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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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Bordeynik-Cohen M, Sperber M, Ebbers L, Messika-Gold N, Krohs C, Koffler-Brill T, Noy Y, Elkon R, Nothwang HG, Avraham KB. Shared and organ-specific gene-expression programs during the development of the cochlea and the superior olivary complex. RNA Biol 2023; 20:629-640. [PMID: 37602850 PMCID: PMC10443965 DOI: 10.1080/15476286.2023.2247628] [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] [Revised: 08/07/2023] [Accepted: 08/09/2023] [Indexed: 08/22/2023] Open
Abstract
The peripheral and central auditory subsystems together form a complex sensory network that allows an organism to hear. The genetic programs of the two subsystems must therefore be tightly coordinated during development. Yet, their interactions and common expression pathways have never been systematically explored. MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression and are essential for normal development of the auditory system. We performed mRNA and small-RNA sequencing of organs from both auditory subsystems at three critical developmental timepoints (E16, P0, P16) to obtain a comprehensive and unbiased insight of their expression profiles. Our analysis reveals common and organ-specific expression patterns for differentially regulated mRNAs and miRNAs, which could be clustered with a particular selection of functions such as inner ear development, Wnt signalling, K+ transport, and axon guidance, based on gene ontology. Bioinformatics detected enrichment of predicted targets of specific miRNAs in the clusters and predicted regulatory interactions by monitoring opposite trends of expression of miRNAs and their targets. This approach identified six miRNAs as strong regulatory candidates for both subsystems. Among them was miR-96, an established critical factor for proper development in both subsystems, demonstrating the strength of our approach. We suggest that other miRNAs identified by this analysis are also common effectors of proper hearing acquirement. This first combined comprehensive analysis of the developmental program of the peripheral and central auditory systems provides important data and bioinformatics insights into the shared genetic program of the two sensory subsystems and their regulation by miRNAs.
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Affiliation(s)
- Mor Bordeynik-Cohen
- Laboratory of Neural and Sensory Genomics, Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Michal Sperber
- Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Lena Ebbers
- Neurogenetics group and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences and Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Naama Messika-Gold
- Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Constanze Krohs
- Neurogenetics group and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences and Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Tal Koffler-Brill
- Laboratory of Neural and Sensory Genomics, Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Yael Noy
- Laboratory of Neural and Sensory Genomics, Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Ran Elkon
- Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hans Gerd Nothwang
- Neurogenetics group and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences and Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Karen B. Avraham
- Laboratory of Neural and Sensory Genomics, Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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Oya R, Tsukamoto O, Sato T, Kato H, Matsuoka K, Oshima K, Kamakura T, Ohta Y, Imai T, Takashima S, Inohara H. Phosphorylation of MYL12 by Myosin Light Chain Kinase Regulates Cellular Shape Changes in Cochlear Hair Cells. J Assoc Res Otolaryngol 2021; 22:425-441. [PMID: 33877471 PMCID: PMC8329122 DOI: 10.1007/s10162-021-00796-1] [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: 12/31/2020] [Accepted: 03/11/2021] [Indexed: 10/21/2022] Open
Abstract
The organ of Corti is an auditory organ located in the cochlea, comprising hair cells (HCs) and other supporting cells. Cellular shape changes of HCs are important for the development of auditory epithelia and hearing function. It was previously observed that HCs and inner sulcus cells (ISCs) demonstrate cellular shape changes similar to the apical constriction of the neural epithelia. Apical constriction is induced via actomyosin cable contraction in the apical junctional complex and necessary for the physiological function of the epithelium. Actomyosin cable contraction is mainly regulated by myosin regulatory light chain (MRLC) phosphorylation by myosin light chain kinase (MLCK). However, MRLC and MLCK isoforms expressed in HCs and ISCs are unknown. Hence, we investigated the expression patterns and roles of MRLCs and MLCKs in HCs. Droplet digital PCR revealed that HCs expressed MYL12A/B and MYL9, which are non-muscle MRLC and smooth muscle MLCK (smMLCK), respectively. Immunofluorescence staining throughout the organ of Corti demonstrated that only MYL12 was expressed in the apical portion of HCs, whereas MYL12 and MYL9 were expressed on ISCs. In addition, purified MYL12B was phosphorylated by smMLCK in vitro, and the harvested HCs contained phosphorylated MYL12. Furthermore, accompanied by the expansion of the cell area of outer HCs, MYL12 phosphorylation was reduced by ML-7, which is an inhibitor of smMLCK. In conclusion, MYL12 phosphorylation by smMLCK contributed to the apical constriction-like cellular shape change of HCs possibly relating to the development of auditory epithelia and hearing function.
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Affiliation(s)
- Ryohei Oya
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Osamu Tsukamoto
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Takashi Sato
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hisakazu Kato
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Ken Matsuoka
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Kazuo Oshima
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Takefumi Kamakura
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Yumi Ohta
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Takao Imai
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Seiji Takashima
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Hidenori Inohara
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
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Guzmán-Herrera A, Mao Y. Polarity during tissue repair, a multiscale problem. Curr Opin Cell Biol 2020; 62:31-36. [PMID: 31514044 PMCID: PMC7036748 DOI: 10.1016/j.ceb.2019.07.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/18/2019] [Accepted: 07/23/2019] [Indexed: 12/12/2022]
Abstract
Tissue repair is essential for all organisms, as it protects the integrity and function of tissues and prevents infections and diseases. It takes place at multiple scales, from macroscopic to microscopic levels. Most mechanisms driving tissue repair rely on the correct polarisation of collective cell behaviours, such as migration and proliferation, and polarisation of cytoskeletal and junctional components. Furthermore, re-establishment and maintenance of cell polarity are fundamental for a tissue to be fully repaired and for withstanding mechanical stress during homeostasis and repair. Recent evidence highlights an important role for the interplay between cell polarity and tissue mechanics that are critical in tissue repair.
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Affiliation(s)
- Alejandra Guzmán-Herrera
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; Institute for the Physics of Living Systems, University College London, London, UK
| | - Yanlan Mao
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; Institute for the Physics of Living Systems, University College London, London, UK; College of Information and Control, Nanjing University of Information Science and Technology, Nanjing, Jiangsu 210044, People's Republic of China.
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Ueyama T. Rho-Family Small GTPases: From Highly Polarized Sensory Neurons to Cancer Cells. Cells 2019; 8:cells8020092. [PMID: 30696065 PMCID: PMC6406560 DOI: 10.3390/cells8020092] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 01/19/2019] [Accepted: 01/23/2019] [Indexed: 12/22/2022] Open
Abstract
The small GTPases of the Rho-family (Rho-family GTPases) have various physiological functions, including cytoskeletal regulation, cell polarity establishment, cell proliferation and motility, transcription, reactive oxygen species (ROS) production, and tumorigenesis. A relatively large number of downstream targets of Rho-family GTPases have been reported for in vitro studies. However, only a small number of signal pathways have been established at the in vivo level. Cumulative evidence for the functions of Rho-family GTPases has been reported for in vivo studies using genetically engineered mouse models. It was based on different cell- and tissue-specific conditional genes targeting mice. In this review, we introduce recent advances in in vivo studies, including human patient trials on Rho-family GTPases, focusing on highly polarized sensory organs, such as the cochlea, which is the primary hearing organ, host defenses involving reactive oxygen species (ROS) production, and tumorigenesis (especially associated with RAC, novel RAC1-GSPT1 signaling, RHOA, and RHOBTB2).
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Affiliation(s)
- Takehiko Ueyama
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
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