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Boff JM, Shrestha AP, Madireddy S, Viswaprakash N, Della Santina L, Vaithianathan T. The Interplay between Neurotransmitters and Calcium Dynamics in Retinal Synapses during Development, Health, and Disease. Int J Mol Sci 2024; 25:2226. [PMID: 38396913 PMCID: PMC10889697 DOI: 10.3390/ijms25042226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
The intricate functionality of the vertebrate retina relies on the interplay between neurotransmitter activity and calcium (Ca2+) dynamics, offering important insights into developmental processes, physiological functioning, and disease progression. Neurotransmitters orchestrate cellular processes to shape the behavior of the retina under diverse circumstances. Despite research to elucidate the roles of individual neurotransmitters in the visual system, there remains a gap in our understanding of the holistic integration of their interplay with Ca2+ dynamics in the broader context of neuronal development, health, and disease. To address this gap, the present review explores the mechanisms used by the neurotransmitters glutamate, gamma-aminobutyric acid (GABA), glycine, dopamine, and acetylcholine (ACh) and their interplay with Ca2+ dynamics. This conceptual outline is intended to inform and guide future research, underpinning novel therapeutic avenues for retinal-associated disorders.
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Affiliation(s)
- Johane M Boff
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Abhishek P Shrestha
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Saivikram Madireddy
- College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Nilmini Viswaprakash
- Department of Medical Education, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | | | - Thirumalini Vaithianathan
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
- Department of Ophthalmology, Hamilton Eye Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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2
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Cepeda AP, Ninov M, Neef J, Parfentev I, Kusch K, Reisinger E, Jahn R, Moser T, Urlaub H. Proteomic Analysis Reveals the Composition of Glutamatergic Organelles of Auditory Inner Hair Cells. Mol Cell Proteomics 2024; 23:100704. [PMID: 38128648 PMCID: PMC10832297 DOI: 10.1016/j.mcpro.2023.100704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 11/08/2023] [Accepted: 12/18/2023] [Indexed: 12/23/2023] Open
Abstract
In the ear, inner hair cells (IHCs) employ sophisticated glutamatergic ribbon synapses with afferent neurons to transmit auditory information to the brain. The presynaptic machinery responsible for neurotransmitter release in IHC synapses includes proteins such as the multi-C2-domain protein otoferlin and the vesicular glutamate transporter 3 (VGluT3). Yet, much of this likely unique molecular machinery remains to be deciphered. The scarcity of material has so far hampered biochemical studies which require large amounts of purified samples. We developed a subcellular fractionation workflow combined with immunoisolation of VGluT3-containing membrane vesicles, allowing for the enrichment of glutamatergic organelles that are likely dominated by synaptic vesicles (SVs) of IHCs. We have characterized their protein composition in mice before and after hearing onset using mass spectrometry and confocal imaging and provide a fully annotated proteome with hitherto unidentified proteins. Despite the prevalence of IHC marker proteins across IHC maturation, the profiles of trafficking proteins differed markedly before and after hearing onset. Among the proteins enriched after hearing onset were VAMP-7, syntaxin-7, syntaxin-8, syntaxin-12/13, SCAMP1, V-ATPase, SV2, and PKCα. Our study provides an inventory of the machinery associated with synaptic vesicle-mediated trafficking and presynaptic activity at IHC ribbon synapses and serves as a foundation for future functional studies.
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Affiliation(s)
- Andreia P Cepeda
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Momchil Ninov
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Department of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Jakob Neef
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience & Synaptic Nanophysiology Group Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Iwan Parfentev
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Kathrin Kusch
- Functional Auditory Genomics Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Ellen Reisinger
- Gene Therapy for Hearing Impairment and Deafness, Department for Otolaryngology, Head & Neck Surgery, University Hospital Tübingen, Tübingen, Germany
| | - Reinhard Jahn
- Laboratory of Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience & Synaptic Nanophysiology Group Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Department of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
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3
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Li G, Gao Y, Wu H, Zhao T. Gentamicin administration leads to synaptic dysfunction in inner hair cells. Toxicol Lett 2024; 391:86-99. [PMID: 38101494 DOI: 10.1016/j.toxlet.2023.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 11/17/2023] [Accepted: 12/11/2023] [Indexed: 12/17/2023]
Abstract
Ototoxicity is a major side effect of aminoglycosides, which can cause irreversible hearing loss. Previous studies on aminoglycoside-induced ototoxicity have primarily focused on the loss of sensory hair cells. Recent investigations have revealed that aminoglycosides can also lead to the loss of ribbon synapses in inner hair cells (IHCs). However, the functional implications of ribbon synapse loss and the underlying mechanisms remain unclear. In this study, we intraperitoneally injected C57BL/6 J mice with 300 mg/kg gentamicin once daily for 3, 10, and 20 days. Then, we performed immunofluorescence staining, patch-clamp recording, proteomics analysis and western blotting to characterize the changes in ribbon synapses in IHCs and the associated mechanisms. After gentamicin treatment, the auditory brainstem response (ABR) threshold was elevated, and the ABR wave I amplitude was decreased. We also observed loss of ribbon synapses in IHCs. Interestingly, ribbon synapse loss occurred on both the modiolar and pillar sides of IHCs. Whole-cell patch-clamp recordings in IHCs revealed a reduction in the calcium current amplitude, along with a shifted half-activation voltage and altered calcium voltage dependency. Moreover, exocytosis of IHCs was reduced, consistent with the reduction in the ABR wave I amplitude. Through proteomic analysis, western blotting, and immunofluorescence staining, we found that gentamicin treatment resulted in downregulation of myosin VI, a protein crucial for synaptic vesicle recycling and replenishment in IHCs. Furthermore, we evaluated the kinetics of endocytosis and found a significant reduction in IHC exocytosis, possibly reflecting the impact of myosin VI downregulation on synaptic vesicle recycling. In summary, our findings demonstrate that gentamicin treatment leads to synaptic dysfunction in IHCs, highlighting the important role of myosin VI downregulation in gentamicin-induced synaptic damage.
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Affiliation(s)
- Gen Li
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Yunge Gao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Ting Zhao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
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Jaime Tobón LM, Moser T. Ca 2+ regulation of glutamate release from inner hair cells of hearing mice. Proc Natl Acad Sci U S A 2023; 120:e2311539120. [PMID: 38019860 DOI: 10.1073/pnas.2311539120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 10/11/2023] [Indexed: 12/01/2023] Open
Abstract
In our hearing organ, sound is encoded at ribbon synapses formed by inner hair cells (IHCs) and spiral ganglion neurons (SGNs). How the underlying synaptic vesicle (SV) release is controlled by Ca2+ in IHCs of hearing animals remained to be investigated. Here, we performed patch-clamp SGN recordings of the initial rate of release evoked by brief IHC Ca2+-influx in an ex vivo cochlear preparation from hearing mice. We aimed to closely mimic physiological conditions by perforated-patch recordings from IHCs kept at the physiological resting potential and at body temperature. We found release to relate supralinearly to Ca2+-influx (power, m: 4.3) when manipulating the [Ca2+] available for SV release by Zn2+-flicker-blocking of the single Ca2+-channel current. In contrast, a near linear Ca2+ dependence (m: 1.2 to 1.5) was observed when varying the number of open Ca2+-channels during deactivating Ca2+-currents and by dihydropyridine channel-inhibition. Concurrent changes of number and current of open Ca2+-channels over the range of physiological depolarizations revealed m: 1.8. These findings indicate that SV release requires ~4 Ca2+-ions to bind to their Ca2+-sensor of fusion. We interpret the near linear Ca2+-dependence of release during manipulations that change the number of open Ca2+-channels to reflect control of SV release by the high [Ca2+] in the Ca2+-nanodomain of one or few nearby Ca2+-channels. We propose that a combination of Ca2+ nanodomain control and supralinear intrinsic Ca2+-dependence of fusion optimally links SV release to the timing and amplitude of the IHC receptor potential and separates it from other IHC Ca2+-signals unrelated to afferent synaptic transmission.
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Affiliation(s)
- Lina María Jaime Tobón
- Auditory Neuroscience and Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen 37077, Germany
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen 37075, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen 37075, Germany
- Multiscale Bioimaging of Excitable Cells, Cluster of Excellence, Göttingen 37075, Germany
| | - Tobias Moser
- Auditory Neuroscience and Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen 37077, Germany
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen 37075, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen 37075, Germany
- Multiscale Bioimaging of Excitable Cells, Cluster of Excellence, Göttingen 37075, Germany
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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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Moser T, Karagulyan N, Neef J, Jaime Tobón LM. Diversity matters - extending sound intensity coding by inner hair cells via heterogeneous synapses. EMBO J 2023; 42:e114587. [PMID: 37800695 PMCID: PMC10690447 DOI: 10.15252/embj.2023114587] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/26/2023] [Accepted: 08/07/2023] [Indexed: 10/07/2023] Open
Abstract
Our sense of hearing enables the processing of stimuli that differ in sound pressure by more than six orders of magnitude. How to process a wide range of stimulus intensities with temporal precision is an enigmatic phenomenon of the auditory system. Downstream of dynamic range compression by active cochlear micromechanics, the inner hair cells (IHCs) cover the full intensity range of sound input. Yet, the firing rate in each of their postsynaptic spiral ganglion neurons (SGNs) encodes only a fraction of it. As a population, spiral ganglion neurons with their respective individual coding fractions cover the entire audible range. How such "dynamic range fractionation" arises is a topic of current research and the focus of this review. Here, we discuss mechanisms for generating the diverse functional properties of SGNs and formulate testable hypotheses. We postulate that an interplay of synaptic heterogeneity, molecularly distinct subtypes of SGNs, and efferent modulation serves the neural decomposition of sound information and thus contributes to a population code for sound intensity.
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Affiliation(s)
- Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging of Excitable Cells”GöttingenGermany
| | - Nare Karagulyan
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
- Hertha Sponer CollegeCluster of Excellence “Multiscale Bioimaging of Excitable Cells” Cluster of ExcellenceGöttingenGermany
| | - Jakob Neef
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Lina María Jaime Tobón
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
- Hertha Sponer CollegeCluster of Excellence “Multiscale Bioimaging of Excitable Cells” Cluster of ExcellenceGöttingenGermany
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Shrestha AP, Stiles M, Grambergs RC, Boff JM, Madireddy S, Mondal K, Rajmanna R, Porter H, Sherry DM, Proia RL, Vaithianathan T, Mandal N. The Role of Sphingosine-1-Phosphate Receptor 2 in Mouse Retina Light Responses. Biomolecules 2023; 13:1691. [PMID: 38136563 PMCID: PMC10741782 DOI: 10.3390/biom13121691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/09/2023] [Accepted: 11/19/2023] [Indexed: 12/24/2023] Open
Abstract
The bioactive sphingolipid sphingosine-1-phosphate (S1P) acts as a ligand for a family of G protein-coupled S1P receptors (S1PR1-5) to participate in a variety of signaling pathways. However, their specific roles in the neural retina remain unclear. We previously showed that S1P receptor subtype 2 (S1PR2) is expressed in murine retinas, primarily in photoreceptors and bipolar cells, and its expression is altered by retinal stress. This study aims to elucidate the role of S1PR2 in the mouse retina. We examined light responses by electroretinography (ERG), structural differences by optical coherence tomography (OCT), and protein levels by immunohistochemistry (IHC) in wild-type (WT) and S1PR2 knockout (KO) mice at various ages between 3 and 6 months. We found that a- and b-wave responses significantly increased at flash intensities between 400~2000 and 4~2000 cd.s/m2, respectively, in S1PR2 KO mice relative to those of WT controls at baseline. S1PR2 KO mice also exhibited significantly increased retinal nerve fiber layer (RNFL) and outer plexiform layer (OPL) thickness by OCT relative to the WT. Finally, in S1PR2 KO mice, we observed differential labeling of synaptic markers by immunohistochemistry (IHC) and quantitative reverse transcription polymerase chain reaction (RT-qPCR). These results suggest a specific involvement of S1PR2 in the structure and synaptic organization of the retina and a potential role in light-mediated functioning of the retina.
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Affiliation(s)
- Abhishek P. Shrestha
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Megan Stiles
- Departments of Cell Biology, Neurosurgery, and Pharmacological Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Richard C. Grambergs
- Department of Ophthalmology, Hamilton Eye Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Johane M. Boff
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Saivikram Madireddy
- College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Koushik Mondal
- Department of Ophthalmology, Hamilton Eye Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Rhea Rajmanna
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Hunter Porter
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - David M. Sherry
- Departments of Cell Biology, Neurosurgery, and Pharmacological Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Richard L. Proia
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Thirumalini Vaithianathan
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Nawajes Mandal
- Department of Ophthalmology, Hamilton Eye Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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Srivastav S, Cui X, Varela RB, Kesby JP, Eyles D. Increasing dopamine synthesis in nigrostriatal circuits increases phasic dopamine release and alters dorsal striatal connectivity: implications for schizophrenia. SCHIZOPHRENIA (HEIDELBERG, GERMANY) 2023; 9:69. [PMID: 37798312 PMCID: PMC10556015 DOI: 10.1038/s41537-023-00397-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 09/18/2023] [Indexed: 10/07/2023]
Abstract
One of the most robust neurochemical abnormalities reported in patients with schizophrenia is an increase in dopamine (DA) synthesis and release, restricted to the dorsal striatum (DS). This hyper functionality is strongly associated with psychotic symptoms and progresses in those who later transition to schizophrenia. To understand the implications of this progressive neurobiology on brain function, we have developed a model in rats which we refer to as EDiPs (Enhanced Dopamine in Prodromal schizophrenia). The EDiPs model features a virally mediated increase in dorsal striatal (DS) DA synthesis capacity across puberty and into adulthood. This protocol leads to progressive changes in behaviour and neurochemistry. Our aim in this study was to explore if increased DA synthesis capacity alters the physiology of DA release and DS connectivity. Using fast scan cyclic voltammetry to assess DA release we show that evoked/phasic DA release is increased in the DS of EDiPs rats, whereas tonic/background levels of DA remain unaffected. Using quantitative immunohistochemistry methods to quantify DS synaptic architecture we show a presynaptic marker for DA release sites (Bassoon) was elevated within TH axons specifically within the DS, consistent with the increased phasic DA release in this region. Alongside changes in DA systems, we also show increased density of vesicular glutamate transporter 1 (VGluT1) synapses in the EDiPs DS suggesting changes in cortical connectivity. Our data may prove relevant in understanding the long-term implications for DS function in response to the robust and prolonged increases in DA synthesis uptake and release reported in schizophrenia.
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Affiliation(s)
- Sunil Srivastav
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Xiaoying Cui
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
- Queensland Centre for Mental Health Research, Brisbane, QLD, Australia
| | | | - James P Kesby
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
- Queensland Centre for Mental Health Research, Brisbane, QLD, Australia
| | - Darryl Eyles
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.
- Queensland Centre for Mental Health Research, Brisbane, QLD, Australia.
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Shrestha AP, Rameshkumar N, Boff JM, Rajmanna R, Chandrasegaran T, Frederick CE, Zenisek D, Vaithianathan T. The Effects of Aging on Rod Bipolar Cell Ribbon Synapses. Cells 2023; 12:2385. [PMID: 37830599 PMCID: PMC10572008 DOI: 10.3390/cells12192385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 09/20/2023] [Accepted: 09/27/2023] [Indexed: 10/14/2023] Open
Abstract
The global health concern posed by age-related visual impairment highlights the need for further research focused on the visual changes that occur during the process of aging. To date, multiple sensory alterations related to aging have been identified, including morphological and functional changes in inner hair cochlear cells, photoreceptors, and retinal ganglion cells. While some age-related morphological changes are known to occur in rod bipolar cells in the retina, their effects on these cells and on their connection to other cells via ribbon synapses remain elusive. To investigate the effects of aging on rod bipolar cells and their ribbon synapses, we compared synaptic calcium currents, calcium dynamics, and exocytosis in zebrafish (Danio rerio) that were middle-aged (MA,18 months) or old-aged (OA, 36 months). The bipolar cell terminal in OA zebrafish exhibited a two-fold reduction in number of synaptic ribbons, an increased ribbon length, and a decrease in local Ca2+ signals at the tested ribbon location, with little change in the overall magnitude of the calcium current or exocytosis in response to brief pulses. Staining of the synaptic ribbons with antibodies specific for PKCa revealed shortening of the inner nuclear and plexiform layers (INL and IPL). These findings shed light on age-related changes in the retina that are related to synaptic ribbons and calcium signals.
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Affiliation(s)
- Abhishek P. Shrestha
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Nirujan Rameshkumar
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Johane M. Boff
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Rhea Rajmanna
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | | | - Courtney E. Frederick
- Department of Molecular and Cellular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA (D.Z.)
| | - David Zenisek
- Department of Molecular and Cellular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA (D.Z.)
| | - Thirumalini Vaithianathan
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
- Department of Ophthalmology, Hamilton Eye Institute, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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10
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Michanski S, Kapoor R, Steyer AM, Möbius W, Früholz I, Ackermann F, Gültas M, Garner CC, Hamra FK, Neef J, Strenzke N, Moser T, Wichmann C. Piccolino is required for ribbon architecture at cochlear inner hair cell synapses and for hearing. EMBO Rep 2023; 24:e56702. [PMID: 37477166 PMCID: PMC10481675 DOI: 10.15252/embr.202256702] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 06/30/2023] [Accepted: 07/06/2023] [Indexed: 07/22/2023] Open
Abstract
Cochlear inner hair cells (IHCs) form specialized ribbon synapses with spiral ganglion neurons that tirelessly transmit sound information at high rates over long time periods with extreme temporal precision. This functional specialization is essential for sound encoding and is attributed to a distinct molecular machinery with unique players or splice variants compared to conventional neuronal synapses. Among these is the active zone (AZ) scaffold protein piccolo/aczonin, which is represented by its short splice variant piccolino at cochlear and retinal ribbon synapses. While the function of piccolo at synapses of the central nervous system has been intensively investigated, the role of piccolino at IHC synapses remains unclear. In this study, we characterize the structure and function of IHC synapses in piccolo gene-trap mutant rats (Pclogt/gt ). We find a mild hearing deficit with elevated thresholds and reduced amplitudes of auditory brainstem responses. Ca2+ channel distribution and ribbon morphology are altered in apical IHCs, while their presynaptic function seems to be unchanged. We conclude that piccolino contributes to the AZ organization in IHCs and is essential for normal hearing.
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Affiliation(s)
- Susann Michanski
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Center for Biostructural Imaging of NeurodegenerationUniversity Medical Center GöttingenGöttingenGermany
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Multiscale Bioimaging of Excitable Cells, Cluster of ExcellenceGöttingenGermany
| | - Rohan Kapoor
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
- IMPRS Molecular Biology, Göttingen Graduate School for Neuroscience and Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Anna M Steyer
- Electron Microscopy Core Unit, Department of NeurogeneticsMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Wiebke Möbius
- Multiscale Bioimaging of Excitable Cells, Cluster of ExcellenceGöttingenGermany
- Electron Microscopy Core Unit, Department of NeurogeneticsMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Iris Früholz
- Developmental, Neural, and Behavioral Biology Master ProgramUniversity of GöttingenGöttingenGermany
| | | | - Mehmet Gültas
- Faculty of AgricultureSouth Westphalia University of Applied SciencesSoestGermany
| | - Craig C Garner
- German Center for Neurodegenerative DiseasesBerlinGermany
- NeuroCureCluster of ExcellenceCharité – UniversitätsmedizinBerlinGermany
| | - F Kent Hamra
- Department of Obstetrics and GynecologyUniversity of Texas Southwestern Medical CenterDallasTXUSA
| | - Jakob Neef
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Nicola Strenzke
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Auditory Systems Physiology Group, Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
| | - Tobias Moser
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Multiscale Bioimaging of Excitable Cells, Cluster of ExcellenceGöttingenGermany
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Synaptic Nanophysiology GroupMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Center for Biostructural Imaging of NeurodegenerationUniversity Medical Center GöttingenGöttingenGermany
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”GöttingenGermany
- Multiscale Bioimaging of Excitable Cells, Cluster of ExcellenceGöttingenGermany
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11
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Karagulyan N, Moser T. Synaptic activity is not required for establishing heterogeneity of inner hair cell ribbon synapses. Front Mol Neurosci 2023; 16:1248941. [PMID: 37745283 PMCID: PMC10512025 DOI: 10.3389/fnmol.2023.1248941] [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: 06/27/2023] [Accepted: 08/17/2023] [Indexed: 09/26/2023] Open
Abstract
Neural sound encoding in the mammalian cochlea faces the challenge of representing audible sound pressures that vary over six orders of magnitude. The cochlea meets this demand through the use of active micromechanics as well as the diversity and adaptation of afferent neurons and their synapses. Mechanisms underlying neural diversity likely include heterogeneous presynaptic input from inner hair cells (IHCs) to spiral ganglion neurons (SGNs) as well as differences in the molecular profile of SGNs and in their efferent control. Here, we tested whether glutamate release from IHCs, previously found to be critical for maintaining different molecular SGN profiles, is required for establishing heterogeneity of active zones (AZs) in IHCs. We analyzed structural and functional heterogeneity of IHC AZs in mouse mutants with disrupted glutamate release from IHCs due to lack of a vesicular glutamate transporter (Vglut3) or impaired exocytosis due to defective otoferlin. We found the variance of the voltage-dependence of presynaptic Ca2+ influx to be reduced in exocytosis-deficient IHCs of otoferlin mutants. Yet, the spatial gradients of maximal amplitude and voltage-dependence of Ca2+ influx along the pillar-modiolar IHC axis were maintained in both mutants. Further immunohistochemical analysis showed an intact spatial gradient of ribbon size in Vglut3-/- mice. These results indicate that IHC exocytosis and glutamate release are not strictly required for establishing the heterogeneity of IHC AZs.
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Affiliation(s)
- Nare Karagulyan
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Nanophysiology Group, Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany
- Hertha Sponer College, Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Nanophysiology Group, Max Planck Institute of Multidisciplinary Sciences, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Göttingen Graduate School for Neurosciences and Molecular Biosciences, University of Göttingen, Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
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12
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Shrestha AP, Stiles M, Grambergs RC, Boff JM, Madireddy S, Mondal K, Rajmanna R, Porter H, Sherry D, Proia RL, Vaithianathan T, Mandal N. The role of sphingosine-1-phosphate receptor 2 in mouse retina light responses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.01.555709. [PMID: 37732206 PMCID: PMC10508730 DOI: 10.1101/2023.09.01.555709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
The bioactive sphingolipid sphingosine-1-phosphate (S1P) acts as a ligand for a family of G protein-coupled S1P receptors (S1PR1-5) to participate in a variety of signaling pathways. However, their specific roles in the neural retina remain unclear. We previously showed that S1P receptor subtype 2 (S1PR2) is expressed in murine retinas, primarily in photoreceptors and bipolar cells, and its expression is altered by retinal stress. This study aims to elucidate the role of S1PR2 in the mouse retina. We examined light responses by electroretinography (ERG), structural differences by optical coherence tomography (OCT), and protein levels by immunohistochemistry (IHC) in wild-type (WT) and S1PR2 knockout (KO) mice at various ages between 3 and 6 months. We found that a- and b-wave responses significantly increased at flash intensities between 400∼2000 and 4∼2,000 cd.s/m 2 respectively, in S1PR2 KO mice relative to those of WT controls at baseline. S1PR2 KO mice also exhibited significantly increased retinal nerve fiber layer (RNFL) and outer plexiform layer (OPL) thickness by OCT relative to the WT. Finally, in S1PR2 KO mice, we observed differential labeling of synaptic markers by immunohistochemistry (IHC) and quantitative reverse transcription polymerase chain reaction (RT-qPCR). These results suggest a specific involvement of S1PR2 in the structure and synaptic organization of the retina and a potential role in light-mediated functioning of the retina.
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13
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Okur MN, Sahbaz BD, Kimura R, Manor U, Patel J, Park J, Andrade L, Puligilla C, Croteau DL, Bohr VA. Long-term NAD+ supplementation prevents the progression of age-related hearing loss in mice. Aging Cell 2023; 22:e13909. [PMID: 37395319 PMCID: PMC10497810 DOI: 10.1111/acel.13909] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 05/27/2023] [Accepted: 05/31/2023] [Indexed: 07/04/2023] Open
Abstract
Age-related hearing loss (ARHL) is the most common sensory disability associated with human aging. Yet, there are no approved measures for preventing or treating this debilitating condition. With its slow progression, continuous and safe approaches are critical for ARHL treatment. Nicotinamide Riboside (NR), a NAD+ precursor, is well tolerated even for long-term use and is already shown effective in various disease models including Alzheimer's and Parkinson's disease. It has also been beneficial against noise-induced hearing loss and in hearing loss associated with premature aging. However, its beneficial impact on ARHL is not known. Using two different wild-type mouse strains, we show that long-term NR administration prevents the progression of ARHL. Through transcriptomic and biochemical analysis, we find that NR administration restores age-associated reduction in cochlear NAD+ levels, upregulates biological pathways associated with synaptic transmission and PPAR signaling, and reduces the number of orphan ribbon synapses between afferent auditory neurons and inner hair cells. We also find that NR targets a novel pathway of lipid droplets in the cochlea by inducing the expression of CIDEC and PLIN1 proteins that are downstream of PPAR signaling and are key for lipid droplet growth. Taken together, our results demonstrate the therapeutic potential of NR treatment for ARHL and provide novel insights into its mechanism of action.
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Affiliation(s)
- Mustafa N. Okur
- Section on DNA Repair, National Institute on AgingNational Institutes of HealthBaltimoreMarylandUSA
| | - Burcin Duan Sahbaz
- Section on DNA Repair, National Institute on AgingNational Institutes of HealthBaltimoreMarylandUSA
| | - Risako Kimura
- Section on DNA Repair, National Institute on AgingNational Institutes of HealthBaltimoreMarylandUSA
| | - Uri Manor
- Waitt Advanced Biophotonics CenterSalk Institute for Biological StudiesLa JollaCaliforniaUSA
| | - Jaimin Patel
- Section on DNA Repair, National Institute on AgingNational Institutes of HealthBaltimoreMarylandUSA
| | - Jae‐Hyeon Park
- Section on DNA Repair, National Institute on AgingNational Institutes of HealthBaltimoreMarylandUSA
| | - Leo Andrade
- Waitt Advanced Biophotonics CenterSalk Institute for Biological StudiesLa JollaCaliforniaUSA
| | - Chandrakala Puligilla
- Section on DNA Repair, National Institute on AgingNational Institutes of HealthBaltimoreMarylandUSA
| | - Deborah L. Croteau
- Section on DNA Repair, National Institute on AgingNational Institutes of HealthBaltimoreMarylandUSA
- Computational Biology & Genomics Core, National Institute on AgingNational Institutes of HealthBaltimoreMarylandUSA
| | - Vilhelm A. Bohr
- Section on DNA Repair, National Institute on AgingNational Institutes of HealthBaltimoreMarylandUSA
- Danish Center for Healthy AgingUniversity of CopenhagenCopenhagen NDenmark
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14
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Yin N, Zhao J, Zhang P, Yu B, Chai R, Li GL. Functional and developmental changes in the inner hair cell ribbon synapses caused by Myosin VI knockout and deafness-inducing point mutation. Cell Death Discov 2023; 9:177. [PMID: 37258513 DOI: 10.1038/s41420-023-01473-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 04/27/2023] [Accepted: 05/16/2023] [Indexed: 06/02/2023] Open
Abstract
Hearing loss is one of the most common neurosensory disorders in humans, and above half of hearing loss is caused by gene mutations. Among more than 100 genes that cause non-syndromic hearing loss, myosin VI (MYO6) is typical in terms of the complexity of underlying mechanisms, which are not well understood. In this study, we used both knock-out (Myo6-/-) and point mutation (Myo6C442Y) mice as animal models, performed whole-cell patch-clamp recording and capacitance measurement in the inner hair cells (IHCs) in the cochlea, and sought to reveal potential functional and developmental changes in their ribbon synapses. In Myo6-/- cochleae of both before (P8-10) and after hearing onset (P18-20), exocytosis from IHCs, measured in whole-cell capacitance change (ΔCm), was significantly reduced, Ca2+ current amplitude (ICa) was unchanged, but Ca2+ voltage dependency was differently altered, causing significant increase in Ca2+ influx in mature IHCs but not in immature IHCs. In immature IHCs of Myo6C442Y/C442Y cochleae, neither ΔCm nor ICa was altered, but both were reduced in mature IHCs of the same animal model. Furthermore, while the reduction of exocytosis was caused by a combination of the slower rate of depleting readily releasable (RRP) pool of synaptic vesicles and slower sustained release rate (SRR) in Myo6-/- immature IHCs, it was likely due to smaller RRP and slower SRR in mature IHCs of both animal models. These results expand our understanding of the mechanisms of deafness caused by MYO6 mutations, and provide a solid theoretical and scientific basis for the diagnosis and treatment of deafness.
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Affiliation(s)
- Ning Yin
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
| | - Jingjing Zhao
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
| | - Panpan Zhang
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Baofu Yu
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, 200011, China
| | - Renjie Chai
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China.
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China.
| | - Geng-Lin Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China.
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China.
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15
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Calcium signaling and genetic rare diseases: An auditory perspective. Cell Calcium 2023; 110:102702. [PMID: 36791536 DOI: 10.1016/j.ceca.2023.102702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/01/2023] [Accepted: 02/02/2023] [Indexed: 02/07/2023]
Abstract
Deafness is a highly heterogeneous disorder which stems, for 50%, from genetic origins. Sensory transduction relies mainly on sensory hair cells of the cochlea, in the inner ear. Calcium is key for the function of these cells and acts as a fundamental signal transduction. Its homeostasis depends on three factors: the calcium influx, through the mechanotransduction channel at the apical pole of the hair cell as well as the voltage-gated calcium channel at the base of the cells; the calcium buffering via Ca2+-binding proteins in the cytoplasm, but also in organelles such as mitochondria and the reticulum endoplasmic mitochondria-associated membranes with specialized proteins; and the calcium extrusion through the Ca-ATPase pump, located all over the plasma membrane. In addition, the synaptic transmission to the central nervous system is also controlled by calcium. Genetic studies of inherited deafness have tremendously helped understand the underlying molecular pathways of calcium signaling. In this review, we discuss these different factors in light of the associated genetic diseases (syndromic and non-syndromic deafness) and the causative genes.
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16
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Wu X, Qiu H, Zhang M. Interactions between Membraneless Condensates and Membranous Organelles at the Presynapse: A Phase Separation View of Synaptic Vesicle Cycle. J Mol Biol 2023; 435:167629. [PMID: 35595170 DOI: 10.1016/j.jmb.2022.167629] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 02/04/2023]
Abstract
Action potential-induced neurotransmitter release in presynaptic boutons involves coordinated actions of a large list of proteins that are associated directly or indirectly with membrane structures including synaptic vesicles and plasma membranes. These proteins are often highly abundant in different synaptic bouton sub-compartments, and they rarely act alone. Instead, these proteins interact with each other forming intricate and distinct molecular complexes. Many of these complexes form condensed clusters on membrane surfaces. This review summarizes findings in recent years showing that many of presynaptic protein complex assemblies are formed via phase separation. These protein condensates extensively interact with lipid membranes via distinct modes, forming various mesoscale structures by different mode of organizations between membraneless condensates and membranous organelles. We discuss that such mesoscale interactions could have deep implications on mobilization, exocytosis, and retrieval of synaptic vesicles.
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Affiliation(s)
- Xiandeng Wu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Hua Qiu
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518036, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
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17
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Cunningham KL, Littleton JT. Mechanisms controlling the trafficking, localization, and abundance of presynaptic Ca 2+ channels. Front Mol Neurosci 2023; 15:1116729. [PMID: 36710932 PMCID: PMC9880069 DOI: 10.3389/fnmol.2022.1116729] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 12/26/2022] [Indexed: 01/14/2023] Open
Abstract
Voltage-gated Ca2+ channels (VGCCs) mediate Ca2+ influx to trigger neurotransmitter release at specialized presynaptic sites termed active zones (AZs). The abundance of VGCCs at AZs regulates neurotransmitter release probability (Pr ), a key presynaptic determinant of synaptic strength. Given this functional significance, defining the processes that cooperate to establish AZ VGCC abundance is critical for understanding how these mechanisms set synaptic strength and how they might be regulated to control presynaptic plasticity. VGCC abundance at AZs involves multiple steps, including channel biosynthesis (transcription, translation, and trafficking through the endomembrane system), forward axonal trafficking and delivery to synaptic terminals, incorporation and retention at presynaptic sites, and protein recycling. Here we discuss mechanisms that control VGCC abundance at synapses, highlighting findings from invertebrate and vertebrate models.
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Affiliation(s)
- Karen L. Cunningham
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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18
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Mauriac SA, Peineau T, Zuberi A, Lutz C, Géléoc GSG. Loss of Pex1 in Inner Ear Hair Cells Contributes to Cochlear Synaptopathy and Hearing Loss. Cells 2022; 11:cells11243982. [PMID: 36552747 PMCID: PMC9777190 DOI: 10.3390/cells11243982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 12/04/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
Peroxisome Biogenesis Disorders (PBD) and Zellweger syndrome spectrum disorders (ZSD) are rare genetic multisystem disorders that include hearing impairment and are associated with defects in peroxisome assembly, function, or both. Mutations in 13 peroxin (PEX) genes have been found to cause PBD-ZSD with ~70% of patients harboring mutations in PEX1. Limited research has focused on the impact of peroxisomal disorders on auditory function. As sensory hair cells are particularly vulnerable to metabolic changes, we hypothesize that mutations in PEX1 lead to oxidative stress affecting hair cells of the inner ear, subsequently resulting in hair cell degeneration and hearing loss. Global deletion of the Pex1 gene is neonatal lethal in mice, impairing any postnatal studies. To overcome this limitation, we created conditional knockout mice (cKO) using Gfi1Creor VGlut3Cre expressing mice crossed to floxed Pex1 mice to allow for selective deletion of Pex1 in the hair cells of the inner ear. We find that Pex1 excision in inner hair cells (IHCs) leads to progressive hearing loss associated with significant decrease in auditory brainstem responses (ABR), specifically ABR wave I amplitude, indicative of synaptic defects. Analysis of IHC synapses in cKO mice reveals a decrease in ribbon synapse volume and functional alterations in exocytosis. Concomitantly, we observe a decrease in peroxisomal number, indicative of oxidative stress imbalance. Taken together, these results suggest a critical function of Pex1 in development and maturation of IHC-spiral ganglion synapses and auditory function.
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Affiliation(s)
- Stephanie A. Mauriac
- Department of Otolaryngology, Boston Children’s Hospital, Boston, MA 02115, USA
- Kirby Neurobiology Center, Harvard Medical School, Boston, MA 02115, USA
| | - Thibault Peineau
- Department of Otolaryngology, Boston Children’s Hospital, Boston, MA 02115, USA
- Kirby Neurobiology Center, Harvard Medical School, Boston, MA 02115, USA
| | - Aamir Zuberi
- Rare Disease Translational Center, The Jackson Laboratory, Bar Harbor, ME 04609, USA
- Technology Evaluation and Development Research Laboratory, The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Cathleen Lutz
- Rare Disease Translational Center, The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Gwénaëlle S. G. Géléoc
- Department of Otolaryngology, Boston Children’s Hospital, Boston, MA 02115, USA
- Kirby Neurobiology Center, Harvard Medical School, Boston, MA 02115, USA
- Correspondence: ; Tel.: +1-617-919-4061
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19
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Sarkar D, Kang J, Wassie AT, Schroeder ME, Peng Z, Tarr TB, Tang AH, Niederst ED, Young JZ, Su H, Park D, Yin P, Tsai LH, Blanpied TA, Boyden ES. Revealing nanostructures in brain tissue via protein decrowding by iterative expansion microscopy. Nat Biomed Eng 2022; 6:1057-1073. [PMID: 36038771 PMCID: PMC9551354 DOI: 10.1038/s41551-022-00912-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Accepted: 06/22/2022] [Indexed: 12/25/2022]
Abstract
Many crowded biomolecular structures in cells and tissues are inaccessible to labelling antibodies. To understand how proteins within these structures are arranged with nanoscale precision therefore requires that these structures be decrowded before labelling. Here we show that an iterative variant of expansion microscopy (the permeation of cells and tissues by a swellable hydrogel followed by isotropic hydrogel expansion, to allow for enhanced imaging resolution with ordinary microscopes) enables the imaging of nanostructures in expanded yet otherwise intact tissues at a resolution of about 20 nm. The method, which we named 'expansion revealing' and validated with DNA-probe-based super-resolution microscopy, involves gel-anchoring reagents and the embedding, expansion and re-embedding of the sample in homogeneous swellable hydrogels. Expansion revealing enabled us to use confocal microscopy to image the alignment of pre-synaptic calcium channels with post-synaptic scaffolding proteins in intact brain circuits, and to uncover periodic amyloid nanoclusters containing ion-channel proteins in brain tissue from a mouse model of Alzheimer's disease. Expansion revealing will enable the further discovery of previously unseen nanostructures within cells and tissues.
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Affiliation(s)
- Deblina Sarkar
- Media Lab, MIT, Cambridge, MA, 02139, USA.,MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, 02139, USA.,These authors contributed equally
| | - Jinyoung Kang
- MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, 02139, USA.,These authors contributed equally
| | - Asmamaw T Wassie
- Department of Biological Engineering, MIT, Cambridge, MA, 02139, USA.,These authors contributed equally
| | - Margaret E. Schroeder
- MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, 02139, USA.,Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, 02139, USA
| | - Zhuyu Peng
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, 02139, USA.,The Picower Institute for Learning and Memory, MIT, Cambridge, MA, 02139, USA
| | - Tyler B. Tarr
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Ai-Hui Tang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,CAS Key Laboratory of Brain Function and Disease, Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230031, China
| | - Emily D. Niederst
- The Picower Institute for Learning and Memory, MIT, Cambridge, MA, 02139, USA
| | - Jennie, Z. Young
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, 02139, USA.,The Picower Institute for Learning and Memory, MIT, Cambridge, MA, 02139, USA
| | - Hanquan Su
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA.,Department of Systems Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Demian Park
- MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, 02139, USA
| | - Peng Yin
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA.,Department of Systems Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Li-Huei Tsai
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, USA. .,The Picower Institute for Learning and Memory, MIT, Cambridge, MA, USA. .,Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Thomas A. Blanpied
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Correspondence and requests for materials should be addressed to Li-Huei Tsai, Thomas A. Blanpied or Edward S. Boyden. , ,
| | - Edward S. Boyden
- MIT Center for Neurobiological Engineering, MIT, Cambridge, MA, 02139, USA.,MIT McGovern Institute for Brain Research, MIT, Cambridge, MA, 02139, USA.,Department of Biological Engineering, MIT, Cambridge, MA, 02139, USA.,Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, 02139, USA.,Koch Institute, MIT, Cambridge, MA, 02139, USA.,Howard Hughes Medical Institute, Cambridge, MA, 02139, USA.,Media Arts and Sciences, MIT, Cambridge, MA, 02139, USA.,K. Lisa Yang Center for Bionics, MIT, Cambridge, MA, 02139, USA.,Correspondence and requests for materials should be addressed to Li-Huei Tsai, Thomas A. Blanpied or Edward S. Boyden. , ,
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20
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Montenegro‐Venegas C, Guhathakurta D, Pina‐Fernandez E, Andres‐Alonso M, Plattner F, Gundelfinger ED, Fejtova A. Bassoon controls synaptic vesicle release via regulation of presynaptic phosphorylation and
cAMP. EMBO Rep 2022; 23:e53659. [PMID: 35766170 PMCID: PMC9346490 DOI: 10.15252/embr.202153659] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 05/23/2022] [Accepted: 06/01/2022] [Indexed: 11/11/2022] Open
Abstract
Neuronal presynaptic terminals contain hundreds of neurotransmitter‐filled synaptic vesicles (SVs). The morphologically uniform SVs differ in their release competence segregating into functional pools that differentially contribute to neurotransmission. The presynaptic scaffold bassoon is required for neurotransmission, but the underlying molecular mechanisms are unknown. We report that glutamatergic synapses lacking bassoon feature decreased SV release competence and increased resting pool of SVs as assessed by imaging of SV release in cultured neurons. CDK5/calcineurin and cAMP/PKA presynaptic signalling are dysregulated, resulting in an aberrant phosphorylation of their downstream effectors synapsin1 and SNAP25, well‐known regulators of SV release competence. An acute pharmacological restoration of physiological CDK5 and cAMP/PKA activity fully normalises the SV pools in neurons lacking bassoon. Finally, we demonstrate that CDK5‐dependent regulation of PDE4 activity interacts with cAMP/PKA signalling and thereby controls SV release competence. These data reveal that bassoon organises SV pools in glutamatergic synapses via regulation of presynaptic phosphorylation and cAMP homeostasis and indicate a role of CDK5/PDE4/cAMP axis in the control of neurotransmitter release.
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Affiliation(s)
- Carolina Montenegro‐Venegas
- Department of Neurochemistry and Molecular Biology Leibniz Institute for Neurobiology Magdeburg Germany
- Center for Behavioral Brain Sciences (CBBS) Magdeburg Germany
- Institute for Pharmacology and Toxicology, Medical Faculty Otto von Guericke University Magdeburg Germany
| | - Debarpan Guhathakurta
- Molecular Psychiatry, Department of Psychiatry and Psychotherapy Universitätsklinikum Erlangen, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg Erlangen Germany
| | | | - Maria Andres‐Alonso
- RG Presynaptic Plasticity Leibniz Institute for Neurobiology Magdeburg Germany
| | | | - Eckart D Gundelfinger
- Department of Neurochemistry and Molecular Biology Leibniz Institute for Neurobiology Magdeburg Germany
- Center for Behavioral Brain Sciences (CBBS) Magdeburg Germany
- Institute for Pharmacology and Toxicology, Medical Faculty Otto von Guericke University Magdeburg Germany
| | - Anna Fejtova
- Department of Neurochemistry and Molecular Biology Leibniz Institute for Neurobiology Magdeburg Germany
- Molecular Psychiatry, Department of Psychiatry and Psychotherapy Universitätsklinikum Erlangen, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg Erlangen Germany
- RG Presynaptic Plasticity Leibniz Institute for Neurobiology Magdeburg Germany
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21
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Mesnard CS, Barta CL, Sladek AL, Zenisek D, Thoreson WB. Eliminating Synaptic Ribbons from Rods and Cones Halves the Releasable Vesicle Pool and Slows Down Replenishment. Int J Mol Sci 2022; 23:ijms23126429. [PMID: 35742873 PMCID: PMC9223732 DOI: 10.3390/ijms23126429] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/03/2022] [Accepted: 06/05/2022] [Indexed: 01/25/2023] Open
Abstract
Glutamate release from rod and cone photoreceptor cells involves presynaptic ribbons composed largely of the protein RIBEYE. To examine roles of ribbons in rods and cones, we studied mice in which GCamP3 replaced the B-domain of RIBEYE. We discovered that ribbons were absent from rods and cones of both knock-in mice possessing GCamP3 and conditional RIBEYE knockout mice. The mice lacking ribbons showed reduced temporal resolution and contrast sensitivity assessed with optomotor reflexes. ERG recordings showed 50% reduction in scotopic and photopic b-waves. The readily releasable pool (RRP) of vesicles in rods and cones measured using glutamate transporter anion currents (IA(glu)) was also halved. We also studied the release from cones by stimulating them optogenetically with ChannelRhodopsin2 (ChR2) while recording postsynaptic currents in horizontal cells. Recovery of the release from paired pulse depression was twofold slower in the rods and cones lacking ribbons. The release from rods at -40 mV in darkness involves regularly spaced multivesicular fusion events. While the regular pattern of release remained in the rods lacking ribbons, the number of vesicles comprising each multivesicular event was halved. Our results support conclusions that synaptic ribbons in rods and cones expand the RRP, speed up vesicle replenishment, and augment some forms of multivesicular release. Slower replenishment and a smaller RRP in photoreceptors lacking ribbons may contribute to diminished temporal frequency responses and weaker contrast sensitivity.
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Affiliation(s)
- Chris S. Mesnard
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA; (C.S.M.); (C.L.B.); (A.L.S.)
- Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Cody L. Barta
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA; (C.S.M.); (C.L.B.); (A.L.S.)
| | - Asia L. Sladek
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA; (C.S.M.); (C.L.B.); (A.L.S.)
| | - David Zenisek
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06510, USA;
| | - Wallace B. Thoreson
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA; (C.S.M.); (C.L.B.); (A.L.S.)
- Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Correspondence: ; Tel.: +1-402-559-4076
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22
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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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23
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Vogl C, Neef J, Wichmann C. Methods for multiscale structural and functional analysis of the mammalian cochlea. Mol Cell Neurosci 2022; 120:103720. [DOI: 10.1016/j.mcn.2022.103720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 02/13/2022] [Accepted: 03/08/2022] [Indexed: 01/11/2023] Open
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24
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Chakrabarti R, Jaime Tobón LM, Slitin L, Redondo Canales M, Hoch G, Slashcheva M, Fritsch E, Bodensiek K, Özçete ÖD, Gültas M, Michanski S, Opazo F, Neef J, Pangrsic T, Moser T, Wichmann C. Optogenetics and electron tomography for structure-function analysis of cochlear ribbon synapses. eLife 2022; 11:79494. [PMID: 36562477 PMCID: PMC9908081 DOI: 10.7554/elife.79494] [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: 04/14/2022] [Accepted: 11/28/2022] [Indexed: 12/24/2022] Open
Abstract
Ribbon synapses of cochlear inner hair cells (IHCs) are specialized to indefatigably transmit sound information at high rates. To understand the underlying mechanisms, structure-function analysis of the active zone (AZ) of these synapses is essential. Previous electron microscopy studies of synaptic vesicle (SV) dynamics at the IHC AZ used potassium stimulation, which limited the temporal resolution to minutes. Here, we established optogenetic IHC stimulation followed by quick freezing within milliseconds and electron tomography to study the ultrastructure of functional synapse states with good temporal resolution in mice. We characterized optogenetic IHC stimulation by patch-clamp recordings from IHCs and postsynaptic boutons revealing robust IHC depolarization and neurotransmitter release. Ultrastructurally, the number of docked SVs increased upon short (17-25 ms) and long (48-76 ms) light stimulation paradigms. We did not observe enlarged SVs or other morphological correlates of homotypic fusion events. Our results indicate a rapid recruitment of SVs to the docked state upon stimulation and suggest that univesicular release prevails as the quantal mechanism of exocytosis at IHC ribbon synapses.
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Affiliation(s)
- Rituparna Chakrabarti
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Center for Biostructural Imaging of Neurodegeneration, University Medical Center GöttingenGöttingenGermany,Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany
| | - Lina María Jaime Tobón
- Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany,Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Loujin Slitin
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Center for Biostructural Imaging of Neurodegeneration, University Medical Center GöttingenGöttingenGermany,Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany
| | - Magdalena Redondo Canales
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Center for Biostructural Imaging of Neurodegeneration, University Medical Center GöttingenGöttingenGermany,Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany
| | - Gerhard Hoch
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Marina Slashcheva
- Göttingen Graduate School for Neuroscience and Molecular Biosciences, University of GöttingenGöttingenGermany
| | - Elisabeth Fritsch
- Göttingen Graduate School for Neuroscience and Molecular Biosciences, University of GöttingenGöttingenGermany
| | - Kai Bodensiek
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany
| | - Özge Demet Özçete
- Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany,Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Mehmet Gültas
- Faculty of Agriculture, South Westphalia University of Applied SciencesSoestGermany
| | - Susann Michanski
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Center for Biostructural Imaging of Neurodegeneration, University Medical Center GöttingenGöttingenGermany,Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany
| | - Felipe Opazo
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center GöttingenGöttingenGermany,NanoTag Biotechnologies GmbHGöttingenGermany,Institute of Neuro- and Sensory Physiology, University Medical Center GöttingenGöttingenGermany
| | - Jakob Neef
- Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany,Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Tina Pangrsic
- Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany,Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany,Multiscale Bioimaging: from Molecular Machines to Networks of Excitable CellsGöttingenGermany,Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany
| | - Tobias Moser
- Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany,Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary SciencesGöttingenGermany,Multiscale Bioimaging: from Molecular Machines to Networks of Excitable CellsGöttingenGermany
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center GöttingenGöttingenGermany,Center for Biostructural Imaging of Neurodegeneration, University Medical Center GöttingenGöttingenGermany,Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing"GöttingenGermany,Multiscale Bioimaging: from Molecular Machines to Networks of Excitable CellsGöttingenGermany
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25
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Joshi Y, Petit CP, Miot S, Guillet M, Sendin G, Bourien J, Wang J, Pujol R, El Mestikawy S, Puel JL, Nouvian R. VGLUT3-p.A211V variant fuses stereocilia bundles and elongates synaptic ribbons. J Physiol 2021; 599:5397-5416. [PMID: 34783032 PMCID: PMC9299590 DOI: 10.1113/jp282181] [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: 08/20/2021] [Accepted: 11/01/2021] [Indexed: 11/16/2022] Open
Abstract
Abstract DFNA25 is an autosomal‐dominant and progressive form of human deafness caused by mutations in the SLC17A8 gene, which encodes the vesicular glutamate transporter type 3 (VGLUT3). To resolve the mechanisms underlying DFNA25, we studied phenotypes of mice harbouring the p.A221V mutation in humans (corresponding to p.A224V in mice). Using auditory brainstem response and distortion product otoacoustic emissions, we showed progressive hearing loss with intact cochlear amplification in the VGLUT3A224V/A224V mouse. The summating potential was reduced, indicating the alteration of inner hair cell (IHC) receptor potential. Scanning electron microscopy examinations demonstrated the collapse of stereocilia bundles in IHCs, leaving those from outer hair cells unaffected. In addition, IHC ribbon synapses underwent structural and functional modifications at later stages. Using super‐resolution microscopy, we observed oversized synaptic ribbons and patch‐clamp membrane capacitance measurements showed an increase in the rate of the sustained releasable pool exocytosis. These results suggest that DFNA25 stems from a failure in the mechano‐transduction followed by a change in synaptic transfer. The VGLUT3A224V/A224V mouse model opens the way to a deeper understanding and to a potential treatment for DFNA25. Key points The vesicular glutamate transporter type 3 (VGLUT3) loads glutamate into the synaptic vesicles of auditory sensory cells, the inner hair cells (IHCs). The VGLUT3‐p.A211V variant is associated with human deafness DFNA25. Mutant mice carrying the VGLUT3‐p.A211V variant show progressive hearing loss. IHCs from mutant mice harbour distorted stereocilary bundles, which detect incoming sound stimulation, followed by oversized synaptic ribbons, which release glutamate onto the afferent nerve fibres. These results suggest that DFNA25 stems from the failure of auditory sensory cells to faithfully transduce acoustic cues into neural messages.
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Affiliation(s)
- Yuvraj Joshi
- INM, Univ Montpellier, INSERM, Montpellier, France
| | | | - Stéphanie Miot
- INM, Univ Montpellier, INSERM, Montpellier, France.,Sorbonne Universités, Université Pierre et Marie Curie UM 119, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris, France
| | | | | | | | - Jing Wang
- INM, Univ Montpellier, INSERM, Montpellier, France
| | - Rémy Pujol
- INM, Univ Montpellier, INSERM, Montpellier, France
| | - Salah El Mestikawy
- Sorbonne Universités, Université Pierre et Marie Curie UM 119, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris, France.,Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
| | | | - Régis Nouvian
- INM, Univ Montpellier, INSERM, Montpellier, France.,INM, Univ Montpellier, INSERM, CNRS, Montpellier, France
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26
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Yu C, Gao HM, Wan G. Macrophages Are Dispensable for Postnatal Pruning of the Cochlear Ribbon Synapses. Front Cell Neurosci 2021; 15:736120. [PMID: 34744631 PMCID: PMC8566810 DOI: 10.3389/fncel.2021.736120] [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: 07/04/2021] [Accepted: 10/05/2021] [Indexed: 11/15/2022] Open
Abstract
Ribbon synapses of cochlear hair cells undergo pruning and maturation before the hearing onset. In the central nervous system (CNS), synaptic pruning was mediated by microglia, the brain-resident macrophages, via activation of the complement system. Whether a similar mechanism regulates ribbon synapse pruning is currently unknown. In this study, we report that the densities of cochlear macrophages surrounding hair cells were highest at around P8, corresponding well to the completion of ribbon synaptic pruning by P8–P9. Surprisingly, using multiple genetic mouse models, we found that postnatal pruning of the ribbon synapses and auditory functions were unaffected by the knockout of the complement receptor 3 (CR3) or by ablations of macrophages expressing either LysM or Cx3cr1. Our results suggest that unlike microglia in the CNS, macrophages in the cochlea do not mediate pruning of the cochlear ribbon synapses.
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Affiliation(s)
- Chaorong Yu
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology-Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China.,Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Hui-Ming Gao
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology-Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China.,Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China.,Institute for Brain Sciences, Nanjing University, Nanjing, China
| | - Guoqiang Wan
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology-Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China.,Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China.,Institute for Brain Sciences, Nanjing University, Nanjing, China.,Research Institute of Otolaryngology, Nanjing, China
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27
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Plazas PV, Elgoyhen AB. The Cholinergic Lateral Line Efferent Synapse: Structural, Functional and Molecular Similarities With Those of the Cochlea. Front Cell Neurosci 2021; 15:765083. [PMID: 34712122 PMCID: PMC8545859 DOI: 10.3389/fncel.2021.765083] [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: 08/26/2021] [Accepted: 09/21/2021] [Indexed: 11/25/2022] Open
Abstract
Vertebrate hair cell (HC) systems are innervated by efferent fibers that modulate their response to external stimuli. In mammals, the best studied efferent-HC synapse, the cholinergic medial olivocochlear (MOC) efferent system, makes direct synaptic contacts with HCs. The net effect of MOC activity is to hyperpolarize HCs through the activation of α9α10 nicotinic cholinergic receptors (nAChRs) and the subsequent activation of Ca2+-dependent SK2 potassium channels. A serious obstacle in research on many mammalian sensory systems in their native context is that their constituent neurons are difficult to access even in newborn animals, hampering circuit observation, mapping, or controlled manipulation. By contrast, fishes and amphibians have a superficial and accessible mechanosensory system, the lateral line (LL), which circumvents many of these problems. LL responsiveness is modulated by efferent neurons which aid to distinguish between external and self-generated stimuli. One component of the LL efferent system is cholinergic and its activation inhibits LL afferent activity, similar to what has been described for MOC efferents. The zebrafish (Danio rerio) has emerged as a powerful model system for studying human hearing and balance disorders, since LL HC are structurally and functionally analogous to cochlear HCs, but are optically and pharmacologically accessible within an intact specimen. Complementing mammalian studies, zebrafish have been used to gain significant insights into many facets of HC biology, including mechanotransduction and synaptic physiology as well as mechanisms of both hereditary and acquired HC dysfunction. With the rise of the zebrafish LL as a model in which to study auditory system function and disease, there has been an increased interest in studying its efferent system and evaluate the similarity between mammalian and piscine efferent synapses. Advances derived from studies in zebrafish include understanding the effect of the LL efferent system on HC and afferent activity, and revealing that an α9-containing nAChR, functionally coupled to SK channels, operates at the LL efferent synapse. In this review, we discuss the tools and findings of these recent investigations into zebrafish efferent-HC synapse, their commonalities with the mammalian counterpart and discuss several emerging areas for future studies.
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Affiliation(s)
- Paola V Plazas
- Instituto de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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28
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Boero LE, Payne S, Gómez-Casati ME, Rutherford MA, Goutman JD. Noise Exposure Potentiates Exocytosis From Cochlear Inner Hair Cells. Front Synaptic Neurosci 2021; 13:740368. [PMID: 34658832 PMCID: PMC8511412 DOI: 10.3389/fnsyn.2021.740368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/10/2021] [Indexed: 11/19/2022] Open
Abstract
Noise-induced hearing loss has gained relevance as one of the most common forms of hearing impairment. The anatomical correlates of hearing loss, principally cell damage and/or death, are relatively well-understood histologically. However, much less is known about the physiological aspects of damaged, surviving cells. Here we addressed the functional consequences of noise exposure on the capacity of inner hair cells (IHCs) to release synaptic vesicles at synapses with spiral ganglion neurons (SGNs). Mice of either sex at postnatal day (P) 15–16 were exposed to 1–12 kHz noise at 120 dB sound pressure level (SPL), for 1 h. Exocytosis was measured by tracking changes in membrane capacitance (ΔCm) from IHCs of the apical cochlea. Upon IHC depolarization to different membrane potentials, ΔCm showed the typical bell-shaped curve that mirrors the voltage dependence of Ca2+ influx, in both exposed and unexposed cells. Surprisingly, from IHCs at 1-day after exposure (d.a.e.), we found potentiation of exocytosis at the peak of the bell-shaped curve. The increase in exocytosis was not accompanied by changes in whole-cell Ca2+ influx, suggesting a modification in coupling between Ca2+ channels and synaptic vesicles. Consistent with this notion, noise exposure also changed the Ca2+-dependence of exocytosis from linear to supralinear. Noise exposure did not cause loss of IHCs, but did result in a small reduction in the number of IHC-SGN synapses at 1-d.a.e. which recovered by 14-d.a.e. In contrast, a strong reduction in auditory brainstem response wave-I amplitude (representing synchronous firing of SGNs) and distortion product otoacoustic emissions (reflecting outer hair cell function) indicated a profound hearing loss at 1- and 14-d.a.e. To determine the role of glutamate release in the noise-induced potentiation of exocytosis, we evaluated vesicular glutamate transporter-3 (Vglut3) knock-out (KO) mice. Unlike WT, IHCs from Vglut3KO mice showed a noise-induced reduction in ΔCm and Ca2+ influx with no change in the Ca2+-dependence of exocytosis. Together, these results indicate that traumatic noise exposure triggers changes of IHC synaptic function including a Vglut3-dependent potentiation of exocytosis.
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Affiliation(s)
- Luis E Boero
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI), Buenos Aires, Argentina.,Instituto de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Shelby Payne
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
| | | | - Mark A Rutherford
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
| | - Juan D Goutman
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI), Buenos Aires, Argentina
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29
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Kesharwani A, Schwarz K, Dembla E, Dembla M, Schmitz F. Early Changes in Exo- and Endocytosis in the EAE Mouse Model of Multiple Sclerosis Correlate with Decreased Synaptic Ribbon Size and Reduced Ribbon-Associated Vesicle Pools in Rod Photoreceptor Synapses. Int J Mol Sci 2021; 22:ijms221910789. [PMID: 34639129 PMCID: PMC8509850 DOI: 10.3390/ijms221910789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 09/29/2021] [Accepted: 10/01/2021] [Indexed: 12/17/2022] Open
Abstract
Multiple sclerosis (MS) is an inflammatory disease of the central nervous system that finally leads to demyelination. Demyelinating optic neuritis is a frequent symptom in MS. Recent studies also revealed synapse dysfunctions in MS patients and MS mouse models. We previously reported alterations of photoreceptor ribbon synapses in the experimental auto-immune encephalomyelitis (EAE) mouse model of MS. In the present study, we found that the previously observed decreased imunosignals of photoreceptor ribbons in early EAE resulted from a decrease in synaptic ribbon size, whereas the number/density of ribbons in photoreceptor synapses remained unchanged. Smaller photoreceptor ribbons are associated with fewer docked and ribbon-associated vesicles. At a functional level, depolarization-evoked exocytosis as monitored by optical recording was diminished even as early as on day 7 after EAE induction. Moreover compensatory, post-depolarization endocytosis was decreased. Decreased post-depolarization endocytosis in early EAE correlated with diminished synaptic enrichment of dynamin3. In contrast, basal endocytosis in photoreceptor synapses of resting non-depolarized retinal slices was increased in early EAE. Increased basal endocytosis correlated with increased de-phosphorylation of dynamin1. Thus, multiple endocytic pathways in photoreceptor synapse are differentially affected in early EAE and likely contribute to the observed synapse pathology in early EAE.
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Affiliation(s)
- Ajay Kesharwani
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
- Correspondence:
| | - Karin Schwarz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
| | - Ekta Dembla
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Mayur Dembla
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Frank Schmitz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
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30
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Ryl M, Urbasik A, Gierke K, Babai N, Joachimsthaler A, Feigenspan A, Frischknecht R, Stallwitz N, Fejtová A, Kremers J, von Wittgenstein J, Brandstätter JH. Genetic disruption of bassoon in two mutant mouse lines causes divergent retinal phenotypes. FASEB J 2021; 35:e21520. [PMID: 33811381 DOI: 10.1096/fj.202001962r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 02/19/2021] [Accepted: 02/26/2021] [Indexed: 11/11/2022]
Abstract
Bassoon (BSN) is a presynaptic cytomatrix protein ubiquitously present at chemical synapses of the central nervous system, where it regulates synaptic vesicle replenishment and organizes voltage-gated Ca2+ channels. In sensory photoreceptor synapses, BSN additionally plays a decisive role in anchoring the synaptic ribbon, a presynaptic organelle and functional extension of the active zone, to the presynaptic membrane. In this study, we functionally and structurally analyzed two mutant mouse lines with a genetic disruption of Bsn-Bsngt and Bsnko -using electrophysiology and high-resolution microscopy. In both Bsn mutant mouse lines, full-length BSN was abolished, and photoreceptor synaptic function was similarly impaired, yet synapse structure was more severely affected in Bsngt/gt than in Bsnko/ko photoreceptors. The synaptic defects in Bsngt/gt retina coincide with remodeling of the outer retina-rod bipolar and horizontal cell sprouting, formation of ectopic ribbon synaptic sites-and death of cone photoreceptors, processes that did not occur in Bsnko/ko retina. An analysis of Bsngt/ko hybrid mice revealed that the divergent retinal phenotypes of Bsngt/gt and Bsnko/ko mice can be attributed to the expression of the Bsngt allele, which triggers cone photoreceptor death and neurite sprouting in the outer retina. These findings shed new light on the existing Bsn mutant mouse models and might help to understand mechanisms that drive photoreceptor death.
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Affiliation(s)
- Miriam Ryl
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Alexander Urbasik
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Kaspar Gierke
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Norbert Babai
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anneka Joachimsthaler
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Feigenspan
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Renato Frischknecht
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Nina Stallwitz
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anna Fejtová
- Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jan Kremers
- Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Julia von Wittgenstein
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Johann Helmut Brandstätter
- Department of Biology, Animal Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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31
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Annamneedi A, del Angel M, Gundelfinger ED, Stork O, Çalışkan G. The Presynaptic Scaffold Protein Bassoon in Forebrain Excitatory Neurons Mediates Hippocampal Circuit Maturation: Potential Involvement of TrkB Signalling. Int J Mol Sci 2021; 22:ijms22157944. [PMID: 34360710 PMCID: PMC8347324 DOI: 10.3390/ijms22157944] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/23/2021] [Accepted: 07/23/2021] [Indexed: 12/30/2022] Open
Abstract
A presynaptic active zone organizer protein Bassoon orchestrates numerous important functions at the presynaptic active zone. We previously showed that the absence of Bassoon exclusively in forebrain glutamatergic presynapses (BsnEmx1cKO) in mice leads to developmental disturbances in dentate gyrus (DG) affecting synaptic excitability, morphology, neurogenesis and related behaviour during adulthood. Here, we demonstrate that hyperexcitability of the medial perforant path-to-DG (MPP-DG) pathway in BsnEmx1cKO mice emerges during adolescence and is sustained during adulthood. We further provide evidence for a potential involvement of tropomyosin-related kinase B (TrkB), the high-affinity receptor for brain-derived neurotrophic factor (BDNF), mediated signalling. We detect elevated TrkB protein levels in the dorsal DG of adult mice (~3–5 months-old) but not in adolescent (~4–5 weeks-old) mice. Electrophysiological analysis reveals increased field-excitatory-postsynaptic-potentials (fEPSPs) in the DG of the adult, but not in adolescent BsnEmx1cKO mice. In line with an increased TrkB expression during adulthood in BsnEmx1cKO, blockade of TrkB normalizes the increased synaptic excitability in the DG during adulthood, while no such effect was observed in adolescence. Accordingly, neurogenesis, which has previously been found to be increased in adult BsnEmx1cKO mice, was unaffected at adolescent age. Our results suggest that Bassoon plays a crucial role in the TrkB-dependent postnatal maturation of the hippocampus.
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Affiliation(s)
- Anil Annamneedi
- Institute of Biology, Otto-Von-Guericke University, 39120 Magdeburg, Germany; (M.d.A.); (O.S.)
- Center for Behavioral Brain Sciences (CBBS), 39120 Magdeburg, Germany;
- Leibniz Institute for Neurobiology (LIN), RG Neuroplasticity, 39118 Magdeburg, Germany
- Correspondence: (A.A.); (G.Ç.)
| | - Miguel del Angel
- Institute of Biology, Otto-Von-Guericke University, 39120 Magdeburg, Germany; (M.d.A.); (O.S.)
| | - Eckart D. Gundelfinger
- Center for Behavioral Brain Sciences (CBBS), 39120 Magdeburg, Germany;
- Leibniz Institute for Neurobiology (LIN), RG Neuroplasticity, 39118 Magdeburg, Germany
- Institute of Pharmacology & Toxicology, Medical Faculty, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - Oliver Stork
- Institute of Biology, Otto-Von-Guericke University, 39120 Magdeburg, Germany; (M.d.A.); (O.S.)
- Center for Behavioral Brain Sciences (CBBS), 39120 Magdeburg, Germany;
| | - Gürsel Çalışkan
- Institute of Biology, Otto-Von-Guericke University, 39120 Magdeburg, Germany; (M.d.A.); (O.S.)
- Center for Behavioral Brain Sciences (CBBS), 39120 Magdeburg, Germany;
- Correspondence: (A.A.); (G.Ç.)
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32
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Peterson AJ, Heil P. A simplified physiological model of rate-level functions of auditory-nerve fibers. Hear Res 2021; 406:108258. [PMID: 34010767 DOI: 10.1016/j.heares.2021.108258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 03/09/2021] [Accepted: 04/23/2021] [Indexed: 12/24/2022]
Abstract
Several approaches have been used to describe the rate-level functions of auditory-nerve fibers (ANFs). One approach uses descriptive models that can be fitted easily to data. Another derives rate-level functions from comprehensive physiological models of auditory peripheral processing. Here, we seek to identify the minimal set of components needed to provide a physiologically plausible account of rate-level functions. Our model consists of a first-order Boltzmann mechanoelectrical transducer function relating the instantaneous stimulus pressure to an instantaneous output, followed by a lowpass filter that eliminates the AC component, followed by an exponential synaptic transfer function relating the DC component to the mean spike rate. This is perhaps the simplest physiologically plausible model capable of accounting for rate-level functions under the assumption that the model parameters for a given ANF and stimulus frequency are level-independent. We find that the model typically accounts well for rate-level functions from cat ANFs for all stimulus frequencies. More complicated model variants having saturating synaptic transfer functions do not perform significantly better, implying the system operates far away from synaptic saturation. Rate saturation in the model is caused by saturation of the DC component of the filter output (e.g., the receptor potential), which in turn is due to the saturation of the transducer function. The maximum mean spike rate is approximately constant across ANFs, such that the slope parameter of the exponential synaptic transfer function decreases with increasing spontaneous rate. If the synaptic parameters for a given ANF are assumed to be constant across stimulus frequencies, then frequency- and level-dependent input nonlinearities are derived that are qualitatively similar to those reported in the literature. Contrary to assumptions in the literature, such nonlinearities are obtained even for ANFs having high spontaneous rates. Finally, spike-rate adaptation is examined and found to be accounted for by a decrease in the slope parameter of the synaptic transfer function over time following stimulus onset.
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Affiliation(s)
- Adam J Peterson
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Peter Heil
- Department of Systems Physiology of Learning, Leibniz Institute for Neurobiology, Magdeburg, Germany; Center for Behavioral Brain Sciences, Magdeburg, Germany.
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Payne SA, Joens MS, Chung H, Skigen N, Frank A, Gattani S, Vaughn K, Schwed A, Nester M, Bhattacharyya A, Iyer G, Davis B, Carlquist J, Patel H, Fitzpatrick JAJ, Rutherford MA. Maturation of Heterogeneity in Afferent Synapse Ultrastructure in the Mouse Cochlea. Front Synaptic Neurosci 2021; 13:678575. [PMID: 34220482 PMCID: PMC8248813 DOI: 10.3389/fnsyn.2021.678575] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/11/2021] [Indexed: 12/11/2022] Open
Abstract
Auditory nerve fibers (ANFs) innervating the same inner hair cell (IHC) may have identical frequency tuning but different sound response properties. In cat and guinea pig, ANF response properties correlate with afferent synapse morphology and position on the IHC, suggesting a causal structure-function relationship. In mice, this relationship has not been fully characterized. Here we measured the emergence of synaptic morphological heterogeneities during maturation of the C57BL/6J mouse cochlea by comparing postnatal day 17 (p17, ∼3 days after hearing onset) with p34, when the mouse cochlea is mature. Using serial block face scanning electron microscopy and three-dimensional reconstruction we measured the size, shape, vesicle content, and position of 70 ribbon synapses from the mid-cochlea. Several features matured over late postnatal development. From p17 to p34, presynaptic densities (PDs) and post-synaptic densities (PSDs) became smaller on average (PDs: 0.75 to 0.33; PSDs: 0.58 to 0.31 μm2) and less round as their short axes shortened predominantly on the modiolar side, from 770 to 360 nm. Membrane-associated synaptic vesicles decreased in number from 53 to 30 per synapse from p17 to p34. Anatomical coupling, measured as PSD to ribbon distance, tightened predominantly on the pillar side. Ribbons became less spherical as long-axes lengthened only on the modiolar side of the IHC, from 372 to 541 nm. A decreasing gradient of synaptic ribbon size along the modiolar-pillar axis was detected only at p34 after aligning synapses of adjacent IHCs to a common reference frame (median volumes in nm3 × 106: modiolar 4.87; pillar 2.38). The number of ribbon-associated synaptic vesicles scaled with ribbon size (range 67 to 346 per synapse at p34), thus acquiring a modiolar-pillar gradient at p34, but overall medians were similar at p17 (120) and p34 (127), like ribbon surface area (0.36 vs. 0.34 μm2). PD and PSD morphologies were tightly correlated to each other at individual synapses, more so at p34 than p17, but not to ribbon morphology. These observations suggest that PDs and PSDs mature according to different cues than ribbons, and that ribbon size may be more influenced by cues from the IHC than the surrounding tissue.
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Affiliation(s)
- Shelby A Payne
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
| | - Matthew S Joens
- Center for Cellular Imaging, Washington University in St. Louis, St. Louis, MO, United States.,TESCAN USA, Inc., Warrendale, PA, United States
| | - Heather Chung
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States.,Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Natalie Skigen
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Adam Frank
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Sonali Gattani
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Kya Vaughn
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Allison Schwed
- Graduate Program in Audiology and Communications Sciences, Washington University School of Medicine, St. Louis, MO, United States
| | - Matt Nester
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Atri Bhattacharyya
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States.,Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Guhan Iyer
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Bethany Davis
- Graduate Program in Audiology and Communications Sciences, Washington University School of Medicine, St. Louis, MO, United States
| | - Jason Carlquist
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States.,Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Honey Patel
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - James A J Fitzpatrick
- Center for Cellular Imaging, Washington University in St. Louis, St. Louis, MO, United States.,Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, United States.,Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States.,Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO, United States
| | - Mark A Rutherford
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
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34
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Young ED, Wu 武靜靜 JS, Niwa M, Glowatzki E. Resolution of subcomponents of synaptic release from postsynaptic currents in rat hair-cell/auditory-nerve fiber synapses. J Neurophysiol 2021; 125:2444-2460. [PMID: 33949889 DOI: 10.1152/jn.00450.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The synapse between inner hair cells and auditory nerve fiber dendrites shows large excitatory postsynaptic currents (EPSCs), which are either monophasic or multiphasic. Multiquantal or uniquantal (flickering) release of neurotransmitter has been proposed to underlie the unusual multiphasic waveforms. Here the nature of multiphasic waveforms is analyzed using EPSCs recorded in vitro in rat afferent dendrites. Spontaneous EPSCs were deconvolved into a sum of presumed release events having monophasic EPSC waveforms. Results include, first, the charge of EPSCs is about the same for multiphasic versus monophasic EPSCs. Second, EPSC amplitudes decline with the number of release events per EPSC. Third, there is no evidence of a mini-EPSC. Most results can be accounted for by versions of either uniquantal or multiquantal release. However, serial neurotransmitter release in multiphasic EPSCs shows properties that are not fully explained by either model, especially that the amplitudes of individual release events are established at the beginning of a multiphasic EPSC, constraining possible models of vesicle release.NEW & NOTEWORTHY How do monophasic and multiphasic waveshapes arise in auditory-nerve dendrites; mainly are they uniquantal, arising from release of a single vesicle, or multiquantal, requiring several vesicles? The charge injected by excitatory postsynaptic currents (EPSCs) is the same for monophasic or multiphasic EPSCs, supporting uniquantal release. Serial adaptation of responses to sequential EPSCs favors a multiquantal model. Finally, neurotransmitter partitioning into similar sized release boluses occurs at the first bolus in the EPSC, not easily explained with either model.
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Affiliation(s)
- Eric D Young
- Center for Hearing and Balance, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Jingjing Sherry Wu 武靜靜
- Center for Hearing and Balance, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Mamiko Niwa
- Center for Hearing and Balance, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Elisabeth Glowatzki
- Center for Hearing and Balance, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland
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35
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Rutherford MA, von Gersdorff H, Goutman JD. Encoding sound in the cochlea: from receptor potential to afferent discharge. J Physiol 2021; 599:2527-2557. [PMID: 33644871 PMCID: PMC8127127 DOI: 10.1113/jp279189] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 02/22/2021] [Indexed: 12/17/2022] Open
Abstract
Ribbon-class synapses in the ear achieve analog to digital transformation of a continuously graded membrane potential to all-or-none spikes. In mammals, several auditory nerve fibres (ANFs) carry information from each inner hair cell (IHC) to the brain in parallel. Heterogeneity of transmission among synapses contributes to the diversity of ANF sound-response properties. In addition to the place code for sound frequency and the rate code for sound level, there is also a temporal code. In series with cochlear amplification and frequency tuning, neural representation of temporal cues over a broad range of sound levels enables auditory comprehension in noisy multi-speaker settings. The IHC membrane time constant introduces a low-pass filter that attenuates fluctuations of the receptor potential above 1-2 kHz. The ANF spike generator adds a high-pass filter via its depolarization-rate threshold that rejects slow changes in the postsynaptic potential and its phasic response property that ensures one spike per depolarization. Synaptic transmission involves several stochastic subcellular processes between IHC depolarization and ANF spike generation, introducing delay and jitter that limits the speed and precision of spike timing. ANFs spike at a preferred phase of periodic sounds in a process called phase-locking that is limited to frequencies below a few kilohertz by both the IHC receptor potential and the jitter in synaptic transmission. During phase-locking to periodic sounds of increasing intensity, faster and facilitated activation of synaptic transmission and spike generation may be offset by presynaptic depletion of synaptic vesicles, resulting in relatively small changes in response phase. Here we review encoding of spike-timing at cochlear ribbon synapses.
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Affiliation(s)
- Mark A. Rutherford
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Henrique von Gersdorff
- Vollum Institute, Oregon Hearing Research Center, Oregon Health and Sciences University, Portland, Oregon 97239
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36
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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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37
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Burger CA, Jiang D, Mackin RD, Samuel MA. Development and maintenance of vision's first synapse. Dev Biol 2021; 476:218-239. [PMID: 33848537 DOI: 10.1016/j.ydbio.2021.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/02/2021] [Accepted: 04/03/2021] [Indexed: 12/21/2022]
Abstract
Synapses in the outer retina are the first information relay points in vision. Here, photoreceptors form synapses onto two types of interneurons, bipolar cells and horizontal cells. Because outer retina synapses are particularly large and highly ordered, they have been a useful system for the discovery of mechanisms underlying synapse specificity and maintenance. Understanding these processes is critical to efforts aimed at restoring visual function through repairing or replacing neurons and promoting their connectivity. We review outer retina neuron synapse architecture, neural migration modes, and the cellular and molecular pathways that play key roles in the development and maintenance of these connections. We further discuss how these mechanisms may impact connectivity in the retina.
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Affiliation(s)
- Courtney A Burger
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Danye Jiang
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Robert D Mackin
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Melanie A Samuel
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA.
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38
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Krinner S, Predoehl F, Burfeind D, Vogl C, Moser T. RIM-Binding Proteins Are Required for Normal Sound-Encoding at Afferent Inner Hair Cell Synapses. Front Mol Neurosci 2021; 14:651935. [PMID: 33867935 PMCID: PMC8044855 DOI: 10.3389/fnmol.2021.651935] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/22/2021] [Indexed: 11/19/2022] Open
Abstract
The afferent synapses between inner hair cells (IHC) and spiral ganglion neurons are specialized to faithfully encode sound with sub-millisecond precision over prolonged periods of time. Here, we studied the role of Rab3 interacting molecule-binding proteins (RIM-BP) 1 and 2 – multidomain proteins of the active zone known to directly interact with RIMs, Bassoon and CaV1.3 – in IHC presynaptic function and hearing. Recordings of auditory brainstem responses and otoacoustic emissions revealed that genetic disruption of RIM-BPs 1 and 2 in mice (RIM-BP1/2–/–) causes a synaptopathic hearing impairment exceeding that found in mice lacking RIM-BP2 (RIM-BP2–/–). Patch-clamp recordings from RIM-BP1/2–/– IHCs indicated a subtle impairment of exocytosis from the readily releasable pool of synaptic vesicles that had not been observed in RIM-BP2–/– IHCs. In contrast, the reduction of Ca2+-influx and sustained exocytosis was similar to that in RIMBP2–/– IHCs. We conclude that both RIM-BPs are required for normal sound encoding at the IHC synapse, whereby RIM-BP2 seems to take the leading role.
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Affiliation(s)
- Stefanie Krinner
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 1286, University of Göttingen, Göttingen, Germany.,Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Friederike Predoehl
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Dinah Burfeind
- Presynaptogenesis and Intracellular Transport in Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Christian Vogl
- Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Presynaptogenesis and Intracellular Transport in Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 1286, University of Göttingen, Göttingen, Germany.,Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Multiscale Bioimaging Cluster of Excellence, University of Göttingen, Göttingen, Germany
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39
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Effertz T, Moser T, Oliver D. Recent advances in cochlear hair cell nanophysiology: subcellular compartmentalization of electrical signaling in compact sensory cells. Fac Rev 2021; 9:24. [PMID: 33659956 PMCID: PMC7886071 DOI: 10.12703/r/9-24] [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] [Indexed: 12/22/2022] Open
Abstract
In recent years, genetics, physiology, and structural biology have advanced into the molecular details of the sensory physiology of auditory hair cells. Inner hair cells (IHCs) and outer hair cells (OHCs) mediate two key functions: active amplification and non-linear compression of cochlear vibrations by OHCs and sound encoding by IHCs at their afferent synapses with the spiral ganglion neurons. OHCs and IHCs share some molecular physiology, e.g. mechanotransduction at the apical hair bundles, ribbon-type presynaptic active zones, and ionic conductances in the basolateral membrane. Unique features enabling their specific function include prestin-based electromotility of OHCs and indefatigable transmitter release at the highest known rates by ribbon-type IHC active zones. Despite their compact morphology, the molecular machineries that either generate electrical signals or are driven by these signals are essentially all segregated into local subcellular structures. This review provides a brief account on recent insights into the molecular physiology of cochlear hair cells with a specific focus on organization into membrane domains.
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Affiliation(s)
- Thomas Effertz
- InnerEarLab, Department of Otorhinolaryngology, University Medical Center Göttingen, 37099 Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, 37075 Göttingen, Germany
| | - Dominik Oliver
- Institute for Physiology and Pathophysiology, Philipps University, Deutschhausstraße 2, 35037 Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Germany
- DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodelling, GRK 2213, Philipps University, Marburg, Germany
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40
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Babai N, Wittgenstein J, Gierke K, Brandstätter JH, Feigenspan A. The absence of functional bassoon at cone photoreceptor ribbon synapses affects signal transmission at Off cone bipolar cell contacts in mouse retina. Acta Physiol (Oxf) 2021; 231:e13584. [PMID: 33222426 DOI: 10.1111/apha.13584] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 10/21/2020] [Accepted: 11/19/2020] [Indexed: 01/05/2023]
Abstract
AIM Off cone bipolar cells of the mammalian retina connect to cone photoreceptor synaptic terminals via non-invaginating flat contacts at a considerable distance from the only established neurotransmitter release site so far, the synaptic ribbon. Diffusion from the ribbon synaptic active zone is considered the most likely mechanism for the neurotransmitter glutamate to reach postsynaptic receptors on the dendritic tips of Off cone bipolar cells. We used a mutant mouse with functionally impaired photoreceptor ribbon synapses to investigate the importance of intact ribbon synaptic active zones for signal transmission at Off cone bipolar cell contacts. METHODS Whole-cell patch-clamp recordings from Off cone bipolar cells in a horizontal slice preparation of wildtype (Bsnwt ) and mutant (BsnΔEx4/5 ) mouse retina were applied to investigate signal transmission between cone photoreceptors and Off cone bipolar cells. The distribution of postsynaptic glutamate receptors in Off cone bipolar cell dendrites was studied using multiplex immunocytochemistry. RESULTS Tonic synaptic activity and evoked release were significantly reduced in mutant animals. Vesicle replenishment rates and the size of the readily releasable pool were likewise decreased. The precisely timed transient current response to light offset changed to a sustained response in the mutant, exemplified by random release events only loosely time-locked to the stimulus. The kainate receptor distribution in postsynaptic Off cone bipolar cell dendritic contacts in BsnΔEx4/5 mice was largely disturbed. CONCLUSION Our results suggest a major role of functional ribbon synaptic active zones for signal transmission and postsynaptic glutamate receptor organization at flat Off cone bipolar cell contacts.
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Affiliation(s)
- Norbert Babai
- Department of Biology, Animal Physiology FAU Erlangen‐Nürnberg Erlangen Germany
| | - Julia Wittgenstein
- Department of Biology, Animal Physiology FAU Erlangen‐Nürnberg Erlangen Germany
| | - Kaspar Gierke
- Department of Biology, Animal Physiology FAU Erlangen‐Nürnberg Erlangen Germany
| | | | - Andreas Feigenspan
- Department of Biology, Animal Physiology FAU Erlangen‐Nürnberg Erlangen Germany
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41
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Holmgren M, Sheets L. Using the Zebrafish Lateral Line to Understand the Roles of Mitochondria in Sensorineural Hearing Loss. Front Cell Dev Biol 2021; 8:628712. [PMID: 33614633 PMCID: PMC7892962 DOI: 10.3389/fcell.2020.628712] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 12/23/2020] [Indexed: 01/05/2023] Open
Abstract
Hair cells are the mechanosensory receptors of the inner ear and can be damaged by noise, aging, and ototoxic drugs. This damage often results in permanent sensorineural hearing loss. Hair cells have high energy demands and rely on mitochondria to produce ATP as well as contribute to intracellular calcium homeostasis. In addition to generating ATP, mitochondria produce reactive oxygen species, which can lead to oxidative stress, and regulate cell death pathways. Zebrafish lateral-line hair cells are structurally and functionally analogous to cochlear hair cells but are optically and pharmacologically accessible within an intact specimen, making the zebrafish a good model in which to study hair-cell mitochondrial activity. Moreover, the ease of genetic manipulation of zebrafish embryos allows for the study of mutations implicated in human deafness, as well as the generation of transgenic models to visualize mitochondrial calcium transients and mitochondrial activity in live organisms. Studies of the zebrafish lateral line have shown that variations in mitochondrial activity can predict hair-cell susceptibility to damage by aminoglycosides or noise exposure. In addition, antioxidants have been shown to protect against noise trauma and ototoxic drug–induced hair-cell death. In this review, we discuss the tools and findings of recent investigations into zebrafish hair-cell mitochondria and their involvement in cellular processes, both under homeostatic conditions and in response to noise or ototoxic drugs. The zebrafish lateral line is a valuable model in which to study the roles of mitochondria in hair-cell pathologies and to develop therapeutic strategies to prevent sensorineural hearing loss in humans.
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Affiliation(s)
- Melanie Holmgren
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
| | - Lavinia Sheets
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States.,Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, United States
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42
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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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43
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Voorn RA, Vogl C. Molecular Assembly and Structural Plasticity of Sensory Ribbon Synapses-A Presynaptic Perspective. Int J Mol Sci 2020; 21:E8758. [PMID: 33228215 PMCID: PMC7699581 DOI: 10.3390/ijms21228758] [Citation(s) in RCA: 9] [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: 10/21/2020] [Revised: 11/16/2020] [Accepted: 11/17/2020] [Indexed: 12/13/2022] Open
Abstract
In the mammalian cochlea, specialized ribbon-type synapses between sensory inner hair cells (IHCs) and postsynaptic spiral ganglion neurons ensure the temporal precision and indefatigability of synaptic sound encoding. These high-through-put synapses are presynaptically characterized by an electron-dense projection-the synaptic ribbon-which provides structural scaffolding and tethers a large pool of synaptic vesicles. While advances have been made in recent years in deciphering the molecular anatomy and function of these specialized active zones, the developmental assembly of this presynaptic interaction hub remains largely elusive. In this review, we discuss the dynamic nature of IHC (pre-) synaptogenesis and highlight molecular key players as well as the transport pathways underlying this process. Since developmental assembly appears to be a highly dynamic process, we further ask if this structural plasticity might be maintained into adulthood, how this may influence the functional properties of a given IHC synapse and how such plasticity could be regulated on the molecular level. To do so, we take a closer look at other ribbon-bearing systems, such as retinal photoreceptors and pinealocytes and aim to infer conserved mechanisms that may mediate these phenomena.
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MESH Headings
- Alcohol Oxidoreductases/genetics
- Alcohol Oxidoreductases/metabolism
- Animals
- Co-Repressor Proteins/genetics
- Co-Repressor Proteins/metabolism
- Cytoskeletal Proteins/genetics
- Cytoskeletal Proteins/metabolism
- Cytoskeleton/metabolism
- Cytoskeleton/ultrastructure
- Gene Expression Regulation, Developmental
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/ultrastructure
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/ultrastructure
- Hair Cells, Vestibular/metabolism
- Hair Cells, Vestibular/ultrastructure
- Mechanotransduction, Cellular
- Mice
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neuronal Plasticity/genetics
- Neuropeptides/genetics
- Neuropeptides/metabolism
- Rats
- Synapses/metabolism
- Synapses/ultrastructure
- Synaptic Transmission/genetics
- Synaptic Vesicles/metabolism
- Synaptic Vesicles/ultrastructure
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Affiliation(s)
- Roos Anouk Voorn
- Presynaptogenesis and Intracellular Transport in Hair Cells Junior Research Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany;
- Göttingen Graduate Center for Neurosciences, Biophysics and Molecular Biosciences, 37075 Goettingen, Germany
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”, 37075 Goettingen, Germany
| | - Christian Vogl
- Presynaptogenesis and Intracellular Transport in Hair Cells Junior Research Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany;
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”, 37075 Goettingen, Germany
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44
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Jeng JY, Ceriani F, Olt J, Brown SDM, Holley MC, Bowl MR, Johnson SL, Marcotti W. Pathophysiological changes in inner hair cell ribbon synapses in the ageing mammalian cochlea. J Physiol 2020; 598:4339-4355. [PMID: 32710572 DOI: 10.1113/jp280018] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/24/2020] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Age-related hearing loss (ARHL) is associated with the loss of inner hair cell (IHC) ribbon synapses, lower hearing sensitivity and decreased ability to understand speech, especially in a noisy environment. Little is known about the age-related physiological and morphological changes that occur at ribbon synapses. We show that the differing degrees of ARHL in four selected mouse stains is correlated with the loss of ribbon synapses, being most severe for the strains C57BL/6NTac and C57BL/6J, less so for C57BL/6NTacCdh23+ -Repaired and lowest for C3H/HeJ. Despite the loss of ribbon synapses with age, the volume of the remaining ribbons increased and the size and kinetics of Ca2+ -dependent exocytosis in IHCs was unaffected, indicating the presence of a previously unknown degree of functional compensation at ribbon synapses. Although the age-related morphological changes at IHC ribbon synapses contribute to the different progression of ARHL, without the observed functional compensation hearing loss could be greater. ABSTRACT Mammalian cochlear inner hair cells (IHCs) are specialized sensory receptors able to provide dynamic coding of sound signals. This ability is largely conferred by their ribbon synapses, which tether a large number of vesicles at the IHC's presynaptic active zones, allowing high rates of sustained synaptic transmission onto the afferent fibres. How the physiological and morphological properties of ribbon synapses change with age remains largely unknown. Here, we have investigated the biophysical and morphological properties of IHC ribbon synapses in the ageing cochlea (9-12 kHz region) of four mouse strains commonly used in hearing research: early-onset progressive hearing loss (C57BL/6J and C57BL/6NTac) and 'good hearing' strains (C57BL/6NTacCdh23+ and C3H/HeJ). We found that with age, both modiolar and pillar sides of the IHC exhibited a loss of ribbons, but there was an increased volume of those that remained. These morphological changes, which only occurred after 6 months of age, were correlated with the level of hearing loss in the different mouse strains, being most severe for C57BL/6NTac and C57BL/6J, less so for C57BL/6NTacCdh23+ and absent for C3H/HeJ strains. Despite the age-related reduction in ribbon number in three of the four strains, the size and kinetics of Ca2+ -dependent exocytosis, as well as the replenishment of synaptic vesicles, in IHCs was not affected. The degree of vesicle release at the fewer, but larger, individual remaining ribbon synapses colocalized with the post-synaptic afferent terminals is likely to increase, indicating the presence of a previously unknown degree of functional compensation in the ageing mouse cochlea.
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Affiliation(s)
- Jing-Yi Jeng
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK.,Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
| | - Federico Ceriani
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK.,Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
| | - Jennifer Olt
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Steve D M Brown
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, UK
| | - Matthew C Holley
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Michael R Bowl
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, UK
| | - Stuart L Johnson
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK.,Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
| | - Walter Marcotti
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK.,Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
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45
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Nosov G, Kahms M, Klingauf J. The Decade of Super-Resolution Microscopy of the Presynapse. Front Synaptic Neurosci 2020; 12:32. [PMID: 32848695 PMCID: PMC7433402 DOI: 10.3389/fnsyn.2020.00032] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 07/21/2020] [Indexed: 01/05/2023] Open
Abstract
The presynaptic compartment of the chemical synapse is a small, yet extremely complex structure. Considering its size, most methods of optical microscopy are not able to resolve its nanoarchitecture and dynamics. Thus, its ultrastructure could only be studied by electron microscopy. In the last decade, new methods of optical superresolution microscopy have emerged allowing the study of cellular structures and processes at the nanometer scale. While this is a welcome addition to the experimental arsenal, it has necessitated careful analysis and interpretation to ensure the data obtained remains artifact-free. In this article we review the application of nanoscopic techniques to the study of the synapse and the progress made over the last decade with a particular focus on the presynapse. We find to our surprise that progress has been limited, calling for imaging techniques and probes that allow dense labeling, multiplexing, longer imaging times, higher temporal resolution, while at least maintaining the spatial resolution achieved thus far.
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Affiliation(s)
- Georgii Nosov
- Institute of Medical Physics and Biophysics, University of Münster, Münster, Germany.,CIM-IMPRS Graduate Program in Münster, Münster, Germany
| | - Martin Kahms
- Institute of Medical Physics and Biophysics, University of Münster, Münster, Germany
| | - Jurgen Klingauf
- Institute of Medical Physics and Biophysics, University of Münster, Münster, Germany
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46
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Krüger JR, Keller-Findeisen J, Geisler C, Egner A. Tomographic STED microscopy. BIOMEDICAL OPTICS EXPRESS 2020; 11:3139-3163. [PMID: 32637247 PMCID: PMC7316010 DOI: 10.1364/boe.391787] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/29/2020] [Accepted: 05/04/2020] [Indexed: 06/11/2023]
Abstract
Stimulated emission depletion (STED) microscopy is a versatile imaging method with diffraction-unlimited resolution. Here, we present a novel STED microscopy variant that achieves either increased resolution at equal laser power or identical super-resolution conditions at significantly lower laser power when compared to the classical implementation. By applying a one-dimensional depletion pattern instead of the well-known doughnut-shaped STED focus, a more efficient depletion is achieved, thereby necessitating less STED laser power to achieve identical resolution. A two-dimensional resolution increase is obtained by recording a sequence of images with different high-resolution directions. This corresponds to a collection of tomographic projections within diffraction-limited spots, an approach that so far has not been explored in super-resolution microscopy. Via appropriate reconstruction algorithms, our method also provides an opportunity to speed up the acquisition process. Both aspects, the necessity of less STED laser power and the feasibility to decrease the recording time, have the potential to reduce photo-bleaching as well as sample damage drastically.
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Affiliation(s)
- Jennifer-Rose Krüger
- Department of Optical Nanoscopy, Laser-Laboratory Göttingen e.V., Hans-Adolf-Krebs-Weg 1, D-37077 Göttingen, Germany
| | - Jan Keller-Findeisen
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Claudia Geisler
- Department of Optical Nanoscopy, Laser-Laboratory Göttingen e.V., Hans-Adolf-Krebs-Weg 1, D-37077 Göttingen, Germany
| | - Alexander Egner
- Department of Optical Nanoscopy, Laser-Laboratory Göttingen e.V., Hans-Adolf-Krebs-Weg 1, D-37077 Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany
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47
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Hoffmann-Conaway S, Brockmann MM, Schneider K, Annamneedi A, Rahman KA, Bruns C, Textoris-Taube K, Trimbuch T, Smalla KH, Rosenmund C, Gundelfinger ED, Garner CC, Montenegro-Venegas C. Parkin contributes to synaptic vesicle autophagy in Bassoon-deficient mice. eLife 2020; 9:56590. [PMID: 32364493 PMCID: PMC7224700 DOI: 10.7554/elife.56590] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 05/02/2020] [Indexed: 12/18/2022] Open
Abstract
Mechanisms regulating the turnover of synaptic vesicle (SV) proteins are not well understood. They are thought to require poly-ubiquitination and degradation through proteasome, endo-lysosomal or autophagy-related pathways. Bassoon was shown to negatively regulate presynaptic autophagy in part by scaffolding Atg5. Here, we show that increased autophagy in Bassoon knockout neurons depends on poly-ubiquitination and that the loss of Bassoon leads to elevated levels of ubiquitinated synaptic proteins per se. Our data show that Bassoon knockout neurons have a smaller SV pool size and a higher turnover rate as indicated by a younger pool of SV2. The E3 ligase Parkin is required for increased autophagy in Bassoon-deficient neurons as the knockdown of Parkin normalized autophagy and SV protein levels and rescued impaired SV recycling. These data indicate that Bassoon is a key regulator of SV proteostasis and that Parkin is a key E3 ligase in the autophagy-mediated clearance of SV proteins.
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Affiliation(s)
| | - Marisa M Brockmann
- Charité - Universitätsmedizin Berlin, Institute of Neurobiology, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | | | - Anil Annamneedi
- Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.,Institute of Biology (IBIO), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Kazi Atikur Rahman
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany
| | - Christine Bruns
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Kathrin Textoris-Taube
- Charité - Universitätsmedizin Berlin, Institute of Biochemistry, Core Facility High Throughput Mass Spectrometry, Berlin, Germany
| | - Thorsten Trimbuch
- Charité - Universitätsmedizin Berlin, Institute of Neurobiology, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Karl-Heinz Smalla
- Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Christian Rosenmund
- Charité - Universitätsmedizin Berlin, Institute of Neurobiology, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Eckart D Gundelfinger
- Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.,Molecular Neurobiology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Craig Curtis Garner
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institute of Neurobiology, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Carolina Montenegro-Venegas
- Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.,Institute for Pharmacology and Toxicology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
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48
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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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49
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Ortner NJ, Pinggera A, Hofer NT, Siller A, Brandt N, Raffeiner A, Vilusic K, Lang I, Blum K, Obermair GJ, Stefan E, Engel J, Striessnig J. RBP2 stabilizes slow Cav1.3 Ca 2+ channel inactivation properties of cochlear inner hair cells. Pflugers Arch 2019; 472:3-25. [PMID: 31848688 PMCID: PMC6960213 DOI: 10.1007/s00424-019-02338-4] [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: 07/23/2019] [Revised: 10/18/2019] [Accepted: 12/04/2019] [Indexed: 01/31/2023]
Abstract
Cav1.3 L-type Ca2+ channels (LTCCs) in cochlear inner hair cells (IHCs) are essential for hearing as they convert sound-induced graded receptor potentials into tonic postsynaptic glutamate release. To enable fast and indefatigable presynaptic Ca2+ signaling, IHC Cav1.3 channels exhibit a negative activation voltage range and uniquely slow inactivation kinetics. Interaction with CaM-like Ca2+-binding proteins inhibits Ca2+-dependent inactivation, while the mechanisms underlying slow voltage-dependent inactivation (VDI) are not completely understood. Here we studied if the complex formation of Cav1.3 LTCCs with the presynaptic active zone proteins RIM2α and RIM-binding protein 2 (RBP2) can stabilize slow VDI. We detected both RIM2α and RBP isoforms in adult mouse IHCs, where they co-localized with Cav1.3 and synaptic ribbons. Using whole-cell patch-clamp recordings (tsA-201 cells), we assessed their effect on the VDI of the C-terminal full-length Cav1.3 (Cav1.3L) and a short splice variant (Cav1.342A) that lacks the C-terminal RBP2 interaction site. When co-expressed with the auxiliary β3 subunit, RIM2α alone (Cav1.342A) or RIM2α/RBP2 (Cav1.3L) reduced Cav1.3 VDI to a similar extent as observed in IHCs. Membrane-anchored β2 variants (β2a, β2e) that inhibit inactivation on their own allowed no further modulation of inactivation kinetics by RIM2α/RBP2. Moreover, association with RIM2α and/or RBP2 consolidated the negative Cav1.3 voltage operating range by shifting the channel's activation threshold toward more hyperpolarized potentials. Taken together, the association with "slow" β subunits (β2a, β2e) or presynaptic scaffolding proteins such as RIM2α and RBP2 stabilizes physiological gating properties of IHC Cav1.3 LTCCs in a splice variant-dependent manner ensuring proper IHC function.
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Affiliation(s)
- Nadine J Ortner
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria.
| | - Alexandra Pinggera
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Nadja T Hofer
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Anita Siller
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Niels Brandt
- Department of Biophysics and CIPMM, Saarland University, Homburg, Germany
| | - Andrea Raffeiner
- Institute of Biochemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Kristina Vilusic
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Isabelle Lang
- Department of Biophysics and CIPMM, Saarland University, Homburg, Germany
| | - Kerstin Blum
- Department of Biophysics and CIPMM, Saarland University, Homburg, Germany
| | - Gerald J Obermair
- Division of Physiology, Medical University Innsbruck, Innsbruck, Austria.,Division Physiology, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Eduard Stefan
- Institute of Biochemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Jutta Engel
- Department of Biophysics and CIPMM, Saarland University, Homburg, Germany
| | - Jörg Striessnig
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria.
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Babai N, Gierke K, Müller T, Regus‐Leidig H, Brandstätter JH, Feigenspan A. Signal transmission at invaginating cone photoreceptor synaptic contacts following deletion of the presynaptic cytomatrix protein Bassoon in mouse retina. Acta Physiol (Oxf) 2019; 226:e13241. [PMID: 30554473 DOI: 10.1111/apha.13241] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/27/2018] [Accepted: 12/03/2018] [Indexed: 01/17/2023]
Abstract
AIM A key feature of the mammalian retina is the segregation of visual information in parallel pathways, starting at the photoreceptor terminals. Cone photoreceptors establish synaptic contacts with On bipolar and horizontal cells at invaginating, ribbon-containing synaptic sites, whereas Off bipolar cells form flat, non-ribbon-containing contacts. The cytomatrix protein Bassoon anchors ribbons at the active zone, and its absence induces detachment of ribbons from the active zone. In this study we investigate the impact of a missing Bassoon on synaptic transmission at the first synapse of the visual system. METHODS Release properties of cone photoreceptors were studied in wild-type and mutant mouse retinae with a genetic disruption of the presynaptic cytomatrix protein Bassoon using whole-cell voltage-clamp recordings. Light and electron microscopy revealed the distribution of Ca2+ channels and synaptic vesicles, respectively, in both mouse lines. RESULTS Whole-cell recordings from postsynaptic horizontal cells of the two mouse lines showed that the presence of Bassoon (and a ribbon) enhanced the rate of exocytosis during tonic and evoked release by increasing synaptic vesicle pool size and replenishment rate, while at the same time slowing synaptic vesicle release. Furthermore, the number of Cav 1.4 channels and synaptic vesicles was significantly higher at wild-type than at Bassoon mutant synaptic sites. CONCLUSION The results of our study demonstrate that glutamate release from cone photoreceptor terminals can occur independent of a synaptic ribbon, but seems restricted to active zones, and they show the importance of a the synaptic ribbon in sustained and spatially and temporally synchronized neurotransmitter release.
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Affiliation(s)
- Norbert Babai
- Department of Biology, Animal Physiology FAU Erlangen‐Nürnberg Erlangen Germany
| | - Kaspar Gierke
- Department of Biology, Animal Physiology FAU Erlangen‐Nürnberg Erlangen Germany
| | - Tanja Müller
- Department of Biology, Animal Physiology FAU Erlangen‐Nürnberg Erlangen Germany
| | - Hanna Regus‐Leidig
- Department of Biology, Animal Physiology FAU Erlangen‐Nürnberg Erlangen Germany
| | | | - Andreas Feigenspan
- Department of Biology, Animal Physiology FAU Erlangen‐Nürnberg Erlangen Germany
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