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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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Membrane prestin expression correlates with the magnitude of prestin-associated charge movement. Hear Res 2016; 339:50-9. [PMID: 27262187 DOI: 10.1016/j.heares.2016.05.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Revised: 05/14/2016] [Accepted: 05/26/2016] [Indexed: 11/20/2022]
Abstract
Full expression of electromotility, generation of non-linear capacitance (NLC), and high-acuity mammalian hearing require prestin function in the lateral wall of cochlear outer hair cells (OHCs). Estimates of the number of prestin molecules in the OHC membrane vary, and a consensus has not emerged about the correlation between prestin expression and prestin-associated charge movement in the OHC. Using an inducible prestin-expressing cell line, we demonstrate that the charge density, but not the voltage at peak capacitance, directly correlates with the amount of prestin in the plasma membrane. This correlation is evident in studies involving a controlled increase of prestin expression with time after induction and inducer dose-response. Conversely, membrane prestin levels and charge density gradually decline together following the reduction of prestin levels from a steady state by removal of the inducer. Thus, charge density directly correlates with the level of membrane prestin expression, whereas changing membrane levels of prestin have no effect on the voltage at peak capacitance in this inducible prestin-expressing cell line.
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Song Y, Xia A, Lee HY, Wang R, Ricci AJ, Oghalai JS. Activity-dependent regulation of prestin expression in mouse outer hair cells. J Neurophysiol 2015; 113:3531-42. [PMID: 25810486 DOI: 10.1152/jn.00869.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 03/19/2015] [Indexed: 12/11/2022] Open
Abstract
Prestin is a membrane protein necessary for outer hair cell (OHC) electromotility and normal hearing. Its regulatory mechanisms are unknown. Several mouse models of hearing loss demonstrate increased prestin, inspiring us to investigate how hearing loss might feedback onto OHCs. To test whether centrally mediated feedback regulates prestin, we developed a novel model of inner hair cell loss. Injection of diphtheria toxin (DT) into adult CBA mice produced significant loss of inner hair cells without affecting OHCs. Thus, DT-injected mice were deaf because they had no afferent auditory input despite OHCs continuing to receive normal auditory mechanical stimulation and having normal function. Patch-clamp experiments demonstrated no change in OHC prestin, indicating that loss of information transfer centrally did not alter prestin expression. To test whether local mechanical feedback regulates prestin, we used Tecta(C1509G) mice, where the tectorial membrane is malformed and only some OHCs are stimulated. OHCs connected to the tectorial membrane had normal prestin levels, whereas OHCs not connected to the tectorial membrane had elevated prestin levels, supporting an activity-dependent model. To test whether the endocochlear potential was necessary for prestin regulation, we studied Tecta(C1509G) mice at different developmental ages. OHCs not connected to the tectorial membrane had lower than normal prestin levels before the onset of the endocochlear potential and higher than normal prestin levels after the onset of the endocochlear potential. Taken together, these data indicate that OHC prestin levels are regulated through local feedback that requires mechanoelectrical transduction currents. This adaptation may serve to compensate for variations in the local mechanical environment.
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Affiliation(s)
- Yohan Song
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Hee Yoon Lee
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Rosalie Wang
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Anthony J Ricci
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - John S Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
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Gao SS, Wang R, Raphael PD, Moayedi Y, Groves AK, Zuo J, Applegate BE, Oghalai JS. Vibration of the organ of Corti within the cochlear apex in mice. J Neurophysiol 2014; 112:1192-204. [PMID: 24920025 DOI: 10.1152/jn.00306.2014] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The tonotopic map of the mammalian cochlea is commonly thought to be determined by the passive mechanical properties of the basilar membrane. The other tissues and cells that make up the organ of Corti also have passive mechanical properties; however, their roles are less well understood. In addition, active forces produced by outer hair cells (OHCs) enhance the vibration of the basilar membrane, termed cochlear amplification. Here, we studied how these biomechanical components interact using optical coherence tomography, which permits vibratory measurements within tissue. We measured not only classical basilar membrane tuning curves, but also vibratory responses from the rest of the organ of Corti within the mouse cochlear apex in vivo. As expected, basilar membrane tuning was sharp in live mice and broad in dead mice. Interestingly, the vibratory response of the region lateral to the OHCs, the "lateral compartment," demonstrated frequency-dependent phase differences relative to the basilar membrane. This was sharply tuned in both live and dead mice. We then measured basilar membrane and lateral compartment vibration in transgenic mice with targeted alterations in cochlear mechanics. Prestin(499/499), Prestin(-/-), and Tecta(C1509G/C1509G) mice demonstrated no cochlear amplification but maintained the lateral compartment phase difference. In contrast, Sfswap(Tg/Tg) mice maintained cochlear amplification but did not demonstrate the lateral compartment phase difference. These data indicate that the organ of Corti has complex micromechanical vibratory characteristics, with passive, yet sharply tuned, vibratory characteristics associated with the supporting cells. These characteristics may tune OHC force generation to produce the sharp frequency selectivity of mammalian hearing.
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Affiliation(s)
- Simon S Gao
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California; Department of Bioengineering, Rice University, Houston, Texas
| | - Rosalie Wang
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California
| | - Patrick D Raphael
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California
| | - Yalda Moayedi
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
| | - Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas; Program in Developmental Biology, Baylor College of Medicine, Houston, Texas
| | - Jian Zuo
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee; and
| | - Brian E Applegate
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas
| | - John S Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California;
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A synthetic prestin reveals protein domains and molecular operation of outer hair cell piezoelectricity. EMBO J 2011; 30:2793-804. [PMID: 21701557 DOI: 10.1038/emboj.2011.202] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 05/24/2011] [Indexed: 11/09/2022] Open
Abstract
Prestin, a transporter-like protein of the SLC26A family, acts as a piezoelectric transducer that mediates the fast electromotility of outer hair cells required for cochlear amplification and auditory acuity in mammals. Non-mammalian prestin orthologues are anion transporters without piezoelectric activity. Here, we generated synthetic prestin (SynPres), a chimera of mammalian and non-mammalian prestin exhibiting both, piezoelectric properties and anion transport. SynPres delineates two distinct domains in the protein's transmembrane core that are necessary and sufficient for generating electromotility and associated non-linear charge movement (NLC). Functional analysis of SynPres showed that the amplitude of NLC and hence electromotility are determined by the transport of monovalent anions. Thus, prestin-mediated electromotility is a dual-step process: transport of anions by an alternate access cycle, followed by an anion-dependent transition generating electromotility. The findings define structural and functional determinants of prestin's piezoelectric activity and indicate that the electromechanical process evolved from the ancestral transport mechanism.
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Xia A, Gao SS, Yuan T, Osborn A, Bress A, Pfister M, Maricich SM, Pereira FA, Oghalai JS. Deficient forward transduction and enhanced reverse transduction in the alpha tectorin C1509G human hearing loss mutation. Dis Model Mech 2010; 3:209-23. [PMID: 20142329 DOI: 10.1242/dmm.004135] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Most forms of hearing loss are associated with loss of cochlear outer hair cells (OHCs). OHCs require the tectorial membrane (TM) for stereociliary bundle stimulation (forward transduction) and active feedback (reverse transduction). Alpha tectorin is a protein constituent of the TM and the C1509G mutation in alpha tectorin in humans results in autosomal dominant hearing loss. We engineered and validated this mutation in mice and found that the TM was shortened in heterozygous Tecta(C1509G/+) mice, reaching only the first row of OHCs. Thus, deficient forward transduction renders OHCs within the second and third rows non-functional, producing partial hearing loss. Surprisingly, both Tecta(C1509G/+) and Tecta(C1509G/C1509G) mice were found to have increased reverse transduction as assessed by sound- and electrically-evoked otoacoustic emissions. We show that an increase in prestin, a protein necessary for electromotility, in all three rows of OHCs underlies this phenomenon. This mouse model demonstrates a human hearing loss mutation in which OHC function is altered through a non-cell-autonomous variation in prestin.
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Affiliation(s)
- Anping Xia
- The Bobby R. Alford Department of Otolaryngology - Head and Neck Surgery, Baylor College of Medicine, Houston, TX 77030, USA
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Gross J, Stute K, Moller R, Fuchs J, Amarjargal N, Pohl EE, Angerstein M, Smorodchenko A, Mazurek B. Expression of prestin and Gata-3,-2,-1 mRNA in the rat organ of Corti during the postnatal period and in culture. Hear Res 2009; 261:9-21. [PMID: 20006695 DOI: 10.1016/j.heares.2009.12.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 11/16/2009] [Accepted: 12/05/2009] [Indexed: 01/15/2023]
Abstract
Based on observations that mutations of GATA-3 are responsible for the HDR-syndrome (hypoparathyroidism, deafness, renal defects) and that GATA-transcription factors have an important role to play in inner ear development, we hypothesized that these transcription factors may be involved in regulatory changes of prestin transcription. To prove this, we examined in parallel the expression of mRNA of prestin and Gata-3,-2 and Gata-1 in the organ of Corti during early postnatal development of rats and in organotypic cultures. Remarkable relations are observed between prestin and Gata-3,-2 expression in organ of Corti preparations in vivo and in vitro: (i) Gata-3,-2 expression display similar apical-basal gradients as prestin mRNA levels. (ii) The prestin expression increases between postnatal day two and postnatal day eight by a factor of about four in the apical and middle segments and by a factor of two in the basal part. Highly significant Pearson correlation coefficients were observed between Gata-3,-2 mRNA and prestin levels when the data were evaluated by regression analyses. (iii) Parallel changes of prestin mRNA and Gata-3,-2 mRNA levels were observed in response to thyroid hormone and to gemfibrozil application. These observations suggest a regulatory role played by the Gata-3,-2 transcription factors in prestin expression.
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Affiliation(s)
- Johann Gross
- Molecular Biology Research Laboratory, Department of Otorhinolaryngology, Institute of Cell- and Neurobiology, Charité-Universitätsmedizin Berlin, 10117 Berlin, Charitéplatz 1, Germany.
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Rask-Andersen H, Liu W, Boström M, Pfaller K, Kinnefors A, Glueckert R, Schrott-Fischer A. Immunolocalization of prestin in the human cochlea. ACTA ACUST UNITED AC 2009. [DOI: 10.3109/16513860903320300] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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