1
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Conrad LJ, Grandi FC, Carlton AJ, Jeng JY, de Tomasi L, Zarecki P, Marcotti W, Johnson SL, Mustapha M. The upregulation of K + and HCN channels in developing spiral ganglion neurons is mediated by cochlear inner hair cells. J Physiol 2024. [PMID: 39324853 DOI: 10.1113/jp286134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 09/02/2024] [Indexed: 09/27/2024] Open
Abstract
Spiral ganglion neurons (SGNs) are primary sensory afferent neurons that relay acoustic information from the cochlear inner hair cells (IHCs) to the brainstem. The response properties of different SGNs diverge to represent a wide range of sound intensities in an action-potential code. This biophysical heterogeneity is established during pre-hearing stages of development, a time when IHCs fire spontaneous Ca2+ action potentials that drive glutamate release from their ribbon synapses onto the SGN terminals. The role of spontaneous IHC activity in the refinement of SGN characteristics is still largely unknown. Using pre-hearing otoferlin knockout mice (Otof-/-), in which Ca2+-dependent exocytosis in IHCs is abolished, we found that developing SGNs fail to upregulate low-voltage-activated K+-channels and hyperpolarisation-activated cyclic-nucleotide-gated channels. This delayed maturation resulted in hyperexcitable SGNs with immature firing characteristics. We have also shown that SGNs that synapse with the pillar side of the IHCs selectively express a resurgent K+ current, highlighting a novel biophysical marker for these neurons. RNA-sequencing showed that several K+ channels are downregulated in Otof-/- mice, further supporting the electrophysiological recordings. Our data demonstrate that spontaneous Ca2+-dependent activity in pre-hearing IHCs regulates some of the key biophysical and molecular features of the developing SGNs. KEY POINTS: Ca2+-dependent exocytosis in inner hair cells (IHCs) is otoferlin-dependent as early as postnatal day 1. A lack of otoferlin in IHCs affects potassium channel expression in SGNs. The absence of otoferlin is associated with SGN hyperexcitability. We propose that type I spiral ganglion neuron functional maturation depends on IHC exocytosis.
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Affiliation(s)
- Linus J Conrad
- School of Biosciences, University of Sheffield, Sheffield, UK
| | - Fiorella C Grandi
- INSERM, Institute de Myologie, Centre de Recherche en Myologie F-75013, Sorbonne Université, Paris, France
| | - Adam J Carlton
- School of Biosciences, University of Sheffield, Sheffield, UK
| | - Jing-Yi Jeng
- School of Biosciences, University of Sheffield, Sheffield, UK
| | - Lara de Tomasi
- School of Biosciences, University of Sheffield, Sheffield, UK
| | - Patryk Zarecki
- School of Biosciences, University of Sheffield, Sheffield, UK
| | - Walter Marcotti
- School of Biosciences, University of Sheffield, Sheffield, UK
- Neuroscience Institute, University of Sheffield, Sheffield, UK
| | - Stuart L Johnson
- School of Biosciences, University of Sheffield, Sheffield, UK
- Neuroscience Institute, University of Sheffield, Sheffield, UK
| | - Mirna Mustapha
- School of Biosciences, University of Sheffield, Sheffield, UK
- Neuroscience Institute, University of Sheffield, Sheffield, UK
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2
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Vincent PFY, Young ED, Edge ASB, Glowatzki E. Auditory hair cells and spiral ganglion neurons regenerate synapses with refined release properties in vitro. Proc Natl Acad Sci U S A 2024; 121:e2315599121. [PMID: 39058581 PMCID: PMC11294990 DOI: 10.1073/pnas.2315599121] [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: 09/10/2023] [Accepted: 06/12/2024] [Indexed: 07/28/2024] Open
Abstract
Ribbon synapses between inner hair cells (IHCs) and type I spiral ganglion neurons (SGNs) in the inner ear are damaged by noise trauma and with aging, causing "synaptopathy" and hearing loss. Cocultures of neonatal denervated organs of Corti and newly introduced SGNs have been developed to find strategies for improving IHC synapse regeneration, but evidence of the physiological normality of regenerated synapses is missing. This study utilizes IHC optogenetic stimulation and SGN recordings, showing that, when P3-5 denervated organs of Corti are cocultured with SGNs, newly formed IHC/SGN synapses are indeed functional, exhibiting glutamatergic excitatory postsynaptic currents. When using older organs of Corti at P10-11, synaptic activity probed by deconvolution showed more mature release properties, closer to the specialized mode of IHC synaptic transmission crucial for coding the sound signal. This functional assessment of newly formed IHC synapses developed here, provides a powerful tool for testing approaches to improve synapse regeneration.
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Affiliation(s)
- Philippe F. Y. Vincent
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD21205
| | - Eric D. Young
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, MD21205
| | - Albert S. B. Edge
- Department of Otolaryngology, Harvard Medical School, Boston, MA02115
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear, Boston, MA02114
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, MA02115
- Harvard Stem Cell Institute, Cambridge, MA02139
| | - Elisabeth Glowatzki
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD21205
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3
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Aguilar C, Williams D, Kurapati R, Bains RS, Mburu P, Parker A, Williams J, Concas D, Tateossian H, Haynes AR, Banks G, Vikhe P, Heise I, Hutchison M, Atkins G, Gillard S, Starbuck B, Oliveri S, Blake A, Sethi S, Kumar S, Bardhan T, Jeng JY, Johnson SL, Corns LF, Marcotti W, Simon M, Wells S, Potter PK, Lad HV. Pleiotropic brain function of whirlin identified by a novel mutation. iScience 2024; 27:110170. [PMID: 38974964 PMCID: PMC11225360 DOI: 10.1016/j.isci.2024.110170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/26/2024] [Accepted: 05/31/2024] [Indexed: 07/09/2024] Open
Abstract
Despite some evidence indicating diverse roles of whirlin in neurons, the functional corollary of whirlin gene function and behavior has not been investigated or broadly characterized. A single nucleotide variant was identified from our recessive ENU-mutagenesis screen at a donor-splice site in whirlin, a protein critical for proper sensorineural hearing function. The mutation (head-bob, hb) led to partial intron-retention causing a frameshift and introducing a premature termination codon. Mutant mice had a head-bobbing phenotype and significant hyperactivity across several phenotyping tests. Lack of complementation of head-bob with whirler mutant mice confirmed the head-bob mutation as functionally distinct with compound mutants having a mild-moderate hearing defect. Utilizing transgenics, we demonstrate rescue of the hyperactive phenotype and combined with the expression profiling data conclude whirlin plays an essential role in activity-related behaviors. These results highlight a pleiotropic role of whirlin within the brain and implicate alternative, central mediated pathways in its function.
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Affiliation(s)
- Carlos Aguilar
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Debbie Williams
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
- Mary Lyon Centre at MRC Harwell, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Ramakrishna Kurapati
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Rasneer S. Bains
- Mary Lyon Centre at MRC Harwell, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Philomena Mburu
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Andy Parker
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Jackie Williams
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Danilo Concas
- Mary Lyon Centre at MRC Harwell, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Hilda Tateossian
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Andrew R. Haynes
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Gareth Banks
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Pratik Vikhe
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Ines Heise
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Marie Hutchison
- Mary Lyon Centre at MRC Harwell, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Gemma Atkins
- Mary Lyon Centre at MRC Harwell, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Simon Gillard
- Mary Lyon Centre at MRC Harwell, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Becky Starbuck
- Mary Lyon Centre at MRC Harwell, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Simona Oliveri
- Mary Lyon Centre at MRC Harwell, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Andrew Blake
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Siddharth Sethi
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Saumya Kumar
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Tanaya Bardhan
- School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK
| | - Jing-Yi Jeng
- School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK
| | - Stuart L. Johnson
- School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK
| | - Lara F. Corns
- School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK
| | - Walter Marcotti
- School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK
- Neuroscience Institute, University of Sheffield, Sheffield, South Yorkshire S10 2TN, UK
| | - Michelle Simon
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Sara Wells
- Mary Lyon Centre at MRC Harwell, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Paul K. Potter
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
| | - Heena V. Lad
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Didcot, Oxfordshire OX11 0RD, UK
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Kersbergen CJ, Bergles DE. Priming central sound processing circuits through induction of spontaneous activity in the cochlea before hearing onset. Trends Neurosci 2024; 47:522-537. [PMID: 38782701 PMCID: PMC11236524 DOI: 10.1016/j.tins.2024.04.007] [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: 12/22/2023] [Revised: 04/02/2024] [Accepted: 04/26/2024] [Indexed: 05/25/2024]
Abstract
Sensory systems experience a period of intrinsically generated neural activity before maturation is complete and sensory transduction occurs. Here we review evidence describing the mechanisms and functions of this 'spontaneous' activity in the auditory system. Both ex vivo and in vivo studies indicate that this correlated activity is initiated by non-sensory supporting cells within the developing cochlea, which induce depolarization and burst firing of groups of nearby hair cells in the sensory epithelium, activity that is conveyed to auditory neurons that will later process similar sound features. This stereotyped neural burst firing promotes cellular maturation, synaptic refinement, acoustic sensitivity, and establishment of sound-responsive domains in the brain. While sensitive to perturbation, the developing auditory system exhibits remarkable homeostatic mechanisms to preserve periodic burst firing in deaf mice. Preservation of this early spontaneous activity in the context of deafness may enhance the efficacy of later interventions to restore hearing.
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Affiliation(s)
- Calvin J Kersbergen
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | - Dwight E Bergles
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA; Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA; Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, USA.
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5
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Echeverría F, Gonzalez-Sanabria N, Alvarado-Sanchez R, Fernández M, Castillo K, Latorre R. Large conductance voltage-and calcium-activated K + (BK) channel in health and disease. Front Pharmacol 2024; 15:1373507. [PMID: 38584598 PMCID: PMC10995336 DOI: 10.3389/fphar.2024.1373507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 03/12/2024] [Indexed: 04/09/2024] Open
Abstract
Large Conductance Voltage- and Calcium-activated K+ (BK) channels are transmembrane pore-forming proteins that regulate cell excitability and are also expressed in non-excitable cells. They play a role in regulating vascular tone, neuronal excitability, neurotransmitter release, and muscle contraction. Dysfunction of the BK channel can lead to arterial hypertension, hearing disorders, epilepsy, and ataxia. Here, we provide an overview of BK channel functioning and the implications of its abnormal functioning in various diseases. Understanding the function of BK channels is crucial for comprehending the mechanisms involved in regulating vital physiological processes, both in normal and pathological conditions, controlled by BK. This understanding may lead to the development of therapeutic interventions to address BK channelopathies.
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Affiliation(s)
- Felipe Echeverría
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Naileth Gonzalez-Sanabria
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Rosangelina Alvarado-Sanchez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Miguel Fernández
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Karen Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
- Centro de Investigación de Estudios Avanzados del Maule, Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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6
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Hakizimana P. The summating potential polarity encodes the ear health condition. Cell Mol Life Sci 2023; 80:163. [PMID: 37225973 DOI: 10.1007/s00018-023-04809-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 05/10/2023] [Accepted: 05/14/2023] [Indexed: 05/26/2023]
Abstract
The summating potential (SP), the DC potential which, along with the AC response, is produced when the hair cells convert the vibrational mechanical energy of sound into electrical signals, is the most enigmatic of the cochlear potentials because its polarity and function have remained elusive for more than seven decades. Despite the tremendous socioeconomic consequences of noise-induced hearing loss and the profound physiological importance of understanding how loud noise exposure impairs the hair cell receptor activation, the relationship between the SP and noise-induced hearing impairment remains poorly characterized. Here, I show that in normally hearing ears, the SP polarity is positive and its amplitude relative to the AC response grows exponentially across frequencies, and becomes negative and decreases exponentially across frequencies following noise-induced hearing injury. Since the SP is thought to be generated by K+ outflow down the gradient through the hair cell basolateral K+ channels, the SP polarity switch to negative values is consistent with a noise-induced shift in the operating point of the hair cells.
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Affiliation(s)
- Pierre Hakizimana
- Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83, Linköping, Sweden.
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7
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Baeza-Loya S, Raible DW. Vestibular physiology and function in zebrafish. Front Cell Dev Biol 2023; 11:1172933. [PMID: 37143895 PMCID: PMC10151581 DOI: 10.3389/fcell.2023.1172933] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 04/06/2023] [Indexed: 05/06/2023] Open
Abstract
The vestibular system of the inner ear provides information about head motion and spatial orientation relative to gravity to ensure gaze stability, balance, and postural control. Zebrafish, like humans, have five sensory patches per ear that serve as peripheral vestibular organs, with the addition of the lagena and macula neglecta. The zebrafish inner ear can be easily studied due to its accessible location, the transparent tissue of larval fish, and the early development of vestibular behaviors. Thus, zebrafish are an excellent model for studying the development, physiology, and function of the vestibular system. Recent work has made great strides to elucidate vestibular neural circuitry in fish, tracing sensory transmission from receptors in the periphery to central computational circuits driving vestibular reflexes. Here we highlight recent work that illuminates the functional organization of vestibular sensory epithelia, innervating first-order afferent neurons, and second-order neuronal targets in the hindbrain. Using a combination of genetic, anatomical, electrophysiological, and optical techniques, these studies have probed the roles of vestibular sensory signals in fish gaze, postural, and swimming behaviors. We discuss remaining questions in vestibular development and organization that are tractable in the zebrafish model.
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Affiliation(s)
| | - David W. Raible
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-HNS and Biological Structure, University of Washington, Seattle, WA, United States
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Nuclear Translocation Triggered at the Onset of Hearing in Cochlear Inner Hair Cells of Rats and Mice. J Assoc Res Otolaryngol 2023:10.1007/s10162-023-00894-2. [PMID: 36932316 DOI: 10.1007/s10162-023-00894-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 02/21/2023] [Indexed: 03/19/2023] Open
Abstract
PURPOSE Nuclear position is precisely orchestrated during cell division, migration, and maturation of cells and tissues. Here we report a previously unrecognized, programmed movement of the nucleus in rat and mouse cochlear inner hair cells (IHCs) coinciding with the functional maturation of inner hair cells around the onset of hearing. METHODS We measured hair cell length and nuclear position from confocal scans of immunofluorescence-labeled hair cells from whole-mount cochlear preparations throughout post-natal development. RESULTS In early post-natal days, the IHC experiences a period of sustained growth, during which the nucleus sits at the very basal pole of the cell, far from the apically located mechano-transducing stereocilia, but close to where synapses with primary afferent and efferent neurons are forming. After IHCs reach their final length, the nucleus moves to occupy a new position half-way along the length of the cell. Nuclear translocation begins in the middle turn, completes throughout the cochlea within 2-3 days, and coincides with the emergence of endolymphatic potential, the acquisition of big-conductance potassium channels (BK), and the onset of acoustic hearing. IHCs cultured in-vitro without endolymphatic potential (EP) do not grow, do not express BK, and do not experience nuclear movement. IHCs cultured in high K+ solutions (to simulate EP) grow but do not experience nuclear movement or acquire BK channels. CONCLUSION Nuclear migration at the onset of hearing is a key step in the morphological maturation of IHCs. Whether this plays a role in functional maturation remains to be explored.
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Kaiser M, Lüdtke TH, Deuper L, Rudat C, Christoffels VM, Kispert A, Trowe MO. TBX2 specifies and maintains inner hair and supporting cell fate in the Organ of Corti. Nat Commun 2022; 13:7628. [PMID: 36494345 PMCID: PMC9734556 DOI: 10.1038/s41467-022-35214-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 11/21/2022] [Indexed: 12/13/2022] Open
Abstract
The auditory function of the mammalian cochlea relies on two types of mechanosensory hair cells and various non-sensory supporting cells. Recent studies identified the transcription factors INSM1 and IKZF2 as regulators of outer hair cell (OHC) fate. However, the transcriptional regulation of the differentiation of inner hair cells (IHCs) and their associated inner supporting cells (ISCs) has remained enigmatic. Here, we show that the expression of the transcription factor TBX2 is restricted to IHCs and ISCs from the onset of differentiation until adulthood and examine its function using conditional deletion and misexpression approaches in the mouse. We demonstrate that TBX2 acts in prosensory progenitors as a patterning factor by specifying the inner compartment of the sensory epithelium that subsequently gives rise to IHCs and ISCs. Hair cell-specific inactivation or misexpression causes transdifferentiation of hair cells indicating a cell-autonomous function of TBX2 in inducing and maintaining IHC fate.
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Affiliation(s)
- Marina Kaiser
- grid.10423.340000 0000 9529 9877Institute of Molecular Biology, Hannover Medical School, Hannover, Germany
| | - Timo H. Lüdtke
- grid.10423.340000 0000 9529 9877Institute of Molecular Biology, Hannover Medical School, Hannover, Germany
| | - Lena Deuper
- grid.10423.340000 0000 9529 9877Institute of Molecular Biology, Hannover Medical School, Hannover, Germany
| | - Carsten Rudat
- grid.10423.340000 0000 9529 9877Institute of Molecular Biology, Hannover Medical School, Hannover, Germany
| | - Vincent M. Christoffels
- grid.509540.d0000 0004 6880 3010Medical Biology, Amsterdam Reproduction & Development, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Andreas Kispert
- grid.10423.340000 0000 9529 9877Institute of Molecular Biology, Hannover Medical School, Hannover, Germany
| | - Mark-Oliver Trowe
- grid.10423.340000 0000 9529 9877Institute of Molecular Biology, Hannover Medical School, Hannover, Germany
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Emerging mechanisms involving brain Kv7 channel in the pathogenesis of hypertension. Biochem Pharmacol 2022; 206:115318. [PMID: 36283445 DOI: 10.1016/j.bcp.2022.115318] [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: 08/24/2022] [Revised: 10/15/2022] [Accepted: 10/17/2022] [Indexed: 12/14/2022]
Abstract
Hypertension is a prevalent health problem inducing many organ damages. The pathogenesis of hypertension involves a complex integration of different organ systems including the brain. The elevated sympathetic nerve activity is closely related to the etiology of hypertension. Ion channels are critical regulators of neuronal excitability. Several mechanisms have been proposed to contribute to hypothalamic-driven elevated sympathetic activity, including altered ion channel function. Recent findings indicate one of the voltage-gated potassium channels, Kv7 channels (M channels), plays a vital role in regulating cardiovascular-related neurons activity, and the expression of Kv7 channels is downregulated in hypertension. This review highlights recent findings that the Kv7 channels in the brain, blood vessels, and kidneys are emerging targets involved in the pathogenesis of hypertension, suggesting new therapeutic targets for treating drug-resistant, neurogenic hypertension.
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11
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Jeng JY, Carlton AJ, Goodyear RJ, Chinowsky C, Ceriani F, Johnson SL, Sung TC, Dayn Y, Richardson GP, Bowl MR, Brown SD, Manor U, Marcotti W. AAV-mediated rescue of Eps8 expression in vivo restores hair-cell function in a mouse model of recessive deafness. Mol Ther Methods Clin Dev 2022; 26:355-370. [PMID: 36034774 PMCID: PMC9382420 DOI: 10.1016/j.omtm.2022.07.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 07/15/2022] [Indexed: 11/24/2022]
Abstract
The transduction of acoustic information by hair cells depends upon mechanosensitive stereociliary bundles that project from their apical surface. Mutations or absence of the stereociliary protein EPS8 cause deafness in humans and mice, respectively. Eps8 knockout mice (Eps8 -/- ) have hair cells with immature stereocilia and fail to become sensory receptors. Here, we show that exogenous delivery of Eps8 using Anc80L65 in P1-P2 Eps8 -/- mice in vivo rescued the hair bundle structure of apical-coil hair cells. Rescued hair bundles correctly localize EPS8, WHIRLIN, MYO15, and BAIAP2L2, and generate normal mechanoelectrical transducer currents. Inner hair cells with normal-looking stereocilia re-expressed adult-like basolateral ion channels (BK and KCNQ4) and have normal exocytosis. The number of hair cells undergoing full recovery was not sufficient to rescue hearing in Eps8 -/- mice. Adeno-associated virus (AAV)-transduction of P3 apical-coil and P1-P2 basal-coil hair cells does not rescue hair cells, nor does Anc80L65-Eps8 delivery in adult Eps8 -/- mice. We propose that AAV-induced gene-base therapy is an efficient strategy to recover the complex hair-cell defects in Eps8 -/- mice. However, this therapeutic approach may need to be performed in utero since, at postnatal ages, Eps8 -/- hair cells appear to have matured or accumulated damage beyond the point of repair.
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Affiliation(s)
- Jing-Yi Jeng
- School of Bioscience, University of Sheffield, Sheffield S10 2TN, UK
| | - Adam J. Carlton
- School of Bioscience, University of Sheffield, Sheffield S10 2TN, UK
| | - Richard J. Goodyear
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Colbie Chinowsky
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Federico Ceriani
- School of Bioscience, University of Sheffield, Sheffield S10 2TN, UK
| | - Stuart L. Johnson
- School of Bioscience, University of Sheffield, Sheffield S10 2TN, UK
- Neuroscience Institute, University of Sheffield, Sheffield S10 2TN, UK
| | - Tsung-Chang Sung
- Transgenic Core, Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Yelena Dayn
- Transgenic Core, Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Guy P. Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Michael R. Bowl
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD UK
| | - Steve D.M. Brown
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD UK
| | - Uri Manor
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Walter Marcotti
- School of Bioscience, University of Sheffield, Sheffield S10 2TN, UK
- Neuroscience Institute, University of Sheffield, Sheffield S10 2TN, UK
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12
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Routier L, Mahmoudzadeh M, Panzani M, Saadatmehr B, Gondry J, Bourel-Ponchel E, Moghimi S, Wallois F. The frontal sharp transient in newborns: An endogenous neurobiomarker concomitant to the physiological and critical transitional period around delivery? Cereb Cortex 2022; 33:4026-4039. [PMID: 36066405 PMCID: PMC10068298 DOI: 10.1093/cercor/bhac324] [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: 04/06/2022] [Revised: 07/21/2022] [Accepted: 07/22/2022] [Indexed: 11/13/2022] Open
Abstract
The frontal sharp transient (FST) consists of transient electrical activity recorded around the transitional period from the in to ex utero environment. Although its positive predictive value is assumed, nothing is known about its functionality or origin. The objectives were (i) to define its characteristics and (ii) to develop functional hypothesis. The 128-channels high-resolution electroencephalograms of 20 healthy newborns (37.1-41.6 weeks) were studied. The morphological and time-frequency characteristics of 418 FSTs were analyzed. The source localization of the FSTs was obtained using a finite element head model (5 layers and fontanels) and various source localization methods (distributed and dipolar). The characteristics (duration, slopes, and amplitude) and the localization of FSTs were not modulated by the huge developmental neuronal processes that occur during the very last period of gestation. The sources were located beneath the ventral median part of the frontal lobe around the interhemispheric fissure, suggesting that the olfactory bulbs and orbitofrontal cortex, essential in olfaction and the mother-infant attachment relationship, are likely candidates for the generation of FSTs. FSTs may contribute to the implementation of the functionalities of brain structures involved in the higher-order processing necessary for survival ahead of delivery, with a genetic fingerprint.
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Affiliation(s)
- Laura Routier
- GRAMFC, INSERM UMR-S 1105, CURS, University of Picardie Jules Verne, rue René Laennec, 80054 Amiens, Cedex 1, France.,Pediatric Clinical Neurophysiology Department, Amiens-Picardie University Hospital, 1 rond-point du Professeur Christian Cabrol, 80054 Amiens, France
| | - Mahdi Mahmoudzadeh
- GRAMFC, INSERM UMR-S 1105, CURS, University of Picardie Jules Verne, rue René Laennec, 80054 Amiens, Cedex 1, France
| | - Marine Panzani
- GRAMFC, INSERM UMR-S 1105, CURS, University of Picardie Jules Verne, rue René Laennec, 80054 Amiens, Cedex 1, France
| | - Bahar Saadatmehr
- GRAMFC, INSERM UMR-S 1105, CURS, University of Picardie Jules Verne, rue René Laennec, 80054 Amiens, Cedex 1, France
| | - Jean Gondry
- GRAMFC, INSERM UMR-S 1105, CURS, University of Picardie Jules Verne, rue René Laennec, 80054 Amiens, Cedex 1, France.,Maternity Department, Amiens-Picardie University Hospital, 1 rond-point du Professeur Christian Cabrol, 80054 Amiens, France
| | - Emilie Bourel-Ponchel
- GRAMFC, INSERM UMR-S 1105, CURS, University of Picardie Jules Verne, rue René Laennec, 80054 Amiens, Cedex 1, France.,Pediatric Clinical Neurophysiology Department, Amiens-Picardie University Hospital, 1 rond-point du Professeur Christian Cabrol, 80054 Amiens, France
| | - Sahar Moghimi
- GRAMFC, INSERM UMR-S 1105, CURS, University of Picardie Jules Verne, rue René Laennec, 80054 Amiens, Cedex 1, France
| | - Fabrice Wallois
- GRAMFC, INSERM UMR-S 1105, CURS, University of Picardie Jules Verne, rue René Laennec, 80054 Amiens, Cedex 1, France.,Pediatric Clinical Neurophysiology Department, Amiens-Picardie University Hospital, 1 rond-point du Professeur Christian Cabrol, 80054 Amiens, France
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13
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Bellairs JA, Redila VA, Wu P, Tong L, Webster A, Simon JA, Rubel EW, Raible DW. An in vivo Biomarker to Characterize Ototoxic Compounds and Novel Protective Therapeutics. Front Mol Neurosci 2022; 15:944846. [PMID: 35923755 PMCID: PMC9342690 DOI: 10.3389/fnmol.2022.944846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 06/21/2022] [Indexed: 11/18/2022] Open
Abstract
There are no approved therapeutics for the prevention of hearing loss and vestibular dysfunction from drugs like aminoglycoside antibiotics. While the mechanisms underlying aminoglycoside ototoxicity remain unresolved, there is considerable evidence that aminoglycosides enter inner ear mechanosensory hair cells through the mechanoelectrical transduction (MET) channel. Inhibition of MET-dependent uptake with small molecules or modified aminoglycosides is a promising otoprotective strategy. To better characterize mammalian ototoxicity and aid in the translation of emerging therapeutics, a biomarker is needed. In the present study we propose that neonatal mice systemically injected with the aminoglycosides G418 conjugated to Texas Red (G418-TR) can be used as a histologic biomarker to characterize in vivo aminoglycoside toxicity. We demonstrate that postnatal day 5 mice, like older mice with functional hearing, show uptake and retention of G418-TR in cochlear hair cells following systemic injection. When we compare G418-TR uptake in other tissues, we find that kidney proximal tubule cells show similar retention. Using ORC-13661, an investigational hearing protection drug, we demonstrate in vivo inhibition of aminoglycoside uptake in mammalian hair cells. This work establishes how systemically administered fluorescently labeled ototoxins in the neonatal mouse can reveal important details about ototoxic drugs and protective therapeutics.
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Affiliation(s)
- Joseph A. Bellairs
- Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA, United States
| | - Van A. Redila
- Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA, United States
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA, United States
| | - Patricia Wu
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA, United States
- Department of Biological Structure, University of Washington, Seattle, WA, United States
| | - Ling Tong
- Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA, United States
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA, United States
| | - Alyssa Webster
- Fred Hutchinson Cancer Research Center, Seattle, WA, United States
| | - Julian A. Simon
- Fred Hutchinson Cancer Research Center, Seattle, WA, United States
| | - Edwin W. Rubel
- Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA, United States
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA, United States
| | - David W. Raible
- Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA, United States
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA, United States
- Department of Biological Structure, University of Washington, Seattle, WA, United States
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14
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Levic S. SK Current, Expressed During the Development and Regeneration of Chick Hair Cells, Contributes to the Patterning of Spontaneous Action Potentials. Front Cell Neurosci 2022; 15:766264. [PMID: 35069114 PMCID: PMC8770932 DOI: 10.3389/fncel.2021.766264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 11/29/2021] [Indexed: 11/30/2022] Open
Abstract
Chick hair cells display calcium (Ca2+)-sensitive spontaneous action potentials during development and regeneration. The role of this activity is unclear but thought to be involved in establishing proper synaptic connections and tonotopic maps, both of which are instrumental to normal hearing. Using an electrophysiological approach, this work investigated the functional expression of Ca2+-sensitive potassium [IK(Ca)] currents and their role in spontaneous electrical activity in the developing and regenerating hair cells (HCs) in the chick basilar papilla. The main IK(Ca) in developing and regenerating chick HCs is an SK current, based on its sensitivity to apamin. Analysis of the functional expression of SK current showed that most dramatic changes occurred between E8 and E16. Specifically, there is a developmental downregulation of the SK current after E16. The SK current gating was very sensitive to the availability of intracellular Ca2+ but showed very little sensitivity to T-type voltage-gated Ca2+ channels, which are one of the hallmarks of developing and regenerating hair cells. Additionally, apamin reduced the frequency of spontaneous electrical activity in HCs, suggesting that SK current participates in patterning the spontaneous electrical activity of HCs.
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Affiliation(s)
- Snezana Levic
- Center for Neuroscience, University of California, Davis, Davis, CA, United States
- Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
- Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
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15
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Newton S, Kong F, Carlton AJ, Aguilar C, Parker A, Codner GF, Teboul L, Wells S, Brown SDM, Marcotti W, Bowl MR. Neuroplastin genetically interacts with Cadherin 23 and the encoded isoform Np55 is sufficient for cochlear hair cell function and hearing. PLoS Genet 2022; 18:e1009937. [PMID: 35100259 PMCID: PMC8830789 DOI: 10.1371/journal.pgen.1009937] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/10/2022] [Accepted: 01/13/2022] [Indexed: 11/25/2022] Open
Abstract
Mammalian hearing involves the mechanoelectrical transduction (MET) of sound-induced fluid waves in the cochlea. Essential to this process are the specialised sensory cochlear cells, the inner (IHCs) and outer hair cells (OHCs). While genetic hearing loss is highly heterogeneous, understanding the requirement of each gene will lead to a better understanding of the molecular basis of hearing and also to therapeutic opportunities for deafness. The Neuroplastin (Nptn) gene, which encodes two protein isoforms Np55 and Np65, is required for hearing, and homozygous loss-of-function mutations that affect both isoforms lead to profound deafness in mice. Here we have utilised several distinct mouse models to elaborate upon the spatial, temporal, and functional requirement of Nptn for hearing. While we demonstrate that both Np55 and Np65 are present in cochlear cells, characterisation of a Np65-specific mouse knockout shows normal hearing thresholds indicating that Np65 is functionally redundant for hearing. In contrast, we find that Nptn-knockout mice have significantly reduced maximal MET currents and MET channel open probabilities in mature OHCs, with both OHCs and IHCs also failing to develop fully mature basolateral currents. Furthermore, comparing the hearing thresholds and IHC synapse structure of Nptn-knockout mice with those of mice that lack Nptn only in IHCs and OHCs shows that the majority of the auditory deficit is explained by hair cell dysfunction, with abnormal afferent synapses contributing only a small proportion of the hearing loss. Finally, we show that continued expression of Neuroplastin in OHCs of adult mice is required for membrane localisation of Plasma Membrane Ca2+ ATPase 2 (PMCA2), which is essential for hearing function. Moreover, Nptn haploinsufficiency phenocopies Atp2b2 (encodes PMCA2) mutations, with heterozygous Nptn-knockout mice exhibiting hearing loss through genetic interaction with the Cdh23ahl allele. Together, our findings provide further insight to the functional requirement of Neuroplastin for mammalian hearing.
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Affiliation(s)
- Sherylanne Newton
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, United Kingdom
| | - Fanbo Kong
- School of Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Adam J. Carlton
- School of Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Carlos Aguilar
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, United Kingdom
| | - Andrew Parker
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, United Kingdom
| | - Gemma F. Codner
- Mary Lyon Centre, MRC Harwell Institute, Harwell Oxford, United Kingdom
| | - Lydia Teboul
- Mary Lyon Centre, MRC Harwell Institute, Harwell Oxford, United Kingdom
| | - Sara Wells
- Mary Lyon Centre, MRC Harwell Institute, Harwell Oxford, United Kingdom
| | - Steve D. M. Brown
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, United Kingdom
| | - Walter Marcotti
- School of Sciences, University of Sheffield, Sheffield, United Kingdom
- Sheffield Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Michael R. Bowl
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, United Kingdom
- UCL Ear Institute, University College London, London, United Kingdom
- * E-mail:
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16
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Manca M, Yen P, Spaiardi P, Russo G, Giunta R, Johnson SL, Marcotti W, Masetto S. Current Response in Ca V 1.3 -/- Mouse Vestibular and Cochlear Hair Cells. Front Neurosci 2021; 15:749483. [PMID: 34955713 PMCID: PMC8694397 DOI: 10.3389/fnins.2021.749483] [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: 07/29/2021] [Accepted: 11/01/2021] [Indexed: 11/24/2022] Open
Abstract
Signal transmission by sensory auditory and vestibular hair cells relies upon Ca2+-dependent exocytosis of glutamate. The Ca2+ current in mammalian inner ear hair cells is predominantly carried through CaV1.3 voltage-gated Ca2+ channels. Despite this, CaV1.3 deficient mice (CaV1.3–/–) are deaf but do not show any obvious vestibular phenotype. Here, we compared the Ca2+ current (ICa) in auditory and vestibular hair cells from wild-type and CaV1.3–/– mice, to assess whether differences in the size of the residual ICa could explain, at least in part, the two phenotypes. Using 5 mM extracellular Ca2+ and near-body temperature conditions, we investigated the cochlear primary sensory receptors inner hair cells (IHCs) and both type I and type II hair cells of the semicircular canals. We found that the residual ICa in both auditory and vestibular hair cells from CaV1.3–/– mice was less than 20% (12–19%, depending on the hair cell type and age investigated) compared to controls, indicating a comparable expression of CaV1.3 Ca2+ channels in both sensory organs. We also showed that, different from IHCs, type I and type II hair cells from CaV1.3–/– mice were able to acquire the adult-like K+ current profile in their basolateral membrane. Intercellular K+ accumulation was still present in CaV1.3–/– mice during IK,L activation, suggesting that the K+-based, non-exocytotic, afferent transmission is still functional in these mice. This non-vesicular mechanism might contribute to the apparent normal vestibular functions in CaV1.3–/– mice.
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Affiliation(s)
- Marco Manca
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.,School of Biosciences, University of Sheffield, Sheffield, United Kingdom
| | - Piece Yen
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
| | - Paolo Spaiardi
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Giancarlo Russo
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Roberta Giunta
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Stuart L Johnson
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom.,Sheffield Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Walter Marcotti
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom.,Sheffield Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Sergio Masetto
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
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17
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Parra-Munevar J, Morse CE, Plummer MR, Davis RL. Dynamic Heterogeneity Shapes Patterns of Spiral Ganglion Activity. J Neurosci 2021; 41:8859-8875. [PMID: 34551939 PMCID: PMC8549539 DOI: 10.1523/jneurosci.0924-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 08/17/2021] [Accepted: 09/08/2021] [Indexed: 11/21/2022] Open
Abstract
Neural response properties that typify primary sensory afferents are critical to fully appreciate because they establish and, ultimately represent, the fundamental coding design used for higher-level processing. Studies illuminating the center-surround receptive fields of retinal ganglion cells, for example, were ground-breaking because they determined the foundation of visual form detection. For the auditory system, a basic organizing principle of the spiral ganglion afferents is their extensive electrophysiological heterogeneity establishing diverse intrinsic firing properties in neurons throughout the spiral ganglion. Moreover, these neurons display an impressively large array of neurotransmitter receptor types that are responsive to efferent feedback. Thus, electrophysiological diversity and its neuromodulation are a fundamental encoding mechanism contributed by the primary afferents in the auditory system. To place these features into context, we evaluated the effects of hyperpolarization and cAMP on threshold level as indicators of overall afferent responsiveness in CBA/CaJ mice of either sex. Hyperpolarization modified threshold gradients such that distinct voltage protocols could shift the relationship between sensitivity and stimulus input to reshape resolution. This resulted in an "accordion effect" that appeared to stretch, compress, or maintain responsivity across the gradient of afferent thresholds. cAMP targeted threshold and kinetic shifts to rapidly adapting neurons, thus revealing multiple cochleotopic properties that could potentially be independently regulated. These examples of dynamic heterogeneity in primary auditory afferents not only have the capacity to shift the range, sensitivity, and resolution, but to do so in a coordinated manner that appears to orchestrate changes with a seemingly unlimited repertoire.SIGNIFICANCE STATEMENT How do we discriminate the more nuanced qualities of the sound around us? Beyond the basics of pitch and loudness, aspects, such as pattern, distance, velocity, and location, are all attributes that must be used to encode acoustic sensations effectively. While higher-level processing is required for perception, it would not be unexpected if the primary auditory afferents optimized receptor input to expedite neural encoding. The findings reported herein are consistent with this design. Neuromodulation compressed, expanded, shifted, or realigned intrinsic electrophysiological heterogeneity to alter neuronal responses selectively and dynamically. This suggests that diverse spiral ganglion phenotypes provide a rich substrate to support an almost limitless array of coding strategies within the first neural element of the auditory pathway.
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Affiliation(s)
- Jeffrey Parra-Munevar
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Charles E Morse
- Department of Neurosurgery, Jefferson Hospital for Neuroscience, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania 19107
| | - Mark R Plummer
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Robin L Davis
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
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18
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Moeinvaziri F, Shojaei A, Haghparast N, Yakhkeshi S, Nemati S, Hassani SN, Baharvand H. Towards maturation of human otic hair cell-like cells in pluripotent stem cell-derived organoid transplants. Cell Tissue Res 2021; 386:321-333. [PMID: 34319434 DOI: 10.1007/s00441-021-03510-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 07/14/2021] [Indexed: 12/21/2022]
Abstract
Human otic organoids generated from pluripotent stem cells (PSCs) provide a promising platform for modeling, drug testing, and cell-based therapies of inner ear diseases. However, providing the appropriate niche that resembles inner ear development and its vasculature to generate otic organoids is less conspicuous. Here, we devised a strategy to enhance maturation of otic progenitor cells toward human hair cell-like cells (HCLCs) by assembling three-dimensional (3D) otic organoids that contain human PSC-derived otic cells, endothelial cells, and mesenchymal stem cells (MSCs). Heterotopic implantation of otic organoids, designated as grafted otic organoids (GOs), in ex ovo chick embryo chorioallantoic membrane (CAM) stimulated maturation of the HCLCs. Functional analysis revealed the presence of voltage-gated potassium currents without detectable sodium currents in these cells in the GOs. Our results demonstrated that implantation of 3D heterotypic cell mixtures of otic organoids improved maturation of human HCLCs. This GO-derived HCLCs could be an attractive source for drug discovery and other biomedical applications.
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Affiliation(s)
- Farideh Moeinvaziri
- Department of Developmental Biology, School of Basic Sciences and Advanced Technologies in Biology, University of Science and Culture, Tehran, Iran.,Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Amir Shojaei
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Newsha Haghparast
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Saeed Yakhkeshi
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Shadman Nemati
- Department of Otolaryngology and Head & Neck Surgery, School of Medicine, Otorhinolaryngology Research Center, Amir Al Momenin Hospital, Guilan University of Medical Sciences, Rasht, Iran
| | - Seyedeh-Nafiseh Hassani
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Hossein Baharvand
- Department of Developmental Biology, School of Basic Sciences and Advanced Technologies in Biology, University of Science and Culture, Tehran, Iran. .,Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran.
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19
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Stalmann U, Franke AJ, Al-Moyed H, Strenzke N, Reisinger E. Otoferlin Is Required for Proper Synapse Maturation and for Maintenance of Inner and Outer Hair Cells in Mouse Models for DFNB9. Front Cell Neurosci 2021; 15:677543. [PMID: 34335185 PMCID: PMC8316924 DOI: 10.3389/fncel.2021.677543] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 06/22/2021] [Indexed: 11/16/2022] Open
Abstract
Deficiency of otoferlin causes profound prelingual deafness in humans and animal models. Here, we closely analyzed developmental deficits and degenerative mechanisms in Otof knock-out (Otof–/–) mice over the course of 48 weeks. We found otoferlin to be required for proper synapse development in the immature rodent cochlea: In absence of otoferlin, synaptic pruning was delayed, and postsynaptic boutons appeared enlarged at 2 weeks of age. At postnatal day 14 (P14), we found on average ∼15 synapses per inner hair cell (IHC) in Otof–/– cochleae as well as in wild-type controls. Further on, the number of synapses in Otof–/– IHCs was reduced to ∼7 at 8 weeks of age and to ∼6 at 48 weeks of age. In the same period, the number of spiral ganglion neurons (SGNs) declined in Otof–/– animals. Importantly, we found an age-progressive loss of IHCs to an overall number of 75% of wildtype IHCs. The IHC loss more prominently but not exclusively affected the basal aspects of the cochlea. For outer hair cells (OHCs), we observed slightly accelerated age-dependent degeneration from base to apex. This was associated with a progressive decay in DPOAE amplitudes for high frequency stimuli, which could first be observed at the age of 24 weeks in Otof–/– mice. Our data will help to plan and predict the outcome of a gene therapy applied at various ages of DFNB9 patients.
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Affiliation(s)
- Ursula Stalmann
- Auditory Systems Physiology Group, Department of Otolaryngology and Institute for Auditory Neuroscience, SFB 889 project A06, University Medical Center Göttingen, Göttingen, Germany
| | - Albert Justin Franke
- Auditory Systems Physiology Group, Department of Otolaryngology and Institute for Auditory Neuroscience, SFB 889 project A06, University Medical Center Göttingen, Göttingen, Germany
| | - Hanan Al-Moyed
- Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany
| | - Nicola Strenzke
- Auditory Systems Physiology Group, Department of Otolaryngology and Institute for Auditory Neuroscience, SFB 889 project A06, University Medical Center Göttingen, Göttingen, Germany
| | - Ellen Reisinger
- Molecular Biology of Cochlear Neurotransmission Group, Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany.,Gene Therapy for Hearing Impairment Group, Department of Otolaryngology, Head and Neck Surgery, University of Tübingen Medical Center, Tübingen, Germany
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20
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Liu S, Wang S, Zou L, Xiong W. Mechanisms in cochlear hair cell mechano-electrical transduction for acquisition of sound frequency and intensity. Cell Mol Life Sci 2021; 78:5083-5094. [PMID: 33871677 PMCID: PMC11072359 DOI: 10.1007/s00018-021-03840-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 03/30/2021] [Accepted: 04/09/2021] [Indexed: 10/21/2022]
Abstract
Sound signals are acquired and digitized in the cochlea by the hair cells that further transmit the coded information to the central auditory pathways. Any defect in hair cell function may induce problems in the auditory system and hearing-based brain function. In the past 2 decades, our understanding of auditory transduction has been substantially deepened because of advances in molecular, structural, and functional studies. Results from these experiments can be perfectly embedded in the previously established profile from anatomical, histological, genetic, and biophysical research. This review aims to summarize the progress on the molecular and cellular mechanisms of the mechano-electrical transduction (MET) channel in the cochlear hair cells, which is involved in the acquisition of sound frequency and intensity-the two major parameters of an acoustic cue. We also discuss recent studies on TMC1, the molecule likely to form the MET channel pore.
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Affiliation(s)
- Shuang Liu
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
| | - Shufeng Wang
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
| | - Linzhi Zou
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China
| | - Wei Xiong
- School of Life Sciences, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China.
- IDG/McGovern Institute for Brain Research at Tsinghua University, Tsinghua University, 1 Qinghuayuan, Beijing, 100084, China.
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21
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Kitcher SR, Pederson AM, Weisz CJC. Diverse identities and sites of action of cochlear neurotransmitters. Hear Res 2021; 419:108278. [PMID: 34108087 DOI: 10.1016/j.heares.2021.108278] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 04/30/2021] [Accepted: 05/18/2021] [Indexed: 11/18/2022]
Abstract
Accurate encoding of acoustic stimuli requires temporally precise responses to sound integrated with cellular mechanisms that encode the complexity of stimuli over varying timescales and orders of magnitude of intensity. Sound in mammals is initially encoded in the cochlea, the peripheral hearing organ, which contains functionally specialized cells (including hair cells, afferent and efferent neurons, and a multitude of supporting cells) to allow faithful acoustic perception. To accomplish the demanding physiological requirements of hearing, the cochlea has developed synaptic arrangements that operate over different timescales, with varied strengths, and with the ability to adjust function in dynamic hearing conditions. Multiple neurotransmitters interact to support the precision and complexity of hearing. Here, we review the location of release, action, and function of neurotransmitters in the mammalian cochlea with an emphasis on recent work describing the complexity of signaling.
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Affiliation(s)
- Siân R Kitcher
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Alia M Pederson
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Catherine J C Weisz
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States.
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22
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Rutherford MA, von Gersdorff H, Goutman JD. Encoding sound in the cochlea: from receptor potential to afferent discharge. J Physiol 2021; 599:2527-2557. [PMID: 33644871 PMCID: PMC8127127 DOI: 10.1113/jp279189] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 02/22/2021] [Indexed: 12/17/2022] Open
Abstract
Ribbon-class synapses in the ear achieve analog to digital transformation of a continuously graded membrane potential to all-or-none spikes. In mammals, several auditory nerve fibres (ANFs) carry information from each inner hair cell (IHC) to the brain in parallel. Heterogeneity of transmission among synapses contributes to the diversity of ANF sound-response properties. In addition to the place code for sound frequency and the rate code for sound level, there is also a temporal code. In series with cochlear amplification and frequency tuning, neural representation of temporal cues over a broad range of sound levels enables auditory comprehension in noisy multi-speaker settings. The IHC membrane time constant introduces a low-pass filter that attenuates fluctuations of the receptor potential above 1-2 kHz. The ANF spike generator adds a high-pass filter via its depolarization-rate threshold that rejects slow changes in the postsynaptic potential and its phasic response property that ensures one spike per depolarization. Synaptic transmission involves several stochastic subcellular processes between IHC depolarization and ANF spike generation, introducing delay and jitter that limits the speed and precision of spike timing. ANFs spike at a preferred phase of periodic sounds in a process called phase-locking that is limited to frequencies below a few kilohertz by both the IHC receptor potential and the jitter in synaptic transmission. During phase-locking to periodic sounds of increasing intensity, faster and facilitated activation of synaptic transmission and spike generation may be offset by presynaptic depletion of synaptic vesicles, resulting in relatively small changes in response phase. Here we review encoding of spike-timing at cochlear ribbon synapses.
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Affiliation(s)
- Mark A. Rutherford
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Henrique von Gersdorff
- Vollum Institute, Oregon Hearing Research Center, Oregon Health and Sciences University, Portland, Oregon 97239
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Optimized Tuning of Auditory Inner Hair Cells to Encode Complex Sound through Synergistic Activity of Six Independent K + Current Entities. Cell Rep 2021; 32:107869. [PMID: 32640234 DOI: 10.1016/j.celrep.2020.107869] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/08/2020] [Accepted: 06/16/2020] [Indexed: 02/06/2023] Open
Abstract
Auditory inner hair cells (IHCs) convert sound vibrations into receptor potentials that drive synaptic transmission. For the precise encoding of sound qualities, receptor potentials are shaped by K+ conductances tuning the properties of the IHC membrane. Using patch-clamp and computational modeling, we unravel this membrane specialization showing that IHCs express an exclusive repertoire of six voltage-dependent K+ conductances mediated by Kv1.8, Kv7.4, Kv11.1, Kv12.1, and BKCa channels. All channels are active at rest but are triggered differentially during sound stimulation. This enables non-saturating tuning over a far larger potential range than in IHCs expressing fewer current entities. Each conductance contributes to optimizing responses, but the combined activity of all channels synergistically improves phase locking and the dynamic range of intensities that IHCs can encode. Conversely, hypothetical simpler IHCs appear limited to encode only certain aspects (frequency or intensity). The exclusive channel repertoire of IHCs thus constitutes an evolutionary adaptation to encode complex sound through multifaceted receptor potentials.
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Boeri J, Meunier C, Le Corronc H, Branchereau P, Timofeeva Y, Lejeune FX, Mouffle C, Arulkandarajah H, Mangin JM, Legendre P, Czarnecki A. Two opposite voltage-dependent currents control the unusual early development pattern of embryonic Renshaw cell electrical activity. eLife 2021; 10:62639. [PMID: 33899737 PMCID: PMC8139835 DOI: 10.7554/elife.62639] [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: 08/31/2020] [Accepted: 04/24/2021] [Indexed: 11/25/2022] Open
Abstract
Renshaw cells (V1R) are excitable as soon as they reach their final location next to the spinal motoneurons and are functionally heterogeneous. Using multiple experimental approaches, in combination with biophysical modeling and dynamical systems theory, we analyzed, for the first time, the mechanisms underlying the electrophysiological properties of V1R during early embryonic development of the mouse spinal cord locomotor networks (E11.5–E16.5). We found that these interneurons are subdivided into several functional clusters from E11.5 and then display an unexpected transitory involution process during which they lose their ability to sustain tonic firing. We demonstrated that the essential factor controlling the diversity of the discharge pattern of embryonic V1R is the ratio of a persistent sodium conductance to a delayed rectifier potassium conductance. Taken together, our results reveal how a simple mechanism, based on the synergy of two voltage-dependent conductances that are ubiquitous in neurons, can produce functional diversity in embryonic V1R and control their early developmental trajectory.
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Affiliation(s)
- Juliette Boeri
- INSERM, UMR_S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Sorbonne Univ, Paris, France
| | - Claude Meunier
- Centre de Neurosciences Intégratives et Cognition, CNRS UMR 8002, Institut Neurosciences et Cognition, Université de Paris, Paris, France
| | - Hervé Le Corronc
- INSERM, UMR_S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Sorbonne Univ, Paris, France.,Univ Angers, Angers, France
| | | | - Yulia Timofeeva
- Department of Computer Science and Centre for Complexity Science, University of Warwick, Coventry, United Kingdom.,Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - François-Xavier Lejeune
- Institut du Cerveau et de la Moelle Epinière, Centre de Recherche CHU Pitié-Salpétrière, INSERM, U975, CNRS, UMR 7225, Sorbonne Univ, Paris, France
| | - Christine Mouffle
- INSERM, UMR_S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Sorbonne Univ, Paris, France
| | - Hervé Arulkandarajah
- INSERM, UMR_S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Sorbonne Univ, Paris, France
| | - Jean Marie Mangin
- INSERM, UMR_S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Sorbonne Univ, Paris, France
| | - Pascal Legendre
- INSERM, UMR_S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Sorbonne Univ, Paris, France
| | - Antonny Czarnecki
- INSERM, UMR_S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Sorbonne Univ, Paris, France.,Univ. Bordeaux, CNRS, EPHE, INCIA, Bordeaux, France
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25
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Chen Y, Gu Y, Li Y, Li GL, Chai R, Li W, Li H. Generation of mature and functional hair cells by co-expression of Gfi1, Pou4f3, and Atoh1 in the postnatal mouse cochlea. Cell Rep 2021; 35:109016. [PMID: 33882317 DOI: 10.1016/j.celrep.2021.109016] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 12/15/2020] [Accepted: 03/30/2021] [Indexed: 12/12/2022] Open
Abstract
The mammalian cochlea cannot regenerate functional hair cells (HCs) spontaneously. Atoh1 overexpression as well as other strategies are unable to generate functional HCs. Here, we simultaneously upregulated the expression of Gfi1, Pou4f3, and Atoh1 in postnatal cochlear supporting cells (SCs) in vivo, which efficiently converted SCs into HCs. The newly regenerated HCs expressed HC markers Myo7a, Calbindin, Parvalbumin, and Ctbp2 and were innervated by neurites. Importantly, many new HCs expressed the mature and terminal marker Prestin or vesicular glutamate transporter 3 (vGlut3), depending on the subtypes of the source SCs. Finally, our patch-clamp analysis showed that the new HCs in the medial region acquired a large K+ current, fired spikes transiently, and exhibited signature refinement of ribbon synapse functions, in close resemblance to native wild-type inner HCs. We demonstrated that co-upregulating Gfi1, Pou4f3, and Atoh1 enhances the efficiency of HC generation and promotes the functional maturation of new HCs.
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Affiliation(s)
- Yan Chen
- ENT institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai 200031, China
| | - Yuyan Gu
- ENT institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai 200031, China
| | - Yige Li
- MOE Key Laboratory for Developmental Genes and Human Disease, School of Life Sciences and Technology, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Geng-Lin Li
- ENT institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai 200031, China
| | - Renjie Chai
- MOE Key Laboratory for Developmental Genes and Human Disease, School of Life Sciences and Technology, 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; Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing, China.
| | - Wenyan Li
- ENT institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai 200031, China.
| | - Huawei Li
- ENT institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai 200031, China; The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China.
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26
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Jeng JY, Harasztosi C, Carlton A, Corns L, Marchetta P, Johnson SL, Goodyear RJ, Legan KP, Rüttiger L, Richardson GP, Marcotti W. MET currents and otoacoustic emissions from mice with a detached tectorial membrane indicate the extracellular matrix regulates Ca 2+ near stereocilia. J Physiol 2021; 599:2015-2036. [PMID: 33559882 PMCID: PMC7612128 DOI: 10.1113/jp280905] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/03/2021] [Indexed: 10/11/2023] Open
Abstract
KEY POINTS The aim was to determine whether detachment of the tectorial membrane (TM) from the organ of Corti in Tecta/Tectb-/- mice affects the biophysical properties of cochlear outer hair cells (OHCs). Tecta/Tectb-/- mice have highly elevated hearing thresholds, but OHCs mature normally. Mechanoelectrical transducer (MET) channel resting open probability (Po ) in mature OHC is ∼50% in endolymphatic [Ca2+ ], resulting in a large standing depolarizing MET current that would allow OHCs to act optimally as electromotile cochlear amplifiers. MET channel resting Po in vivo is also high in Tecta/Tectb-/- mice, indicating that the TM is unlikely to statically bias the hair bundles of OHCs. Distortion product otoacoustic emissions (DPOAEs), a readout of active, MET-dependent, non-linear cochlear amplification in OHCs, fail to exhibit long-lasting adaptation to repetitive stimulation in Tecta/Tectb-/- mice. We conclude that during prolonged, sound-induced stimulation of the cochlea the TM may determine the extracellular Ca2+ concentration near the OHC's MET channels. ABSTRACT The tectorial membrane (TM) is an acellular structure of the cochlea that is attached to the stereociliary bundles of the outer hair cells (OHCs), electromotile cells that amplify motion of the cochlear partition and sharpen its frequency selectivity. Although the TM is essential for hearing, its role is still not fully understood. In Tecta/Tectb-/- double knockout mice, in which the TM is not coupled to the OHC stereocilia, hearing sensitivity is considerably reduced compared with that of wild-type animals. In vivo, the OHC receptor potentials, assessed using cochlear microphonics, are symmetrical in both wild-type and Tecta/Tectb-/- mice, indicating that the TM does not bias the hair bundle resting position. The functional maturation of hair cells is also unaffected in Tecta/Tectb-/- mice, and the resting open probability of the mechanoelectrical transducer (MET) channel reaches values of ∼50% when the hair bundles of mature OHCs are bathed in an endolymphatic-like Ca2+ concentration (40 μM) in vitro. The resultant large MET current depolarizes OHCs to near -40 mV, a value that would allow optimal activation of the motor protein prestin and normal cochlear amplification. Although the set point of the OHC receptor potential transfer function in vivo may therefore be determined primarily by endolymphatic Ca2+ concentration, repetitive acoustic stimulation fails to produce adaptation of MET-dependent otoacoustic emissions in vivo in the Tecta/Tectb-/- mice. Therefore, the TM is likely to contribute to the regulation of Ca2+ levels around the stereocilia, and thus adaptation of the OHC MET channel during prolonged sound stimulation.
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Affiliation(s)
- Jing-Yi Jeng
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Csaba Harasztosi
- Department of Otolaryngology Head & Neck Surgery, THRC, University of Tübingen, 72076 Tübingen, Germany
| | - Adam Carlton
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Laura Corns
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Philine Marchetta
- Department of Otolaryngology Head & Neck Surgery, THRC, University of Tübingen, 72076 Tübingen, Germany
| | - Stuart L. Johnson
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
- Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
| | | | - Kevin P. Legan
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Lukas Rüttiger
- Department of Otolaryngology Head & Neck Surgery, THRC, University of Tübingen, 72076 Tübingen, Germany
| | - Guy P. Richardson
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Walter Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
- Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
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27
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Huang G, Eckrich S. Quantitative Fluorescent in situ Hybridization Reveals Differential Transcription Profile Sharpening of Endocytic Proteins in Cochlear Hair Cells Upon Maturation. Front Cell Neurosci 2021; 15:643517. [PMID: 33716676 PMCID: PMC7952526 DOI: 10.3389/fncel.2021.643517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/09/2021] [Indexed: 12/04/2022] Open
Abstract
The organ of Corti (OC) comprises two types of sensory cells: outer hair cells (OHCs) and inner hair cells (IHCs). While both are mechanotransducers, OHCs serve as cochlear amplifiers, whereas IHCs transform sound into transmitter release. Reliable sound encoding is ensured by indefatigable exocytosis of synaptic vesicles associated with efficient replenishment of the vesicle pool. Vesicle reformation requires retrieval of vesicle membrane from the hair cell’s membrane via endocytosis. So far, the protein machinery for endocytosis in pre-mature and terminally differentiated hair cells has only partially been deciphered. Here, we studied three endocytic proteins, dynamin-1, dynamin-3, and endophilin-A1, by assessing their transcription profiles in pre-mature and mature mouse OCs. State-of-the-art RNAscope® fluorescent in situ hybridization (FISH) of whole-mount OCs was used for quantification of target mRNAs on single-cell level. We found that pre-mature IHCs contained more mRNA transcripts of dnm1 (encoding dynamin-1) and sh3gl2 (endophilin-A1), but less of dnm3 (dynamin-3) than OHCs. These differential transcription profiles between OHCs and IHCs were sharpened upon maturation. It is noteworthy that low but heterogeneous signal numbers were found between individual negative controls, which highlights the importance of corresponding analyses in RNAscope® assays. Complementary immunolabeling revealed strong expression of dynamin-1 in the soma of mature IHCs, which was much weaker in pre-mature IHCs. By contrast, dynamin-3 was predominantly found in the soma and at the border of the cuticular plates of pre-mature and mature OHCs. In summary, using quantitative RNAscope® FISH and immunohistochemistry on whole-mount tissue of both pre-mature and mature OCs, we disclosed the cellular upregulation of endocytic proteins at the level of transcription/translation during terminal differentiation of the OC. Dynamin-1 and endophilin-A1 likely contribute to the strengthening of the endocytic machinery in IHCs after the onset of hearing, whereas expression of dynamin-3 at the cuticular plate of pre-mature and mature OHCs suggests its possible involvement in activity-independent apical endocytosis.
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Affiliation(s)
- Guobin Huang
- Center for Integrative Physiology and Molecular Medicine, School of Medicine, Department of Biophysics, Saarland University, Homburg, Germany
| | - Stephanie Eckrich
- Center for Integrative Physiology and Molecular Medicine, School of Medicine, Department of Biophysics, Saarland University, Homburg, Germany
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28
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Carlton AJ, Halford J, Underhill A, Jeng J, Avenarius MR, Gilbert ML, Ceriani F, Ebisine K, Brown SDM, Bowl MR, Barr‐Gillespie PG, Marcotti W. Loss of Baiap2l2 destabilizes the transducing stereocilia of cochlear hair cells and leads to deafness. J Physiol 2021; 599:1173-1198. [PMID: 33151556 PMCID: PMC7898316 DOI: 10.1113/jp280670] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/27/2020] [Indexed: 12/17/2022] Open
Abstract
KEY POINTS Mechanoelectrical transduction at auditory hair cells requires highly specialized stereociliary bundles that project from their apical surface, forming a characteristic graded 'staircase' structure. The morphogenesis and maintenance of these stereociliary bundles is a tightly regulated process requiring the involvement of several actin-binding proteins, many of which are still unidentified. We identify a new stereociliary protein, the I-BAR protein BAIAP2L2, which localizes to the tips of the shorter transducing stereocilia in both inner and outer hair cells (IHCs and OHCs). We find that Baiap2l2 deficient mice lose their second and third rows of stereocilia, their mechanoelectrical transducer current, and develop progressive hearing loss, becoming deaf by 8 months of age. We demonstrate that BAIAP2L2 localization to stereocilia tips is dependent on the motor protein MYO15A and its cargo EPS8. We propose that BAIAP2L2 is a new key protein required for the maintenance of the transducing stereocilia in mature cochlear hair cells. ABSTRACT The transduction of sound waves into electrical signals depends upon mechanosensitive stereociliary bundles that project from the apical surface of hair cells within the cochlea. The height and width of these actin-based stereocilia is tightly regulated throughout life to establish and maintain their characteristic staircase-like structure, which is essential for normal mechanoelectrical transduction. Here, we show that BAIAP2L2, a member of the I-BAR protein family, is a newly identified hair bundle protein that is localized to the tips of the shorter rows of transducing stereocilia in mouse cochlear hair cells. BAIAP2L2 was detected by immunohistochemistry from postnatal day 2.5 (P2.5) throughout adulthood. In Baiap2l2 deficient mice, outer hair cells (OHCs), but not inner hair cells (IHCs), began to lose their third row of stereocilia and showed a reduction in the size of the mechanoelectrical transducer current from just after P9. Over the following post-hearing weeks, the ordered staircase structure of the bundle progressively deteriorates, such that, by 8 months of age, both OHCs and IHCs of Baiap2l2 deficient mice have lost most of the second and third rows of stereocilia and become deaf. We also found that BAIAP2L2 interacts with other key stereociliary proteins involved in normal hair bundle morphogenesis, such as CDC42, RAC1, EPS8 and ESPNL. Furthermore, we show that BAIAP2L2 localization to the stereocilia tips depends on the motor protein MYO15A and its cargo EPS8. We propose that BAIAP2L2 is key to maintenance of the normal actin structure of the transducing stereocilia in mature mouse cochlear hair cells.
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Affiliation(s)
- Adam J. Carlton
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
- Neuroscience InstituteUniversity of SheffieldSheffieldUK
| | - Julia Halford
- Oregon Hearing Research Center & Vollum InstituteOregon Health & Science UniversityPortlandORUSA
| | - Anna Underhill
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
- Neuroscience InstituteUniversity of SheffieldSheffieldUK
| | - Jing‐Yi Jeng
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
- Neuroscience InstituteUniversity of SheffieldSheffieldUK
| | - Matthew R. Avenarius
- Oregon Hearing Research Center & Vollum InstituteOregon Health & Science UniversityPortlandORUSA
- Present address: Department of Pathology Wexner Medical CenterThe Ohio State UniversityColumbusOHUSA
| | - Merle L. Gilbert
- Oregon Hearing Research Center & Vollum InstituteOregon Health & Science UniversityPortlandORUSA
- Present address: US Army Medical Department Activity‐KoreaCamp HumphreysRepublic of Korea
| | - Federico Ceriani
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
- Neuroscience InstituteUniversity of SheffieldSheffieldUK
| | | | - Steve D. M. Brown
- Mammalian Genetics UnitMRC Harwell InstituteHarwell CampusOxfordshireUK
| | - Michael R. Bowl
- Mammalian Genetics UnitMRC Harwell InstituteHarwell CampusOxfordshireUK
- Present address: UCL Ear InstituteUniversity College LondonLondonUK
| | - Peter G. Barr‐Gillespie
- Oregon Hearing Research Center & Vollum InstituteOregon Health & Science UniversityPortlandORUSA
- Oregon Hearing Research CenterOregon Health & Science UniversityPortlandORUSA
| | - Walter Marcotti
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
- Neuroscience InstituteUniversity of SheffieldSheffieldUK
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Jeng JY, Carlton A, Johnson SL, Brown SDM, Holley MC, Bowl MR, Marcotti W. Biophysical and morphological changes in inner hair cells and their efferent innervation in the ageing mouse cochlea. J Physiol 2021; 599:269-287. [PMID: 33179774 PMCID: PMC7612127 DOI: 10.1113/jp280256] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 10/01/2020] [Indexed: 09/18/2023] Open
Abstract
KEY POINTS Age-related hearing loss is a progressive hearing loss involving environmental and genetic factors, leading to a decrease in hearing sensitivity, threshold and speech discrimination. We compared age-related changes in inner hair cells (IHCs) between four mouse strains with different levels of progressive hearing loss. The surface area of apical coil IHCs (9-12 kHz cochlear region) decreases by about 30-40% with age. The number of BK channels progressively decreases with age in the IHCs from most mouse strains, but the basolateral membrane current profile remains unchanged. The mechanoelectrical transducer current is smaller in mice harbouring the hypomorphic Cdh23 allele Cdh23ahl (C57BL/6J; C57BL/6NTac), but not in Cdh23-repaired mice (C57BL/6NTacCdh23+ ), indicating that it could contribute to the different progression of hearing loss among mouse strains. The degree of efferent rewiring onto aged IHCs, most likely coming from the lateral olivocochlea fibres, was correlated with hearing loss in the different mouse strains. ABSTRACT Inner hair cells (IHCs) are the primary sensory receptors of the mammalian cochlea, transducing acoustic information into electrical signals that are relayed to the afferent neurons. Functional changes in IHCs are a potential cause of age-related hearing loss. Here, we have investigated the functional characteristics of IHCs from early-onset hearing loss mice harbouring the allele Cdh23ahl (C57BL/6J and C57BL/6NTac), from late-onset hearing loss mice (C3H/HeJ), and from mice corrected for the Cdh23ahl mutation (C57BL/6NTacCdh23+ ) with an intermediate hearing phenotype. There was no significant loss of IHCs in the 9-12 kHz cochlear region up to at least 15 months of age, but their surface area decreased progressively by 30-40% starting from ∼6 months of age. Although the size of the BK current decreased with age, IHCs retained a normal KCNQ4 current and resting membrane potential. These basolateral membrane changes were most severe for C57BL/6J and C57BL/6NTac, less so for C57BL/6NTacCdh23+ and minimal or absent in C3H/HeJ mice. We also found that lateral olivocochlear (LOC) efferent fibres re-form functional axon-somatic connections with aged IHCs, but this was seen only sporadically in C3H/HeJ mice. The efferent post-synaptic SK2 channels appear prior to the establishment of the efferent contacts, suggesting that IHCs may play a direct role in re-establishing the LOC-IHC synapses. Finally, we showed that the size of the mechanoelectrical transducer (MET) current from IHCs decreased significantly with age in mice harbouring the Cdh23ahl allele but not in C57BL/6NTacCdh23+ mice, indicating that the MET apparatus directly contributes to the progression of age-related hearing loss.
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Affiliation(s)
- Jing-Yi Jeng
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Adam Carlton
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Stuart L. Johnson
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
- Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
| | - Steve D. M. Brown
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - Matthew C. Holley
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Michael R. Bowl
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - Walter Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
- Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
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30
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Age-related hearing loss pertaining to potassium ion channels in the cochlea and auditory pathway. Pflugers Arch 2020; 473:823-840. [PMID: 33336302 PMCID: PMC8076138 DOI: 10.1007/s00424-020-02496-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/27/2020] [Accepted: 11/10/2020] [Indexed: 12/12/2022]
Abstract
Age-related hearing loss (ARHL) is the most prevalent sensory deficit in the elderly and constitutes the third highest risk factor for dementia. Lifetime noise exposure, genetic predispositions for degeneration, and metabolic stress are assumed to be the major causes of ARHL. Both noise-induced and hereditary progressive hearing have been linked to decreased cell surface expression and impaired conductance of the potassium ion channel KV7.4 (KCNQ4) in outer hair cells, inspiring future therapies to maintain or prevent the decline of potassium ion channel surface expression to reduce ARHL. In concert with KV7.4 in outer hair cells, KV7.1 (KCNQ1) in the stria vascularis, calcium-activated potassium channels BK (KCNMA1) and SK2 (KCNN2) in hair cells and efferent fiber synapses, and KV3.1 (KCNC1) in the spiral ganglia and ascending auditory circuits share an upregulated expression or subcellular targeting during final differentiation at hearing onset. They also share a distinctive fragility for noise exposure and age-dependent shortfalls in energy supply required for sustained surface expression. Here, we review and discuss the possible contribution of select potassium ion channels in the cochlea and auditory pathway to ARHL. We postulate genes, proteins, or modulators that contribute to sustained ion currents or proper surface expressions of potassium channels under challenging conditions as key for future therapies of ARHL.
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Wallois F, Routier L, Heberlé C, Mahmoudzadeh M, Bourel-Ponchel E, Moghimi S. Back to basics: the neuronal substrates and mechanisms that underlie the electroencephalogram in premature neonates. Neurophysiol Clin 2020; 51:5-33. [PMID: 33162287 DOI: 10.1016/j.neucli.2020.10.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/05/2020] [Accepted: 10/05/2020] [Indexed: 02/06/2023] Open
Abstract
Electroencephalography is the only clinically available technique that can address the premature neonate normal and pathological functional development week after week. The changes in the electroencephalogram (EEG) result from gradual structural and functional modifications that arise during the last trimester of pregnancy. Here, we review the structural changes over time that underlie the establishment of functional immature neural networks, the impact of certain anatomical specificities (fontanelles, connectivity, etc.) on the EEG, limitations in EEG interpretation, and the utility of high-resolution EEG (HR-EEG) in premature newborns (a promising technique with a high degree of spatiotemporal resolution). In particular, we classify EEG features according to whether they are manifestations of endogenous generators (i.e. theta activities that coalesce with a slow wave or delta brushes) or come from a broader network. Furthermore, we review publications on EEG in premature animals because the data provide a better understanding of what is happening in premature newborns. We then discuss the results and limitations of functional connectivity analyses in premature newborns. Lastly, we report on the magnetoelectroencephalographic studies of brain activity in the fetus. A better understanding of complex interactions at various structural and functional levels during normal neurodevelopment (as assessed using electroencephalography as a benchmark method) might lead to better clinical care and monitoring for premature neonates.
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Affiliation(s)
- Fabrice Wallois
- INSERM U1105, Research Group on Multimodal Analysis of Brain Function, Jules Verne University of Picardie, Amiens, France; Service d'Explorations Fonctionnelles du Système Nerveux Pédiatrique, Amiens-Picardie Medical Center, Amiens, France.
| | - Laura Routier
- INSERM U1105, Research Group on Multimodal Analysis of Brain Function, Jules Verne University of Picardie, Amiens, France; Service d'Explorations Fonctionnelles du Système Nerveux Pédiatrique, Amiens-Picardie Medical Center, Amiens, France
| | - Claire Heberlé
- INSERM U1105, Research Group on Multimodal Analysis of Brain Function, Jules Verne University of Picardie, Amiens, France; Service d'Explorations Fonctionnelles du Système Nerveux Pédiatrique, Amiens-Picardie Medical Center, Amiens, France
| | - Mahdi Mahmoudzadeh
- INSERM U1105, Research Group on Multimodal Analysis of Brain Function, Jules Verne University of Picardie, Amiens, France; Service d'Explorations Fonctionnelles du Système Nerveux Pédiatrique, Amiens-Picardie Medical Center, Amiens, France
| | - Emilie Bourel-Ponchel
- INSERM U1105, Research Group on Multimodal Analysis of Brain Function, Jules Verne University of Picardie, Amiens, France; Service d'Explorations Fonctionnelles du Système Nerveux Pédiatrique, Amiens-Picardie Medical Center, Amiens, France
| | - Sahar Moghimi
- INSERM U1105, Research Group on Multimodal Analysis of Brain Function, Jules Verne University of Picardie, Amiens, France; Service d'Explorations Fonctionnelles du Système Nerveux Pédiatrique, Amiens-Picardie Medical Center, Amiens, France
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32
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Developmental and Functional Hair Cell-Like Cells Induced by Atoh1 Overexpression in the Adult Mammalian Cochlea In Vitro. Neural Plast 2020; 2020:8885813. [PMID: 33204251 PMCID: PMC7661126 DOI: 10.1155/2020/8885813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 09/17/2020] [Accepted: 10/21/2020] [Indexed: 12/22/2022] Open
Abstract
Hair cells (HCs) in the mammalian cochleae cannot spontaneously regenerate once damaged, resulting in permanent hearing loss. It has been shown that Atoh1 overexpression induces hair cell-like cells (HCLCs) in the cochlea of newborn rodents, but this is hard to achieve in adult mammals. In this study, we used a three-dimensional cochlear culture system and an adenoviral-mediated delivery vector to overexpress Atoh1 in adult mouse cochleae. HCLCs were successfully induced from 3 days after virus infection (3 DVI) in vitro, and the number increased with time. HCLCs were myosin7a positive and distinguishable from remnant HCs in a culture environment. Meanwhile, patch-clamp results showed that noninactive outward potassium currents (sustained outward potassium currents) could be recorded in HCLCs and that their magnitude increased with time, similar to normal HCs. Furthermore, transient HCN currents were recorded in some HCLCs, indicating that the HCLCs experienced a developmental stage similar to normal HCs. We also compared the electrophysiological features of HCLCs from adult mice with native HCs and found the HCLCs gradually matured, similar to the normal HCs. Meanwhile, HCLCs from adult mice possessed the same bundles as developmental HCs. However, these HCLCs did not express prestin, which is a special marker for outer hair cells (OHCs), even at 13 DVI. These results demonstrate that Atoh1 overexpression induces HCLC formation in the adult mammalian cochlea and that these HCLCs were functional and experienced a developmental process similar to that of normal HCs.
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33
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Martelletti E, Ingham NJ, Houston O, Pass JC, Chen J, Marcotti W, Steel KP. Synaptojanin2 Mutation Causes Progressive High-frequency Hearing Loss in Mice. Front Cell Neurosci 2020; 14:561857. [PMID: 33100973 PMCID: PMC7546894 DOI: 10.3389/fncel.2020.561857] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/14/2020] [Indexed: 12/04/2022] Open
Abstract
Progressive hearing loss is very common in the human population but we know little about the underlying molecular mechanisms. Synaptojanin2 (Synj2) has been reported to be involved, as a mouse mutation led to a progressive increase in auditory thresholds with age. Synaptojanin2 is a phosphatidylinositol (PI) phosphatase that removes the five-position phosphates from phosphoinositides, such as PIP2 and PIP3, and is a key enzyme in clathrin-mediated endocytosis. To investigate the mechanisms underlying progressive hearing loss, we have studied a different mutation of mouse Synj2 to look for any evidence of involvement of vesicle trafficking particularly affecting the synapses of sensory hair cells. Auditory brainstem responses (ABR) developed normally at first but started to decline between 3 and 4 weeks of age in Synj2tm1b mutants. At 6 weeks old, some evidence of outer hair cell (OHC) stereocilia fusion and degeneration was observed, but this was only seen in the extreme basal turn so cannot explain the raised ABR thresholds that correspond to more apical regions of the cochlear duct. We found no evidence of any defect in inner hair cell (IHC) exocytosis or endocytosis using single hair cell recordings, nor any sign of hair cell synaptic abnormalities. Endocochlear potentials (EP) were normal. The mechanism underlying progressive hearing loss in these mutants remains elusive, but our findings of raised distortion product otoacoustic emission (DPOAE) thresholds and signs of OHC degeneration both suggest an OHC origin for the hearing loss. Synaptojanin2 is not required for normal development of hearing but it is important for its maintenance.
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Affiliation(s)
- Elisa Martelletti
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Neil J Ingham
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Oliver Houston
- Department of Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Johanna C Pass
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Jing Chen
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Walter Marcotti
- Department of Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom.,Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Karen P Steel
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
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Jovanovic S, Milenkovic I. Purinergic Modulation of Activity in the Developing Auditory Pathway. Neurosci Bull 2020; 36:1285-1298. [PMID: 33040238 DOI: 10.1007/s12264-020-00586-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 09/10/2020] [Indexed: 12/11/2022] Open
Abstract
Purinergic P2 receptors, activated by endogenous ATP, are prominently expressed on neuronal and non-neuronal cells during development of the auditory periphery and central auditory neurons. In the mature cochlea, extracellular ATP contributes to ion homeostasis, and has a protective function against noise exposure. Here, we focus on the modulation of activity by extracellular ATP during early postnatal development of the lower auditory pathway. In mammals, spontaneous patterned activity is conveyed along afferent auditory pathways before the onset of acoustically evoked signal processing. During this critical developmental period, inner hair cells fire bursts of action potentials that are believed to provide a developmental code for synaptic maturation and refinement of auditory circuits, thereby establishing a precise tonotopic organization. Endogenous ATP-release triggers such patterned activity by raising the extracellular K+ concentration and contributes to firing by increasing the excitability of auditory nerve fibers, spiral ganglion neurons, and specific neuron types within the auditory brainstem, through the activation of diverse P2 receptors. We review recent studies that provide new models on the contribution of purinergic signaling to early development of the afferent auditory pathway. Further, we discuss potential future directions of purinergic research in the auditory system.
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Affiliation(s)
- Sasa Jovanovic
- School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
| | - Ivan Milenkovic
- School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany.
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35
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Bai J, Xue N, Lawal O, Nyati A, Santos‐Sacchi J, Navaratnam D. Calcium-induced calcium release in proximity to hair cell BK channels revealed by PKA activation. Physiol Rep 2020; 8:e14449. [PMID: 32748549 PMCID: PMC7399380 DOI: 10.14814/phy2.14449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 11/24/2022] Open
Abstract
Large-conductance calcium-activated potassium (BK) channels play a critical role in electrical resonance, a mechanism of frequency selectivity in chicken hair cells. We determine that BK currents are dependent on inward flow of Ca2+ , and intracellular buffering of Ca2+ . Entry of Ca2+ is further amplified locally by calcium-induced Ca2+ release (CICR) in close proximity to plasma membrane BK channels. Ca2+ imaging reveals peripheral clusters of high concentrations of Ca2+ that are suprathreshold to that needed to activate BK channels. Protein kinase A (PKA) activation increases the size of BK currents likely by recruiting more BK channels due to spatial spread of high Ca2+ concentrations in turn from increasing CICR. STORM imaging confirms the presence of nanodomains with ryanodine and IP3 receptors in close proximity to the Slo subunit of BK channels. Together, these data require a rethinking of how electrical resonance is brought about and suggest effects of CICR in synaptic release. Both genders were included in this study.
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Affiliation(s)
- Jun‐ping Bai
- Department of NeurologyYale School of MedicineNew HavenCTUSA
| | - Na Xue
- Department of Otolaryngology‐Head and Neck SurgeryShanghai Ninth People's HospitalShanghai Jiaotong University School of MedicineShanghaiChina
| | - Omolara Lawal
- Department of NeurologyYale School of MedicineNew HavenCTUSA
| | - Anda Nyati
- Undergraduate ProgramJohns Hopkins UniversityBaltimoreMDUSA
| | - Joseph Santos‐Sacchi
- Department of SurgeryYale School of MedicineNew HavenCTUSA
- Department of Cell and Molecular PhysiologyYale School of MedicineNew HavenCTUSA
- Department of NeuroscienceYale School of MedicineNew HavenCTUSA
| | - Dhasakumar Navaratnam
- Department of NeurologyYale School of MedicineNew HavenCTUSA
- Department of SurgeryYale School of MedicineNew HavenCTUSA
- Department of NeuroscienceYale School of MedicineNew HavenCTUSA
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36
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Babola TA, Kersbergen CJ, Wang HC, Bergles DE. Purinergic signaling in cochlear supporting cells reduces hair cell excitability by increasing the extracellular space. eLife 2020; 9:e52160. [PMID: 31913121 PMCID: PMC7015667 DOI: 10.7554/elife.52160] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 01/07/2020] [Indexed: 11/13/2022] Open
Abstract
Neurons in developing sensory pathways exhibit spontaneous bursts of electrical activity that are critical for survival, maturation and circuit refinement. In the auditory system, intrinsically generated activity arises within the cochlea, but the molecular mechanisms that initiate this activity remain poorly understood. We show that burst firing of mouse inner hair cells prior to hearing onset requires P2RY1 autoreceptors expressed by inner supporting cells. P2RY1 activation triggers K+ efflux and depolarization of hair cells, as well as osmotic shrinkage of supporting cells that dramatically increased the extracellular space and speed of K+ redistribution. Pharmacological inhibition or genetic disruption of P2RY1 suppressed neuronal burst firing by reducing K+ release, but unexpectedly enhanced their tonic firing, as water resorption by supporting cells reduced the extracellular space, leading to K+ accumulation. These studies indicate that purinergic signaling in supporting cells regulates hair cell excitability by controlling the volume of the extracellular space.
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Affiliation(s)
- Travis A Babola
- The Solomon Snyder Department of NeuroscienceJohns Hopkins UniversityBaltimoreUnited States
| | - Calvin J Kersbergen
- The Solomon Snyder Department of NeuroscienceJohns Hopkins UniversityBaltimoreUnited States
| | - Han Chin Wang
- The Solomon Snyder Department of NeuroscienceJohns Hopkins UniversityBaltimoreUnited States
| | - Dwight E Bergles
- The Solomon Snyder Department of NeuroscienceJohns Hopkins UniversityBaltimoreUnited States
- Department of Otolaryngology Head and Neck SurgeryJohns Hopkins UniversityBaltimoreUnited States
- Kavli Neuroscience Discovery InstituteJohns Hopkins UniversityBaltimoreUnited States
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37
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Fernandez KA, Guo D, Micucci S, De Gruttola V, Liberman MC, Kujawa SG. Noise-induced Cochlear Synaptopathy with and Without Sensory Cell Loss. Neuroscience 2019; 427:43-57. [PMID: 31887361 DOI: 10.1016/j.neuroscience.2019.11.051] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 11/28/2019] [Accepted: 11/29/2019] [Indexed: 11/28/2022]
Abstract
Prior work has provided extensive documentation of threshold sensitivity and sensory hair cell losses after noise exposure. It is now clear, however, that cochlear synaptic loss precedes such losses, at least at low-moderate noise doses, silencing affected neurons. To address questions of whether, and how, cochlear synaptopathy and underlying mechanisms change as noise dose is varied, we assessed cochlear physiologic and histologic consequences of a range of exposures varied in duration from 15 min to 8 h and in level from 85 to 112 dB SPL. Exposures delivered to adult CBA/CaJ mice produced acute elevations in hair cell- and neural-based response thresholds ranging from trivial (∼5 dB) to large (∼50 dB), followed by varying degrees of recovery. Males appeared more noise vulnerable for some conditions of exposure. There was little to no inner hair cell (IHC) loss, but outer hair cell (OHC) loss could be substantial at highest frequencies for highest noise doses. Synapse loss was an early manifestation of noise injury and did not scale directly with either temporary or permanent threshold shift. With increasing noise dose, synapse loss grew to ∼50%, then declined for exposures yielding permanent hair cell injury/loss. All synaptopathic, but no non-synaptopathic exposures produced persistent neural response amplitude declines; those additionally yielding permanent OHC injury/loss also produced persistent reductions in OHC-based responses and exaggerated neural amplitude declines. Findings show that widespread cochlear synaptopathy can be present with and without noise-induced sensory cell loss and that differing patterns of cellular injury influence synaptopathic outcomes.
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Affiliation(s)
- Katharine A Fernandez
- Eaton-Peabody Laboratories, Massachusetts Eye & Ear, Boston, MA 02114, USA; Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
| | - Dan Guo
- Eaton-Peabody Laboratories, Massachusetts Eye & Ear, Boston, MA 02114, USA; Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
| | - Steven Micucci
- Eaton-Peabody Laboratories, Massachusetts Eye & Ear, Boston, MA 02114, USA
| | - Victor De Gruttola
- Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye & Ear, Boston, MA 02114, USA; Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
| | - Sharon G Kujawa
- Eaton-Peabody Laboratories, Massachusetts Eye & Ear, Boston, MA 02114, USA; Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115, USA.
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38
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Jeng JY, Ceriani F, Hendry A, Johnson SL, Yen P, Simmons DD, Kros CJ, Marcotti W. Hair cell maturation is differentially regulated along the tonotopic axis of the mammalian cochlea. J Physiol 2019; 598:151-170. [PMID: 31661723 PMCID: PMC6972525 DOI: 10.1113/jp279012] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 10/24/2019] [Indexed: 12/15/2022] Open
Abstract
Key points Outer hair cells (OHCs) enhance the sensitivity and the frequency tuning of the mammalian cochlea. Similar to the primary sensory receptor, the inner hair cells (IHCs), the mature functional characteristics of OHCs are acquired before hearing onset. We found that OHCs, like IHCs, fire spontaneous Ca2+‐induced action potentials (APs) during immature stages of development, which are driven by CaV1.3 Ca2+ channels. We also showed that the development of low‐ and high‐frequency hair cells is differentially regulated during pre‐hearing stages, with the former cells being more strongly dependent on experience‐independent Ca2+ action potential activity.
Abstract Sound amplification within the mammalian cochlea depends upon specialized hair cells, the outer hair cells (OHCs), which possess both sensory and motile capabilities. In various altricial rodents, OHCs become functionally competent from around postnatal day 7 (P7), before the primary sensory inner hair cells (IHCs), which become competent at about the onset of hearing (P12). The mechanisms responsible for the maturation of OHCs and their synaptic specialization remain poorly understood. We report that spontaneous Ca2+ activity in the immature cochlea, which is generated by CaV1.3 Ca2+ channels, differentially regulates the maturation of hair cells along the cochlea. Under near‐physiological recording conditions we found that, similar to IHCs, immature OHCs elicited spontaneous Ca2+ action potentials (APs), but only during the first few postnatal days. Genetic ablation of these APs in vivo, using CaV1.3−/− mice, prevented the normal developmental acquisition of mature‐like basolateral membrane currents in low‐frequency (apical) hair cells, such as IK,n (carried by KCNQ4 channels), ISK2 and IACh (α9α10nAChRs) in OHCs and IK,n and IK,f (BK channels) in IHCs. Electromotility and prestin expression in OHCs were normal in CaV1.3−/− mice. The maturation of high‐frequency (basal) hair cells was also affected in CaV1.3−/− mice, but to a much lesser extent than apical cells. However, a characteristic feature in CaV1.3−/− mice was the reduced hair cell size irrespective of their cochlear location. We conclude that the development of low‐ and high‐frequency hair cells is differentially regulated during development, with apical cells being more strongly dependent on experience‐independent Ca2+ APs. Outer hair cells (OHCs) enhance the sensitivity and the frequency tuning of the mammalian cochlea. Similar to the primary sensory receptor, the inner hair cells (IHCs), the mature functional characteristics of OHCs are acquired before hearing onset. We found that OHCs, like IHCs, fire spontaneous Ca2+‐induced action potentials (APs) during immature stages of development, which are driven by CaV1.3 Ca2+ channels. We also showed that the development of low‐ and high‐frequency hair cells is differentially regulated during pre‐hearing stages, with the former cells being more strongly dependent on experience‐independent Ca2+ action potential activity.
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Affiliation(s)
- Jing-Yi Jeng
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Federico Ceriani
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Aenea Hendry
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Stuart L Johnson
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Piece Yen
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | | | - Corné J Kros
- School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK
| | - Walter Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
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39
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Johnson SL, Safieddine S, Mustapha M, Marcotti W. Hair Cell Afferent Synapses: Function and Dysfunction. Cold Spring Harb Perspect Med 2019; 9:a033175. [PMID: 30617058 PMCID: PMC6886459 DOI: 10.1101/cshperspect.a033175] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
To provide a meaningful representation of the auditory landscape, mammalian cochlear hair cells are optimized to detect sounds over an incredibly broad range of frequencies and intensities with unparalleled accuracy. This ability is largely conferred by specialized ribbon synapses that continuously transmit acoustic information with high fidelity and sub-millisecond precision to the afferent dendrites of the spiral ganglion neurons. To achieve this extraordinary task, ribbon synapses employ a unique combination of molecules and mechanisms that are tailored to sounds of different frequencies. Here we review the current understanding of how the hair cell's presynaptic machinery and its postsynaptic afferent connections are formed, how they mature, and how their function is adapted for an accurate perception of sound.
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Affiliation(s)
- Stuart L Johnson
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Saaid Safieddine
- UMRS 1120, Institut Pasteur, Paris, France
- Sorbonne Universités, UPMC Université Paris 06, Complexité du Vivant, Paris, France
| | - Mirna Mustapha
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
- Department of Otolaryngology-Head & Neck Surgery, Stanford University, Stanford, California 94035
| | - Walter Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, United Kingdom
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40
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Liu S, Wang S, Zou L, Li J, Song C, Chen J, Hu Q, Liu L, Huang P, Xiong W. TMC1 is an essential component of a leak channel that modulates tonotopy and excitability of auditory hair cells in mice. eLife 2019; 8:47441. [PMID: 31661074 PMCID: PMC6853638 DOI: 10.7554/elife.47441] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 10/24/2019] [Indexed: 11/13/2022] Open
Abstract
Hearing sensation relies on the mechano-electrical transducer (MET) channel of cochlear hair cells, in which transmembrane channel-like 1 (TMC1) and transmembrane channel-like 2 (TMC2) have been proposed to be the pore-forming subunits in mammals. TMCs were also found to regulate biological processes other than MET in invertebrates, ranging from sensations to motor function. However, whether TMCs have a non-MET role remains elusive in mammals. Here, we report that in mouse hair cells, TMC1, but not TMC2, provides a background leak conductance, with properties distinct from those of the MET channels. By cysteine substitutions in TMC1, we characterized four amino acids that are required for the leak conductance. The leak conductance is graded in a frequency-dependent manner along the length of the cochlea and is indispensable for action potential firing. Taken together, our results show that TMC1 confers a background leak conductance in cochlear hair cells, which may be critical for the acquisition of sound-frequency and -intensity.
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Affiliation(s)
- Shuang Liu
- School of Life Sciences, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
| | - Shufeng Wang
- School of Life Sciences, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
| | - Linzhi Zou
- School of Life Sciences, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
| | - Jie Li
- School of Life Sciences, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
| | - Chenmeng Song
- School of Life Sciences, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
| | - Jiaofeng Chen
- School of Life Sciences, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
| | - Qun Hu
- School of Life Sciences, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
| | - Lian Liu
- School of Life Sciences, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
| | - Pingbo Huang
- Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology, Hong Kong, China.,State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China.,Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
| | - Wei Xiong
- School of Life Sciences, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, China
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41
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Saini S, Kaur C, Pal I, Kumar P, Jacob TG, Thakar A, Roy KK, Roy TS. Morphological development of the human cochlear nucleus. Hear Res 2019; 382:107784. [DOI: 10.1016/j.heares.2019.107784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 07/19/2019] [Accepted: 08/15/2019] [Indexed: 11/29/2022]
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42
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Dunbar LA, Patni P, Aguilar C, Mburu P, Corns L, Wells HRR, Delmaghani S, Parker A, Johnson S, Williams D, Esapa CT, Simon MM, Chessum L, Newton S, Dorning J, Jeyarajan P, Morse S, Lelli A, Codner GF, Peineau T, Gopal SR, Alagramam KN, Hertzano R, Dulon D, Wells S, Williams FM, Petit C, Dawson SJ, Brown SDM, Marcotti W, El‐Amraoui A, Bowl MR. Clarin-2 is essential for hearing by maintaining stereocilia integrity and function. EMBO Mol Med 2019; 11:e10288. [PMID: 31448880 PMCID: PMC6728604 DOI: 10.15252/emmm.201910288] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 11/21/2022] Open
Abstract
Hearing relies on mechanically gated ion channels present in the actin-rich stereocilia bundles at the apical surface of cochlear hair cells. Our knowledge of the mechanisms underlying the formation and maintenance of the sound-receptive structure is limited. Utilizing a large-scale forward genetic screen in mice, genome mapping and gene complementation tests, we identified Clrn2 as a new deafness gene. The Clrn2clarinet/clarinet mice (p.Trp4* mutation) exhibit a progressive, early-onset hearing loss, with no overt retinal deficits. Utilizing data from the UK Biobank study, we could show that CLRN2 is involved in human non-syndromic progressive hearing loss. Our in-depth morphological, molecular and functional investigations establish that while it is not required for initial formation of cochlear sensory hair cell stereocilia bundles, clarin-2 is critical for maintaining normal bundle integrity and functioning. In the differentiating hair bundles, lack of clarin-2 leads to loss of mechano-electrical transduction, followed by selective progressive loss of the transducing stereocilia. Together, our findings demonstrate a key role for clarin-2 in mammalian hearing, providing insights into the interplay between mechano-electrical transduction and stereocilia maintenance.
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Affiliation(s)
- Lucy A Dunbar
- Mammalian Genetics UnitMRC Harwell InstituteHarwellUK
| | - Pranav Patni
- Déficits Sensoriels ProgressifsInstitut PasteurINSERM UMR‐S 1120Sorbonne UniversitésParisFrance
| | | | | | - Laura Corns
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Helena RR Wells
- Department of Twin Research & Genetic EpidemiologyKing's College LondonLondonUK
| | - Sedigheh Delmaghani
- Déficits Sensoriels ProgressifsInstitut PasteurINSERM UMR‐S 1120Sorbonne UniversitésParisFrance
| | - Andrew Parker
- Mammalian Genetics UnitMRC Harwell InstituteHarwellUK
| | - Stuart Johnson
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | | | | | | | | | | | | | | | - Susan Morse
- Mammalian Genetics UnitMRC Harwell InstituteHarwellUK
| | - Andrea Lelli
- Génétique et Physiologie de l'AuditionInstitut PasteurINSERM UMR‐S 1120Collège de FranceSorbonne UniversitésParisFrance
| | | | - Thibault Peineau
- Laboratoire de Neurophysiologie de la Synapse AuditiveUniversité de BordeauxBordeauxFrance
| | - Suhasini R Gopal
- Department of Otolaryngology – Head and Neck SurgeryUniversity Hospitals Cleveland Medical CenterCase Western Reserve UniversityClevelandOHUSA
| | - Kumar N Alagramam
- Department of Otolaryngology – Head and Neck SurgeryUniversity Hospitals Cleveland Medical CenterCase Western Reserve UniversityClevelandOHUSA
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head and Neck Surgery, Anatomy and Neurobiology and Institute for Genome SciencesUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Didier Dulon
- Laboratoire de Neurophysiologie de la Synapse AuditiveUniversité de BordeauxBordeauxFrance
| | - Sara Wells
- Mary Lyon CentreMRC Harwell InstituteHarwellUK
| | - Frances M Williams
- Department of Twin Research & Genetic EpidemiologyKing's College LondonLondonUK
| | - Christine Petit
- Génétique et Physiologie de l'AuditionInstitut PasteurINSERM UMR‐S 1120Collège de FranceSorbonne UniversitésParisFrance
| | | | | | - Walter Marcotti
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Aziz El‐Amraoui
- Déficits Sensoriels ProgressifsInstitut PasteurINSERM UMR‐S 1120Sorbonne UniversitésParisFrance
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Liu H, Lu J, Wang Z, Song L, Wang X, Li GL, Wu H. Functional alteration of ribbon synapses in inner hair cells by noise exposure causing hidden hearing loss. Neurosci Lett 2019; 707:134268. [DOI: 10.1016/j.neulet.2019.05.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/23/2019] [Accepted: 05/13/2019] [Indexed: 01/30/2023]
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Bardhan T, Jeng J, Waldmann M, Ceriani F, Johnson SL, Olt J, Rüttiger L, Marcotti W, Holley MC. Gata3 is required for the functional maturation of inner hair cells and their innervation in the mouse cochlea. J Physiol 2019; 597:3389-3406. [PMID: 31069810 PMCID: PMC6636704 DOI: 10.1113/jp277997] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 05/07/2019] [Indexed: 01/14/2023] Open
Abstract
KEY POINTS The physiological maturation of auditory hair cells and their innervation requires precise temporal and spatial control of cell differentiation. The transcription factor gata3 is essential for the earliest stages of auditory system development and for survival and synaptogenesis in auditory sensory afferent neurons. We show that during postnatal development in the mouse inner ear gata3 is required for the biophysical maturation, growth and innervation of inner hair cells; in contrast, it is required only for the survival of outer hair cells. Loss of gata3 in inner hair cells causes progressive hearing loss and accounts for at least some of the deafness associated with the human hypoparathyroidism, deafness and renal anomaly (HDR) syndrome. The results show that gata3 is critical for later stages of mammalian auditory system development where it plays distinct, complementary roles in the coordinated maturation of sensory hair cells and their innervation. ABSTRACT The zinc finger transcription factor gata3 regulates inner ear development from the formation of the embryonic otic placode. Throughout development, gata3 is expressed dynamically in all the major cochlear cell types. Its role in afferent formation is well established but its possible involvement in hair cell maturation remains unknown. Here, we find that in heterozygous gata3 null mice (gata3+/- ) outer hair cells (OHCs) differentiate normally but their numbers are significantly lower. In contrast, inner hair cells (IHCs) survive normally but they fail to acquire adult basolateral membrane currents, retain pre-hearing current and efferent innervation profiles and have fewer ribbon synapses. Targeted deletion of gata3 driven by otoferlin-cre recombinase (gata3fl/fl otof-cre+/- ) in IHCs does not affect OHCs or the number of IHC afferent synapses but it leads to a failure in IHC maturation comparable to that observed in gata3+/- mice. Auditory brainstem responses in gata3fl/fl otof-cre+/- mice reveal progressive hearing loss that becomes profound by 6-7 months, whilst distortion product otoacoustic emissions are no different to control animals up to this age. Our results, alongside existing data, indicate that gata3 has specific, complementary functions in different cell types during inner ear development and that its continued expression in the sensory epithelium orchestrates critical aspects of physiological development and neural connectivity. Furthermore, our work indicates that hearing loss in human hypoparathyroidism, deafness and renal anomaly (HDR) syndrome arises from functional deficits in IHCs as well as loss of function from OHCs and both afferent and efferent neurons.
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MESH Headings
- Animals
- Cell Differentiation/physiology
- Cochlea/metabolism
- Cochlea/physiology
- GATA3 Transcription Factor/metabolism
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/physiology
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/physiology
- Hair Cells, Vestibular/metabolism
- Hair Cells, Vestibular/physiology
- Hearing/physiology
- Hearing Loss/metabolism
- Hearing Loss/physiopathology
- Membrane Proteins/metabolism
- Mice, Knockout
- Mice, Transgenic
- Sensory Receptor Cells/metabolism
- Sensory Receptor Cells/physiology
- Synapses/metabolism
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Affiliation(s)
- Tanaya Bardhan
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Jing‐Yi Jeng
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Marco Waldmann
- Department of OtolaryngologyTübingen Hearing Research CenterSection of Physiological Acoustics and CommunicationUniversity of Tübingen72076TübingenGermany
| | - Federico Ceriani
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | | | - Jennifer Olt
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Lukas Rüttiger
- Department of OtolaryngologyTübingen Hearing Research CenterSection of Physiological Acoustics and CommunicationUniversity of Tübingen72076TübingenGermany
| | - Walter Marcotti
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
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Mammano F. Inner Ear Connexin Channels: Roles in Development and Maintenance of Cochlear Function. Cold Spring Harb Perspect Med 2019; 9:a033233. [PMID: 30181354 PMCID: PMC6601451 DOI: 10.1101/cshperspect.a033233] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Connexin 26 and connexin 30 are the prevailing isoforms in the epithelial and connective tissue gap junction systems of the developing and mature cochlea. The most frequently encountered variants of the genes that encode these connexins, which are transcriptionally coregulated, determine complete loss of protein function and are the predominant cause of prelingual hereditary deafness. Reducing connexin 26 expression by Cre/loxP recombination in the inner ear of adult mice results in a decreased endocochlear potential, increased hearing thresholds, and loss of >90% of outer hair cells, indicating that this connexin is essential for maintenance of cochlear function. In the developing cochlea, connexins are necessary for intercellular calcium signaling activity. Ribbon synapses and basolateral membrane currents fail to mature in inner hair cells of mice that are born with reduced connexin expression, even though hair cells do not express any connexin. In contrast, pannexin 1, an alternative mediator of intercellular signaling, is dispensable for hearing acquisition and auditory function.
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Affiliation(s)
- Fabio Mammano
- University of Padova, Department of Physics and Astronomy "G. Galilei," Padova 35129, Italy
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China
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Carignano C, Barila EP, Rías EI, Dionisio L, Aztiria E, Spitzmaul G. Inner Hair Cell and Neuron Degeneration Contribute to Hearing Loss in a DFNA2-Like Mouse Model. Neuroscience 2019; 410:202-216. [PMID: 31102762 DOI: 10.1016/j.neuroscience.2019.05.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/03/2019] [Accepted: 05/07/2019] [Indexed: 01/19/2023]
Abstract
DFNA2 is a progressive deafness caused by mutations in the voltage-activated potassium channel KCNQ4. Hearing loss develops with age from a mild increase in the hearing threshold to profound deafness. Studies using transgenic mice for Kcnq4 expressed in a mixed background demonstrated the implication of outer hair cells at the initial phase. However, it could not explain the last phase mechanisms of the disease. Genetic backgrounds are known to influence disease expressivity. To unmask the cause of profound deafness phenotype, we backcrossed the Kcnq4 knock-out allele to the inbred strain C3H/HeJ and investigated inner and outer hair cell and spiral ganglion neuron degeneration across the lifespan. In addition to the already reported outer hair cell death, the C3H/HeJ strain also exhibited inner hair cell and spiral ganglion neuron death. We tracked the spatiotemporal survival of cochlear cells by plotting cytocochleograms and neuronal counts at different ages. Cell loss progressed from basal to apical turns with age. Interestingly, the time-course of cell degeneration was different for each cell-type. While for outer hair cells it was already present by week 3, inner hair cell and neuronal loss started 30 weeks later. We also established that outer hair cell loss kinetics slowed down from basal to apical regions correlating with KCNQ4 expression pattern determined in wild-type mice. Our findings indicate that KCNQ4 plays differential roles in each cochlear cell-type impacting in their survival ability. Inner hair cell and spiral ganglion neuron death generates severe hearing loss that could be associated with the last phase of DFNA2.
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Affiliation(s)
- Camila Carignano
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina
| | - Esteban Pablo Barila
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina
| | - Ezequiel Ignacio Rías
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina.; Departamento de Biología, Bioquímica y Farmacia (BByF)-UNS, San Juan 670, 8000 Bahía Blanca, Argentina
| | - Leonardo Dionisio
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina.; Departamento de Biología, Bioquímica y Farmacia (BByF)-UNS, San Juan 670, 8000 Bahía Blanca, Argentina
| | - Eugenio Aztiria
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina.; Departamento de Biología, Bioquímica y Farmacia (BByF)-UNS, San Juan 670, 8000 Bahía Blanca, Argentina
| | - Guillermo Spitzmaul
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina.; Departamento de Biología, Bioquímica y Farmacia (BByF)-UNS, San Juan 670, 8000 Bahía Blanca, Argentina..
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Kearney G, Zorrilla de San Martín J, Vattino LG, Elgoyhen AB, Wedemeyer C, Katz E. Developmental Synaptic Changes at the Transient Olivocochlear-Inner Hair Cell Synapse. J Neurosci 2019; 39:3360-3375. [PMID: 30755493 PMCID: PMC6495135 DOI: 10.1523/jneurosci.2746-18.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/04/2019] [Accepted: 01/30/2019] [Indexed: 12/18/2022] Open
Abstract
In the mature mammalian cochlea, inner hair cells (IHCs) are mainly innervated by afferent fibers that convey sound information to the CNS. During postnatal development, however, medial olivocochlear (MOC) efferent fibers transiently innervate the IHCs. The MOC-IHC synapse, functional from postnatal day 0 (P0) to hearing onset (P12), undergoes dramatic changes in the sensitivity to acetylcholine (ACh) and in the expression of key postsynaptic proteins. To evaluate whether there are associated changes in the properties of ACh release during this period, we used a cochlear preparation from mice of either sex at P4, P6-P7, and P9-P11 and monitored transmitter release from MOC terminals in voltage-clamped IHCs in the whole-cell configuration. The quantum content increased 5.6× from P4 to P9-P11 due to increases in the size and replenishment rate of the readily releasable pool of synaptic vesicles without changes in their probability of release or quantum size. This strengthening in transmission was accompanied by changes in short-term plasticity properties, which switched from facilitation at P4 to depression at P9-P11. We have previously shown that at P9-P11, ACh release is supported by P/Q- and N-type voltage-gated calcium channels (VGCCs) and negatively regulated by BK potassium channels activated by Ca2+ influx through L-type VGCCs. We now show that at P4 and P6-P7, release is mediated by P/Q-, R- and L-type VGCCs. Interestingly, L-type VGCCs have a dual role: they both support release and fuel BK channels, suggesting that at immature stages presynaptic proteins involved in release are less compartmentalized.SIGNIFICANCE STATEMENT During postnatal development before the onset of hearing, cochlear inner hair cells (IHCs) present spontaneous Ca2+ action potentials that release glutamate at the first auditory synapse in the absence of sound stimulation. The IHC Ca2+ action potential frequency pattern, which is crucial for the correct establishment and function of the auditory system, is regulated by the efferent medial olivocochlear (MOC) system that transiently innervates IHCs during this period. We show here that developmental changes in synaptic strength and synaptic plasticity properties at the MOC-IHC synapse upon MOC fiber activation at different frequencies might be crucial for tightly shaping the pattern of afferent activity during this critical period.
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Affiliation(s)
- Graciela Kearney
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Ciudad Autónoma de Buenos Aires, Argentina
| | - Javier Zorrilla de San Martín
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Ciudad Autónoma de Buenos Aires, Argentina
| | - Lucas G Vattino
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Ciudad Autónoma de Buenos Aires, Argentina
| | - Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Ciudad Autónoma de Buenos Aires, Argentina
- Instituto de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, 1121 Ciudad Autónoma de Buenos Aires, Argentina, and
| | - Carolina Wedemeyer
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Ciudad Autónoma de Buenos Aires, Argentina
| | - Eleonora Katz
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Ciudad Autónoma de Buenos Aires, Argentina,
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, C1428EGA Ciudad Autónoma de Buenos Aires, Argentina
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Ca v3.2 T-Type Calcium Channels Are Physiologically Mandatory for the Auditory System. Neuroscience 2019; 409:81-100. [PMID: 31029730 DOI: 10.1016/j.neuroscience.2019.04.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 04/11/2019] [Accepted: 04/12/2019] [Indexed: 02/07/2023]
Abstract
Voltage-gated Ca2+ channels (VGCCs) play key roles in auditory perception and information processing within the inner ear and brainstem. Pharmacological inhibition of low voltage-activated (LVA) T-type Ca2+ channels is related to both age- and noise induced hearing loss in experimental animals and may represent a promising approach to the treatment of auditory impairment of various etiologies. Within the LVA Ca2+ channel subgroup, Cav3.2 is the most prominently expressed T-type channel entity in the cochlea and auditory brainstem. Thus, we performed a complete gender specific click and tone burst based auditory brainstem response (ABR) analysis of Cav3.2+/- and Cav3.2-/- mice, including i.a. temporal progression in hearing loss, amplitude growth function and wave latency analysis as well as a cochlear qPCR based evaluation of other VGCCs transcripts. Our results, based on a self-programmed automated wavelet approach, demonstrate that both heterozygous and Cav3.2 null mutant mice exhibit age-dependent increases in hearing thresholds at 5 months of age. In addition, complex alterations in WI-IV amplitudes and latencies were detected that were not attributable to alterations in the expression of other VGCCs in the auditory tract. Our results clearly demonstrate the important physiological role of Cav3.2 VGCCs in the spatiotemporal organization of auditory processing in young adult mice and suggest potential pharmacological targets for interventions in the future.
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49
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Ingham NJ, Pearson SA, Vancollie VE, Rook V, Lewis MA, Chen J, Buniello A, Martelletti E, Preite L, Lam CC, Weiss FD, Powis Z, Suwannarat P, Lelliott CJ, Dawson SJ, White JK, Steel KP. Mouse screen reveals multiple new genes underlying mouse and human hearing loss. PLoS Biol 2019; 17:e3000194. [PMID: 30973865 PMCID: PMC6459510 DOI: 10.1371/journal.pbio.3000194] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 03/07/2019] [Indexed: 11/23/2022] Open
Abstract
Adult-onset hearing loss is very common, but we know little about the underlying molecular pathogenesis impeding the development of therapies. We took a genetic approach to identify new molecules involved in hearing loss by screening a large cohort of newly generated mouse mutants using a sensitive electrophysiological test, the auditory brainstem response (ABR). We review here the findings from this screen. Thirty-eight unexpected genes associated with raised thresholds were detected from our unbiased sample of 1,211 genes tested, suggesting extreme genetic heterogeneity. A wide range of auditory pathophysiologies was found, and some mutant lines showed normal development followed by deterioration of responses, revealing new molecular pathways involved in progressive hearing loss. Several of the genes were associated with the range of hearing thresholds in the human population and one, SPNS2, was involved in childhood deafness. The new pathways required for maintenance of hearing discovered by this screen present new therapeutic opportunities. This study uses an electrophysiological screen of over a thousand new mutant mouse lines to identify 38 new genes underlying deafness, some associated with human hearing function, revealing a wide range of molecular and pathological mechanisms. Progressive hearing loss with age is extremely common in the population, leading to difficulties in understanding speech, increased social isolation, and associated depression. We know it has a significant heritability, but so far we know very little about the molecular pathways leading to hearing loss, hampering the development of treatments. Here, we describe a large-scale screen of 1,211 new targeted mouse mutant lines, resulting in the identification of 38 genes underlying hearing loss that were not previously suspected of involvement in hearing. Some of these genes reveal molecular pathways that may be useful targets for drug development. Our further analysis of the genes identified and the varied pathological mechanisms within the ear resulting from the mutations suggests that hearing loss is an extremely heterogeneous disorder and may have as many as 1,000 genes involved.
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Affiliation(s)
- Neil J. Ingham
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | | | | | - Victoria Rook
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Morag A. Lewis
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Jing Chen
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Annalisa Buniello
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Elisa Martelletti
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Lorenzo Preite
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Chi Chung Lam
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Felix D. Weiss
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Zӧe Powis
- Department of Emerging Genetics Medicine, Ambry Genetics, Aliso Viejo, California, United States of America
| | - Pim Suwannarat
- Mid-Atlantic Permanente Medical Group, Rockville, Maryland, United States of America
| | | | - Sally J. Dawson
- UCL Ear Institute, University College London, London, United Kingdom
| | | | - Karen P. Steel
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- * E-mail:
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50
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Wong VSC, Meadows M, Goldberg D, Willis DE. Semaphorin 3A induces acute changes in membrane excitability in spiral ganglion neurons in vitro. Eur J Neurosci 2019; 50:1741-1758. [PMID: 30706560 DOI: 10.1111/ejn.14360] [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: 07/20/2018] [Revised: 01/10/2019] [Accepted: 01/23/2019] [Indexed: 11/29/2022]
Abstract
The development and survival of spiral ganglion neurons (SGNs) are dependent on multiple trophic factors as well as membrane electrical activity. Semaphorins (Sema) constitute a family of membrane-associated and secreted proteins that have garnered significant attention as a potential SGN "navigator" during cochlea development. Previous studies using mutant mice demonstrated that Sema3A plays a role in the SGN pathfinding. The mechanisms, however, by which Sema3A shapes SGNs firing behavior are not known. In these studies, we found that Sema3A plays a novel role in regulating SGN resting membrane potential and excitability. Using dissociated SGN from pre-hearing (P3-P5) and post-hearing mice (P12-P15), we recorded membrane potentials using whole-cell patch clamp recording techniques in apical and basal SGN populations. Recombinant Sema3A was applied to examine the effects on intrinsic membrane properties and action potentials evoked by current injections. Apical and basal SGNs from newborn mice treated with recombinant Sema3A (100 ng/ml) displayed a higher resting membrane potential, higher threshold, decreased amplitude, and prolonged latency and duration of spikes. Although a similar phenomenon was observed in SGNs from post-hearing mice, the resting membrane potential was essentially indistinguishable before and after Sema3A exposure. Sema3A-mediated changes in membrane excitability were associated with a significant decrease in K+ and Ca2+ currents. Sema3A acts through linopirdine-sensitive K+ channels in apical, but not in the basal SGNs. Therefore, Sema3A induces differential effects in SGN membrane excitability that are dependent on age and location, and constitutes an additional early and novel effect of Sema3A SGNs in vitro.
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Affiliation(s)
| | - Marc Meadows
- The Vollum Institute, Oregon Health and Science University, Portland, Oregon
| | - David Goldberg
- The Burke Neurological Institute, White Plains, New York
| | - Dianna E Willis
- The Burke Neurological Institute, White Plains, New York.,Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York
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