1
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Kitcher SR, Pederson AM, Weisz CJC. Diverse identities and sites of action of cochlear neurotransmitters. Hear Res 2021; 419:108278. [PMID: 34108087 DOI: 10.1016/j.heares.2021.108278] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 04/30/2021] [Accepted: 05/18/2021] [Indexed: 11/18/2022]
Abstract
Accurate encoding of acoustic stimuli requires temporally precise responses to sound integrated with cellular mechanisms that encode the complexity of stimuli over varying timescales and orders of magnitude of intensity. Sound in mammals is initially encoded in the cochlea, the peripheral hearing organ, which contains functionally specialized cells (including hair cells, afferent and efferent neurons, and a multitude of supporting cells) to allow faithful acoustic perception. To accomplish the demanding physiological requirements of hearing, the cochlea has developed synaptic arrangements that operate over different timescales, with varied strengths, and with the ability to adjust function in dynamic hearing conditions. Multiple neurotransmitters interact to support the precision and complexity of hearing. Here, we review the location of release, action, and function of neurotransmitters in the mammalian cochlea with an emphasis on recent work describing the complexity of signaling.
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Affiliation(s)
- Siân R Kitcher
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Alia M Pederson
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States
| | - Catherine J C Weisz
- Section on Neuronal Circuitry, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, United States.
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2
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Hussein RA, Ahmed M, Sticht H, Breitinger HG, Breitinger U. Fine-Tuning of Neuronal Ion Channels-Mapping of Residues Involved in Glucose Sensitivity of Recombinant Human Glycine Receptors. ACS Chem Neurosci 2020; 11:3474-3483. [PMID: 33007159 DOI: 10.1021/acschemneuro.0c00566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The inhibitory glycine receptor (GlyR) mediates synaptic inhibition in the spinal cord, brain stem, and other regions of the mammalian central nervous system. Glucose was shown to potentiate α1 GlyRs by interacting with K143. Here, additional amino acids involved in glucose modulation were identified using a structure-based approach of site-directed mutagenesis followed by whole-cell patch-clamp analysis. We identified two additional lysine residues in the α1 GlyR extracellular domain, K16 and K281, that were involved in glucose modulation. Mutation of either residue to alanine abolished glucose potentiation. Residue K281 is located in the same pocket as K143 and could thus contribute to glucose binding. The double mutant K143A-K281A showed a 6-fold increase of EC50, while EC50 of both single mutants K143A and K281A was only slightly increased (1.7- and 1.3-fold, respectively). K16 is located at an analgesic binding site that is distant from the agonist or glucose sites, and the K16A mutation may generate a receptor species that is not potentiated. GlyR position α1-S267 is close to the postulated glucose binding site and known for interactions with ethanol and anesthetics. In the presence of glucose, GlyR α1 mutants S267A, S267I, and S267R showed potentiation, no effect, and reduction of current responses, respectively. This pattern follows that of ethanol modulation and suggests that the interaction sites of glucose and ethanol are identical or located close to each other. Our results support the presence of a distinct binding site for glucose on the glycine receptor, overlapping with the ivermectin/ethanol binding pocket near the transmembrane region and the TM2-3 loop.
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Affiliation(s)
- Rama Ashraf Hussein
- Department of Biochemistry, The German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Marwa Ahmed
- Department of Biochemistry, The German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Fahrstrasse 17, D-91054 Erlangen, Germany
| | - Hans-Georg Breitinger
- Department of Biochemistry, The German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Ulrike Breitinger
- Department of Biochemistry, The German University in Cairo, Main Entrance of Al Tagamoa Al Khames, New Cairo 11835, Egypt
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Tziridis K, Buerbank S, Eulenburg V, Dlugaiczyk J, Schulze H. Deficit in acoustic signal-in-noise detection in glycine receptor α3 subunit knockout mice. Eur J Neurosci 2017; 45:581-586. [PMID: 27891689 DOI: 10.1111/ejn.13489] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/24/2016] [Accepted: 11/21/2016] [Indexed: 12/31/2022]
Abstract
Hearing is an essential sense for communication in animals and humans. Normal function of the cochlea of higher vertebrates relies on a fine-tuned interplay of afferent and efferent innervation of both inner and outer hair cells. Efferent inhibition is controlled via olivocochlear feedback loops, mediated mainly by acetylcholine, γ-aminobutyric acid (GABA) and glycine, and is one of the first sites affected by synapto- and neuropathy in the development of hearing loss. While the functions of acetylcholine, GABA and other inhibitory transmitters within these feedback loops are at least partially understood, especially the function of glycine still remains elusive. To address this question, we investigated hearing in glycine receptor (GlyR) α3 knockout (KO) and wildtype (WT) mice. We found no differences in pure tone hearing thresholds at 11.3 and 16 kHz between the two groups as assessed by auditory brainstem response (ABR) measurements. Detailed analysis of the ABR waves at 11.3 kHz, however, revealed a latency decrease of wave III and an amplitude increase of wave IV in KO compared to WT animals. GlyRα3 KO animals showed significantly impaired prepulse inhibition of the auditory startle response in a noisy environment, indicating that GlyRα3-mediated glycinergic inhibition is important for signal-in-noise detection.
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Affiliation(s)
- Konstantin Tziridis
- Experimental Otolaryngology, ENT Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Waldstrasse 1, 91054, Erlangen, Germany
| | - Stefanie Buerbank
- Experimental Otolaryngology, ENT Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Waldstrasse 1, 91054, Erlangen, Germany
| | - Volker Eulenburg
- Institute of Biochemistry, Emil-Fischer-Zentrum, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Julia Dlugaiczyk
- Department of Otorhinolaryngology, Saarland University Hospital, Homburg/Saar, Germany
| | - Holger Schulze
- Experimental Otolaryngology, ENT Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Waldstrasse 1, 91054, Erlangen, Germany
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4
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Krauss P, Tziridis K, Metzner C, Schilling A, Hoppe U, Schulze H. Stochastic Resonance Controlled Upregulation of Internal Noise after Hearing Loss as a Putative Cause of Tinnitus-Related Neuronal Hyperactivity. Front Neurosci 2016; 10:597. [PMID: 28082861 PMCID: PMC5187388 DOI: 10.3389/fnins.2016.00597] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 12/14/2016] [Indexed: 11/25/2022] Open
Abstract
Subjective tinnitus is generally assumed to be a consequence of hearing loss. In animal studies it has been demonstrated that acoustic trauma induced cochlear damage can lead to behavioral signs of tinnitus. In addition it was shown that noise trauma may lead to deafferentation of cochlear inner hair cells (IHC) even in the absence of elevated hearing thresholds, and it seems conceivable that such hidden hearing loss may be sufficient to cause tinnitus. Numerous studies have indicated that tinnitus is correlated with pathologically increased spontaneous firing rates and hyperactivity of neurons along the auditory pathway. It has been proposed that this hyperactivity is the consequence of a mechanism aiming to compensate for reduced input to the auditory system by increasing central neuronal gain, a mechanism referred to as homeostatic plasticity (HP), thereby maintaining mean firing rates over longer timescales for stabilization of neuronal processing. Here we propose an alternative, new interpretation of tinnitus-related development of neuronal hyperactivity in terms of information theory. In particular, we suggest that stochastic resonance (SR) plays a key role in both short- and long-term plasticity within the auditory system and that SR is the primary cause of neuronal hyperactivity and tinnitus. We argue that following hearing loss, SR serves to lift signals above the increased neuronal thresholds, thereby partly compensating for the hearing loss. In our model, the increased amount of internal noise-which is crucial for SR to work-corresponds to neuronal hyperactivity which subsequently causes neuronal plasticity along the auditory pathway and finally may lead to the development of a phantom percept, i.e., subjective tinnitus. We demonstrate the plausibility of our hypothesis using a computational model and provide exemplary findings in human patients that are consistent with that model. Finally we discuss the observed asymmetry in human tinnitus pitch distribution as a consequence of asymmetry of the distribution of auditory nerve type I fibers along the cochlea in the context of our model.
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Affiliation(s)
- Patrick Krauss
- Experimental Otolaryngology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
- Biophysics Group, Department of Physics, Center for Medical Physics and Technology, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Konstantin Tziridis
- Experimental Otolaryngology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Claus Metzner
- Biophysics Group, Department of Physics, Center for Medical Physics and Technology, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Achim Schilling
- Experimental Otolaryngology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
- Biophysics Group, Department of Physics, Center for Medical Physics and Technology, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Ulrich Hoppe
- Department of Audiology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Holger Schulze
- Experimental Otolaryngology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
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Breitinger U, Sticht H, Breitinger HG. Modulation of Recombinant Human α1 Glycine Receptors by Mono- and Disaccharides: A Kinetic Study. ACS Chem Neurosci 2016; 7:1077-87. [PMID: 27227552 DOI: 10.1021/acschemneuro.6b00044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Glycine receptors (GlyRs) mediate fast synaptic inhibition in spinal cord, brainstem, and higher brain centers. Recently, glucose was identified as a positive modulator of GlyR-mediated currents. Here, we investigated extent and kinetics of the positive modulation of recombinant human α1 glycine receptors by different mono- and disaccharides and sorbitol using patch-clamp recording techniques. Glucose and fructose augmented glycine-mediated whole-cell currents with an EC50 of 6-7 mM. At concentrations > 10 mM, the maximum of current enhancement was reached within ∼30 min. Kinetics of GlyR modulation resemble those of protein glycation. On-rates were <0.5 h for saturating concentrations of monosaccharides and ∼1.5 h for disaccharides. Off-rates were considerably slower (>24 h). Galactose, the C4-epimer of glucose, and the sugar alcohol sorbitol had no effect on GlyR currents. Recent cryoelectron microscopy structures were used to identify a potential binding site for saccharides near the ivermectin binding pocket with lysine 143 as possible attachment site. The GlyR mutant α1(K143A) was not potentiated by glucose, suggesting an involvement of this residue in glycine receptor modulation by saccharides.
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Affiliation(s)
- Ulrike Breitinger
- Department
of Biochemistry, The German University in Cairo, Main Entrance
of Al Tagamoa Al Khames, New Cairo 11835, Egypt
| | - Heinrich Sticht
- Bioinformatics, Institute for Biochemistry, Friedrich-Alexander-Universität Erlangen-Nümberg, Fahrstrasse 17, D-91054 Erlangen, Germany
| | - Hans-Georg Breitinger
- Department
of Biochemistry, The German University in Cairo, Main Entrance
of Al Tagamoa Al Khames, New Cairo 11835, Egypt
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6
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Langlhofer G, Villmann C. The Intracellular Loop of the Glycine Receptor: It's not all about the Size. Front Mol Neurosci 2016; 9:41. [PMID: 27330534 PMCID: PMC4891346 DOI: 10.3389/fnmol.2016.00041] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 05/17/2016] [Indexed: 11/15/2022] Open
Abstract
The family of Cys-loop receptors (CLRs) shares a high degree of homology and sequence identity. The overall structural elements are highly conserved with a large extracellular domain (ECD) harboring an α-helix and 10 β-sheets. Following the ECD, four transmembrane domains (TMD) are connected by intracellular and extracellular loop structures. Except the TM3–4 loop, their length comprises 7–14 residues. The TM3–4 loop forms the largest part of the intracellular domain (ICD) and exhibits the most variable region between all CLRs. The ICD is defined by the TM3–4 loop together with the TM1–2 loop preceding the ion channel pore. During the last decade, crystallization approaches were successful for some members of the CLR family. To allow crystallization, the intracellular loop was in most structures replaced by a short linker present in prokaryotic CLRs. Therefore, no structural information about the large TM3–4 loop of CLRs including the glycine receptors (GlyRs) is available except for some basic stretches close to TM3 and TM4. The intracellular loop has been intensively studied with regard to functional aspects including desensitization, modulation of channel physiology by pharmacological substances, posttranslational modifications, and motifs important for trafficking. Furthermore, the ICD interacts with scaffold proteins enabling inhibitory synapse formation. This review focuses on attempts to define structural and functional elements within the ICD of GlyRs discussed with the background of protein-protein interactions and functional channel formation in the absence of the TM3–4 loop.
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Affiliation(s)
- Georg Langlhofer
- Institute of Clinical Neurobiology, University of Würzburg Würzburg, Germany
| | - Carmen Villmann
- Institute of Clinical Neurobiology, University of Würzburg Würzburg, Germany
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Breitinger U, Breitinger HG. Augmentation of glycine receptor alpha3 currents suggests a mechanism for glucose-mediated analgesia. Neurosci Lett 2016; 612:110-115. [DOI: 10.1016/j.neulet.2015.11.051] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/17/2015] [Accepted: 11/30/2015] [Indexed: 11/16/2022]
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8
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Singer W, Geisler HS, Panford-Walsh R, Knipper M. Detection of Excitatory and Inhibitory Synapses in the Auditory System Using Fluorescence Immunohistochemistry and High-Resolution Fluorescence Microscopy. Methods Mol Biol 2016; 1427:263-76. [PMID: 27259932 DOI: 10.1007/978-1-4939-3615-1_15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In sensory systems, a balanced excitatory and inhibitory circuit along the ascending pathway is not only important for the establishment of topographically ordered connections from the periphery to the cortex but also for temporal precision of signal processing. The accomplishment of spatial and temporal cortical resolution in the central nervous system is a process that is likely initiated by the first sensory experiences that drive a period of increased intracortical inhibition. In the auditory system, the time of first sensory experience is also the period in which a reorganization of cochlear efferent and afferent fibers occurs leading to the mature innervation of inner and outer hair cells. This mature hair cell innervation is the basis of accurate sound processing along the ascending pathway up to the auditory cortex. We describe here, a protocol for detecting excitatory and inhibitory marker proteins along the ascending auditory pathway, which could be a useful tool for detecting changes in auditory signal processing during various forms of hearing disorders. Our protocol uses fluorescence immunohistochemistry in combination with high-resolution fluorescence microscopy in cochlear and brain tissue.
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Affiliation(s)
- Wibke Singer
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Elfriede-Aulhorn-Str. 5, Tübingen, 72076, Germany
| | - Hyun-Soon Geisler
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Elfriede-Aulhorn-Str. 5, Tübingen, 72076, Germany
| | - Rama Panford-Walsh
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Elfriede-Aulhorn-Str. 5, Tübingen, 72076, Germany.,DNA Genotek Inc., Ottawa, ON, Canada
| | - Marlies Knipper
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Elfriede-Aulhorn-Str. 5, Tübingen, 72076, Germany.
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9
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Maleeva G, Buldakova S, Bregestovski P. Selective potentiation of alpha 1 glycine receptors by ginkgolic acid. Front Mol Neurosci 2015; 8:64. [PMID: 26578878 PMCID: PMC4624854 DOI: 10.3389/fnmol.2015.00064] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 10/16/2015] [Indexed: 12/18/2022] Open
Abstract
Glycine receptors (GlyRs) belong to the superfamily of pentameric cys-loop receptor-operated channels and are involved in numerous physiological functions, including movement, vision, and pain. In search for compounds performing subunit-specific modulation of GlyRs we studied action of ginkgolic acid, an abundant Ginkgo biloba product. Using patch-clamp recordings, we analyzed the effects of ginkgolic acid in concentrations from 30 nM to 25 μM on α1–α3 and α1/β, α2/β configurations of GlyR and on GABAARs expressed in cultured CHO-K1 cells and mouse neuroblastoma (N2a) cells. Ginkgolic acid caused an increase in the amplitude of currents mediated by homomeric α1 and heteromeric α1/β GlyRs and provoked a left-shift of the concentration-dependent curves for glycine. Even at high concentrations (10–25 μM) ginkgolic acid was not able to augment ionic currents mediated by α2, α2/β, and α3 GlyRs, or by GABAAR consisting of α1/β2/γ2 subunits. Mutation of three residues (T59A/A261G/A303S) in the α2 GlyR subunit to the corresponding ones from the α1 converted the action of ginkgolic acid to potentiation with a distinct decrease in EC50 for glycine, suggesting an important role for these residues in modulation by ginkgolic acid. Our results suggest that ginkgolic acid is a novel selective enhancer of α1 GlyRs.
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Affiliation(s)
- Galyna Maleeva
- Aix Marseille Université, INS UMR_S 1106 Marseille, France ; INSERM, UMR_S 1106 Marseille, France ; Department of Cytology, Bogomoletz Institute of Physiology Kyiv, Ukraine
| | - Svetlana Buldakova
- Aix Marseille Université, INS UMR_S 1106 Marseille, France ; INSERM, UMR_S 1106 Marseille, France
| | - Piotr Bregestovski
- Aix Marseille Université, INS UMR_S 1106 Marseille, France ; INSERM, UMR_S 1106 Marseille, France
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Notelaers K, Rocha S, Paesen R, Swinnen N, Vangindertael J, Meier JC, Rigo JM, Ameloot M, Hofkens J. Membrane distribution of the glycine receptor α3 studied by optical super-resolution microscopy. Histochem Cell Biol 2014; 142:79-90. [PMID: 24553792 DOI: 10.1007/s00418-014-1197-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2014] [Indexed: 11/24/2022]
Abstract
In this study, the effect of glycine receptor (GlyR) α3 alternative RNA splicing on the distribution of receptors in the membrane of human embryonic kidney 293 cells is investigated using optical super-resolution microscopy. Direct stochastic optical reconstruction microscopy is used to image both α3K and α3L splice variants individually and together using single- and dual-color imaging. Pair correlation analysis is used to extract quantitative measures from the resulting images. Autocorrelation analysis of the individually expressed variants reveals clustering of both variants, yet with differing properties. The cluster size is increased for α3L compared to α3K (mean radius 92 ± 4 and 56 ± 3 nm, respectively), yet an even bigger difference is found in the cluster density (9,870 ± 1,433 and 1,747 ± 200 μm(-2), respectively). Furthermore, cross-correlation analysis revealed that upon co-expression, clusters colocalize on the same spatial scales as for individually expressed receptors (mean co-cluster radius 94 ± 6 nm). These results demonstrate that RNA splicing determines GlyR α3 membrane distribution, which has consequences for neuronal GlyR physiology and function.
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Affiliation(s)
- Kristof Notelaers
- Biomedical Research Institute, Hasselt University and School of Life Sciences, Transnational University Limburg, Agoralaan Gebouw C, 3590, Diepenbeek, Belgium
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Singer W, Panford-Walsh R, Knipper M. The function of BDNF in the adult auditory system. Neuropharmacology 2013; 76 Pt C:719-28. [PMID: 23688926 DOI: 10.1016/j.neuropharm.2013.05.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 02/06/2023]
Abstract
The inner ear of vertebrates is specialized to perceive sound, gravity and movements. Each of the specialized sensory organs within the cochlea (sound) and vestibular system (gravity, head movements) transmits information to specific areas of the brain. During development, brain-derived neurotrophic factor (BDNF) orchestrates the survival and outgrowth of afferent fibers connecting the vestibular organ and those regions in the cochlea that map information for low frequency sound to central auditory nuclei and higher-auditory centers. The role of BDNF in the mature inner ear is less understood. This is mainly due to the fact that constitutive BDNF mutant mice are postnatally lethal. Only in the last few years has the improved technology of performing conditional cell specific deletion of BDNF in vivo allowed the study of the function of BDNF in the mature developed organ. This review provides an overview of the current knowledge of the expression pattern and function of BDNF in the peripheral and central auditory system from just prior to the first auditory experience onwards. A special focus will be put on the differential mechanisms in which BDNF drives refinement of auditory circuitries during the onset of sensory experience and in the adult brain. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.
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Affiliation(s)
- Wibke Singer
- University of Tübingen, Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, Elfriede-Aulhorn-Straße 5, 72076 Tübingen, Germany
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12
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Abstract
Strychnine-sensitive glycine receptors (GlyRs) mediate synaptic inhibition in the spinal cord, brainstem, and other regions of the mammalian central nervous system. In this minireview, we summarize our current view of the structure, ligand-binding sites, and chloride channel of these receptors and discuss recently emerging functions of distinct GlyR isoforms. GlyRs not only regulate the excitability of motor and afferent sensory neurons, including pain fibers, but also are involved in the processing of visual and auditory signals. Hence, GlyRs constitute promising targets for the development of therapeutically useful compounds.
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Affiliation(s)
- Sébastien Dutertre
- From the Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Cord-Michael Becker
- the Institute of Biochemistry, University of Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Heinrich Betz
- the Max-Planck-Institute for Medical Research, 69120 Heidelberg, Germany, and
- the Department of Molecular Neurobiology, Max-Planck-Institute for Experimental Medicine, 37075 Göttingen, Germany
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13
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Schaefer N, Vogel N, Villmann C. Glycine receptor mutants of the mouse: what are possible routes of inhibitory compensation? Front Mol Neurosci 2012; 5:98. [PMID: 23118727 PMCID: PMC3484359 DOI: 10.3389/fnmol.2012.00098] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 10/11/2012] [Indexed: 12/02/2022] Open
Abstract
Defects in glycinergic inhibition result in a complex neuromotor disorder in humans known as hyperekplexia (OMIM 149400) with similar phenotypes in rodents characterized by an exaggerated startle reflex and hypertonia. Analogous to genetic defects in humans single point mutations, microdeletions, or insertions in the Glra1 gene but also in the Glrb gene underlie the pathology in mice. The mutations either localized in the α (spasmodic, oscillator, cincinnati, Nmf11) or the β (spastic) subunit of the glycine receptor (GlyR) are much less tolerated in mice than in humans, leaving the question for the existence of different regulatory elements of the pathomechanisms in humans and rodents. In addition to the spontaneous mutations, new insights into understanding of the regulatory pathways in hyperekplexia or glycine encephalopathy arose from the constantly increasing number of knock-out as well as knock-in mutants of GlyRs. Over the last five years, various efforts using in vivo whole cell recordings provided a detailed analysis of the kinetic parameters underlying glycinergic dysfunction. Presynaptic compensation as well as postsynaptic compensatory mechanisms in these mice by other GlyR subunits or GABAA receptors, and the role of extra-synaptic GlyRs is still a matter of debate. A recent study on the mouse mutant oscillator displayed a novel aspect for compensation of functionality by complementation of receptor domains that fold independently. This review focuses on defects in glycinergic neurotransmission in mice discussed with the background of human hyperekplexia en route to strategies of compensation.
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Affiliation(s)
- Natascha Schaefer
- Emil Fischer Center, Institute of Biochemistry, University Erlangen-Nuernberg Erlangen, Germany ; Institute for Clinical Neurobiology, University of Wuerzburg Wuerzburg, Germany
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Hübner S, Efthymiadis A. Recent progress in histochemistry and cell biology. Histochem Cell Biol 2012; 137:403-57. [PMID: 22366957 DOI: 10.1007/s00418-012-0933-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2012] [Indexed: 01/06/2023]
Abstract
Studies published in Histochemistry and Cell Biology in the year 2011 represent once more a manifest of established and newly sophisticated techniques being exploited to put tissue- and cell type-specific molecules into a functional context. The review is therefore the Histochemistry and Cell Biology's yearly intention to provide interested readers appropriate summaries of investigations touching the areas of tissue biology, developmental biology, the biology of the immune system, stem cell research, the biology of subcellular compartments, in order to put the message of such studies into natural scientific-/human- and also pathological-relevant correlations.
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Affiliation(s)
- Stefan Hübner
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany.
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15
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Knipper M, Müller M, Zimmermann U. Molecular Mechanism of Tinnitus. SPRINGER HANDBOOK OF AUDITORY RESEARCH 2012. [DOI: 10.1007/978-1-4614-3728-4_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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16
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Buerbank S, Becker K, Becker CM, Brandt N, Engel J, Knipper M, Schick B, Dlugaiczyk J. Developmental regulation of glycine receptors at efferent synapses of the murine cochlea. Histochem Cell Biol 2011; 136:387-98. [DOI: 10.1007/s00418-011-0855-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2011] [Indexed: 11/30/2022]
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Lendvai B, Halmos GB, Polony G, Kapocsi J, Horváth T, Aller M, Sylvester Vizi E, Zelles T. Chemical neuroprotection in the cochlea: The modulation of dopamine release from lateral olivocochlear efferents. Neurochem Int 2011; 59:150-8. [DOI: 10.1016/j.neuint.2011.05.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 05/12/2011] [Accepted: 05/17/2011] [Indexed: 01/16/2023]
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Extending the knowledge in histochemistry and cell biology. Histochem Cell Biol 2009; 133:1-40. [PMID: 19946696 DOI: 10.1007/s00418-009-0665-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2009] [Indexed: 01/21/2023]
Abstract
Central to modern Histochemistry and Cell Biology stands the need for visualization of cellular and molecular processes. In the past several years, a variety of techniques has been achieved bridging traditional light microscopy, fluorescence microscopy and electron microscopy with powerful software-based post-processing and computer modeling. Researchers now have various tools available to investigate problems of interest from bird's- up to worm's-eye of view, focusing on tissues, cells, proteins or finally single molecules. Applications of new approaches in combination with well-established traditional techniques of mRNA, DNA or protein analysis have led to enlightening and prudent studies which have paved the way toward a better understanding of not only physiological but also pathological processes in the field of cell biology. This review is intended to summarize articles standing for the progress made in "histo-biochemical" techniques and their manifold applications.
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Sun W, Salvi RJ. Brain derived neurotrophic factor and neurotrophic factor 3 modulate neurotransmitter receptor expressions on developing spiral ganglion neurons. Neuroscience 2009; 164:1854-66. [PMID: 19778585 DOI: 10.1016/j.neuroscience.2009.09.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 09/12/2009] [Accepted: 09/14/2009] [Indexed: 12/25/2022]
Abstract
Cochlear spiral ganglion neurons (SGN) provide the only pathway for transmitting sound evoked activity from the hair cells to the central auditory system. Neurotrophic factor 3 (NT-3) and brain derived neurotrophic factor (BDNF) released from hair cells and supporting cells exert a profound effect on SGN survival and neural firing patterns; however, it is unclear what the effects NT-3 and BDNF have on the type of neurotransmitter receptors expressed on SGN. To address this question, the whole-cell patch clamp recording technique was used to determine what effect NT-3 and BDNF had on the function and expression of glutamate, GABA and glycine receptors (GlyR) on SGN of cochlea from postnatal C57 mouse. Receptor currents induced by the agonist of each receptor were recorded from SGN cultured with or without BDNF or NT-3. NT-3 and BDNF exerted different effects. NT-3, and to a lesser extent BDNF, enhanced the expression of GABA receptors and had comparatively little effect on glutamate receptors. Absence of BDNF and NT-3 resulted in the emergence of glycine-induced currents; however, GlyR currents were absent from the short term cultured SGN. In contrast, NT-3 and BDNF suppressed GlyR expression on SGN. These results indicate that NT-3 and BDNF exert a profound effect on the types of neurotransmitter receptors expressed on postnatal SGN, results that may have important implications for neural development and plasticity.
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Affiliation(s)
- W Sun
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, 137 Cary Hall, State University of New York at Buffalo, 3435 Main Street, Buffalo, NY 14214, USA.
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Eichler SA, Förstera B, Smolinsky B, Jüttner R, Lehmann TN, Fähling M, Schwarz G, Legendre P, Meier JC. Splice-specific roles of glycine receptor alpha3 in the hippocampus. Eur J Neurosci 2009; 30:1077-91. [PMID: 19723286 DOI: 10.1111/j.1460-9568.2009.06903.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Glycine receptor (GlyR) alpha3 is involved in vision, and processing of acoustic and nociceptive signals, and RNA editing of GLRA3 transcripts was associated with hippocampal pathophysiology of mesial temporal lobe epilepsy (TLE). However, neither the role of GlyR alpha3 splicing in hippocampal neurons nor the expression of splice variants have yet been elucidated. We report here that the long (L) splice variant of GlyR alpha3 predominates in the brain of rodents. Cellular analysis using primary hippocampal neurons and hippocampus cryosections revealed preferential association of synaptic alpha3L clusters with glutamatergic nerve endings in strata granulare and pyramidale. In primary hippocampal neurons GlyR alpha3L clusters also preferred glutamatergic nerve endings while alpha3K was mainly in a diffuse state. Co-expression of GlyR beta subunit with alpha3L or alpha3K produced heteromeric receptor clusters and favoured their association with GABAergic terminals. However, heteromeric alpha3L was still more efficient than heteromeric alpha3K in associating with glutamatergic nerve endings. To give physiological relevance to these results we have finally analysed GlyR alpha3 splicing in human hippocampus obtained from patients with intractable TLE. As up-regulation of alpha3K occurred at the expense of alpha3L in TLE patients with a severe course of disease and a high degree of hippocampal damage, our results again involve post-transcriptional processing of GLRA3 transcripts in the pathophysiology of TLE.
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State-of-the-art technologies, current opinions and developments, and novel findings: news from the field of histochemistry and cell biology. Histochem Cell Biol 2008; 130:1205-51. [PMID: 18985372 DOI: 10.1007/s00418-008-0535-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2008] [Indexed: 10/25/2022]
Abstract
Investigations of cell and tissue structure and function using innovative methods and approaches have again yielded numerous exciting findings in recent months and have added important data to current knowledge, inspiring new ideas and hypotheses in various fields of modern life sciences. Topics and contents of comprehensive expert reviews covering different aspects in methodological advances, cell biology, tissue function and morphology, and novel findings reported in original papers are summarized in the present review.
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