditary hearing loss in a Chinese family with ADNSHL, we undertook a targeted sequencing of 180 genes using a custom capture panel (MiamiOtoGenes). Results The onset of hearing loss in the family occurred between the ages of 15 and 18 years. Hearing loss was bilateral, started in the high frequency and progressed to lower frequencies. The c.353A>T (K118M) in the AC TG1 gene was identified by panel and was confirmed by Sanger sequencing and was present in all affected family members. So far, five of the 23 DFNA20/26 families worldwide have been found to carry mutation involving the residue K118. Conclusions This is the first report of K118M mutation in the ACTG1 gene causing hearing loss in the Chinese population. The present data are in line with previous evidence to suggest that codon K118 of ACTG1 may represent a mutational hot spot that justifies a mutation screen for diagnostic purpose in the genetically heterogeneous group of DFNA20/26.
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Affiliation(s)
- Li Wang
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China.,Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, USA
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, USA
| | - Litao Qin
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Tao Li
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Hongjian Liu
- Department of Otorhinolaryngology, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Wan Li
- Department of Otorhinolaryngology, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Rahul Mittal
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Feng Yong
- Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, China
| | - Prem Chapagain
- Department of Physics, Florida International University, Miami, Florida.,Biomolecular Sciences Institute, Florida International University, Miami, Florida
| | - Shixiu Liao
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Xuezhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, USA
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Lymphocyte-specific protein 1 regulates mechanosensory oscillation of podosomes and actin isoform-based actomyosin symmetry breaking. Nat Commun 2018; 9:515. [PMID: 29410425 PMCID: PMC5802837 DOI: 10.1038/s41467-018-02904-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 01/05/2018] [Indexed: 01/06/2023] Open
Abstract
Subcellular fine-tuning of the actomyosin cytoskeleton is a prerequisite for polarized cell migration. We identify LSP (lymphocyte-specific protein) 1 as a critical regulator of actomyosin contractility in primary macrophages. LSP1 regulates adhesion and migration, including the parameters cell area and speed, and also podosome turnover, oscillation and protrusive force. LSP1 recruits myosin IIA and its regulators, including myosin light chain kinase and calmodulin, and competes with supervillin, a myosin hyperactivator, for myosin regulators, and for actin isoforms, notably β-actin. Actin isoforms are anisotropically distributed in myosin IIA-expressing macrophages, and contribute to the differential recruitment of LSP1 and supervillin, thus enabling an actomyosin symmetry break, analogous to the situation in cells expressing two myosin II isoforms. Collectively, these results show that the cellular pattern of actin isoforms builds the basis for the differential distribution of two actomyosin machineries with distinct properties, leading to the establishment of discrete zones of actomyosin contractility. The actomyosin cytoskeleton plays an important role in polarised cell migration. Here the authors identify lymphocyte-specific protein (LSP)-1 as a regulator of actomyosin contractility in macrophages, by competing with supervillin for myosin IIA activators acting specifically on the β-actin isoform.
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33
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Xie X, Deliorman M, Qasaimeh MA, Percipalle P. The relative composition of actin isoforms regulates cell surface biophysical features and cellular behaviors. Biochim Biophys Acta Gen Subj 2018; 1862:1079-1090. [PMID: 29410074 DOI: 10.1016/j.bbagen.2018.01.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 01/28/2018] [Accepted: 01/31/2018] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cell surface mechanics is able to physically and biomechanically affect cell shape and motility, vesicle trafficking and actin dynamics. The biophysical properties of cell surface are strongly influenced by cytoskeletal elements. In mammals, tissue-specific expression of six actin isoforms is thought to confer differential biomechanical properties. However, the relative contribution of actin isoforms to cell surface properties is not well understood. Here, we sought to investigate whether and how the composition of endogenous actin isoforms directly affects the biomechanical features of cell surface and cellular behavior. METHODS We used fibroblasts isolated from wild type (WT), heterozygous (HET) and from knockout (KO) mouse embryos where both β-actin alleles are not functional. We applied a combination of genome-wide analysis and biophysical methods such as RNA-seq and atomic force microscopy. RESULTS We found that endogenous β-actin levels are essential in controlling cell surface stiffness and pull-off force, which was not compensated by the up-regulation of other actin isoforms. The variations of surface biophysical features and actin contents were associated with distinct cell behaviors in 2D and 3D WT, HET and KO cell cultures. Since β-actin in WT cells and smooth muscle α-actin up-regulated in KO cells showed different organization patterns, our data support the differential localization and organization as a mechanism to regulate the biophysical properties of cell surface by actin isoforms. CONCLUSIONS We propose that variations in actin isoforms composition impact on the biophysical features of cell surface and cause the changes in cell behavior.
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Affiliation(s)
- Xin Xie
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, United Arab Emirates
| | - Muhammedin Deliorman
- Engineering Division, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, United Arab Emirates
| | - Mohammad A Qasaimeh
- Engineering Division, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, United Arab Emirates; Department of Mechanical and Aerospace Engineering, New York University, USA
| | - Piergiorgio Percipalle
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, United Arab Emirates; Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden.
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O'Rourke AR, Lindsay A, Tarpey MD, Yuen S, McCourt P, Nelson DM, Perrin BJ, Thomas DD, Spangenburg EE, Lowe DA, Ervasti JM. Impaired muscle relaxation and mitochondrial fission associated with genetic ablation of cytoplasmic actin isoforms. FEBS J 2018; 285:481-500. [PMID: 29265728 DOI: 10.1111/febs.14367] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 11/06/2017] [Accepted: 12/13/2017] [Indexed: 12/28/2022]
Abstract
While α-actin isoforms predominate in adult striated muscle, skeletal muscle-specific knockouts (KOs) of nonmuscle cytoplasmic βcyto - or γcyto -actin each cause a mild, but progressive myopathy effected by an unknown mechanism. Using transmission electron microscopy, we identified morphological abnormalities in both the mitochondria and the sarcoplasmic reticulum (SR) in aged muscle-specific βcyto - and γcyto -actin KO mice. We found βcyto - and γcyto -actin proteins to be enriched in isolated mitochondrial-associated membrane preparations, which represent the interface between mitochondria and sarco-endoplasmic reticulum important in signaling and mitochondrial dynamics. We also measured significantly elongated and interconnected mitochondrial morphologies associated with a significant decrease in mitochondrial fission events in primary mouse embryonic fibroblasts lacking βcyto - and/or γcyto -actin. Interestingly, mitochondrial respiration in muscle was not measurably affected as oxygen consumption was similar in skeletal muscle fibers from 12 month-old muscle-specific βcyto - and γcyto -actin KO mice. Instead, we found that the maximal rate of relaxation after isometric contraction was significantly slowed in muscles of 12-month-old βcyto - and γcyto -actin muscle-specific KO mice. Our data suggest that impaired Ca2+ re-uptake may presage development of the observed SR morphological changes in aged mice while providing a potential pathological mechanism for the observed myopathy.
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Affiliation(s)
- Allison R O'Rourke
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Angus Lindsay
- Department of Rehabilitation Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Michael D Tarpey
- Department of Physiology, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Samantha Yuen
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Preston McCourt
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - D'anna M Nelson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Benjamin J Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, IN, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Espen E Spangenburg
- Department of Physiology, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Dawn A Lowe
- Department of Rehabilitation Medicine, University of Minnesota, Minneapolis, MN, USA
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
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35
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Jain RK, Pingle SK, Tumane RG, Thakkar LR, Jawade AA, Barapatre A, Trivedi M. Cochlear Proteins Associated with Noise-induced Hearing Loss: An Update. Indian J Occup Environ Med 2018; 22:60-73. [PMID: 30319226 PMCID: PMC6176698 DOI: 10.4103/ijoem.ijoem_43_18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Noise-induced hearing loss (NIHL) is one of the major occupational disease that has influence on the quality of life of mining workers. Several reports suggest NIHL is attributed to noise exposure at workplace and approximately 16% of hearing loss is due to it. NIHL occurs as a result of exposure to high-level noise (>85 dB) in the workplace. Noise disrupts proteins present in the micromachinery of the ear that is required for mechano-electric transduction of sound waves. High-level noise exposure can lead to hearing impairment owing to mechanical and metabolic exhaustion in cochlea, the major organ responsible for resilience of sound. Several key proteins of cochlea include tectorial membrane, inner hair cells, outer hair cells, and stereocilia are damaged due to high-level noise exposure. Numerous studies conducted in animals have shown cochlear proteins involvement in NIHL, but the pertinent literature remains limited in humans. Detection of proteins and pathways perturbed within the micromachinery of the ear after excessive sound induction leads toward the early identification of hearing loss. The situation insisted to present this review as an update on cochlear proteins associated with NIHL after an extensive literature search using several electronic databases which help to understand the pathophysiology of NIHL.
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Affiliation(s)
- Ruchika K Jain
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Shubhangi K Pingle
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Rajani G Tumane
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Lucky R Thakkar
- National Centre for Microbial Resources, National Centre for Cell Science, University of Pune Campus, Pune, Maharashtra, India
| | - Aruna A Jawade
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Anand Barapatre
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Minal Trivedi
- B. K. Birla College of Science, Arts & Commerce (Autonomous), Kalyan, Maharashtra, India
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36
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Vélez-Ortega AC, Freeman MJ, Indzhykulian AA, Grossheim JM, Frolenkov GI. Mechanotransduction current is essential for stability of the transducing stereocilia in mammalian auditory hair cells. eLife 2017; 6. [PMID: 28350294 PMCID: PMC5407859 DOI: 10.7554/elife.24661] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 03/27/2017] [Indexed: 01/02/2023] Open
Abstract
Mechanotransducer channels at the tips of sensory stereocilia of inner ear hair cells are gated by the tension of 'tip links' interconnecting stereocilia. To ensure maximal sensitivity, tip links are tensioned at rest, resulting in a continuous influx of Ca2+ into the cell. Here, we show that this constitutive Ca2+ influx, usually considered as potentially deleterious for hair cells, is in fact essential for stereocilia stability. In the auditory hair cells of young postnatal mice and rats, a reduction in mechanotransducer current, via pharmacological channel blockers or disruption of tip links, leads to stereocilia shape changes and shortening. These effects occur only in stereocilia that harbor mechanotransducer channels, recover upon blocker washout or tip link regeneration and can be replicated by manipulations of extracellular Ca2+ or intracellular Ca2+ buffering. Thus, our data provide the first experimental evidence for the dynamic control of stereocilia morphology by the mechanotransduction current. DOI:http://dx.doi.org/10.7554/eLife.24661.001 Our sense of hearing depends on cells known as hair cells that line the inner ear. Each hair cell has tiny projections called stereocilia, which are arranged in a bundle with rows of increasing height like a staircase and are connected to each other by tiny filaments called tip-links. When sound waves hit the stereocilia, the tension on the tip-links increases, which opens “mechanotransduction” channels on the shorter stereocilia that allow calcium ions to flow into the cells. To ensure that the ears can detect even the softest sounds, the tip-links always have a small amount of tension which allows a small, but continuous flow of calcium ions into the cell. Scientists generally consider this continuous flow of calcium ions as a potentially harmful byproduct of sensitive hearing. Vélez-Ortega et al. isolated inner ear tissues from young mice and rats and exposed them to drugs that either block the flow of calcium ions through the mechanotransduction channels or break the tip-links on stereocilia. Surprisingly, these drugs made profound changes in the shape of individual stereocilia and the staircase architecture of the stereocilia bundle. When the drugs were rinsed out of the hair cells, the stereocilia went back to their normal shape. Sequestering of free calcium ions inside the hair cells had a similar effect on the shape of stereocilia. These findings show that the flow of calcium ions into the sterocilia via mechanotransduction channels controls the exquisite staircase-like architecture of the stereocilia bundle. More research is needed to identify which structural proteins cause the stereocilia shape changes and to work out exactly how calcium ions are involved. DOI:http://dx.doi.org/10.7554/eLife.24661.002
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Affiliation(s)
- A Catalina Vélez-Ortega
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, United States
| | - Mary J Freeman
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, United States
| | - Artur A Indzhykulian
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, United States
| | - Jonathan M Grossheim
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, United States
| | - Gregory I Frolenkov
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, United States
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37
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Patrinostro X, O'Rourke AR, Chamberlain CM, Moriarity BS, Perrin BJ, Ervasti JM. Relative importance of β cyto- and γ cyto-actin in primary mouse embryonic fibroblasts. Mol Biol Cell 2017; 28:771-782. [PMID: 28077619 PMCID: PMC5349784 DOI: 10.1091/mbc.e16-07-0503] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/29/2016] [Accepted: 01/05/2017] [Indexed: 12/14/2022] Open
Abstract
The highly homologous β (βcyto) and γ (γcyto) cytoplasmic actins are hypothesized to carry out both redundant and unique essential functions, but studies using targeted gene knockout and siRNA-mediated transcript knockdown to examine βcyto- and γcyto-isoform--specific functions in various cell types have yielded conflicting data. Here we quantitatively characterized actin transcript and protein levels, as well as cellular phenotypes, in both gene- and transcript-targeted primary mouse embryonic fibroblasts. We found that the smooth muscle αsm-actin isoform was the dominantly expressed actin isoform in WT primary fibroblasts and was also the most dramatically up-regulated in primary βcyto- or β/γcyto-actin double-knockout fibroblasts. Gene targeting of βcyto-actin, but not γcyto-actin, led to greatly decreased cell proliferation, decreased levels of cellular ATP, and increased serum response factor signaling in primary fibroblasts, whereas immortalization induced by SV40 large T antigen supported fibroblast proliferation in the absence of βcyto-actin. Consistent with in vivo gene-targeting studies in mice, both gene- and transcript-targeting approaches demonstrate that the loss of βcyto-actin protein is more disruptive to primary fibroblast function than is the loss of γcyto-actin.
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Affiliation(s)
- Xiaobai Patrinostro
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455
| | - Allison R O'Rourke
- Program in Molecular, Cellular, Developmental Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Christopher M Chamberlain
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455
| | | | - Benjamin J Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46022
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455 .,Program in Molecular, Cellular, Developmental Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
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38
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Yates TM, Turner CL, Firth HV, Berg J, Pilz DT. Baraitser-Winter cerebrofrontofacial syndrome. Clin Genet 2016; 92:3-9. [PMID: 27625340 DOI: 10.1111/cge.12864] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Revised: 09/07/2016] [Accepted: 09/07/2016] [Indexed: 01/31/2023]
Abstract
Baraitser-Winter cerebrofrontofacial syndrome (BWCFF) (BRWS; MIM #243310, 614583) is a rare developmental disorder affecting multiple organ systems. It is characterised by intellectual disability (mild to severe) and distinctive facial appearance (metopic ridging/trigonocephaly, bilateral ptosis, hypertelorism). The additional presence of cortical malformations (pachygyria/lissencephaly) and ocular colobomata are also suggestive of this syndrome. Other features include moderate short stature, contractures, congenital cardiac disease and genitourinary malformations. BWCFF is caused by missense mutations in the cytoplasmic beta- and gamma-actin genes ACTB and ACTG1. We provide an overview of the clinical characteristics (including some novel findings in four recently diagnosed patients), diagnosis, management, mutation spectrum and genetic counselling.
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Affiliation(s)
- T M Yates
- Department of Medical Genetics, University of Glasgow, Glasgow, UK
| | - C L Turner
- Peninsula Clinical Genetics Service, Royal Devon and Exeter Hospital, Exeter, UK
| | - H V Firth
- Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
| | - J Berg
- Department of Clinical Genetics, Ninewells Hospital, Dundee, UK
| | - D T Pilz
- West of Scotland Genetics Service, Queen Elizabeth University Hospital, Glasgow, UK
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39
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Krey JF, Krystofiak ES, Dumont RA, Vijayakumar S, Choi D, Rivero F, Kachar B, Jones SM, Barr-Gillespie PG. Plastin 1 widens stereocilia by transforming actin filament packing from hexagonal to liquid. J Cell Biol 2016; 215:467-482. [PMID: 27811163 PMCID: PMC5119939 DOI: 10.1083/jcb.201606036] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 09/29/2016] [Accepted: 10/11/2016] [Indexed: 11/24/2022] Open
Abstract
With their essential role in inner ear function, stereocilia of sensory hair cells demonstrate the importance of cellular actin protrusions. Actin packing in stereocilia is mediated by cross-linkers of the plastin, fascin, and espin families. Although mice lacking espin (ESPN) have no vestibular or auditory function, we found that mice that either lacked plastin 1 (PLS1) or had nonfunctional fascin 2 (FSCN2) had reduced inner ear function, with double-mutant mice most strongly affected. Targeted mass spectrometry indicated that PLS1 was the most abundant cross-linker in vestibular stereocilia and the second most abundant protein overall; ESPN only accounted for ∼15% of the total cross-linkers in bundles. Mouse utricle stereocilia lacking PLS1 were shorter and thinner than wild-type stereocilia. Surprisingly, although wild-type stereocilia had random liquid packing of their actin filaments, stereocilia lacking PLS1 had orderly hexagonal packing. Although all three cross-linkers are required for stereocilia structure and function, PLS1 biases actin toward liquid packing, which allows stereocilia to grow to a greater diameter.
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Affiliation(s)
- Jocelyn F Krey
- Oregon Hearing Research Center, Oregon Health and Science University, Portland, OR 97239
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239
| | - Evan S Krystofiak
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892
| | - Rachel A Dumont
- Oregon Hearing Research Center, Oregon Health and Science University, Portland, OR 97239
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239
| | - Sarath Vijayakumar
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, NE 68583
| | - Dongseok Choi
- Oregon Health and Science University-Portland State University School of Public Health, Oregon Health and Science University, Portland, OR 97239
- Graduate School of Dentistry, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Francisco Rivero
- Centre for Cardiovascular and Metabolic Research, The Hull York Medical School, University of Hull, Hull HU6 7RX, England, UK
| | - Bechara Kachar
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892
| | - Sherri M Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, NE 68583
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center, Oregon Health and Science University, Portland, OR 97239
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239
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40
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Actin Is Crucial for All Kinetically Distinguishable Forms of Endocytosis at Synapses. Neuron 2016; 92:1020-1035. [PMID: 27840001 DOI: 10.1016/j.neuron.2016.10.014] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 06/16/2016] [Accepted: 10/04/2016] [Indexed: 01/18/2023]
Abstract
Mechanical force is needed to mediate endocytosis. Whether actin, the most abundant force-generating molecule, is essential for endocytosis is highly controversial in mammalian cells, particularly synapses, likely due to the use of actin blockers, the efficiency and specificity of which are often unclear in the studied cell. Here we addressed this issue using a knockout approach combined with measurements of membrane capacitance and fission pore conductance, imaging of vesicular protein endocytosis, and electron microscopy. We found that two actin isoforms, β- and γ-actin, are crucial for slow, rapid, bulk, and overshoot endocytosis at large calyx-type synapses, and for slow endocytosis and bulk endocytosis at small hippocampal synapses. Polymerized actin provides mechanical force to form endocytic pits. Actin also facilitates replenishment of the readily releasable vesicle pool, likely via endocytic clearance of active zones. We conclude that polymerized actin provides mechanical force essential for all kinetically distinguishable forms of endocytosis at synapses.
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41
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Wen PJ, Grenklo S, Arpino G, Tan X, Liao HS, Heureaux J, Peng SY, Chiang HC, Hamid E, Zhao WD, Shin W, Näreoja T, Evergren E, Jin Y, Karlsson R, Ebert SN, Jin A, Liu AP, Shupliakov O, Wu LG. Actin dynamics provides membrane tension to merge fusing vesicles into the plasma membrane. Nat Commun 2016; 7:12604. [PMID: 27576662 PMCID: PMC5013665 DOI: 10.1038/ncomms12604] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 07/13/2016] [Indexed: 01/22/2023] Open
Abstract
Vesicle fusion is executed via formation of an Ω-shaped structure (Ω-profile), followed by closure (kiss-and-run) or merging of the Ω-profile into the plasma membrane (full fusion). Although Ω-profile closure limits release but recycles vesicles economically, Ω-profile merging facilitates release but couples to classical endocytosis for recycling. Despite its crucial role in determining exocytosis/endocytosis modes, how Ω-profile merging is mediated is poorly understood in endocrine cells and neurons containing small ∼30–300 nm vesicles. Here, using confocal and super-resolution STED imaging, force measurements, pharmacology and gene knockout, we show that dynamic assembly of filamentous actin, involving ATP hydrolysis, N-WASP and formin, mediates Ω-profile merging by providing sufficient plasma membrane tension to shrink the Ω-profile in neuroendocrine chromaffin cells containing ∼300 nm vesicles. Actin-directed compounds also induce Ω-profile accumulation at lamprey synaptic active zones, suggesting that actin may mediate Ω-profile merging at synapses. These results uncover molecular and biophysical mechanisms underlying Ω-profile merging. As vesicles fuse to the plasma membrane, they form intermediate Ω-shaped structures followed by either closure of the pore or full merging with the plasma membrane. Here Wen et al. show that dynamic actin assembly provides membrane tension to promote Ω merging in neuroendocrine cells and synapses.
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Affiliation(s)
- Peter J Wen
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Staffan Grenklo
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden.,Department of Cell Biology, WGI, Stockholm University, 106 91 Stockholm, Sweden
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA.,Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Xinyu Tan
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Hsien-Shun Liao
- National Institute of Biomedical Imaging and Bioengineering (NIBIB), Bethesda, Maryland 20892, USA
| | - Johanna Heureaux
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Shi-Yong Peng
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Hsueh-Cheng Chiang
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Edaeni Hamid
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Wei-Dong Zhao
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Wonchul Shin
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Tuomas Näreoja
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Emma Evergren
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Yinghui Jin
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Roger Karlsson
- Department of Cell Biology, WGI, Stockholm University, 106 91 Stockholm, Sweden
| | - Steven N Ebert
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, 6900 Lake Nona Boulevard, Orlando, Florida 32827, USA
| | - Albert Jin
- National Institute of Biomedical Imaging and Bioengineering (NIBIB), Bethesda, Maryland 20892, USA
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Oleg Shupliakov
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden.,Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
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42
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McGrath J, Roy P, Perrin BJ. Stereocilia morphogenesis and maintenance through regulation of actin stability. Semin Cell Dev Biol 2016; 65:88-95. [PMID: 27565685 DOI: 10.1016/j.semcdb.2016.08.017] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 08/09/2016] [Accepted: 08/22/2016] [Indexed: 12/24/2022]
Abstract
Stereocilia are actin-based protrusions on auditory and vestibular sensory cells that are required for hearing and balance. They convert physical force from sound, head movement or gravity into an electrical signal, a process that is called mechanoelectrical transduction. This function depends on the ability of sensory cells to grow stereocilia of defined lengths. These protrusions form a bundle with a highly precise geometry that is required to detect nanoscale movements encountered in the inner ear. Congenital or progressive stereocilia degeneration causes hearing loss. Thus, understanding stereocilia hair bundle structure, development, and maintenance is pivotal to understanding the pathogenesis of deafness. Stereocilia cores are made from a tightly packed array of parallel, crosslinked actin filaments, the length and stability of which are regulated in part by myosin motors, actin crosslinkers and capping proteins. This review aims to describe stereocilia actin regulation in the context of an emerging "tip turnover" model where actin assembles and disassembles at stereocilia tips while the remainder of the core is exceptionally stable.
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Affiliation(s)
- Jamis McGrath
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46022, USA
| | - Pallabi Roy
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46022, USA
| | - Benjamin J Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46022, USA.
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43
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Abstract
Actin is the central building block of the actin cytoskeleton, a highly regulated filamentous network enabling dynamic processes of cells and simultaneously providing structure. Mammals have six actin isoforms that are very conserved and thus share common functions. Tissue-specific expression in part underlies their differential roles, but actin isoforms also coexist in various cell types and tissues, suggesting specific functions and preferential interaction partners. Gene deletion models, antibody-based staining patterns, gene silencing effects, and the occurrence of isoform-specific mutations in certain diseases have provided clues for specificity on the subcellular level and its consequences on the organism level. Yet, the differential actin isoform functions are still far from understood in detail. Biochemical studies on the different isoforms in pure form are just emerging, and investigations in cells have to deal with a complex and regulated system, including compensatory actin isoform expression.
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Affiliation(s)
- Christophe Ampe
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, A. Baertsoenkaai 3, 9000, Ghent, Belgium.
| | - Marleen Van Troys
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, A. Baertsoenkaai 3, 9000, Ghent, Belgium
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44
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Schreiber J, Végh MJ, Dawitz J, Kroon T, Loos M, Labonté D, Li KW, Van Nierop P, Van Diepen MT, De Zeeuw CI, Kneussel M, Meredith RM, Smit AB, Van Kesteren RE. Ubiquitin ligase TRIM3 controls hippocampal plasticity and learning by regulating synaptic γ-actin levels. J Cell Biol 2015; 211:569-86. [PMID: 26527743 PMCID: PMC4639863 DOI: 10.1083/jcb.201506048] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 10/06/2015] [Indexed: 12/24/2022] Open
Abstract
TRIM3 regulates synaptic γ-actin levels. TRIM3-deficient mice consequently have higher hippocampal spine densities, increased long-term potentiation, and enhanced contextual fear memory consolidation, indicating that temporal control of ACTG1 levels by TRIM3 is required to constrain hippocampal plasticity within physiological boundaries. Synaptic plasticity requires remodeling of the actin cytoskeleton. Although two actin isoforms, β- and γ-actin, are expressed in dendritic spines, the specific contribution of γ-actin in the expression of synaptic plasticity is unknown. We show that synaptic γ-actin levels are regulated by the E3 ubiquitin ligase TRIM3. TRIM3 protein and Actg1 transcript are colocalized in messenger ribonucleoprotein granules responsible for the dendritic targeting of messenger RNAs. TRIM3 polyubiquitylates γ-actin, most likely cotranslationally at synaptic sites. Trim3−/− mice consequently have increased levels of γ-actin at hippocampal synapses, resulting in higher spine densities, increased long-term potentiation, and enhanced short-term contextual fear memory consolidation. Interestingly, hippocampal deletion of Actg1 caused an increase in long-term fear memory. Collectively, our findings suggest that temporal control of γ-actin levels by TRIM3 is required to regulate the timing of hippocampal plasticity. We propose a model in which TRIM3 regulates synaptic γ-actin turnover and actin filament stability and thus forms a transient inhibitory constraint on the expression of hippocampal synaptic plasticity.
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Affiliation(s)
- Joerg Schreiber
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
| | - Marlene J Végh
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
| | - Julia Dawitz
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
| | - Tim Kroon
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
| | - Maarten Loos
- Sylics (Synaptologics BV), 1008 BA Amsterdam, Netherlands
| | - Dorthe Labonté
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, D-20251 Hamburg, Germany
| | - Ka Wan Li
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
| | - Pim Van Nierop
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
| | - Michiel T Van Diepen
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
| | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, 3000 DR Rotterdam, Netherlands Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Science, 1105 BA Amsterdam, Netherlands
| | - Matthias Kneussel
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, D-20251 Hamburg, Germany
| | - Rhiannon M Meredith
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
| | - Ronald E Van Kesteren
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, 1081 HV Amsterdam, Netherlands
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45
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Lu X, Sipe CW. Developmental regulation of planar cell polarity and hair-bundle morphogenesis in auditory hair cells: lessons from human and mouse genetics. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 5:85-101. [PMID: 26265594 DOI: 10.1002/wdev.202] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/12/2015] [Accepted: 06/29/2015] [Indexed: 12/11/2022]
Abstract
Hearing loss is the most common and costly sensory defect in humans and genetic causes underlie a significant proportion of affected individuals. In mammals, sound is detected by hair cells (HCs) housed in the cochlea of the inner ear, whose function depends on a highly specialized mechanotransduction organelle, the hair bundle. Understanding the factors that regulate the development and functional maturation of the hair bundle is crucial for understanding the pathophysiology of human deafness. Genetic analysis of deafness genes in animal models, together with complementary forward genetic screens and conditional knock-out mutations in essential genes, have provided great insights into the molecular machinery underpinning hair-bundle development and function. In this review, we highlight recent advances in our understanding of hair-bundle morphogenesis, with an emphasis on the molecular pathways governing hair-bundle polarity and orientation. We next discuss the proteins and structural elements important for hair-cell mechanotransduction as well as hair-bundle cohesion and maintenance. In addition, developmental signals thought to regulate tonotopic features of HCs are introduced. Finally, novel approaches that complement classic genetics for studying the molecular etiology of human deafness are presented. WIREs Dev Biol 2016, 5:85-101. doi: 10.1002/wdev.202 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Xiaowei Lu
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - Conor W Sipe
- Department of Biology, University of Virginia, Charlottesville, VA, USA
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46
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Jahan I, Pan N, Kersigo J, Fritzsch B. Neurog1 can partially substitute for Atoh1 function in hair cell differentiation and maintenance during organ of Corti development. Development 2015. [PMID: 26209643 DOI: 10.1242/dev.123091] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Atoh1, a basic helix-loop-helix (bHLH) transcription factor (TF), is essential for the differentiation of hair cells (HCs), mechanotransducers that convert sound into auditory signals in the mammalian organ of Corti (OC). Previous work demonstrated that replacing mouse Atoh1 with the fly ortholog atonal rescues HC differentiation, indicating functional replacement by other bHLH genes. However, replacing Atoh1 with Neurog1 resulted in reduced HC differentiation compared with transient Atoh1 expression in a 'self-terminating' Atoh1 conditional null mouse (Atoh1-Cre; Atoh1(f/f)). We now show that combining Neurog1 in one allele with removal of floxed Atoh1 in a self-terminating conditional mutant (Atoh1-Cre; Atoh1(f/kiNeurog1)) mouse results in significantly more differentiated inner HCs and outer HCs that have a prolonged longevity of 9 months compared with Atoh1 self-terminating littermates. Stereocilia bundles are partially disorganized, disoriented and not HC type specific. Replacement of Atoh1 with Neurog1 maintains limited expression of Pou4f3 and Barhl1 and rescues HCs quantitatively, but not qualitatively. OC patterning and supporting cell differentiation are also partially disrupted. Diffusible factors involved in patterning are reduced (Fgf8) and factors involved in cell-cell interactions are affected (Jag1, Hes5). Despite the presence of many HCs with stereocilia these mice are deaf, possibly owing to HC and OC patterning defects. This study provides a novel approach to disrupt OC development through modulating the HC-specific intracellular TF network. The resulting disorganized OC indicates that normally differentiated HCs act as 'self-organizers' for OC development and that Atoh1 plays a crucial role to initiate HC stereocilia differentiation independently of HC viability.
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Affiliation(s)
- Israt Jahan
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Ning Pan
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Jennifer Kersigo
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Bernd Fritzsch
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
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47
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Andrade LR. Evidence for changes in beta- and gamma-actin proportions during inner ear hair cell life. Cytoskeleton (Hoboken) 2015; 72:282-91. [PMID: 26033950 DOI: 10.1002/cm.21227] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 05/11/2015] [Accepted: 05/21/2015] [Indexed: 12/18/2022]
Abstract
Cytoplasmic actin isoforms beta (β-) and gamma (γ-) perform crucial physiological roles in inner ear hair cells (HC). The stereocilium, which is structured by parallel actin filaments composed of both isoforms, is the responsive organelle to mechanical stimuli such as sound, gravity and head movements. Modifications in isoform proportions affect the function of the stereocilia as previously shown in genetic studies of mutant mice. Here, immunogold labeling TEM studies in mice showed that both β- and γ-actin isoforms colocalize throughout stereocilia actin filaments, adherens junctions and cuticular plates as early as embryonic stage 16.5. Gold-particle quantification indicated that there was 40% more γ- actin than β-actin at E16.5. In contrast, β- and γ-actin were equally concentrated in adult stereocilia of cochlear and vestibular HC. Interestingly, all actin-based structures presented almost five-fold more β-actin than γ-actin in 22 month- old mice, suggesting that γ-actin is probably under-expressed during the aging process. These data provide evidence of dynamic modifications of the actin isoforms in stereocilia, cuticular plates and cell junctions during the whole HC life.
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Affiliation(s)
- Leonardo R Andrade
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.,Laboratory of Biomineralization, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil
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48
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Pollock LM, McDermott BM. The cuticular plate: A riddle, wrapped in a mystery, inside a hair cell. ACTA ACUST UNITED AC 2015; 105:126-39. [DOI: 10.1002/bdrc.21098] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 05/31/2015] [Indexed: 01/11/2023]
Affiliation(s)
- Lana M. Pollock
- Department of Otolaryngology-Head and Neck Surgery; Case Western Reserve University; Cleveland Ohio
- Department of Genetics and Genome Sciences; Case Western Reserve University; Cleveland Ohio
| | - Brian M. McDermott
- Department of Otolaryngology-Head and Neck Surgery; Case Western Reserve University; Cleveland Ohio
- Department of Genetics and Genome Sciences; Case Western Reserve University; Cleveland Ohio
- Department of Biology; Case Western Reserve University; Cleveland Ohio
- Department of Neurosciences; Case Western Reserve University; Cleveland Ohio
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49
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Narayanan P, Chatterton P, Ikeda A, Ikeda S, Corey DP, Ervasti JM, Perrin BJ. Length regulation of mechanosensitive stereocilia depends on very slow actin dynamics and filament-severing proteins. Nat Commun 2015; 6:6855. [PMID: 25897778 PMCID: PMC4523390 DOI: 10.1038/ncomms7855] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 03/05/2015] [Indexed: 12/15/2022] Open
Abstract
Auditory sensory hair cells depend on stereocilia with precisely regulated lengths to detect sound. Since stereocilia are primarily composed of cross-linked, parallel actin filaments, regulated actin dynamics are essential for controlling stereocilia length. Here, we assessed stereocilia actin turnover by monitoring incorporation of inducibly expressed β-actin-GFP in adult mouse hair cells in vivo and by directly measuring β-actin-GFP turnover in explants. Stereocilia actin incorporation is remarkably slow and restricted to filament barbed ends in a small tip compartment, with minimal accumulation in the rest of the actin core. Shorter rows of stereocilia, which have mechanically-gated ion channels, show more variable actin turnover than the tallest stereocilia, which lack channels. Finally, the proteins ADF and AIP1, which both mediate actin filament severing, contribute to stereocilia length maintenance. Together, the data support a model whereby stereocilia actin cores are largely static, with dynamic regulation at the tips to maintain a critical length.
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Affiliation(s)
- Praveena Narayanan
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Paul Chatterton
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Akihiro Ikeda
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Sakae Ikeda
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - David P Corey
- Department of Neurobiology, Harvard Medical School and Howard Hughes Medical Institute, Boston, Massachusetts 02115, USA
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Benjamin J Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46022, USA
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50
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Drummond MC, Barzik M, Bird JE, Zhang DS, Lechene CP, Corey DP, Cunningham LL, Friedman TB. Live-cell imaging of actin dynamics reveals mechanisms of stereocilia length regulation in the inner ear. Nat Commun 2015; 6:6873. [PMID: 25898120 PMCID: PMC4411292 DOI: 10.1038/ncomms7873] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 03/06/2015] [Indexed: 02/05/2023] Open
Abstract
The maintenance of sensory hair cell stereocilia is critical for lifelong hearing; however, mechanisms of structural homeostasis remain poorly understood. Conflicting models propose that stereocilia F-actin cores are either continually renewed every 24-48 h via a treadmill or are stable, exceptionally long-lived structures. Here to distinguish between these models, we perform an unbiased survey of stereocilia actin dynamics in more than 500 utricle hair cells. Live-imaging EGFP-β-actin or dendra2-β-actin reveal stable F-actin cores with turnover and elongation restricted to stereocilia tips. Fixed-cell microscopy of wild-type and mutant β-actin demonstrates that incorporation of actin monomers into filaments is required for localization to stereocilia tips. Multi-isotope imaging mass spectrometry and live imaging of single differentiating hair cells capture stereociliogenesis and explain uniform incorporation of (15)N-labelled protein and EGFP-β-actin into nascent stereocilia. Collectively, our analyses support a model in which stereocilia actin cores are stable structures that incorporate new F-actin only at the distal tips.
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Affiliation(s)
- Meghan C Drummond
- Laboratory of Molecular Genetics, Section on Human Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Melanie Barzik
- Laboratory of Molecular Genetics, Section on Human Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jonathan E Bird
- Laboratory of Molecular Genetics, Section on Human Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Duan-Sun Zhang
- Department of Neurobiology, Harvard Medical School and Howard Hughes Medical Institute, Boston, Massachusetts 02115, USA
| | - Claude P Lechene
- 1] National Resource for Imaging Mass Spectrometry, Brigham and Women's Hospital and Harvard Medical School, Cambridge, Massachusetts 02139, USA [2] Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Cambridge, Massachusetts 02139, USA
| | - David P Corey
- Department of Neurobiology, Harvard Medical School and Howard Hughes Medical Institute, Boston, Massachusetts 02115, USA
| | - Lisa L Cunningham
- Section on Sensory Cell Biology, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, Section on Human Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
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