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Steenken F, Pektaş A, Köppl C. Age-related changes in olivocochlear efferent innervation in gerbils. Front Synaptic Neurosci 2024; 16:1422330. [PMID: 38887655 PMCID: PMC11180762 DOI: 10.3389/fnsyn.2024.1422330] [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: 04/23/2024] [Accepted: 05/20/2024] [Indexed: 06/20/2024] Open
Abstract
Introduction Age-related hearing difficulties have a complex etiology that includes degenerative processes in the sensory cochlea. The cochlea comprises the start of the afferent, ascending auditory pathway, but also receives efferent feedback innervation by two separate populations of brainstem neurons: the medial olivocochlear and lateral olivocochlear pathways, innervating the outer hair cells and auditory-nerve fibers synapsing on inner hair cells, respectively. Efferents are believed to improve hearing under difficult conditions, such as high background noise. Here, we compare olivocochlear efferent innervation density along the tonotopic axis in young-adult and aged gerbils (at ~50% of their maximum lifespan potential), a classic animal model for age-related hearing loss. Methods Efferent synaptic terminals and sensory hair cells were labeled immunohistochemically with anti-synaptotagmin and anti-myosin VIIa, respectively. Numbers of hair cells, numbers of efferent terminals, and the efferent innervation area were quantified at seven tonotopic locations along the organ of Corti. Results The tonotopic distribution of olivocochlear innervation in the gerbil was similar to that previously shown for other species, with a slight apical cochlear bias in presumed lateral olivocochlear innervation (inner-hair-cell region), and a broad mid-cochlear peak for presumed medial olivocochlear innervation (outer-hair-cell region). We found significant, age-related declines in overall efferent innervation to both the inner-hair-cell and the outer-hair-cell region. However, when accounting for the age-related losses in efferent target structures, the innervation density of surviving elements proved unchanged in the inner-hair-cell region. For outer hair cells, a pronounced increase of orphaned outer hair cells, i.e., lacking efferent innervation, was observed. Surviving outer hair cells that were still efferently innervated retained a nearly normal innervation. Discussion A comparison across species suggests a basic aging scenario where outer hair cells, type-I afferents, and the efferents associated with them, steadily die away with advancing age, but leave the surviving cochlear circuitry largely intact until an advanced age, beyond 50% of a species' maximum lifespan potential. In the outer-hair-cell region, MOC degeneration may precede outer-hair-cell death, leaving a putatively transient population of orphaned outer hair cells that are no longer under efferent control.
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Affiliation(s)
- Friederike Steenken
- Department of Neuroscience, School of Medicine and Health Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Cluster of Excellence “Hearing4all”, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Asli Pektaş
- Department of Neuroscience, School of Medicine and Health Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Christine Köppl
- Department of Neuroscience, School of Medicine and Health Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Cluster of Excellence “Hearing4all”, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Research Centre Neurosensory Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
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David S, Pinter K, Nguyen KK, Lee DS, Lei Z, Sokolova Y, Sheets L, Kindt KS. Kif1a and intact microtubules maintain synaptic-vesicle populations at ribbon synapses in zebrafish hair cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.20.595037. [PMID: 38903095 PMCID: PMC11188139 DOI: 10.1101/2024.05.20.595037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Sensory hair cells of the inner ear utilize specialized ribbon synapses to transmit sensory stimuli to the central nervous system. This sensory transmission necessitates rapid and sustained neurotransmitter release, which relies on a large pool of synaptic vesicles at the hair-cell presynapse. Work in neurons has shown that kinesin motor proteins traffic synaptic material along microtubules to the presynapse, but how new synaptic material reaches the presynapse in hair cells is not known. We show that the kinesin motor protein Kif1a and an intact microtubule network are necessary to enrich synaptic vesicles at the presynapse in hair cells. We use genetics and pharmacology to disrupt Kif1a function and impair microtubule networks in hair cells of the zebrafish lateral-line system. We find that these manipulations decrease synaptic-vesicle populations at the presynapse in hair cells. Using electron microscopy, along with in vivo calcium imaging and electrophysiology, we show that a diminished supply of synaptic vesicles adversely affects ribbon-synapse function. Kif1a mutants exhibit dramatic reductions in spontaneous vesicle release and evoked postsynaptic calcium responses. Additionally, we find that kif1a mutants exhibit impaired rheotaxis, a behavior reliant on the ability of hair cells in the lateral line to respond to sustained flow stimuli. Overall, our results demonstrate that Kif1a-based microtubule transport is critical to enrich synaptic vesicles at the active zone in hair cells, a process that is vital for proper ribbon-synapse function.
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Affiliation(s)
- Sandeep David
- Section on Sensory Cell Development and Function, National Institute on Deafness and other Communication Disorders, Bethesda, MD, USA
- National Institutes of Health-Brown University Graduate Partnership Program, Bethesda, MD, USA
| | - Katherine Pinter
- Section on Sensory Cell Development and Function, National Institute on Deafness and other Communication Disorders, Bethesda, MD, USA
| | - Keziah-Khue Nguyen
- Department of Otolaryngology - Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - David S Lee
- Department of Otolaryngology - Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Zhengchang Lei
- Section on Sensory Cell Development and Function, National Institute on Deafness and other Communication Disorders, Bethesda, MD, USA
| | - Yuliya Sokolova
- Advanced Imaging Core, National Institute on Deafness and other Communication Disorders, Bethesda, MD, USA
| | - Lavinia Sheets
- Department of Otolaryngology - Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Katie S Kindt
- Section on Sensory Cell Development and Function, National Institute on Deafness and other Communication Disorders, Bethesda, MD, USA
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Rodríguez-Morales R. Sensing in the dark: Constructive evolution of the lateral line system in blind populations of Astyanax mexicanus. Ecol Evol 2024; 14:e11286. [PMID: 38654714 PMCID: PMC11036076 DOI: 10.1002/ece3.11286] [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: 12/04/2023] [Revised: 03/26/2024] [Accepted: 04/03/2024] [Indexed: 04/26/2024] Open
Abstract
Cave-adapted animals evolve a suite of regressive and constructive traits that allow survival in the dark. Most studies aiming at understanding cave animal evolution have focused on the genetics and environmental underpinnings of regressive traits, with special emphasis on vision loss. Possibly as a result of vision loss, other non-visual sensory systems have expanded and compensated in cave species. For instance, in many cave-dwelling fish species, including the blind cavefish of the Mexican tetra, Astyanax mexicanus, a major non-visual mechanosensory system called the lateral line, compensated for vision loss through morphological expansions. While substantial work has shed light on constructive adaptation of this system, there are still many open questions regarding its developmental origin, synaptic plasticity, and overall adaptive value. This review provides a snapshot of the current state of knowledge of lateral line adaption in A. mexicanus, with an emphasis on anatomy, synaptic plasticity, and behavior. Multiple open avenues for future research in this system, and how these can be leveraged as tools for both evolutionary biology and evolutionary medicine, are discussed.
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Affiliation(s)
- Roberto Rodríguez-Morales
- Department of Anatomy & Neurobiology, School of Medicine University of Puerto Rico San Juan Puerto Rico
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4
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Jukic A, Lei Z, Cebul ER, Pinter K, Mosqueda N, David S, Tarchini B, Kindt K. Presynaptic Nrxn3 is essential for ribbon-synapse assembly in hair cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580267. [PMID: 38410471 PMCID: PMC10896334 DOI: 10.1101/2024.02.14.580267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Hair cells of the inner ear rely on specialized ribbon synapses to transmit sensory information to the central nervous system. The molecules required to assemble these synapses are not fully understood. We show that Nrxn3, a presynaptic adhesion molecule, is critical for ribbon-synapse assembly in hair cells. In both mouse and zebrafish models, loss of Nrxn3 results in significantly fewer intact ribbon synapses. In zebrafish we demonstrate that a 60% loss of synapses in nrxn3 mutants dramatically reduces both presynaptic responses in hair cells and postsynaptic responses in afferent neurons. Despite a reduction in synapse function in this model, we find no deficits in the acoustic startle response, a behavior reliant on these synapses. Overall, this work demonstrates that Nrxn3 is a critical and conserved molecule required to assemble ribbon synapses. Understanding how ribbon synapses assemble is a key step towards generating novel therapies to treat forms of age-related and noise-induced hearing loss that occur due to loss of ribbon synapses.
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Affiliation(s)
- Alma Jukic
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Zhengchang Lei
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Elizabeth R Cebul
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Katherine Pinter
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Natalie Mosqueda
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | - Sandeep David
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
| | | | - Katie Kindt
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, Bethesda, MD, 20892, USA
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Tichacek O, Mistrík P, Jungwirth P. From the outer ear to the nerve: A complete computer model of the peripheral auditory system. Hear Res 2023; 440:108900. [PMID: 37944408 DOI: 10.1016/j.heares.2023.108900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 10/03/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023]
Abstract
Computer models of the individual components of the peripheral auditory system - the outer, middle, and inner ears and the auditory nerve - have been developed in the past, with varying level of detail, breadth, and faithfulness of the underlying parameters. Building on previous work, we advance the modeling of the ear by presenting a complete, physiologically justified, bottom-up computer model based on up-to-date experimental data that integrates all of these parts together seamlessly. The detailed bottom-up design of the present model allows for the investigation of partial hearing mechanisms and their defects, including genetic, molecular, and microscopic factors. Also, thanks to the completeness of the model, one can study microscopic effects in the context of their implications on hearing as a whole, enabling the correlation with neural recordings and non-invasive psychoacoustic methods. Such a model is instrumental for advancing quantitative understanding of the mechanism of hearing, for investigating various forms of hearing impairment, as well as for devising next generation hearing aids and cochlear implants.
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Affiliation(s)
- Ondrej Tichacek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 160 00 Prague 6, Czech Republic.
| | | | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 160 00 Prague 6, Czech Republic.
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Michanski S, Henneck T, Mukhopadhyay M, Steyer AM, Gonzalez PA, Grewe K, Ilgen P, Gültas M, Fornasiero EF, Jakobs S, Möbius W, Vogl C, Pangršič T, Rizzoli SO, Wichmann C. Age-dependent structural reorganization of utricular ribbon synapses. Front Cell Dev Biol 2023; 11:1178992. [PMID: 37635868 PMCID: PMC10447907 DOI: 10.3389/fcell.2023.1178992] [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: 03/03/2023] [Accepted: 07/17/2023] [Indexed: 08/29/2023] Open
Abstract
In mammals, spatial orientation is synaptically-encoded by sensory hair cells of the vestibular labyrinth. Vestibular hair cells (VHCs) harbor synaptic ribbons at their presynaptic active zones (AZs), which play a critical role in molecular scaffolding and facilitate synaptic release and vesicular replenishment. With advancing age, the prevalence of vestibular deficits increases; yet, the underlying mechanisms are not well understood and the possible accompanying morphological changes in the VHC synapses have not yet been systematically examined. We investigated the effects of maturation and aging on the ultrastructure of the ribbon-type AZs in murine utricles using various electron microscopic techniques and combined them with confocal and super-resolution light microscopy as well as metabolic imaging up to 1 year of age. In older animals, we detected predominantly in type I VHCs the formation of floating ribbon clusters, mostly consisting of newly synthesized ribbon material. Our findings suggest that VHC ribbon-type AZs undergo dramatic structural alterations upon aging.
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Affiliation(s)
- Susann Michanski
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
| | - Timo Henneck
- Biology Bachelor Program, University of Göttingen, Göttingen, Germany
| | - Mohona Mukhopadhyay
- Experimental Otology Group, InnerEarLab, Department of Otolaryngology, Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
| | - Anna M. Steyer
- Electron Microscopy-City Campus, Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), University of Göttingen, Göttingen, Germany
| | - Paola Agüi Gonzalez
- Department for Neuro-and Sensory Physiology, University Medical Center Göttingen, Center for Biostructural Imaging of Neurodegeneration (BIN), Göttingen, Germany
| | - Katharina Grewe
- Department for Neuro-and Sensory Physiology, University Medical Center Göttingen, Center for Biostructural Imaging of Neurodegeneration (BIN), Göttingen, Germany
| | - Peter Ilgen
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Translational Neuroinflammation and Automated Microscopy TNM, Göttingen, Germany
| | - Mehmet Gültas
- Faculty of Agriculture, South Westphalia University of Applied Sciences, Soest, Germany
| | - Eugenio F. Fornasiero
- Department for Neuro-and Sensory Physiology, University Medical Center Göttingen, Center for Biostructural Imaging of Neurodegeneration (BIN), Göttingen, Germany
| | - Stefan Jakobs
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Translational Neuroinflammation and Automated Microscopy TNM, Göttingen, Germany
| | - Wiebke Möbius
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
- Electron Microscopy-City Campus, Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Christian Vogl
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Presynaptogenesis and Intracellular Transport in Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience Group, Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Tina Pangršič
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
- Experimental Otology Group, InnerEarLab, Department of Otolaryngology, Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
| | - Silvio O. Rizzoli
- Department for Neuro-and Sensory Physiology, University Medical Center Göttingen, Center for Biostructural Imaging of Neurodegeneration (BIN), Göttingen, Germany
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
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Vijayakumar KA, Cho GW, Maharajan N, Jang CH. A Review on Peripheral Tinnitus, Causes, and Treatments from the Perspective of Autophagy. Exp Neurobiol 2022; 31:232-242. [PMID: 36050223 PMCID: PMC9471415 DOI: 10.5607/en22002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 08/03/2022] [Accepted: 08/10/2022] [Indexed: 01/18/2023] Open
Abstract
Tinnitus is the perception of phantom noise without any external auditory sources. The degeneration of the function or activity of the peripheral or central auditory nervous systems is one of the causes of tinnitus. This damage has numerous causes, such as loud noise, aging, and ototoxicity. All these sources excite the cells of the auditory pathway, producing reactive oxygen species that leads to the death of sensory neural hair cells. This causes involuntary movement of the tectorial membrane, resulting in the buzzing noise characteristic of tinnitus. Autophagy is an evolutionarily conserved catabolic scavenging activity inside a cell that has evolved as a cell survival mechanism. Numerous studies have demonstrated the effect of autophagy against oxidative stress, which is one of the reasons for cell excitation. This review compiles several studies that highlight the role of autophagy in protecting sensory neural hair cells against oxidative stress-induced damage. This could facilitate the development of strategies to treat tinnitus by activating autophagy.
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Affiliation(s)
- Karthikeyan A Vijayakumar
- Department of Biology, College of Natural Science, Chosun University, Gwangju 61452, Korea.,BK21 FOUR Education Research Group for Age-Associated Disorder Control Technology, Department of Integrative Biological Science, Chosun University, Gwangju 61452, Korea
| | - Gwang-Won Cho
- Department of Biology, College of Natural Science, Chosun University, Gwangju 61452, Korea.,BK21 FOUR Education Research Group for Age-Associated Disorder Control Technology, Department of Integrative Biological Science, Chosun University, Gwangju 61452, Korea
| | - Nagarajan Maharajan
- Department of Biology, College of Natural Science, Chosun University, Gwangju 61452, Korea.,BK21 FOUR Education Research Group for Age-Associated Disorder Control Technology, Department of Integrative Biological Science, Chosun University, Gwangju 61452, Korea
| | - Chul Ho Jang
- Department of Otolaryngology, Chonnam National University Medical School, Gwangju 61469, Korea
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Spaiardi P, Marcotti W, Masetto S, Johnson SL. Signal transmission in mature mammalian vestibular hair cells. Front Cell Neurosci 2022; 16:806913. [PMID: 35936492 PMCID: PMC9353129 DOI: 10.3389/fncel.2022.806913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 06/27/2022] [Indexed: 11/13/2022] Open
Abstract
The maintenance of balance and gaze relies on the faithful and rapid signaling of head movements to the brain. In mammals, vestibular organs contain two types of sensory hair cells, type-I and type-II, which convert the head motion-induced movement of their hair bundles into a graded receptor potential that drives action potential activity in their afferent fibers. While signal transmission in both hair cell types involves Ca2+-dependent quantal release of glutamate at ribbon synapses, type-I cells appear to also exhibit a non-quantal mechanism that is believed to increase transmission speed. However, the reliance of mature type-I hair cells on non-quantal transmission remains unknown. Here we investigated synaptic transmission in mammalian utricular hair cells using patch-clamp recording of Ca2+ currents and changes in membrane capacitance (ΔCm). We found that mature type-II hair cells showed robust exocytosis with a high-order dependence on Ca2+ entry. By contrast, exocytosis was approximately 10 times smaller in type-I hair cells. Synaptic vesicle exocytosis was largely absent in mature vestibular hair cells of CaV1.3 (CaV1.3−/−) and otoferlin (Otof−/−) knockout mice. Even though Ca2+-dependent exocytosis was small in type-I hair cells of wild-type mice, or absent in CaV1.3−/− and Otof−/−mice, these cells were able to drive action potential activity in the postsynaptic calyces. This supports a functional role for non-quantal synaptic transmission in type-I cells. The large vesicle pools in type-II cells would facilitate sustained transmission of tonic or low-frequency signals. In type-I cells, the restricted vesicle pool size, together with a rapid non-quantal mechanism, could allow them to sustain high-frequency phasic signal transmission at their specialized large calyceal synapses.
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Affiliation(s)
- Paolo Spaiardi
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - 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 Behavioural 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
- *Correspondence: Stuart L. Johnson
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Contini D, Holstein GR, Art JJ. Simultaneous Dual Recordings From Vestibular Hair Cells and Their Calyx Afferents Demonstrate Multiple Modes of Transmission at These Specialized Endings. Front Neurol 2022; 13:891536. [PMID: 35899268 PMCID: PMC9310783 DOI: 10.3389/fneur.2022.891536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/02/2022] [Indexed: 11/18/2022] Open
Abstract
In the vestibular periphery, transmission via conventional synaptic boutons is supplemented by post-synaptic calyceal endings surrounding Type I hair cells. This review focusses on the multiple modes of communication between these receptors and their enveloping calyces as revealed by simultaneous dual-electrode recordings. Classic orthodromic transmission is accompanied by two forms of bidirectional communication enabled by the extensive cleft between the Type I hair cell and its calyx. The slowest cellular communication low-pass filters the transduction current with a time constant of 10–100 ms: potassium ions accumulate in the synaptic cleft, depolarizing both the hair cell and afferent to potentials greater than necessary for rapid vesicle fusion in the receptor and potentially triggering action potentials in the afferent. On the millisecond timescale, conventional glutamatergic quantal transmission occurs when hair cells are depolarized to potentials sufficient for calcium influx and vesicle fusion. Depolarization also permits a third form of transmission that occurs over tens of microseconds, resulting from the large voltage- and ion-sensitive cleft-facing conductances in both the hair cell and the calyx that are open at their resting potentials. Current flowing out of either the hair cell or the afferent divides into the fraction flowing across the cleft into its cellular partner, and the remainder flowing out of the cleft and into the surrounding fluid compartment. These findings suggest multiple biophysical bases for the extensive repertoire of response dynamics seen in the population of primary vestibular afferent fibers. The results further suggest that evolutionary pressures drive selection for the calyx afferent.
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Affiliation(s)
- Donatella Contini
- Department of Anatomy & Cell Biology, University of Illinois College of Medicine, Chicago, IL, United States
| | - Gay R. Holstein
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Jonathan J. Art
- Department of Anatomy & Cell Biology, University of Illinois College of Medicine, Chicago, IL, United States
- *Correspondence: Jonathan J. Art
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Ripley S, Xia L, Zhang Z, Aiken SJ, Wang J. Animal-to-Human Translation Difficulties and Problems With Proposed Coding-in-Noise Deficits in Noise-Induced Synaptopathy and Hidden Hearing Loss. Front Neurosci 2022; 16:893542. [PMID: 35720689 PMCID: PMC9199355 DOI: 10.3389/fnins.2022.893542] [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: 03/10/2022] [Accepted: 04/22/2022] [Indexed: 12/26/2022] Open
Abstract
Noise induced synaptopathy (NIS) and hidden hearing loss (NIHHL) have been hot topic in hearing research since a massive synaptic loss was identified in CBA mice after a brief noise exposure that did not cause permanent threshold shift (PTS) in 2009. Based upon the amount of synaptic loss and the bias of it to synapses with a group of auditory nerve fibers (ANFs) with low spontaneous rate (LSR), coding-in-noise deficit (CIND) has been speculated as the major difficult of hearing in subjects with NIS and NIHHL. This speculation is based upon the idea that the coding of sound at high level against background noise relies mainly on the LSR ANFs. However, the translation from animal data to humans for NIS remains to be justified due to the difference in noise exposure between laboratory animals and human subjects in real life, the lack of morphological data and reliable functional methods to quantify or estimate the loss of the afferent synapses by noise. Moreover, there is no clear, robust data revealing the CIND even in animals with the synaptic loss but no PTS. In humans, both positive and negative reports are available. The difficulty in verifying CINDs has led a re-examination of the hypothesis that CIND is the major deficit associated with NIS and NIHHL, and the theoretical basis of this idea on the role of LSR ANFs. This review summarized the current status of research in NIS and NIHHL, with focus on the translational difficulty from animal data to human clinicals, the technical difficulties in quantifying NIS in humans, and the problems with the SR theory on signal coding. Temporal fluctuation profile model was discussed as a potential alternative for signal coding at high sound level against background noise, in association with the mechanisms of efferent control on the cochlea gain.
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Affiliation(s)
- Sara Ripley
- School of Communication Sciences and Disorders, Dalhousie University, Halifax, NS, Canada
| | - Li Xia
- Department of Otolaryngology-Head and Neck Surgery, Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Mianyang, China
| | - Zhen Zhang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
- Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai, China
| | - Steve J. Aiken
- School of Communication Sciences and Disorders, Dalhousie University, Halifax, NS, Canada
| | - Jian Wang
- School of Communication Sciences and Disorders, Dalhousie University, Halifax, NS, Canada
- Department of Otolaryngology-Head and Neck Surgery, Mianyang Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Mianyang, China
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Maudoux A, Vitry S, El-Amraoui A. Vestibular Deficits in Deafness: Clinical Presentation, Animal Modeling, and Treatment Solutions. Front Neurol 2022; 13:816534. [PMID: 35444606 PMCID: PMC9013928 DOI: 10.3389/fneur.2022.816534] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/23/2022] [Indexed: 11/13/2022] Open
Abstract
The inner ear is responsible for both hearing and balance. These functions are dependent on the correct functioning of mechanosensitive hair cells, which convert sound- and motion-induced stimuli into electrical signals conveyed to the brain. During evolution of the inner ear, the major changes occurred in the hearing organ, whereas the structure of the vestibular organs remained constant in all vertebrates over the same period. Vestibular deficits are highly prevalent in humans, due to multiple intersecting causes: genetics, environmental factors, ototoxic drugs, infections and aging. Studies of deafness genes associated with balance deficits and their corresponding animal models have shed light on the development and function of these two sensory systems. Bilateral vestibular deficits often impair individual postural control, gaze stabilization, locomotion and spatial orientation. The resulting dizziness, vertigo, and/or falls (frequent in elderly populations) greatly affect patient quality of life. In the absence of treatment, prosthetic devices, such as vestibular implants, providing information about the direction, amplitude and velocity of body movements, are being developed and have given promising results in animal models and humans. Novel methods and techniques have led to major progress in gene therapies targeting the inner ear (gene supplementation and gene editing), 3D inner ear organoids and reprograming protocols for generating hair cell-like cells. These rapid advances in multiscale approaches covering basic research, clinical diagnostics and therapies are fostering interdisciplinary research to develop personalized treatments for vestibular disorders.
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Affiliation(s)
- Audrey Maudoux
- Unit Progressive Sensory Disorders, Pathophysiology and Therapy, Institut Pasteur, Institut de l'Audition, Université de Paris, INSERM-UMRS1120, Paris, France.,Center for Balance Evaluation in Children (EFEE), Otolaryngology Department, Assistance Publique des Hôpitaux de Paris, Robert-Debré University Hospital, Paris, France
| | - Sandrine Vitry
- Unit Progressive Sensory Disorders, Pathophysiology and Therapy, Institut Pasteur, Institut de l'Audition, Université de Paris, INSERM-UMRS1120, Paris, France
| | - Aziz El-Amraoui
- Unit Progressive Sensory Disorders, Pathophysiology and Therapy, Institut Pasteur, Institut de l'Audition, Université de Paris, INSERM-UMRS1120, Paris, France
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12
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Metabotropic Glutamate Receptors at Ribbon Synapses in the Retina and Cochlea. Cells 2022; 11:cells11071097. [PMID: 35406660 PMCID: PMC8998116 DOI: 10.3390/cells11071097] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/17/2022] [Accepted: 03/22/2022] [Indexed: 02/01/2023] Open
Abstract
Our senses define our view of the world. They allow us to adapt to environmental stimuli and are essential for communication and social behaviour. For most humans, seeing and hearing are central senses for their daily life. Our eyes and ears respond to an extraordinary broad range of stimuli covering about 12 log units of light intensity or acoustic power, respectively. The cellular basis is represented by sensory cells (photoreceptors in the retina and inner hair cells in the cochlea) that convert sensory inputs into electrical signals. Photoreceptors and inner hair cells have developed a specific pre-synaptic structure, termed synaptic ribbon, that is decorated with numerous vesicles filled with the excitatory neurotransmitter glutamate. At these ribbon synapses, glutamatergic signal transduction is guided by distinct sets of metabotropic glutamate receptors (mGluRs). MGluRs belong to group II and III of the receptor classification can inhibit neuronal activity, thus protecting neurons from overstimulation and subsequent degeneration. Consequently, dysfunction of mGluRs is associated with vision and hearing disorders. In this review, we introduce the principle characteristics of ribbon synapses and describe group II and III mGluRs in these fascinating structures in the retina and cochlea.
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13
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Wichmann C, Kuner T. Heterogeneity of glutamatergic synapses: cellular mechanisms and network consequences. Physiol Rev 2022; 102:269-318. [PMID: 34727002 DOI: 10.1152/physrev.00039.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chemical synapses are commonly known as a structurally and functionally highly diverse class of cell-cell contacts specialized to mediate communication between neurons. They represent the smallest "computational" unit of the brain and are typically divided into excitatory and inhibitory as well as modulatory categories. These categories are subdivided into diverse types, each representing a different structure-function repertoire that in turn are thought to endow neuronal networks with distinct computational properties. The diversity of structure and function found among a given category of synapses is referred to as heterogeneity. The main building blocks for this heterogeneity are synaptic vesicles, the active zone, the synaptic cleft, the postsynaptic density, and glial processes associated with the synapse. Each of these five structural modules entails a distinct repertoire of functions, and their combination specifies the range of functional heterogeneity at mammalian excitatory synapses, which are the focus of this review. We describe synapse heterogeneity that is manifested on different levels of complexity ranging from the cellular morphology of the pre- and postsynaptic cells toward the expression of different protein isoforms at individual release sites. We attempt to define the range of structural building blocks that are used to vary the basic functional repertoire of excitatory synaptic contacts and discuss sources and general mechanisms of synapse heterogeneity. Finally, we explore the possible impact of synapse heterogeneity on neuronal network function.
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Affiliation(s)
- Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Institute for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg, Germany
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14
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Lee J, Kawai K, Holt JR, Géléoc GSG. Sensory transduction is required for normal development and maturation of cochlear inner hair cell synapses. eLife 2021; 10:e69433. [PMID: 34734805 PMCID: PMC8598158 DOI: 10.7554/elife.69433] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 11/01/2021] [Indexed: 12/23/2022] Open
Abstract
Acoustic overexposure and aging can damage auditory synapses in the inner ear by a process known as synaptopathy. These insults may also damage hair bundles and the sensory transduction apparatus in auditory hair cells. However, a connection between sensory transduction and synaptopathy has not been established. To evaluate potential contributions of sensory transduction to synapse formation and development, we assessed inner hair cell synapses in several genetic models of dysfunctional sensory transduction, including mice lacking transmembrane channel-like (Tmc) 1, Tmc2, or both, in Beethoven mice which carry a dominant Tmc1 mutation and in Spinner mice which carry a recessive mutation in transmembrane inner ear (Tmie). Our analyses reveal loss of synapses in the absence of sensory transduction and preservation of synapses in Tmc1-null mice following restoration of sensory transduction via Tmc1 gene therapy. These results provide insight into the requirement of sensory transduction for hair cell synapse development and maturation.
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Affiliation(s)
- John Lee
- Speech and Hearing Bioscience & Technology Program, Division of Medical Sciences, Harvard UniversityBostonUnited States
- Department of Otolaryngology, Boston Children’s Hospital and Harvard Medical SchoolBostonUnited States
| | - Kosuke Kawai
- Department of Otolaryngology, Boston Children’s Hospital and Harvard Medical SchoolBostonUnited States
| | - Jeffrey R Holt
- Department of Otolaryngology, Boston Children’s Hospital and Harvard Medical SchoolBostonUnited States
- Department of Neurology, Boston Children’s Hospital and Harvard Medical SchoolBostonUnited States
| | - Gwenaëlle SG Géléoc
- Department of Otolaryngology, Boston Children’s Hospital and Harvard Medical SchoolBostonUnited States
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15
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Stone JS, Pujol R, Nguyen TB, Cox BC. The Transcription Factor Sox2 Is Required to Maintain the Cell Type-Specific Properties and Innervation of Type II Vestibular Hair Cells in Adult Mice. J Neurosci 2021; 41:6217-6233. [PMID: 34099510 PMCID: PMC8287988 DOI: 10.1523/jneurosci.1831-20.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 04/11/2021] [Accepted: 05/25/2021] [Indexed: 11/21/2022] Open
Abstract
The sense of balance relies on vestibular hair cells, which detect head motions. Mammals have two types of vestibular hair cell, I and II, with unique morphological, molecular, and physiological properties. Furthermore, each hair cell type signals to a unique form of afferent nerve terminal. Little is known about the mechanisms in mature animals that maintain the specific features of each hair cell type or its postsynaptic innervation. We found that deletion of the transcription factor Sox2 from Type II hair cells in adult mice of both sexes caused many cells in utricles to acquire features unique to Type I hair cells and to lose Type II-specific features. This cellular transdifferentiation, which included changes in nuclear size, chromatin condensation, soma and stereocilium morphology, and marker expression, resulted in a significantly higher proportion of Type I-like hair cells in all epithelial zones. Furthermore, Sox2 deletion from Type II hair cells triggered non-cell autonomous changes in vestibular afferent neurons; they retracted bouton terminals (normally present on only Type II cells) from transdifferentiating hair cells and replaced them with a calyx terminal (normally present on only Type I cells). These changes were accompanied by significant expansion of the utricle's central zone, called the striola. Our study presents the first example of a transcription factor required to maintain the type-specific hair cell phenotype in adult inner ears. Furthermore, we demonstrate that a single genetic change in Type II hair cells is sufficient to alter the morphology of their postsynaptic partners, the vestibular afferent neurons.SIGNIFICANCE STATEMENT The sense of balance relies on two types of sensory cells in the inner ear, Type I and Type II hair cells. These two cell types have unique properties. Furthermore, their postsynaptic partners, the vestibular afferent neurons, have differently shaped terminals on Type I versus Type II hair cells. We show that the transcription factor Sox2 is required to maintain the cell-specific features of Type II hair cells and their postsynaptic terminals in adult mice. This is the first evidence of a molecule that maintains the phenotypes of hair cells and, non-cell autonomously, their postsynaptic partners in mature animals.
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Affiliation(s)
- Jennifer S Stone
- Department of Otolaryngology-Head and Neck Surgery and the Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, Washington 98195-7923
| | - Rémy Pujol
- Department of Otolaryngology-Head and Neck Surgery and the Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, Washington 98195-7923
- Institut National de la Santé et de la Recherche Médicale Unit 1051, Institute of Neuroscience, University of Montpellier, 34000 Montpellier, France
| | - Tot Bui Nguyen
- Department of Otolaryngology-Head and Neck Surgery and the Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, Washington 98195-7923
| | - Brandon C Cox
- Departments of Pharmacology and Otolaryngology, Southern Illinois University School of Medicine, Springfield, Illinois 62794-9624
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16
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Disruption of the autism-related gene Pak1 causes stereocilia disorganization, hair cell loss, and deafness in mice. J Genet Genomics 2021; 48:324-332. [PMID: 34049799 DOI: 10.1016/j.jgg.2021.03.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/18/2021] [Accepted: 03/12/2021] [Indexed: 01/06/2023]
Abstract
Several clinical studies have reported that hearing loss is correlated with autism in children. However, little is known about the underlying mechanism between hearing loss and autism. p21-activated kinases (PAKs) are a family of serine/threonine kinases that can be activated by multiple signaling molecules, particularly the Rho family of small GTPases. Previous studies have shown that Pak1 mutations are associated with autism. In the present study, we take advantage of Pak1 knockout (Pak1-/-) mice to investigate the role of PAK1 in hearing function. We find that PAK1 is highly expressed in the postnatal mouse cochlea and that PAK1 deficiency leads to hair cell (HC) apoptosis and severe hearing loss. Further investigation indicates that PAK1 deficiency downregulates the phosphorylation of cofilin and ezrin-radixin-moesin and the expression of βII-spectrin, which further decreases the HC synapse density in the basal turn of cochlea and disorganized the HC stereocilia in all three turns of cochlea in Pak1-/- mice. Overall, our work demonstrates that the autism-related gene Pak1 plays a crucial role in hearing function. As the first candidate gene linking autism and hearing loss, Pak1 may serve as a potential target for the clinical diagnosis of autism-related hearing loss.
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17
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Piccolo is essential for the maintenance of mouse retina but not cochlear hair cell function. Aging (Albany NY) 2021; 13:11678-11695. [PMID: 33882456 PMCID: PMC8109093 DOI: 10.18632/aging.202861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/16/2021] [Indexed: 12/14/2022]
Abstract
Piccolo is a presynaptic protein with high conservation among different species, and the expression of Piccolo is extensive in vertebrates. Recently, a small fragment of Piccolo (Piccolino), arising due to the incomplete splicing of intron 5/6, was found to be present in the synapses of retinas and cochleae. However, the comprehensive function of Piccolo in the retina and cochlea remains unclear. In this study, we generated Piccolo knockout mice using CRISPR-Cas9 technology to explore the function of Piccolo. Unexpectedly, whereas no abnormalities were found in the cochlear hair cells of the mutant mice, significant differences were found in the retinas, in which two layers (the outer nuclear layer and the outer plexiform layer) were absent. Additionally, the amplitudes of electroretinograms were significantly reduced and pigmentation was observed in the fundoscopy of the mutant mouse retinas. The expression levels of Bassoon, a homolog of Piccolo, as well as synapse-associated proteins CtBP1, CtBP2, Kif3A, and Rim1 were down-regulated. The numbers of ribbon synapses in the retinas of the mutant mice were also reduced. Altogether, the phenotype of Piccolo-/- mice resembled the symptoms of retinitis pigmentosa (RP) in humans, suggesting Piccolo might be a candidate gene of RP and indicates Piccolo knockout mice are a good model for elucidating the molecular mechanisms of RP.
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18
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Colón-Cruz L, Rodriguez-Morales R, Santana-Cruz A, Cantres-Velez J, Torrado-Tapias A, Lin SJ, Yudowski G, Kensler R, Marie B, Burgess SM, Renaud O, Varshney GK, Behra M. Cnr2 Is Important for Ribbon Synapse Maturation and Function in Hair Cells and Photoreceptors. Front Mol Neurosci 2021; 14:624265. [PMID: 33958989 PMCID: PMC8093779 DOI: 10.3389/fnmol.2021.624265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 02/24/2021] [Indexed: 02/04/2023] Open
Abstract
The role of the cannabinoid receptor 2 (CNR2) is still poorly described in sensory epithelia. We found strong cnr2 expression in hair cells (HCs) of the inner ear and the lateral line (LL), a superficial sensory structure in fish. Next, we demonstrated that sensory synapses in HCs were severely perturbed in larvae lacking cnr2. Appearance and distribution of presynaptic ribbons and calcium channels (Cav1.3) were profoundly altered in mutant animals. Clustering of membrane-associated guanylate kinase (MAGUK) in post-synaptic densities (PSDs) was also heavily affected, suggesting a role for cnr2 for maintaining the sensory synapse. Furthermore, vesicular trafficking in HCs was strongly perturbed suggesting a retrograde action of the endocannabinoid system (ECs) via cnr2 that was modulating HC mechanotransduction. We found similar perturbations in retinal ribbon synapses. Finally, we showed that larval swimming behaviors after sound and light stimulations were significantly different in mutant animals. Thus, we propose that cnr2 is critical for the processing of sensory information in the developing larva.
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Affiliation(s)
- Luis Colón-Cruz
- Department of Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico
| | - Roberto Rodriguez-Morales
- Department of Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico
| | - Alexis Santana-Cruz
- Department of Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico
| | - Juan Cantres-Velez
- Department of Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico
| | - Aranza Torrado-Tapias
- Department of Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico
| | - Sheng-Jia Lin
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
| | - Guillermo Yudowski
- Department of Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico.,School of Medicine, Institute of Neurobiology, University of Puerto Rico, San Juan, Puerto Rico
| | - Robert Kensler
- Department of Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico
| | - Bruno Marie
- Department of Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico.,School of Medicine, Institute of Neurobiology, University of Puerto Rico, San Juan, Puerto Rico
| | - Shawn M Burgess
- Developmental Genomics Section, Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, United States
| | - Olivier Renaud
- Cell and Tissue Imaging Facility (PICT-IBiSA, FranceBioImaging), Institut Curie, PSL Research University, U934/UMR3215, Paris, France
| | - Gaurav K Varshney
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States
| | - Martine Behra
- Department of Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico
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19
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Koleilat A, Dugdale JA, Christenson TA, Bellah JL, Lambert AM, Masino MA, Ekker SC, Schimmenti LA. L-type voltage-gated calcium channel agonists mitigate hearing loss and modify ribbon synapse morphology in the zebrafish model of Usher syndrome type 1. Dis Model Mech 2020; 13:13/11/dmm043885. [PMID: 33361086 PMCID: PMC7710014 DOI: 10.1242/dmm.043885] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 09/15/2020] [Indexed: 01/19/2023] Open
Abstract
The mariner (myo7aa−/−) mutant is a zebrafish model for Usher syndrome type 1 (USH1). To further characterize hair cell synaptic elements in myo7aa−/− mutants, we focused on the ribbon synapse and evaluated ultrastructure, number and distribution of immunolabeled ribbons, and postsynaptic densities. By transmission electron microscopy, we determined that myo7aa−/− zebrafish have fewer glutamatergic vesicles tethered to ribbon synapses, yet maintain a comparable ribbon area. In myo7aa−/− hair cells, immunolocalization of Ctbp2 showed fewer ribbon-containing cells in total and an altered distribution of Ctbp2 puncta compared to wild-type hair cells. myo7aa−/− mutants have fewer postsynaptic densities – as assessed by MAGUK immunolabeling – compared to wild-type zebrafish. We quantified the circular swimming behavior of myo7aa−/− mutant fish and measured a greater turning angle (absolute smooth orientation). It has previously been shown that L-type voltage-gated calcium channels are necessary for ribbon localization and occurrence of postsynaptic density; thus, we hypothesized and observed that L-type voltage-gated calcium channel agonists change behavioral and synaptic phenotypes in myo7aa−/− mutants in a drug-specific manner. Our results indicate that treatment with L-type voltage-gated calcium channel agonists alter hair cell synaptic elements and improve behavioral phenotypes of myo7aa−/− mutants. Our data support that L-type voltage-gated calcium channel agonists induce morphological changes at the ribbon synapse – in both the number of tethered vesicles and regarding the distribution of Ctbp2 puncta – shift swimming behavior and improve acoustic startle response. Summary: We quantified behavioral and synaptic morphology differences between wild-type zebrafish larvae and the mariner (myo7aa−/−) mutant, finding that these differences can be modified by L-type voltage-gated calcium channel agonists.
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Affiliation(s)
- Alaa Koleilat
- College of Continuing and Professional Studies, University of Minnesota, Minneapolis, MN 55108, USA.,Mayo Clinic Graduate School of Biomedical Sciences, Clinical and Translational Science Track, Rochester, MN 55905, USA.,Center for Clinical and Translational Science, Mayo Clinic, Rochester, MN 55905, USA
| | - Joseph A Dugdale
- Department of Otorhinolaryngology, Mayo Clinic, Rochester, MN 55905, USA
| | | | - Jeffrey L Bellah
- Center for Clinical and Translational Science, Mayo Clinic, Rochester, MN 55905, USA.,Department of Genetics and Development, Columbia University, New York City, NY 10032, USA
| | - Aaron M Lambert
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Mark A Masino
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Stephen C Ekker
- Center for Clinical and Translational Science, Mayo Clinic, Rochester, MN 55905, USA.,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Lisa A Schimmenti
- Department of Otorhinolaryngology, Mayo Clinic, Rochester, MN 55905, USA .,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA.,Department of Pediatrics, University of Minnesota, Minneapolis, MN 55455, USA.,Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.,Department of Ophthalmology and Visual Neuroscience, University of Minnesota, Minneapolis, MN 55454, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
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20
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Wood MB, Nowak N, Mull K, Goldring A, Lehar M, Fuchs PA. Acoustic Trauma Increases Ribbon Number and Size in Outer Hair Cells of the Mouse Cochlea. J Assoc Res Otolaryngol 2020; 22:19-31. [PMID: 33151428 PMCID: PMC7822997 DOI: 10.1007/s10162-020-00777-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/19/2020] [Indexed: 01/01/2023] Open
Abstract
Outer hair cells (OHCs) in the mouse cochlea are contacted by up to three type II afferent boutons. On average, only half of these are postsynaptic to presynaptic ribbons. Mice of both sexes were subjected to acoustic trauma that produced a threshold shift of 44.2 ± 9.1 dB 7 days after exposure. Ribbon synapses of OHCs were quantified in post-trauma and littermate controls using immunolabeling of CtBP2. Visualization with virtual reality was used to determine 3-D cytoplasmic localization of CtBP2 puncta to the synaptic pole of OHCs. Acoustic trauma was associated with a statistically significant increase in the number of synaptic ribbons per OHC. Serial section TEM was carried out on similarly treated mice. This also showed a significant increase in the number of ribbons in post-trauma OHCs, as well as a significant increase in ribbon volume compared to ribbons in control OHCs. An increase in OHC ribbon synapses after acoustic trauma is a novel observation that has implications for OHC:type II afferent signaling. A mathematical model showed that the observed increase in OHC ribbons considered alone could produce a significant increase in action potentials among type II afferent neurons during strong acoustic stimulation.
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Affiliation(s)
- Megan B Wood
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA.
| | - Nathaniel Nowak
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA
| | - Keira Mull
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA
| | - Adam Goldring
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA.,Sutter Instrument, Co. 1 Digital Drive, Novato, CA, 94949, USA
| | - Mohamed Lehar
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA
| | - Paul Albert Fuchs
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA
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21
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Wang K, Tang D, Ma J, Sun S. Auditory Neural Plasticity in Tinnitus Mechanisms and Management. Neural Plast 2020; 2020:7438461. [PMID: 32684922 PMCID: PMC7349625 DOI: 10.1155/2020/7438461] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 06/15/2020] [Accepted: 06/20/2020] [Indexed: 11/24/2022] Open
Abstract
Tinnitus, which is the perception of sound in the absence of a corresponding external acoustic stimulus, including change of hearing and neural plasticity, has become an increasingly important ailment affecting the daily life of a considerable proportion of the population and causing significant burdens for both the affected individuals and society as a whole. Here, we briefly review the epidemiology and classification of tinnitus, and the currently available treatments are discussed in terms of the available evidence for their mechanisms and efficacy. The conclusion drawn from the available evidence is that there is no specific medication for tinnitus treatment at present, and tinnitus management might provide better solutions. Therapeutic interventions for tinnitus should be based on a comprehensive understanding of the etiology and features of individual cases of tinnitus, and more high quality and large-scale research studies are urgently needed to develop more efficacious medications.
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Affiliation(s)
- Kunkun Wang
- ENT institute and Otorhinolaryngology Department of 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
| | - Dongmei Tang
- ENT institute and Otorhinolaryngology Department of 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
| | - Jiaoyao Ma
- ENT institute and Otorhinolaryngology Department of 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
| | - Shan Sun
- ENT institute and Otorhinolaryngology Department of 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
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22
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Moser T, Grabner CP, Schmitz F. Sensory Processing at Ribbon Synapses in the Retina and the Cochlea. Physiol Rev 2020; 100:103-144. [DOI: 10.1152/physrev.00026.2018] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In recent years, sensory neuroscientists have made major efforts to dissect the structure and function of ribbon synapses which process sensory information in the eye and ear. This review aims to summarize our current understanding of two key aspects of ribbon synapses: 1) their mechanisms of exocytosis and endocytosis and 2) their molecular anatomy and physiology. Our comparison of ribbon synapses in the cochlea and the retina reveals convergent signaling mechanisms, as well as divergent strategies in different sensory systems.
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Affiliation(s)
- Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany; Synaptic Nanophysiology Group, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; and Institute for Anatomy and Cell Biology, Department of Neuroanatomy, Medical School, Saarland University, Homburg, Germany
| | - Chad P. Grabner
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany; Synaptic Nanophysiology Group, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; and Institute for Anatomy and Cell Biology, Department of Neuroanatomy, Medical School, Saarland University, Homburg, Germany
| | - Frank Schmitz
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany; Synaptic Nanophysiology Group, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; and Institute for Anatomy and Cell Biology, Department of Neuroanatomy, Medical School, Saarland University, Homburg, Germany
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23
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Wong HTC, Zhang Q, Beirl AJ, Petralia RS, Wang YX, Kindt K. Synaptic mitochondria regulate hair-cell synapse size and function. eLife 2019; 8:e48914. [PMID: 31609202 PMCID: PMC6879205 DOI: 10.7554/elife.48914] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/13/2019] [Indexed: 11/21/2022] Open
Abstract
Sensory hair cells in the ear utilize specialized ribbon synapses. These synapses are defined by electron-dense presynaptic structures called ribbons, composed primarily of the structural protein Ribeye. Previous work has shown that voltage-gated influx of Ca2+ through CaV1.3 channels is critical for hair-cell synapse function and can impede ribbon formation. We show that in mature zebrafish hair cells, evoked presynaptic-Ca2+ influx through CaV1.3 channels initiates mitochondrial-Ca2+ (mito-Ca2+) uptake adjacent to ribbons. Block of mito-Ca2+ uptake in mature cells depresses presynaptic-Ca2+ influx and impacts synapse integrity. In developing zebrafish hair cells, mito-Ca2+ uptake coincides with spontaneous rises in presynaptic-Ca2+ influx. Spontaneous mito-Ca2+ loading lowers cellular NAD+/NADH redox and downregulates ribbon size. Direct application of NAD+ or NADH increases or decreases ribbon size respectively, possibly acting through the NAD(H)-binding domain on Ribeye. Our results present a mechanism where presynaptic- and mito-Ca2+ couple to confer proper presynaptic function and formation.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Animals, Genetically Modified
- Calcium/metabolism
- Calcium Channel Agonists/pharmacology
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Signaling
- Cell Size
- Embryo, Nonmammalian
- Evoked Potentials, Auditory/physiology
- Eye Proteins/chemistry
- Eye Proteins/genetics
- Eye Proteins/metabolism
- Gene Expression
- Hair Cells, Auditory/cytology
- Hair Cells, Auditory/drug effects
- Hair Cells, Auditory/metabolism
- Isradipine/pharmacology
- Mitochondria/drug effects
- Mitochondria/metabolism
- Mitochondria/ultrastructure
- NAD/metabolism
- Oxidation-Reduction
- Protein Binding
- Protein Interaction Domains and Motifs
- Ruthenium Compounds/pharmacology
- Synapses/drug effects
- Synapses/metabolism
- Synapses/ultrastructure
- Synaptic Transmission
- Zebrafish
- Zebrafish Proteins/agonists
- Zebrafish Proteins/antagonists & inhibitors
- Zebrafish Proteins/chemistry
- Zebrafish Proteins/genetics
- Zebrafish Proteins/metabolism
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Affiliation(s)
- Hiu-tung C Wong
- Section on Sensory Cell Development and FunctionNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
- National Institutes of Health-Johns Hopkins University Graduate Partnership ProgramNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Qiuxiang Zhang
- Section on Sensory Cell Development and FunctionNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Alisha J Beirl
- Section on Sensory Cell Development and FunctionNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Ronald S Petralia
- Advanced Imaging CoreNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Ya-Xian Wang
- Advanced Imaging CoreNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Katie Kindt
- Section on Sensory Cell Development and FunctionNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
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24
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Cassel R, Bordiga P, Carcaud J, Simon F, Beraneck M, Le Gall A, Benoit A, Bouet V, Philoxene B, Besnard S, Watabe I, Pericat D, Hautefort C, Assie A, Tonetto A, Dyhrfjeld-Johnsen J, Llorens J, Tighilet B, Chabbert C. Morphological and functional correlates of vestibular synaptic deafferentation and repair in a mouse model of acute-onset vertigo. Dis Model Mech 2019; 12:dmm.039115. [PMID: 31213478 PMCID: PMC6679379 DOI: 10.1242/dmm.039115] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 06/06/2019] [Indexed: 12/25/2022] Open
Abstract
Damage to cochlear primary afferent synapses has been shown to be a key factor in various auditory pathologies. Similarly, the selective lesioning of primary vestibular synapses might be an underlying cause of peripheral vestibulopathies that cause vertigo and dizziness, for which the pathophysiology is currently unknown. To thoroughly address this possibility, we selectively damaged the synaptic contacts between hair cells and primary vestibular neurons in mice through the transtympanic administration of a glutamate receptor agonist. Using a combination of histological and functional approaches, we demonstrated four key findings: (1) selective synaptic deafferentation is sufficient to generate acute vestibular syndrome with characteristics similar to those reported in patients; (2) the reduction of the vestibulo-ocular reflex and posturo-locomotor deficits mainly depends on spared synapses; (3) damaged primary vestibular synapses can be repaired over the days and weeks following deafferentation; and (4) the synaptic repair process occurs through the re-expression and re-pairing of synaptic proteins such as CtBP2 and SHANK-1. Primary synapse repair might contribute to re-establishing the initial sensory network. Deciphering the molecular mechanism that supports synaptic repair could offer a therapeutic opportunity to rescue full vestibular input and restore gait and balance in patients. Summary: The molecular rearrangements of the synaptic proteins that accompany the deafferentation and subsequent reafferentation of the inner ear sensors following an excitotoxic insult are demonstrated for the first time.
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Affiliation(s)
- Raphaelle Cassel
- Aix Marseille Université, CNRS, UMR 7260, Laboratoire de Neurosciences Sensorielles et Cognitives - Equipe Physiopathologie et Thérapie des Désordres Vestibulaires, Marseille, 13000 France
| | - Pierrick Bordiga
- Aix Marseille Université, CNRS, UMR 7260, Laboratoire de Neurosciences Sensorielles et Cognitives - Equipe Physiopathologie et Thérapie des Désordres Vestibulaires, Marseille, 13000 France
| | - Julie Carcaud
- Integrative Neuroscience and Cognition Center, UMR 8002, CNRS, 75006 Paris, France
| | - François Simon
- Integrative Neuroscience and Cognition Center, UMR 8002, CNRS, 75006 Paris, France.,Sorbonne Paris Cité, Université Paris Descartes, 75006 Paris, France
| | - Mathieu Beraneck
- Integrative Neuroscience and Cognition Center, UMR 8002, CNRS, 75006 Paris, France.,Sorbonne Paris Cité, Université Paris Descartes, 75006 Paris, France
| | | | | | | | | | | | - Isabelle Watabe
- Aix Marseille Université, CNRS, UMR 7260, Laboratoire de Neurosciences Sensorielles et Cognitives - Equipe Physiopathologie et Thérapie des Désordres Vestibulaires, Marseille, 13000 France
| | - David Pericat
- Aix Marseille Université, CNRS, UMR 7260, Laboratoire de Neurosciences Sensorielles et Cognitives - Equipe Physiopathologie et Thérapie des Désordres Vestibulaires, Marseille, 13000 France
| | | | - Axel Assie
- Aix-Marseille Université, CNRS, Centrale Marseille, FSCM (FR1739), PRATIM, Marseille, 13000 France
| | - Alain Tonetto
- Aix-Marseille Université, CNRS, Centrale Marseille, FSCM (FR1739), PRATIM, Marseille, 13000 France
| | | | | | - Brahim Tighilet
- Aix Marseille Université, CNRS, UMR 7260, Laboratoire de Neurosciences Sensorielles et Cognitives - Equipe Physiopathologie et Thérapie des Désordres Vestibulaires, Marseille, 13000 France
| | - Christian Chabbert
- Aix Marseille Université, CNRS, UMR 7260, Laboratoire de Neurosciences Sensorielles et Cognitives - Equipe Physiopathologie et Thérapie des Désordres Vestibulaires, Marseille, 13000 France
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25
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Okawa H, Yu WQ, Matti U, Schwarz K, Odermatt B, Zhong H, Tsukamoto Y, Lagnado L, Rieke F, Schmitz F, Wong ROL. Dynamic assembly of ribbon synapses and circuit maintenance in a vertebrate sensory system. Nat Commun 2019; 10:2167. [PMID: 31092821 PMCID: PMC6520400 DOI: 10.1038/s41467-019-10123-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 04/10/2019] [Indexed: 11/11/2022] Open
Abstract
Ribbon synapses transmit information in sensory systems, but their development is not well understood. To test the hypothesis that ribbon assembly stabilizes nascent synapses, we performed simultaneous time-lapse imaging of fluorescently-tagged ribbons in retinal cone bipolar cells (BCs) and postsynaptic densities (PSD95-FP) of retinal ganglion cells (RGCs). Ribbons and PSD95-FP clusters were more stable when these components colocalized at synapses. However, synapse density on ON-alpha RGCs was unchanged in mice lacking ribbons (ribeye knockout). Wildtype BCs make both ribbon-containing and ribbon-free synapses with these GCs even at maturity. Ribbon assembly and cone BC-RGC synapse maintenance are thus regulated independently. Despite the absence of synaptic ribbons, RGCs continued to respond robustly to light stimuli, although quantitative examination of the responses revealed reduced frequency and contrast sensitivity.
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Affiliation(s)
- Haruhisa Okawa
- Department of Biological Structure, University of Washington, Seattle, 98195, WA, USA
| | - Wan-Qing Yu
- Department of Biological Structure, University of Washington, Seattle, 98195, WA, USA
| | - Ulf Matti
- Department of Neuroanatomy, Medical School Homburg/Saar, Institute for Anatomy and Cell Biology, Saarland University, Homburg/Saar, 66421, Germany
| | - Karin Schwarz
- Department of Neuroanatomy, Medical School Homburg/Saar, Institute for Anatomy and Cell Biology, Saarland University, Homburg/Saar, 66421, Germany
| | | | - Haining Zhong
- Vollum institute, Oregon Health and Science University, Portland, 97239, OR, USA
| | - Yoshihiko Tsukamoto
- Department of Biology, Hyogo College of Medicine, Nishinomiya, 663-8501, Hyogo, Japan
| | - Leon Lagnado
- School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, 98195, WA, USA
| | - Frank Schmitz
- Department of Neuroanatomy, Medical School Homburg/Saar, Institute for Anatomy and Cell Biology, Saarland University, Homburg/Saar, 66421, Germany
| | - Rachel O L Wong
- Department of Biological Structure, University of Washington, Seattle, 98195, WA, USA.
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26
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Holman HA, Poppi LA, Frerck M, Rabbitt RD. Spontaneous and Acetylcholine Evoked Calcium Transients in the Developing Mouse Utricle. Front Cell Neurosci 2019; 13:186. [PMID: 31133810 PMCID: PMC6514437 DOI: 10.3389/fncel.2019.00186] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 04/12/2019] [Indexed: 11/13/2022] Open
Abstract
Spontaneous calcium transients are present during early postnatal development in the mouse retina and cochlea, and play an important role in maturation of the sensory organs and neural circuits in the central nervous system (CNS). It is not known whether similar calcium transients occur during postnatal development in the vestibular sensory organs. Here we demonstrate spontaneous intracellular calcium transients in sensory hair cells (HCs) and supporting cells (SCs) in the murine utricular macula during the first two postnatal weeks. Calcium transients were monitored using a genetically encoded calcium indicator, GCaMP5G (G5), at 100 ms-frame−1 in excised utricle sensory epithelia, including HCs, SCs, and neurons. The reporter line expressed G5 and tdTomato (tdT) in a Gad2-Cre dependent manner within a subset of utricular HCs, SCs and neurons. Kinetics of the G5 reporter limited temporal resolution to calcium events lasting longer than 200 ms. Spontaneous calcium transients lasting 1-2 s were observed in the expressing population of HCs at birth and slower spontaneous transients lasting 10-30 s appeared in SCs by P3. Beginning at P5, calcium transients could be modulated by application of the efferent neurotransmitter acetylcholine (ACh). In mature mice, calcium transients in the utricular macula occurred spontaneously, had a duration 1-2 s, and could be modulated by the exogenous application of acetylcholine (ACh) or muscarine. Long-lasting calcium transients evoked by ACh in mature mice were blocked by atropine, consistent with previous reports describing the role of muscarinic receptors expressed in calyx bearing afferents in efferent control of vestibular sensation. Large spontaneous and ACh evoked transients were reversibly blocked by the inositol trisphosphate receptor (IP3R) antagonist aminoethoxydiphenyl borate (2-APB). Results demonstrate long-lasting calcium transients are present in the utricular macula during the first postnatal week, and that responses to ACh mature over this same time period.
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Affiliation(s)
- Holly A Holman
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Lauren A Poppi
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States.,School of Biomedical Science and Pharmacy, Hunter Medical Research Institute, University of Newcastle, Newcastle, NSW, Australia
| | - Micah Frerck
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Richard D Rabbitt
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States.,Neuroscience Program, University of Utah, Salt Lake City, UT, United States.,Otolaryngology-Head and Neck Surgery, University of Utah, Salt Lake City, UT, United States
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27
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Chakrabarti R, Wichmann C. Nanomachinery Organizing Release at Neuronal and Ribbon Synapses. Int J Mol Sci 2019; 20:E2147. [PMID: 31052288 PMCID: PMC6539712 DOI: 10.3390/ijms20092147] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 04/26/2019] [Accepted: 04/26/2019] [Indexed: 11/17/2022] Open
Abstract
A critical aim in neuroscience is to obtain a comprehensive view of how regulated neurotransmission is achieved. Our current understanding of synapses relies mainly on data from electrophysiological recordings, imaging, and molecular biology. Based on these methodologies, proteins involved in a synaptic vesicle (SV) formation, mobility, and fusion at the active zone (AZ) membrane have been identified. In the last decade, electron tomography (ET) combined with a rapid freezing immobilization of neuronal samples opened a window for understanding the structural machinery with the highest spatial resolution in situ. ET provides significant insights into the molecular architecture of the AZ and the organelles within the presynaptic nerve terminal. The specialized sensory ribbon synapses exhibit a distinct architecture from neuronal synapses due to the presence of the electron-dense synaptic ribbon. However, both synapse types share the filamentous structures, also commonly termed as tethers that are proposed to contribute to different steps of SV recruitment and exocytosis. In this review, we discuss the emerging views on the role of filamentous structures in SV exocytosis gained from ultrastructural studies of excitatory, mainly central neuronal compared to ribbon-type synapses with a focus on inner hair cell (IHC) ribbon synapses. Moreover, we will speculate on the molecular entities that may be involved in filament formation and hence play a crucial role in the SV cycle.
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Affiliation(s)
- Rituparna Chakrabarti
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37075 Göttingen, Germany.
- Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing", 37099 Göttingen, Germany.
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37075 Göttingen, Germany.
- Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing", 37099 Göttingen, Germany.
- Collaborative Research Center 1286 "Quantitative Synaptology", 37099 Göttingen, Germany.
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany.
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28
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Rabbitt RD. Semicircular canal biomechanics in health and disease. J Neurophysiol 2019; 121:732-755. [PMID: 30565972 PMCID: PMC6520623 DOI: 10.1152/jn.00708.2018] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
Abstract
The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS) essential for agile mobility, stable vision, and autonomic control of the cardiovascular and other gravity-sensitive systems. Sensation relies on fluid mechanics within the labyrinth to selectively convert angular head acceleration into sensory hair bundle displacements in each of three inner ear sensory organs. Canal afferent neurons encode the direction and time course of head movements over a broad range of movement frequencies and amplitudes. Disorders altering canal mechanics result in pathological inputs to the CNS, often leading to debilitating symptoms. Vestibular disorders and conditions with mechanical substrates include benign paroxysmal positional nystagmus, direction-changing positional nystagmus, alcohol positional nystagmus, caloric nystagmus, Tullio phenomena, and others. Here, the mechanics of angular motion transduction and how it contributes to neural encoding by the semicircular canals is reviewed in both health and disease.
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Affiliation(s)
- R. D. Rabbitt
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah
- Otolaryngology-Head Neck Surgery, University of Utah, Salt Lake City, Utah
- Neuroscience Program, University of Utah, Salt Lake City, Utah
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29
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A Multiple Piccolino-RIBEYE Interaction Supports Plate-Shaped Synaptic Ribbons in Retinal Neurons. J Neurosci 2019; 39:2606-2619. [PMID: 30696732 DOI: 10.1523/jneurosci.2038-18.2019] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 01/08/2019] [Accepted: 01/08/2019] [Indexed: 01/28/2023] Open
Abstract
Active zones at chemical synapses are highly specialized sites for the regulated release of neurotransmitters. Despite a high degree of active zone protein conservation in vertebrates, every type of chemical synapse expresses a given set of protein isoforms and splice variants adapted to the demands on neurotransmitter release. So far, we know little about how specific active zone proteins contribute to the structural and functional diversity of active zones. In this study, we explored the nanodomain organization of ribbon-type active zones by addressing the significance of Piccolino, the ribbon synapse-specific splice variant of Piccolo, for shaping the ribbon structure. We followed up on previous results, which indicated that rod photoreceptor synaptic ribbons lose their structural integrity in a knockdown of Piccolino. Here, we demonstrate an interaction between Piccolino and the major ribbon component RIBEYE that supports plate-shaped synaptic ribbons in retinal neurons. In a detailed ultrastructural analysis of three different types of retinal ribbon synapses in Piccolo/Piccolino-deficient male and female rats, we show that the absence of Piccolino destabilizes the superstructure of plate-shaped synaptic ribbons, although with variable manifestation in the cell types examined. Our analysis illustrates how the expression of a specific active zone protein splice variant (e.g., Piccolino) contributes to structural diversity of vertebrate active zones.SIGNIFICANCE STATEMENT Retinal ribbon synapses are a specialized type of chemical synapse adapted for the regulated fast and tonic release of neurotransmitter. The hallmark of retinal ribbon synapses is the plate-shaped synaptic ribbon, which extends from the release site into the terminals' cytoplasm and tethers hundreds of synaptic vesicles. Here, we show that Piccolino, the synaptic ribbon specific splice variant of Piccolo, interacts with RIBEYE, the main component of synaptic ribbons. This interaction occurs via several PxDLS-like motifs located at the C terminus of Piccolino, which can connect multiple RIBEYE molecules. Loss of Piccolino disrupts the characteristic plate-shaped structure of synaptic ribbons, indicating a role of Piccolino in synaptic ribbon assembly.
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30
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Peterson HP, Troconis EL, Ordoobadi AJ, Thibodeau-Beganny S, Trapani JG. Teaching Dose-response Relationships Through Aminoglycoside Block of Mechanotransduction Channels in Lateral Line Hair Cells of Larval Zebrafish. JOURNAL OF UNDERGRADUATE NEUROSCIENCE EDUCATION : JUNE : A PUBLICATION OF FUN, FACULTY FOR UNDERGRADUATE NEUROSCIENCE 2018; 17:A40-A49. [PMID: 30618498 PMCID: PMC6312140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/21/2018] [Accepted: 08/23/2018] [Indexed: 06/09/2023]
Abstract
Here we introduce a novel set of laboratory exercises for teaching about hair cell structure and function and dose-response relationships via fluorescence microscopy. Through fluorescent labeling of lateral line hair cells, students assay aminoglycoside block of mechanoelectrical transduction (MET) channels in larval zebrafish. Students acquire and quantify images of hair cells fluorescently labeled with FM 1-43, which enters the hair cell through MET channels. Blocking FM 1-43 uptake with different concentrations of dihydrostreptomycin (DHS) results in dose-dependent reduction in hair-cell fluorescence. This method allows students to generate dose-response curves for the percent fluorescence reduction at different concentrations of DHS, which are then visualized to examine the blocking behavior of DHS using the Hill equation. Finally, students present their findings in lab reports structured as scientific papers. Together these laboratory exercises give students the opportunity to learn about hair cell mechanotransduction, pharmacological block of ion channels, and dose-dependent relationships including the Hill equation, while also exposing students to the zebrafish model organism, fluorescent labeling and microscopy, acquisition and analysis of images, and the presentation of experimental findings. These simple yet comprehensive techniques are appropriate for an undergraduate biology or neuroscience classroom laboratory.
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Affiliation(s)
| | - Eileen L Troconis
- Department of Biology and Neuroscience Program, Amherst College, Amherst, MA 01002 USA
| | - Alexander J Ordoobadi
- Department of Biology and Neuroscience Program, Amherst College, Amherst, MA 01002 USA
| | | | - Josef G Trapani
- Department of Biology and Neuroscience Program, Amherst College, Amherst, MA 01002 USA
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31
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Lukasz D, Kindt KS. In Vivo Calcium Imaging of Lateral-line Hair Cells in Larval Zebrafish. J Vis Exp 2018. [PMID: 30582593 DOI: 10.3791/58794] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Sensory hair cells are mechanoreceptors found in the inner ear that are required for hearing and balance. Hair cells are activated in response to sensory stimuli that mechanically deflect apical protrusions called hair bundles. Deflection opens mechanotransduction (MET) channels in hair bundles, leading to an influx of cations, including calcium. This cation influx depolarizes the cell and opens voltage-gated calcium channels located basally at the hair-cell presynapse. In mammals, hair cells are encased in bone, and it is challenging to functionally assess these activities in vivo. In contrast, larval zebrafish are transparent and possess an externally located lateral-line organ that contains hair cells. These hair cells are functionally and structurally similar to mammalian hair cells and can be functionally assessed in vivo. This article outlines a technique that utilizes a genetically encoded calcium indicator (GECI), GCaMP6s, to measure stimulus-evoked calcium signals in zebrafish lateral-line hair cells. GCaMP6s can be used, along with confocal imaging, to measure in vivo calcium signals at the apex and base of lateral-line hair cells. These signals provide a real-time, quantifiable readout of both mechanosensation- and presynapse-dependent calcium activities within these hair cells. These calcium signals also provide important functional information regarding how hair cells detect and transmit sensory stimuli. Overall, this technique generates useful data about relative changes in calcium activity in vivo. It is less well-suited for quantification of the absolute magnitude of calcium changes. This in vivo technique is sensitive to motion artifacts. A reasonable amount of practice and skill are required for proper positioning, immobilization, and stimulation of larvae. Ultimately, when properly executed, the protocol outlined in this article provides a powerful way to collect valuable information about the activity of hair-cells in their natural, fully integrated states within a live animal.
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Affiliation(s)
- Daria Lukasz
- Section on Sensory Cell Development and Function, NIDCD/National Institutes of Health; National Institutes of Health-Johns Hopkins University Graduate Partnerships Program
| | - Katie S Kindt
- Section on Sensory Cell Development and Function, NIDCD/National Institutes of Health;
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32
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Boyle R, Popova Y, Varelas J. Influence of Magnitude and Duration of Altered Gravity and Readaptation to 1 g on the Structure and Function of the Utricle in Toadfish, Opsanus tau. Front Physiol 2018; 9:1469. [PMID: 30405430 PMCID: PMC6204554 DOI: 10.3389/fphys.2018.01469] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 09/28/2018] [Indexed: 11/13/2022] Open
Abstract
Gravity has remained constant during animal evolution and the neural sensory systems detecting acceleration forces have remained remarkably conserved among vertebrates. The utricular organ senses the sum of inertial force due to head translation and head tilt relative to gravitational vertical. Change in gravitational force would be expected to have profound effects on how an organism maintains equilibrium. We characterize the physiology of utricular afferents to applied accelerations in the oyster toadfish, Opsanus tau, in normal 1 g to establish benchmarks, after 1–32-day exposures to 2.24 g (resultant) via centrifugation (hypergravity, HG), after 4- and 16-day exposures to 1.12 g (resultant), and following 1–8 days recovery to HG exposures to study re-adaptation to 1 g. Afferents were also examined during activation of efferent vestibular pathway. Centrifugation at 2.24 g included 228°/s constant angular velocity component, and thus horizontal canal afferent responses to yaw rotation were recorded as an internal control in each fish. Afferents studied after 228°/s rotation for 4 and 16 days without centripetal acceleration, called On-Center-Control, were indistinguishable from their control counterparts. Principal response to HG was an adjustment of afferent sensitivity as a function of magnitude and duration of exposure: an initial robust increase at 3–4 days followed by a significant decrease from 16 to 32 days. Initial increase observed after 4 days of HG took >4 days in 1 g to recover, and the decrease observed after 16 days of HG took >2 days to readapt to 1 g. Hair cells in striola and medial extrastriola macula regions were serially reconstructed in 3D from thin sections using transmission electron microscopy in control fish and fish exposed to 4 and 16 days of HG. Despite the highly significant differences in afferent physiology, synaptic body counts quantified in the same fish were equivalent in their inter-animal variability and averages. No clear role of the efferent pathway as a feedback mechanism regulating afferent behavior to HG was found. Transfer from 1 g to HG imparts profound effects on gravitational sensitivity of utricular afferents and the accompanying transfer from the HG back to the 1 g resembles in part (as an analog) the transfer from 1 g to the micrograms.
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Affiliation(s)
- Richard Boyle
- National Aeronautics and Space Administration Ames Research Center, Moffett Field, CA, United States
| | - Yekaterina Popova
- National Aeronautics and Space Administration Ames Research Center, Moffett Field, CA, United States
| | - Joseph Varelas
- National Aeronautics and Space Administration Ames Research Center, Moffett Field, CA, United States.,Universities Space Research Association (USRA) Science & Technology Innovation Labs at NASA Ames Research Center, Moffett Field, CA, United States
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33
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Pangrsic T, Vogl C. Balancing presynaptic release and endocytic membrane retrieval at hair cell ribbon synapses. FEBS Lett 2018; 592:3633-3650. [PMID: 30251250 DOI: 10.1002/1873-3468.13258] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/18/2018] [Accepted: 09/19/2018] [Indexed: 11/07/2022]
Abstract
The timely and reliable processing of auditory and vestibular information within the inner ear requires highly sophisticated sensory transduction pathways. On a cellular level, these demands are met by hair cells, which respond to sound waves - or alterations in body positioning - by releasing glutamate-filled synaptic vesicles (SVs) from their presynaptic active zones with unprecedented speed and exquisite temporal fidelity, thereby initiating the auditory and vestibular pathways. In order to achieve this, hair cells have developed anatomical and molecular specializations, such as the characteristic and name-giving 'synaptic ribbons' - presynaptically anchored dense bodies that tether SVs prior to release - as well as other unique or unconventional synaptic proteins. The tightly orchestrated interplay between these molecular components enables not only ultrafast exocytosis, but similarly rapid and efficient compensatory endocytosis. So far, the knowledge of how endocytosis operates at hair cell ribbon synapses is limited. In this Review, we summarize recent advances in our understanding of the SV cycle and molecular anatomy of hair cell ribbon synapses, with a focus on cochlear inner hair cells.
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Affiliation(s)
- Tina Pangrsic
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, University Medical Center Göttingen, Germany
| | - Christian Vogl
- Presynaptogenesis and Intracellular Transport in Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, University Medical Center Göttingen, Germany
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Kindt KS, Sheets L. Transmission Disrupted: Modeling Auditory Synaptopathy in Zebrafish. Front Cell Dev Biol 2018; 6:114. [PMID: 30258843 PMCID: PMC6143809 DOI: 10.3389/fcell.2018.00114] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/23/2018] [Indexed: 01/04/2023] Open
Abstract
Sensorineural hearing loss is the most common form of hearing loss in humans, and results from either dysfunction in hair cells, the sensory receptors of sound, or the neurons that innervate hair cells. A specific type of sensorineural hearing loss, referred to as auditory synaptopathy, occurs when hair cells are able to detect sound but fail to transmit sound stimuli at the hair-cell synapse. Auditory synaptopathy can originate from genetic alterations that specifically disrupt hair-cell synapse function. Additionally, environmental factors such as noise exposure can leave hair cells intact but result in loss of hair-cell synapses, and represent an acquired form of auditory synaptopathy. The zebrafish model has emerged as a valuable system for studies of hair-cell function, and specifically hair-cell synaptopathy. In this review, we describe the experimental tools that have been developed to study hair-cell synapses in zebrafish. We discuss how zebrafish genetics has helped identify and define the roles of hair-cell synaptic proteins crucial for hearing in humans, and highlight how studies in zebrafish have contributed to our understanding of hair-cell synapse formation and function. In addition, we also discuss work that has used noise exposure or pharmacological mimic of noise-induced excitotoxicity in zebrafish to define cellular mechanisms underlying noise-induced hair-cell damage and synapse loss. Lastly, we highlight how future studies in zebrafish could enhance our understanding of the pathological processes underlying synapse loss in both genetic and acquired auditory synaptopathy. This knowledge is critical in order to develop therapies that protect or repair auditory synaptic contacts.
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Affiliation(s)
- Katie S. Kindt
- Section on Sensory Cell Development and Function, NIDCD/National Institutes of Health, Bethesda, MD, United States
| | - Lavinia Sheets
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
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Chakrabarti R, Michanski S, Wichmann C. Vesicle sub-pool organization at inner hair cell ribbon synapses. EMBO Rep 2018; 19:embr.201744937. [PMID: 30201800 DOI: 10.15252/embr.201744937] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/07/2018] [Accepted: 08/21/2018] [Indexed: 02/02/2023] Open
Abstract
The afferent inner hair cell synapse harbors the synaptic ribbon, which ensures a constant vesicle supply. Synaptic vesicles (SVs) are arranged in morphologically discernable pools, linked via filaments to the ribbon or the presynaptic membrane. We propose that filaments play a major role in SV resupply and exocytosis at the ribbon. Using advanced electron microscopy, we demonstrate that SVs are organized in sub-pools defined by the filament number per vesicle and its connections. Upon stimulation, SVs increasingly linked to other vesicles and to the ribbon, whereas single-tethered SVs dominated at the membrane. Mutant mice for the hair cell protein otoferlin (pachanga, Otof Pga/Pga ) are profoundly deaf with reduced sustained release, serving as a model to investigate the SV replenishment at IHCs. Upon stimulation, multiple-tethered and docked vesicles (rarely observed in wild-type) accumulated at Otof Pga/Pga active zones due to an impairment downstream of docking. Conclusively, vesicles are organized in sub-pools at ribbon-type active zones by filaments to support vesicle supply, transport, and finally release.
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Affiliation(s)
- Rituparna Chakrabarti
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing", Göttingen, Germany.,Göttingen Graduate School for Neurosciences, Biophysics and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Susann Michanski
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing", Göttingen, Germany.,Georg-August University School of Science, Göttingen, Germany
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany .,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing", Göttingen, Germany
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Zhang L, Engler S, Koepcke L, Steenken F, Köppl C. Concurrent gradients of ribbon volume and AMPA-receptor patch volume in cochlear afferent synapses on gerbil inner hair cells. Hear Res 2018; 364:81-89. [DOI: 10.1016/j.heares.2018.03.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/26/2018] [Accepted: 03/28/2018] [Indexed: 11/16/2022]
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Yousaf R, Gu C, Ahmed ZM, Khan SN, Friedman TB, Riazuddin S, Shears SB, Riazuddin S. Mutations in Diphosphoinositol-Pentakisphosphate Kinase PPIP5K2 are associated with hearing loss in human and mouse. PLoS Genet 2018; 14:e1007297. [PMID: 29590114 PMCID: PMC5891075 DOI: 10.1371/journal.pgen.1007297] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 04/09/2018] [Accepted: 03/06/2018] [Indexed: 01/07/2023] Open
Abstract
Autosomal recessive nonsyndromic hearing loss is a genetically heterogeneous disorder. Here, we report a severe-to-profound sensorineural hearing loss locus, DFNB100 on chromosome 5q13.2-q23.2. Exome enrichment followed by massive parallel sequencing revealed a c.2510G>A transition variant in PPIP5K2 that segregated with DFNB100-associated hearing loss in two large apparently unrelated Pakistani families. PPIP5Ks enzymes interconvert 5-IP7 and IP8, two key members of the inositol pyrophosphate (PP-IP) cell-signaling family. Their actions at the interface of cell signaling and bioenergetic homeostasis can impact many biological processes. The c.2510G>A transition variant is predicted to substitute a highly invariant arginine residue with histidine (p.Arg837His) in the phosphatase domain of PPIP5K2. Biochemical studies revealed that the p.Arg837His variant reduces the phosphatase activity of PPIP5K2 and elevates its kinase activity. We found that in mouse inner ear, PPIP5K2 is expressed in the cochlear and vestibular sensory hair cells, supporting cells and spiral ganglion neurons. Mice homozygous for a targeted deletion of the Ppip5k2 phosphatase domain exhibit degeneration of cochlear outer hair cells and elevated hearing thresholds. Our demonstration that PPIP5K2 has a role in hearing in humans indicates that PP-IP signaling is important to hair cell maintenance and function within inner ear. Exome sequencing coupled with homozygosity mapping was used to identify a missense variant [c.2510G>A; p.(Arg837His)] in PPIP5K2 at the DFNB100 locus that is associated with nonsyndromic, prelingual sensorineural deafness in two large consanguineous Pakistani families. PPIP5Ks are pivotal enzymes for regulating inositol pyrophosphate (PP-IP) turnover. Biochemical analyses revealed that, compared to wild type human PPIP5K2, the PPIP5K2R837H variant exhibited lower phosphatase activity and higher kinase activity, indicating that it promotes increased metabolic flux from 5-IP7 to IP8 in vivo. In rodent inner ears, PPIP5K2 immunoreactivity was observed in the cochlear and vestibular hair cells, supporting cells, and spiral ganglion neurons. Mouse mutants homozygous for the targeted deletion of Ppip5k2 phosphatase domain exhibit degeneration of cochlear outer hair cells and progressive hearing loss. Our work provides the first description of any amino acid variant of PPIP5K2 that is both functionally-significant and associates with a human disorder. The ‘futile cycling’ of the kinase/phosphatase activity of PPIP5K2 makes inner ear function particularly susceptible to even minor changes in the phosphatase activity of PPIP5K2. We have shown that a pathogenic variant in PPIP5K2 is associated with hearing loss in humans. Thus, PPIP5K2 is given new clinical significance by our observations.
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Affiliation(s)
- Rizwan Yousaf
- Laboratory of Molecular Genetics, Department of Otorhinolaryngology-Head & Neck Surgery, School of Medicine University of Maryland, Baltimore, MD, United States of America
| | - Chunfang Gu
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, United States of America
| | - Zubair M. Ahmed
- Laboratory of Neurogenetics and Regenerative Medicine, Department of Otorhinolaryngology-Head & Neck Surgery, School of Medicine University of Maryland, Baltimore, MD, United States of America
| | - Shaheen N. Khan
- National Center for Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Thomas B. Friedman
- Section on Human Genetics, Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States of America
| | - Sheikh Riazuddin
- Shaheed Zulfiqar Ali Bhutto Medical University, Pakistan Institute of Medical Sciences, Islamabad, Pakistan
| | - Stephen B. Shears
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, United States of America
| | - Saima Riazuddin
- Laboratory of Molecular Genetics, Department of Otorhinolaryngology-Head & Neck Surgery, School of Medicine University of Maryland, Baltimore, MD, United States of America
- * E-mail:
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Cai R, Montgomery SC, Graves KA, Caspary DM, Cox BC. The FBN rat model of aging: investigation of ABR waveforms and ribbon synapse changes. Neurobiol Aging 2018; 62:53-63. [PMID: 29107847 PMCID: PMC5743589 DOI: 10.1016/j.neurobiolaging.2017.09.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 09/22/2017] [Accepted: 09/30/2017] [Indexed: 01/25/2023]
Abstract
Age-related hearing loss is experienced by one-third of individuals aged 65 years and older and can be socially debilitating. Historically, there has been poor correlation between age-related threshold changes, loss of speech understanding, and loss of cochlear hair cells. We examined changes in ribbon synapse number at four different ages in Fisher Brown Norway rats, an extensively studied rat model of aging. In contrast to previous work in mice/Wistar rats, we found minimal ribbon synapse loss before 20 months, with significant differences in 24- and 28-month-old rats at 4 kHz. Significant outer HC loss was observed at 24 and 28 months in low- to mid-frequency regions. Age-related reductions in auditory brainstem response wave I amplitude and increases in threshold were strongly correlated with ribbon synapse loss. Wave V/I ratios increased across age for click, 2, 4, and 24 kHz. Together, we find that ribbon synapses in the Fisher Brown Norway rat cochlea show resistance to aging until ∼60% of their life span, suggesting species/strain differences may underpin decreased peripheral input into the aging central processor.
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Affiliation(s)
- Rui Cai
- Division of Otolaryngology, Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Scott C Montgomery
- Division of Otolaryngology, Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, USA; Division of Otolaryngology, Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Kaley A Graves
- Division of Otolaryngology, Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Donald M Caspary
- Division of Otolaryngology, Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, USA; Division of Otolaryngology, Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, USA.
| | - Brandon C Cox
- Division of Otolaryngology, Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, USA; Division of Otolaryngology, Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, USA.
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Yang L, Chen D, Qu T, Ding T, Yan A, Gong P, Liu Y, Zhang J, Gong S, Yang S, Peng H, Liu K. Maximal number of pre-synaptic ribbons are formed in cochlear region corresponding to middle frequency in mice. Acta Otolaryngol 2018; 138:25-30. [PMID: 28949268 DOI: 10.1080/00016489.2017.1367417] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To investigate whether there are more quantitative pre-synaptic ribbons formed in the cochlear region corresponding to middle-frequency in cochlea of mice. METHODS Counts of pre-synaptic ribbons were performed using immunostaining and laser confocal microscopy. Hearing thresholds and function of ribbon synapses were estimated by auditory brain response (ABR) and compound action potential (CAP). Cochlear mapping has been achieved to match the frequencies and corresponding regions along the cochlear spiral. RESULTS The number of pre-synaptic ribbons in per inner hair cell (IHC) has been found to increase gradually from the base turn, the maximal quantity appeared at the region of 50-70% from the apex. Next, ABR thresholds showed that there was the lowest ABR threshold in the frequency around 8-16 kHz, corresponding to the region of 50-70% from the apex according to the cochlear mapping. Further, CAP amplitudes were estimated, and the maximal value identified at the same frequency (8-16 kHz). CONCLUSIONS Maximal number of pre-synaptic ribbons is formed in the cochlear region of middle frequency in mice, coupling with the lowest ABR threshold and highest CAP amplitudes. Our study shows that the middle frequency (8-16 kHz) could be the most sensitive region to sound stimuli in mice.
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Affiliation(s)
- Le Yang
- Department of Otolaryngology-Head and Neck Surgery, Guangdong Second Provincial General Hospital, Southern Medical University, Guangzhou, People’s Republic of China
| | - DaiShi Chen
- Department of Otolaryngology-Head and Neck Surgery, Chinese PLA General Hospital, Beijing, People’s Republic of China
| | - TengFei Qu
- Department of Otolaryngology-Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - TongHui Ding
- Department of Otolaryngology-Head and Neck Surgery, The First Affiliated Hospital of China Medical University, Shenyang, People’s Republic of China
| | - AiHui Yan
- Department of Otolaryngology-Head and Neck Surgery, The First Affiliated Hospital of China Medical University, Shenyang, People’s Republic of China
| | - Pinggui Gong
- Department of Otolaryngology-Head and Neck Surgery, Guangdong Second Provincial General Hospital, Southern Medical University, Guangzhou, People’s Republic of China
| | - Yunyi Liu
- Department of Otolaryngology-Head and Neck Surgery, Guangdong Second Provincial General Hospital, Southern Medical University, Guangzhou, People’s Republic of China
| | - Junjun Zhang
- Department of Otolaryngology-Head and Neck Surgery, Guangdong Second Provincial General Hospital, Southern Medical University, Guangzhou, People’s Republic of China
| | - ShuSheng Gong
- Department of Otolaryngology-Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - ShiMing Yang
- Department of Otolaryngology-Head and Neck Surgery, Chinese PLA General Hospital, Beijing, People’s Republic of China
| | - Hong Peng
- Department of Otolaryngology-Head and Neck Surgery, Guangdong Second Provincial General Hospital, Guangzhou, People's Republic of China
| | - Ke Liu
- Department of Otolaryngology-Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, People’s Republic of China
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Michalski N, Goutman JD, Auclair SM, Boutet de Monvel J, Tertrais M, Emptoz A, Parrin A, Nouaille S, Guillon M, Sachse M, Ciric D, Bahloul A, Hardelin JP, Sutton RB, Avan P, Krishnakumar SS, Rothman JE, Dulon D, Safieddine S, Petit C. Otoferlin acts as a Ca 2+ sensor for vesicle fusion and vesicle pool replenishment at auditory hair cell ribbon synapses. eLife 2017; 6:e31013. [PMID: 29111973 PMCID: PMC5700815 DOI: 10.7554/elife.31013] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 11/06/2017] [Indexed: 01/01/2023] Open
Abstract
Hearing relies on rapid, temporally precise, and sustained neurotransmitter release at the ribbon synapses of sensory cells, the inner hair cells (IHCs). This process requires otoferlin, a six C2-domain, Ca2+-binding transmembrane protein of synaptic vesicles. To decipher the role of otoferlin in the synaptic vesicle cycle, we produced knock-in mice (OtofAla515,Ala517/Ala515,Ala517) with lower Ca2+-binding affinity of the C2C domain. The IHC ribbon synapse structure, synaptic Ca2+ currents, and otoferlin distribution were unaffected in these mutant mice, but auditory brainstem response wave-I amplitude was reduced. Lower Ca2+ sensitivity and delay of the fast and sustained components of synaptic exocytosis were revealed by membrane capacitance measurement upon modulations of intracellular Ca2+ concentration, by varying Ca2+ influx through voltage-gated Ca2+-channels or Ca2+ uncaging. Otoferlin thus functions as a Ca2+ sensor, setting the rates of primed vesicle fusion with the presynaptic plasma membrane and synaptic vesicle pool replenishment in the IHC active zone.
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Affiliation(s)
- Nicolas Michalski
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
| | - Juan D Goutman
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y TécnicasBuenos AiresArgentina
| | - Sarah Marie Auclair
- Department of Cell BiologyYale University School of MedicineNew HavenUnited States
| | - Jacques Boutet de Monvel
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
| | - Margot Tertrais
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Laboratoire de Neurophysiologie de la Synapse Auditive, Bordeaux NeurocampusUniversité de BordeauxBordeauxFrance
| | - Alice Emptoz
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
| | - Alexandre Parrin
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
| | - Sylvie Nouaille
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
| | - Marc Guillon
- Wave Front Engineering Microscopy Group, Neurophotonics Laboratory, Centre National de la Recherche Scientifique, UMR 8250University Paris Descartes, Sorbonne Paris CitéParisFrance
| | - Martin Sachse
- Center for Innovation & Technological ResearchUltrapole, Institut PasteurParisFrance
| | - Danica Ciric
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
| | - Amel Bahloul
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
- Centre National de la Recherche ScientifiqueFrance
| | - Jean-Pierre Hardelin
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
| | - Roger Bryan Sutton
- Department of Cell Physiology and Molecular BiophysicsTexas Tech University Health Sciences CenterLubbockUnited States
- Center for Membrane Protein ResearchTexas Tech University Health Sciences CenterLubbockUnited States
| | - Paul Avan
- Laboratoire de Biophysique SensorielleUniversité Clermont AuvergneClermont-FerrandFrance
- UMR 1107, Institut National de la Santé et de la Recherche MédicaleClermont-FerrandFrance
- Centre Jean PerrinClermont-FerrandFrance
| | - Shyam S Krishnakumar
- Department of Cell BiologyYale University School of MedicineNew HavenUnited States
- Department of Clinical and Experimental EpilepsyInstitute of Neurology, University College LondonLondonUnited Kingdom
| | - James E Rothman
- Department of Cell BiologyYale University School of MedicineNew HavenUnited States
- Department of Clinical and Experimental EpilepsyInstitute of Neurology, University College LondonLondonUnited Kingdom
| | - Didier Dulon
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Laboratoire de Neurophysiologie de la Synapse Auditive, Bordeaux NeurocampusUniversité de BordeauxBordeauxFrance
| | - Saaid Safieddine
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
- Centre National de la Recherche ScientifiqueFrance
| | - Christine Petit
- Unité de Génétique et Physiologie de l’AuditionInstitut PasteurParisFrance
- UMRS 1120, Institut National de la Santé et de la Recherche MédicaleParisFrance
- Sorbonne Universités, UPMC Université Paris 06, Complexité du VivantParisFrance
- Syndrome de Usher et Autres Atteintes Rétino-CochléairesInstitut de la VisionParisFrance
- Collège de FranceParisFrance
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Enlargement of Ribbons in Zebrafish Hair Cells Increases Calcium Currents But Disrupts Afferent Spontaneous Activity and Timing of Stimulus Onset. J Neurosci 2017; 37:6299-6313. [PMID: 28546313 PMCID: PMC5490065 DOI: 10.1523/jneurosci.2878-16.2017] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 04/26/2017] [Accepted: 04/27/2017] [Indexed: 12/26/2022] Open
Abstract
In sensory hair cells of auditory and vestibular organs, the ribbon synapse is required for the precise encoding of a wide range of complex stimuli. Hair cells have a unique presynaptic structure, the synaptic ribbon, which organizes both synaptic vesicles and calcium channels at the active zone. Previous work has shown that hair-cell ribbon size is correlated with differences in postsynaptic activity. However, additional variability in postsynapse size presents a challenge to determining the specific role of ribbon size in sensory encoding. To selectively assess the impact of ribbon size on synapse function, we examined hair cells in transgenic zebrafish that have enlarged ribbons, without postsynaptic alterations. Morphologically, we found that enlarged ribbons had more associated vesicles and reduced presynaptic calcium-channel clustering. Functionally, hair cells with enlarged ribbons had larger global and ribbon-localized calcium currents. Afferent neuron recordings revealed that hair cells with enlarged ribbons resulted in reduced spontaneous spike rates. Additionally, despite larger presynaptic calcium signals, we observed fewer evoked spikes with longer latencies from stimulus onset. Together, our work indicates that hair-cell ribbon size influences the spontaneous spiking and the precise encoding of stimulus onset in afferent neurons. SIGNIFICANCE STATEMENT Numerous studies support that hair-cell ribbon size corresponds with functional sensitivity differences in afferent neurons and, in the case of inner hair cells of the cochlea, vulnerability to damage from noise trauma. Yet it is unclear whether ribbon size directly influences sensory encoding. Our study reveals that ribbon enlargement results in increased ribbon-localized calcium signals, yet reduces afferent spontaneous activity and disrupts the timing of stimulus onset, a distinct aspect of auditory and vestibular encoding. These observations suggest that varying ribbon size alone can influence sensory encoding, and give further insight into how hair cells transduce signals that cover a wide dynamic range of stimuli.
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Troconis EL, Ordoobadi AJ, Sommers TF, Aziz‐Bose R, Carter AR, Trapani JG. Intensity-dependent timing and precision of startle response latency in larval zebrafish. J Physiol 2017; 595:265-282. [PMID: 27228964 PMCID: PMC5199724 DOI: 10.1113/jp272466] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/17/2016] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS Using high-speed videos time-locked with whole-animal electrical recordings, simultaneous measurement of behavioural kinematics and field potential parameters of C-start startle responses allowed for discrimination between short-latency and long-latency C-starts (SLCs vs. LLCs) in larval zebrafish. Apart from their latencies, SLC kinematics and SLC field potential parameters were intensity independent. Increasing stimulus intensity increased the probability of evoking an SLC and decreased mean SLC latencies while increasing their precision; subtraction of field potential latencies from SLC latencies revealed a fixed time delay between the two measurements that was intensity independent. The latency and the precision in the latency of the SLC field potentials were linearly correlated to the latencies and precision of the first evoked action potentials (spikes) in hair-cell afferent neurons of the lateral line. Together, these findings indicate that first spike latency (FSL) is a fast encoding mechanism that can serve to precisely initiate startle responses when speed is critical for survival. ABSTRACT Vertebrates rely on fast sensory encoding for rapid and precise initiation of startle responses. In afferent sensory neurons, trains of action potentials (spikes) encode stimulus intensity within the onset time of the first evoked spike (first spike latency; FSL) and the number of evoked spikes. For speed of initiation of startle responses, FSL would be the more advantageous mechanism to encode the intensity of a threat. However, the intensity dependence of FSL and spike number and whether either determines the precision of startle response initiation is not known. Here, we examined short-latency startle responses (SLCs) in larval zebrafish and tested the hypothesis that first spike latencies and their precision (jitter) determine the onset time and precision of SLCs. We evoked startle responses via activation of Channelrhodopsin (ChR2) expressed in ear and lateral line hair cells and acquired high-speed videos of head-fixed larvae while simultaneously recording underlying field potentials. This method allowed for discrimination between primary SLCs and less frequent, long-latency startle responses (LLCs). Quantification of SLC kinematics and field potential parameters revealed that, apart from their latencies, they were intensity independent. We found that increasing stimulus intensity decreased SLC latencies while increasing their precision, which was significantly correlated with corresponding changes in field potential latencies and their precision. Single afferent neuron recordings from the lateral line revealed a similar intensity-dependent decrease in first spike latencies and their jitter, which could account for the intensity-dependent changes in timing and precision of startle response latencies.
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Affiliation(s)
| | | | | | | | - Ashley R. Carter
- Department of Physics and AstronomyAmherst CollegeAmherstMA01002USA
| | - Josef G. Trapani
- Department of BiologyAmherst CollegeAmherstMA01002USA
- Neuroscience ProgramAmherst CollegeAmherstMA01002USA
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43
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Global Analysis of Protein Expression of Inner Ear Hair Cells. J Neurosci 2016; 37:1320-1339. [PMID: 28039372 DOI: 10.1523/jneurosci.2267-16.2016] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 11/29/2016] [Accepted: 12/19/2016] [Indexed: 11/21/2022] Open
Abstract
The mammalian inner ear (IE) subserves auditory and vestibular sensations via highly specialized cells and proteins. Sensory receptor hair cells (HCs) are necessary for transducing mechanical inputs and stimulating sensory neurons by using a host of known and as yet unknown protein machinery. To understand the protein composition of these unique postmitotic cells, in which irreversible protein degradation or damage can lead to impaired hearing and balance, we analyzed IE samples by tandem mass spectrometry to generate an unbiased, shotgun-proteomics view of protein identities and abundances. By using Pou4f3/eGFP-transgenic mice in which HCs express GFP driven by Pou4f3, we FACS purified a population of HCs to analyze and compare the HC proteome with other IE subproteomes from sensory epithelia and whole IE. We show that the mammalian HC proteome comprises hundreds of uniquely or highly expressed proteins. Our global proteomic analysis of purified HCs extends the existing HC transcriptome, revealing previously undetected gene products and isoform-specific protein expression. Comparison of our proteomic data with mouse and human databases of genetic auditory/vestibular impairments confirms the critical role of the HC proteome for normal IE function, providing a cell-specific pool of candidates for novel, important HC genes. Several proteins identified exclusively in HCs by proteomics and verified by immunohistochemistry map to human genetic deafness loci, potentially representing new deafness genes. SIGNIFICANCE STATEMENT Hearing and balance rely on specialized sensory hair cells (HCs) in the inner ear (IE) to convey information about sound, acceleration, and orientation to the brain. Genetically and environmentally induced perturbations to HC proteins can result in deafness and severe imbalance. We used transgenic mice with GFP-expressing HCs, coupled with FACS sorting and tandem mass spectrometry, to define the most complete HC and IE proteome to date. We show that hundreds of proteins are uniquely identified or enriched in HCs, extending previous gene expression analyses to reveal novel HC proteins and isoforms. Importantly, deafness-linked proteins were significantly enriched in HCs, suggesting that this in-depth proteomic analysis of IE sensory cells may hold potential for deafness gene discovery.
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Cochlear Synaptopathy and Noise-Induced Hidden Hearing Loss. Neural Plast 2016; 2016:6143164. [PMID: 27738526 PMCID: PMC5050381 DOI: 10.1155/2016/6143164] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 08/09/2016] [Accepted: 08/21/2016] [Indexed: 11/18/2022] Open
Abstract
Recent studies on animal models have shown that noise exposure that does not lead to permanent threshold shift (PTS) can cause considerable damage around the synapses between inner hair cells (IHCs) and type-I afferent auditory nerve fibers (ANFs). Disruption of these synapses not only disables the innervated ANFs but also results in the slow degeneration of spiral ganglion neurons if the synapses are not reestablished. Such a loss of ANFs should result in signal coding deficits, which are exacerbated by the bias of the damage toward synapses connecting low-spontaneous-rate (SR) ANFs, which are known to be vital for signal coding in noisy background. As there is no PTS, these functional deficits cannot be detected using routine audiological evaluations and may be unknown to subjects who have them. Such functional deficits in hearing without changes in sensitivity are generally called “noise-induced hidden hearing loss (NIHHL).” Here, we provide a brief review to address several critical issues related to NIHHL: (1) the mechanism of noise induced synaptic damage, (2) reversibility of the synaptic damage, (3) the functional deficits as the nature of NIHHL in animal studies, (4) evidence of NIHHL in human subjects, and (5) peripheral and central contribution of NIHHL.
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Abstract
The inner ear uses specialized synapses to indefatigably transmit sound information from hair cells to spiral ganglion neurons at high rates with submillisecond precision. The emerging view is that hair cell synapses achieve their demanding function by employing an unconventional presynaptic molecular composition. Hair cell active zones hold the synaptic ribbon, an electron-dense projection made primarily of RIBEYE, which tethers a halo of synaptic vesicles and is thought to enable a large readily releasable pool of vesicles and to contribute to its rapid replenishment. Another important presynaptic player is otoferlin, coded by a deafness gene, which assumes a multi-faceted role in vesicular exocytosis and, when disrupted, causes auditory synaptopathy. A functional peculiarity of hair cell synapses is the massive heterogeneity in the sizes and shapes of excitatory postsynaptic currents. Currently, there is controversy as to whether this reflects multiquantal release with a variable extent of synchronization or uniquantal release through a dynamic fusion pore. Another important question in the field has been the precise mechanisms of coupling presynaptic Ca
2+ channels and vesicular Ca
2+ sensors. This commentary provides an update on the current understanding of sound encoding in the cochlea with a focus on presynaptic mechanisms.
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Affiliation(s)
- Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience Group, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany; Synaptic Nanophysiology Group, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; Auditory Neuroscience and Optogenetics Group, German Primate Center, Göttingen, Germany
| | - Christian Vogl
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience Group, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
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46
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Moezzi B, Iannella N, McDonnell MD. Ion channel noise can explain firing correlation in auditory nerves. J Comput Neurosci 2016; 41:193-206. [DOI: 10.1007/s10827-016-0613-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 06/18/2016] [Accepted: 06/22/2016] [Indexed: 01/13/2023]
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47
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Yu F, Hao S, Yang B, Zhao Y, Yang J. Low Iron Diet Increases Susceptibility to Noise-Induced Hearing Loss in Young Rats. Nutrients 2016; 8:nu8080456. [PMID: 27483303 PMCID: PMC4997371 DOI: 10.3390/nu8080456] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 07/20/2016] [Accepted: 07/25/2016] [Indexed: 12/25/2022] Open
Abstract
We evaluated the role of iron deficiency (ID) without anemia on hearing function and cochlear pathophysiology of young rats before and after noise exposure. We used rats at developmental stages as an animal model to induce ID without anemia by dietary iron restriction. We have established this dietary restriction model in the rat that should enable us to study the effects of iron deficiency in the absence of severe anemia on hearing and ribbon synapses. Hearing function was measured on Postnatal Day (PND) 21 after induction of ID using auditory brainstem response (ABR). Then, the young rats were exposed to loud noise on PND 21. After noise exposure, hearing function was again measured. We observed the morphology of ribbon synapses, hair cells and spiral ganglion cells (SGCs), and assessed the expression of myosin VIIa, vesicular glutamate transporter 3 and prestin in the cochlea. ID without anemia did not elevate ABR threshold shifts, but reduced ABR wave I peak amplitude of young rats. At 70, 80, and 90 dB SPL, amplitudes of wave I (3.11 ± 0.96 µV, 3.52 ± 1.31 µV, and 4.37 ± 1.08 µV, respectively) in pups from the ID group were decreased compared to the control (5.92 ± 1.67 µV, 6.53 ± 1.70 µV, and 6.90 ± 1.76 µV, respectively) (p < 0.05). Moreover, ID without anemia did not impair the morphology hair cells and SGCs, but decreased the number of ribbon synapses. Before noise exposure, the mean number of ribbon synapses per inner hair cell (IHC) was significantly lower in the ID group (8.44 ± 1.21) compared to that seen in the control (13.08 ± 1.36) (p < 0.05). In addition, the numbers of ribbon synapses per IHC of young rats in the control (ID group) were 6.61 ± 1.59, 3.07 ± 0.83, 5.85 ± 1.63 and 12.25 ± 1.97 (3.75 ± 1.45, 2.03 ± 1.08, 3.81 ± 1.70 and 4.01 ± 1.65) at 1, 4, 7 and 14 days after noise exposure, respectively. Moreover, ABR thresholds at 4 and 8 kHz in young rats from the ID group were significantly elevated at 7 and 14 days after noise exposure compared to control (p < 0.05). The average number of young rat SGCs from the ID group were significantly decreased in the basal turn of the cochlea compared to the control (p < 0.05). Therefore, ID without anemia delayed the recovery from noise-induced hearing loss and ribbon synapses damage, increased SGCs loss, and upregulated prestin after noise exposure. Thus, the cochleae in rat pups with ID without anemia were potentially susceptible to loud noise exposure, and this deficit may be attributed to the reduction of ribbon synapses and SGCs.
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MESH Headings
- Anemia, Iron-Deficiency/diet therapy
- Anemia, Iron-Deficiency/metabolism
- Anemia, Iron-Deficiency/pathology
- Anemia, Iron-Deficiency/physiopathology
- Animals
- Auditory Cortex/metabolism
- Auditory Cortex/physiopathology
- Auditory Cortex/ultrastructure
- Auditory Threshold/radiation effects
- Brain Stem/metabolism
- Brain Stem/physiopathology
- Brain Stem/ultrastructure
- Cochlea/innervation
- Cochlea/metabolism
- Cochlea/physiopathology
- Cochlea/ultrastructure
- Cochlear Nerve/metabolism
- Cochlear Nerve/physiopathology
- Cochlear Nerve/radiation effects
- Cochlear Nerve/ultrastructure
- Disease Models, Animal
- Disease Susceptibility
- Female
- Gene Expression Regulation, Developmental/radiation effects
- Hearing Loss, Noise-Induced/etiology
- Hearing Loss, Noise-Induced/prevention & control
- Iron, Dietary/therapeutic use
- Male
- Microscopy, Electron, Scanning
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Noise/adverse effects
- Nutritional Status
- Random Allocation
- Rats, Sprague-Dawley
- Spiral Ganglion/metabolism
- Spiral Ganglion/physiopathology
- Spiral Ganglion/ultrastructure
- Weaning
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Affiliation(s)
- Fei Yu
- Department of Nutrition and Food Hygiene, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, China.
| | - Shuai Hao
- Department of Otolaryngology, First Affiliated Hospital of China Medical University, No. 155, Nanjing North Street, Heping District, Shenyang 110001, China.
| | - Bo Yang
- Department of Otolaryngology, First Affiliated Hospital of China Medical University, No. 155, Nanjing North Street, Heping District, Shenyang 110001, China.
| | - Yue Zhao
- Department of Nutrition and Food Hygiene, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, China.
| | - Jun Yang
- Department of Nutrition and Food Hygiene, School of Public Health, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang 110122, China.
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48
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Shi L, Chang Y, Li X, Aiken SJ, Liu L, Wang J. Coding Deficits in Noise-Induced Hidden Hearing Loss May Stem from Incomplete Repair of Ribbon Synapses in the Cochlea. Front Neurosci 2016; 10:231. [PMID: 27252621 PMCID: PMC4879136 DOI: 10.3389/fnins.2016.00231] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 05/09/2016] [Indexed: 12/01/2022] Open
Abstract
Recent evidence has shown that noise-induced damage to the synapse between inner hair cells (IHCs) and type I afferent auditory nerve fibers (ANFs) may occur in the absence of permanent threshold shift (PTS), and that synapses connecting IHCs with low spontaneous rate (SR) ANFs are disproportionately affected. Due to the functional importance of low-SR ANF units for temporal processing and signal coding in noisy backgrounds, deficits in cochlear coding associated with noise-induced damage may result in significant difficulties with temporal processing and hearing in noise (i.e., “hidden hearing loss”). However, significant noise-induced coding deficits have not been reported at the single unit level following the loss of low-SR units. We have found evidence to suggest that some aspects of neural coding are not significantly changed with the initial loss of low-SR ANFs, and that further coding deficits arise in association with the subsequent reestablishment of the synapses. This suggests that synaptopathy in hidden hearing loss may be the result of insufficient repair of disrupted synapses, and not simply due to the loss of low-SR units. These coding deficits include decreases in driven spike rate for intensity coding as well as several aspects of temporal coding: spike latency, peak-to-sustained spike ratio and the recovery of spike rate as a function of click-interval.
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Affiliation(s)
- Lijuan Shi
- Department of Physiology, Medical College of Southeast University Nanjing, China
| | - Yin Chang
- Department of Physiology, Medical College of Southeast University Nanjing, China
| | - Xiaowei Li
- Department of Physiology, Medical College of Southeast University Nanjing, China
| | - Steven J Aiken
- School of Human Communication Disorders, Dalhousie University Halifax, NS, Canada
| | - Lijie Liu
- Department of Physiology, Medical College of Southeast University Nanjing, China
| | - Jian Wang
- Department of Physiology, Medical College of Southeast UniversityNanjing, China; School of Human Communication Disorders, Dalhousie UniversityHalifax, NS, Canada
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49
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Suli A, Pujol R, Cunningham DE, Hailey DW, Prendergast A, Rubel EW, Raible DW. Innervation regulates synaptic ribbons in lateral line mechanosensory hair cells. J Cell Sci 2016; 129:2250-60. [PMID: 27103160 DOI: 10.1242/jcs.182592] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 04/15/2016] [Indexed: 01/24/2023] Open
Abstract
Failure to form proper synapses in mechanosensory hair cells, the sensory cells responsible for hearing and balance, leads to deafness and balance disorders. Ribbons are electron-dense structures that tether synaptic vesicles to the presynaptic zone of mechanosensory hair cells where they are juxtaposed with the post-synaptic endings of afferent fibers. They are initially formed throughout the cytoplasm, and, as cells mature, ribbons translocate to the basolateral membrane of hair cells to form functional synapses. We have examined the effect of post-synaptic elements on ribbon formation and maintenance in the zebrafish lateral line system by observing mutants that lack hair cell innervation, wild-type larvae whose nerves have been transected and ribbons in regenerating hair cells. Our results demonstrate that innervation is not required for initial ribbon formation but suggest that it is crucial for regulating the number, size and localization of ribbons in maturing hair cells, and for ribbon maintenance at the mature synapse.
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Affiliation(s)
- Arminda Suli
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602, USA Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Remy Pujol
- V.M. Bloedel Hearing Center, University of Washington, Seattle, WA 98195, USA INSERM-Unit 1051, Université Montpellier, France
| | - Dale E Cunningham
- V.M. Bloedel Hearing Center, University of Washington, Seattle, WA 98195, USA
| | - Dale W Hailey
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA V.M. Bloedel Hearing Center, University of Washington, Seattle, WA 98195, USA
| | - Andrew Prendergast
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA Institut du Cerveau et de la Moelle Épinère 47, Boulevard de l'Hôpital, 75013 Paris, France
| | - Edwin W Rubel
- V.M. Bloedel Hearing Center, University of Washington, Seattle, WA 98195, USA
| | - David W Raible
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
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50
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Barclay M, Constable R, James NR, Thorne PR, Montgomery JM. Reduced sensory stimulation alters the molecular make-up of glutamatergic hair cell synapses in the developing cochlea. Neuroscience 2016; 325:50-62. [PMID: 27012610 DOI: 10.1016/j.neuroscience.2016.03.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 02/26/2016] [Accepted: 03/16/2016] [Indexed: 12/20/2022]
Abstract
Neural activity during early development is known to alter innervation pathways in the central and peripheral nervous systems. We sought to examine how reduced sound-induced sensory activity in the cochlea affected the consolidation of glutamatergic synapses between inner hair cells (IHC) and the primary auditory neurons as these synapses play a primary role in transmitting sound information to the brain. A unilateral conductive hearing loss was induced prior to the onset of sound-mediated stimulation of the sensory hair cells, by rupturing the tympanic membrane and dislocating the auditory ossicles in the left ear of P11 mice. Auditory brainstem responses at P15 and P21 showed a 40-50-dB increase in thresholds for frequencies 8-32kHz in the dislocated ear relative to the control ear. Immunohistochemistry and confocal microscopy were subsequently used to examine the effect of this attenuation of sound stimulation on the expression of RIBEYE, which comprises the presynaptic ribbons, Shank-1, a postsynaptic scaffolding protein, and the GluA2/3 and 4 subunits of postsynaptic AMPA receptors. Our results show that dislocation did not alter the number of pre- or postsynaptic protein puncta. However, dislocation did increase the size of RIBEYE, GluA4, GluA2/3 and Shank-1 puncta, with postsynaptic changes preceding presynaptic changes. Our data suggest that a reduction in sound stimulation during auditory development induces plasticity in the molecular make-up of IHC glutamatergic synapses, but does not affect the number of these synapses. Up-regulation of synaptic proteins with sound attenuation may facilitate a compensatory increase in synaptic transmission due to the reduced sensory stimulation of the IHC.
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Affiliation(s)
- M Barclay
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - R Constable
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - N R James
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - P R Thorne
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Section of Audiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - J M Montgomery
- Department of Physiology and Centre for Brain Research, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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