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Vincent PFY, Young ED, Edge ASB, Glowatzki E. Auditory hair cells and spiral ganglion neurons regenerate synapses with refined release properties in vitro. Proc Natl Acad Sci U S A 2024; 121:e2315599121. [PMID: 39058581 PMCID: PMC11294990 DOI: 10.1073/pnas.2315599121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 06/12/2024] [Indexed: 07/28/2024] Open
Abstract
Ribbon synapses between inner hair cells (IHCs) and type I spiral ganglion neurons (SGNs) in the inner ear are damaged by noise trauma and with aging, causing "synaptopathy" and hearing loss. Cocultures of neonatal denervated organs of Corti and newly introduced SGNs have been developed to find strategies for improving IHC synapse regeneration, but evidence of the physiological normality of regenerated synapses is missing. This study utilizes IHC optogenetic stimulation and SGN recordings, showing that, when P3-5 denervated organs of Corti are cocultured with SGNs, newly formed IHC/SGN synapses are indeed functional, exhibiting glutamatergic excitatory postsynaptic currents. When using older organs of Corti at P10-11, synaptic activity probed by deconvolution showed more mature release properties, closer to the specialized mode of IHC synaptic transmission crucial for coding the sound signal. This functional assessment of newly formed IHC synapses developed here, provides a powerful tool for testing approaches to improve synapse regeneration.
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Affiliation(s)
- Philippe F. Y. Vincent
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD21205
| | - Eric D. Young
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, MD21205
| | - Albert S. B. Edge
- Department of Otolaryngology, Harvard Medical School, Boston, MA02115
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear, Boston, MA02114
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, MA02115
- Harvard Stem Cell Institute, Cambridge, MA02139
| | - Elisabeth Glowatzki
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, MD21205
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD21205
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2
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Vecchi JT, Claussen AD, Hansen MR. Decreasing the physical gap in the neural-electrode interface and related concepts to improve cochlear implant performance. Front Neurosci 2024; 18:1425226. [PMID: 39114486 PMCID: PMC11303154 DOI: 10.3389/fnins.2024.1425226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 07/11/2024] [Indexed: 08/10/2024] Open
Abstract
Cochlear implants (CI) represent incredible devices that restore hearing perception for those with moderate to profound sensorineural hearing loss. However, the ability of a CI to restore complex auditory function is limited by the number of perceptually independent spectral channels provided. A major contributor to this limitation is the physical gap between the CI electrodes and the target spiral ganglion neurons (SGNs). In order for CI electrodes to stimulate SGNs more precisely, and thus better approximate natural hearing, new methodologies need to be developed to decrease this gap, (i.e., transitioning CIs from a far-field to near-field device). In this review, strategies aimed at improving the neural-electrode interface are discussed in terms of the magnitude of impact they could have and the work needed to implement them. Ongoing research suggests current clinical efforts to limit the CI-related immune response holds great potential for improving device performance. This could eradicate the dense, fibrous capsule surrounding the electrode and enhance preservation of natural cochlear architecture, including SGNs. In the long term, however, optimized future devices will likely need to induce and guide the outgrowth of the peripheral process of SGNs to be in closer proximity to the CI electrode in order to better approximate natural hearing. This research is in its infancy; it remains to be seen which strategies (surface patterning, small molecule release, hydrogel coating, etc.) will be enable this approach. Additionally, these efforts aimed at optimizing CI function will likely translate to other neural prostheses, which face similar issues.
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Affiliation(s)
- Joseph T. Vecchi
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, United States
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
| | - Alexander D. Claussen
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
| | - Marlan R. Hansen
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, United States
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
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3
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Tan F, Li X, Li X, Xu M, Shahzad KA, Hou L. GelMA/PEDOT:PSS Composite Conductive Hydrogel-Based Generation and Protection of Cochlear Hair Cells through Multiple Signaling Pathways. Biomolecules 2024; 14:95. [PMID: 38254695 PMCID: PMC10812993 DOI: 10.3390/biom14010095] [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: 11/12/2023] [Revised: 12/18/2023] [Accepted: 01/05/2024] [Indexed: 01/24/2024] Open
Abstract
Recent advances in cochlear implantology are exemplified by novel functional strategies such as bimodal electroacoustic stimulation, in which the patient has intact low-frequency hearing and profound high-frequency hearing pre-operatively. Therefore, the synergistic restoration of dysfunctional cochlear hair cells and the protection of hair cells from ototoxic insults have become a persistent target pursued for this hybrid system. In this study, we developed a composite GelMA/PEDOT:PSS conductive hydrogel that is suitable as a coating for the cochlear implant electrode for the potential local delivery of otoregenerative and otoprotective drugs. Various material characterization methods (e.g., 1H NMR spectroscopy, FT-IR, EIS, and SEM), experimental models (e.g., murine cochlear organoid and aminoglycoside-induced ototoxic HEI-OC1 cellular model), and biological analyses (e.g., confocal laser scanning microscopy, real time qPCR, flow cytometry, and bioinformatic sequencing) were used. The results demonstrated decent material properties of the hydrogel, such as mechanical (e.g., high tensile stress and Young's modulus), electrochemical (e.g., low impedance and high conductivity), biocompatibility (e.g., satisfactory cochlear cell interaction and free of systemic toxicity), and biosafety (e.g., minimal hemolysis and cell death) features. In addition, the CDR medicinal cocktail sustainably released by the hydrogel not only promoted the expansion of the cochlear stem cells but also boosted the trans-differentiation from cochlear supporting cells into hair cells. Furthermore, hydrogel-based drug delivery protected the hair cells from oxidative stress and various forms of programmed cell death (e.g., apoptosis and ferroptosis). Finally, using large-scale sequencing, we enriched a complex network of signaling pathways that are potentially downstream to various metabolic processes and abundant metabolites. In conclusion, we present a conductive hydrogel-based local delivery of bifunctional drug cocktails, thereby serving as a potential solution to intracochlear therapy of bimodal auditory rehabilitation and diseases beyond.
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Affiliation(s)
- Fei Tan
- Department of ORL-HNS, Shanghai Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200070, China; (X.L.); (M.X.); (K.A.S.)
- Plasma Medicine and Surgical Implants Center, School of Medicine, Tongji University, Shanghai 200070, China
- Department of ORL-HNS, The Royal College of Surgeons in Ireland, D02 YN77 Dublin, Ireland
- Department of ORL-HNS, The Royal College of Surgeons of England, London WC2A 3PE, UK
| | - Xuran Li
- Department of ORL-HNS, Shanghai Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200070, China; (X.L.); (M.X.); (K.A.S.)
- Plasma Medicine and Surgical Implants Center, School of Medicine, Tongji University, Shanghai 200070, China
| | - Xiao Li
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology & Center for Advanced Low-Dimension Materials, Donghua University, Shanghai 200051, China; (X.L.); (L.H.)
| | - Maoxiang Xu
- Department of ORL-HNS, Shanghai Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200070, China; (X.L.); (M.X.); (K.A.S.)
- Plasma Medicine and Surgical Implants Center, School of Medicine, Tongji University, Shanghai 200070, China
| | - Khawar Ali Shahzad
- Department of ORL-HNS, Shanghai Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200070, China; (X.L.); (M.X.); (K.A.S.)
- Plasma Medicine and Surgical Implants Center, School of Medicine, Tongji University, Shanghai 200070, China
| | - Lei Hou
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology & Center for Advanced Low-Dimension Materials, Donghua University, Shanghai 200051, China; (X.L.); (L.H.)
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Liu W, Yin D, Li Z, Zhu X, Zhang S, Zhang P, Lin D, Hua Z, Cao Z, Zhang H, Zhang J, Ying C, Xu P, Dong G, Liu K. Comparative Blood Transcriptome Analysis of Semi-Natural and Controlled Environment Populations of Yangtze Finless Porpoise. Animals (Basel) 2024; 14:199. [PMID: 38254368 PMCID: PMC10812818 DOI: 10.3390/ani14020199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/23/2023] [Accepted: 01/03/2024] [Indexed: 01/24/2024] Open
Abstract
The Yangtze finless porpoises (Neophocaena asiaeorientalis asiaeorientalis) living in different environments display significant differences in behavior and physiology. To compare and analyze gene expression differences between an ex situ population and a controlled environment population of the Yangtze finless porpoise, we sequenced the transcriptome of blood tissues living in a semi-natural reserve and an artificial facility, respectively. We identified 6860 differentially expressed genes (DEGs), of which 6603 were up-regulated and 257 were down-regulated in the controlled environment vs ex situ comparison. GO and KEGG enrichment analysis showed that the up-regulated genes in the controlled environment population were significantly associated with glucose metabolism, amino acid metabolism, and the nervous system, while those up-regulated in the ex situ population were significantly associated with energy supply and biosynthesis. Further analysis showed that metabolic and hearing-related genes were significantly affected by changes in the environment, and key metabolic genes such as HK, PFK, IDH, and GLS and key hearing-related genes such as OTOA, OTOF, SLC38A1, and GABBR2 were identified. These results suggest that the controlled environment population may have enhanced glucose metabolic ability via activation of glycolysis/gluconeogenesis, the TCA cycle, and inositol phosphate metabolism, while the ex situ population may meet higher energy requirements via enhancement of the amino acid metabolism of the liver and muscle and oxidative phosphorylation. Additionally, the acoustic behavior and auditory-related genes of Yangtze finless porpoise may show responsive changes and differential expression under different environment conditions, and thus the auditory sensitivity may also show corresponding adaptive characteristics. This study provides a new perspective for further exploration of the responsive changes of the two populations to various environments and provides a theoretical reference for further improvements in conservation practices for the Yangtze finless porpoise.
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Affiliation(s)
- Wang Liu
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China; (W.L.); (D.Y.); (D.L.); (Z.H.); (J.Z.); (P.X.)
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China;
| | - Denghua Yin
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China; (W.L.); (D.Y.); (D.L.); (Z.H.); (J.Z.); (P.X.)
| | - Zhanwei Li
- Zhuhai Chimelong Investment & Development Co., Ltd., Zhuhai 519000, China; (Z.L.); (P.Z.)
| | - Xiaoyan Zhu
- Anqing Aquatic Technology Promotion Center Station, Anqing 246000, China; (X.Z.); (S.Z.)
| | - Sigang Zhang
- Anqing Aquatic Technology Promotion Center Station, Anqing 246000, China; (X.Z.); (S.Z.)
| | - Peng Zhang
- Zhuhai Chimelong Investment & Development Co., Ltd., Zhuhai 519000, China; (Z.L.); (P.Z.)
| | - Danqing Lin
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China; (W.L.); (D.Y.); (D.L.); (Z.H.); (J.Z.); (P.X.)
| | - Zhong Hua
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China; (W.L.); (D.Y.); (D.L.); (Z.H.); (J.Z.); (P.X.)
| | - Zhichen Cao
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China; (Z.C.); (H.Z.)
| | - Han Zhang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China; (Z.C.); (H.Z.)
| | - Jialu Zhang
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China; (W.L.); (D.Y.); (D.L.); (Z.H.); (J.Z.); (P.X.)
| | - Congping Ying
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China;
| | - Pao Xu
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China; (W.L.); (D.Y.); (D.L.); (Z.H.); (J.Z.); (P.X.)
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China;
| | - Guixin Dong
- Guangdong South China Rare Wild Animal Species Conservation Center, Zhuhai 519031, China
| | - Kai Liu
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China; (W.L.); (D.Y.); (D.L.); (Z.H.); (J.Z.); (P.X.)
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China;
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China; (Z.C.); (H.Z.)
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Vincent PF, Young ED, Edge AS, Glowatzki E. Auditory Hair Cells and Spiral Ganglion Neurons Regenerate Synapses with Refined Release Properties In Vitro. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.05.561095. [PMID: 38076928 PMCID: PMC10705289 DOI: 10.1101/2023.10.05.561095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Ribbon synapses between inner hair cells (IHCs) and type I spiral ganglion neurons (SGNs) in the inner ear are damaged by noise trauma and with aging, causing 'synaptopathy 'and hearing loss. Co-cultures of neonatal denervated organs of Corti and newly introduced SGNs have been developed to find strategies for improving IHC synapse regeneration, but evidence of the physiological normality of regenerated synapses is missing. This study utilizes IHC optogenetic stimulation and SGN recordings, showing that newly formed IHC synapses are indeed functional, exhibiting glutamatergic excitatory postsynaptic currents. When older organs of Corti were plated, synaptic activity probed by deconvolution, showed more mature release properties, closer to the highly specialized mode of IHC synaptic transmission that is crucial for coding the sound signal. This newly developed functional assessment of regenerated IHC synapses provides a powerful tool for testing approaches to improve synapse regeneration.
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Affiliation(s)
- Philippe F.Y. Vincent
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Eric D. Young
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Albert S.B. Edge
- Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, USA
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, USA
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts, USA
- Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Elisabeth Glowatzki
- The Center for Hearing and Balance, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Otolaryngology Head and Neck Surgery, The Johns Hopkins School of Medicine, Baltimore, Maryland
- Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, Maryland
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Hosoya M, Kitama T, Shimanuki MN, Nishiyama T, Oishi N, Okano H, Ozawa H. Distribution of macrophages in the developing cochlea of the common marmoset, a primate model animal. Front Immunol 2023; 14:1229414. [PMID: 37675123 PMCID: PMC10477578 DOI: 10.3389/fimmu.2023.1229414] [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: 05/26/2023] [Accepted: 08/04/2023] [Indexed: 09/08/2023] Open
Abstract
Introduction Macrophages are essential immune cells in the cochlea that contribute to inflammation, tissue repair, and homeostasis. They also play an important role in local cochlear immunity. The developmental immigration and maturation of macrophages in the cochlea have been investigated and are considered essential for normal hearing acquisition. Most of our current knowledge regarding cochlear development is based on rodent models because of the ethical challenges of using human fetal samples for research. However, inter-species differences between rodents and humans have been reported. In this study, we used a primate animal model to investigate the distributions of macrophages in the developing cochlea. The common marmoset (Callithrix jacchus), a small monkey species that inhabits the New World, was used as the model. Methods We investigated the distribution of macrophages in the developing cochlea of the common marmoset by performing immunohistochemical analyses of cochlear tissue from common marmoset embryos at different development stages. Results We revealed detailed distribution changes in the macrophages of a primate animal model cochlea. This observation indicates that most of the changes in the general distribution of macrophages were well preserved between rodents and this primate. The distribution changes observed in the common marmoset were also compatible with observations in the human fetus; although, observations in the human fetus are limited. Our observations in this study also revealed several differences between common marmosets and rodents. Conclusion The time course of immunological development and maturations established in this study will aid in the study of the primate-specific developmental biology of the inner ear. These observations may eventually lead to new therapeutic strategies for hearing loss in humans. In addition, understanding the immunological steady-state of the cochlea may help in the study of age- and genetic-induced hearing loss and in the design of regenerative therapies.
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Affiliation(s)
- Makoto Hosoya
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Tsubasa Kitama
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Marie N. Shimanuki
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Takanori Nishiyama
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Naoki Oishi
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
- Laboratory for Marmoset Neural Architecture, Center for Brain Science, RIKEN, Saitama, Japan
| | - Hiroyuki Ozawa
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
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Hong G, Fu X, Qi J, Shao B, Han X, Fang Y, Liu S, Cheng C, Zhu C, Gao J, Gao X, Chen J, Xia M, Xiong W, Chai R. Dock4 is required for the maintenance of cochlear hair cells and hearing function. FUNDAMENTAL RESEARCH 2023; 3:557-569. [PMID: 38933554 PMCID: PMC11197514 DOI: 10.1016/j.fmre.2022.04.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 04/22/2022] [Accepted: 04/24/2022] [Indexed: 12/27/2022] Open
Abstract
Auditory hair cells (HCs) are the mechanosensory receptors of the cochlea, and HC loss or malfunction can result from genetic defects. Dock4, a member of the Dock180-related protein superfamily, is a guanine nucleotide exchange factor for Rac1, and previous reports have shown that Dock4 mutations are associated with autism spectrum disorder, myelodysplastic syndromes, and tumorigenesis. Here, we found that Dock4 is highly expressed in the cochlear HCs of mice. However, the role of Dock4 in the inner ear has not yet been investigated. Taking advantage of the piggyBac transposon system, Dock4 knockdown (KD) mice were established to explore the role of Dock4 in the cochlea. Compared to wild-type controls, Dock4 KD mice showed significant hearing impairment from postnatal day 60. Dock4 KD mice showed hair bundle deficits and increased oxidative stress, which eventually led to HC apoptosis, late-onset HC loss, and progressive hearing loss. Furthermore, molecular mechanism studies showed that Rac1/β-catenin signaling was significantly downregulated in Dock4 KD cochleae and that this was the cause for the disorganized stereocilia and increased oxidative stress in HCs. Overall, our work demonstrates that the Dock4/Rac1/β-catenin signaling pathway plays a critical role in the maintenance of auditory HCs and hearing function.
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Affiliation(s)
- Guodong Hong
- State Key Laboratory of Digital Medical Engineering, 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
| | - Xiaolong Fu
- State Key Laboratory of Digital Medical Engineering, 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
| | - Jieyu Qi
- State Key Laboratory of Digital Medical Engineering, 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
| | - Buwei Shao
- State Key Laboratory of Digital Medical Engineering, 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
| | - Xuan Han
- State Key Laboratory of Digital Medical Engineering, 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
| | - Yuan Fang
- State Key Laboratory of Digital Medical Engineering, 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
| | - Shuang Liu
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100083, China
| | - Cheng Cheng
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, China
- Research Institute of Otolaryngology, Nanjing 210008, China
| | - Chengwen Zhu
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, China
| | - Junyan Gao
- Jiangsu Rehabilitation Research Center for Hearing and Speech Impairment, Nanjing, Jiangsu 210004, China
| | - Xia Gao
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, China
- Research Institute of Otolaryngology, Nanjing 210008, China
| | - Jie Chen
- Department of Otolaryngology Head and Neck Surgery, Jiangsu Provincial Key Medical Discipline (Laboratory), Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, China
- Research Institute of Otolaryngology, Nanjing 210008, China
| | - Ming Xia
- Department of Otolaryngology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Shandong 250000, China
- Medical Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Shandong 250022, China
| | - Wei Xiong
- School of Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100083, China
| | - Renjie Chai
- State Key Laboratory of Digital Medical Engineering, 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
- Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing 100101, China
- Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 610072, China
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8
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Zhang Y, Neng L, Sharma K, Hou Z, Johnson A, Song J, Dabdoub A, Shi X. Pericytes control vascular stability and auditory spiral ganglion neuron survival. eLife 2023; 12:e83486. [PMID: 36719173 PMCID: PMC9940910 DOI: 10.7554/elife.83486] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 01/26/2023] [Indexed: 02/01/2023] Open
Abstract
The inner ear has a rich population of pericytes, a multi-functional mural cell essential for sensory hair cell heath and normal hearing. However, the mechanics of how pericytes contribute to the homeostasis of the auditory vascular-neuronal complex in the spiral ganglion are not yet known. In this study, using an inducible and conditional pericyte depletion mouse (PDGFRB-CreERT2; ROSA26iDTR) model, we demonstrate, for the first time, that pericyte depletion causes loss of vascular volume and spiral ganglion neurons (SGNs) and adversely affects hearing sensitivity. Using an in vitro trans-well co-culture system, we show pericytes markedly promote neurite and vascular branch growth in neonatal SGN explants and adult SGNs. The pericyte-controlled neural growth is strongly mediated by pericyte-released exosomes containing vascular endothelial growth factor-A (VEGF-A). Treatment of neonatal SGN explants or adult SGNs with pericyte-derived exosomes significantly enhances angiogenesis, SGN survival, and neurite growth, all of which were inhibited by a selective blocker of VEGF receptor 2 (Flk1). Our study demonstrates that pericytes in the adult ear are critical for vascular stability and SGN health. Cross-talk between pericytes and SGNs via exosomes is essential for neuronal and vascular health and normal hearing.
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Affiliation(s)
- Yunpei Zhang
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science UniversityPortlandUnited States
| | - Lingling Neng
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science UniversityPortlandUnited States
| | - Kushal Sharma
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science UniversityPortlandUnited States
| | - Zhiqiang Hou
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science UniversityPortlandUnited States
| | - Anatasiya Johnson
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science UniversityPortlandUnited States
| | - Junha Song
- Life Sciences Division, Lawrence Berkeley National LaboratoryBerkeleyUnited States
| | - Alain Dabdoub
- Biological Sciences, Sunnybrook Research InstituteTorontoCanada
- Department of Otolaryngology-Head & Neck Surgery, University of TorontoTorontoCanada
- Department of Laboratory Medicine and Pathobiology, University of TorontoTorontoCanada
| | - Xiaorui Shi
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science UniversityPortlandUnited States
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9
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Song X, Li Y, Guo R, Yu Q, Liu S, Teng Q, Chen ZR, Xie J, Gong S, Liu K. Cochlear resident macrophage mediates development of ribbon synapses via CX3CR1/CX3CL1 axis. Front Mol Neurosci 2022; 15:1031278. [PMID: 36518186 PMCID: PMC9742371 DOI: 10.3389/fnmol.2022.1031278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/31/2022] [Indexed: 08/11/2023] Open
Abstract
Cochlear ribbon synapses formed between spiral ganglion neurons and inner hair cells in postnatal mice must undergo significant morphological and functional development to reach auditory maturation. However, the mechanisms underlying cochlear ribbon synapse remodeling remain unclear. This study found that cochlear resident macrophages are essential for cochlear ribbon synapse development and maturation in mice via the CX3CR1/CX3CL1 axis. CX3CR1 expression (a macrophage surface-specific receptor) and macrophage count in the cochlea were significantly increased from postnatal day 7 then decreased from days 14 to 28. Seven-day treatment with CX3CR1 inhibitors and artificial upregulation of CX3CL1 levels in the inner ear environment using the semicircular canal injection technique were initiated on day 7, and this resulted in a significant increase in hearing threshold on day 28. Additionally, abnormalities in the morphology and number of cochlear ribbon synapses were detected on day P14, which may be associated with hearing impairment. In conclusion, macrophage regulation of cochlear ribbon synapse remodeling via the CX3CR1/CX3CL1 axis is required during hearing development and offers a new perspective on immune-related hearing loss throughout auditory development. Importantly, it could be a new treatment target for sensorineural hearing loss.
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Affiliation(s)
- Xinyu Song
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
| | - Yang Li
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
| | - Rui Guo
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
| | - Qianru Yu
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
| | - Shan Liu
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
| | - Qi Teng
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
| | - Zhong-Rui Chen
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
| | - Jing Xie
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
| | - Shusheng Gong
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
| | - Ke Liu
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Clinical Center for Hearing Loss, Capital Medical University, Beijing, China
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10
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Wan H, Zhang Y, Hua Q. Cellular autophagy, the compelling roles in hearing function and dysfunction. Front Cell Neurosci 2022; 16:966202. [PMID: 36246522 PMCID: PMC9561951 DOI: 10.3389/fncel.2022.966202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 09/14/2022] [Indexed: 11/21/2022] Open
Abstract
Sensorineural hearing loss (SNHL) is currently a major health issue. As one of the most common neurodegenerative diseases, SNHL is associated with the degradation of hair cells (HCs), spiral ganglion neurons (SGNs), the stria vascularis, supporting cells and central auditory system cells. Autophagy is a highly integrated cellular system that eliminates impaired components and replenishes energy to benefit cellular homeostasis. Etiological links between autophagy alterations and neurodegenerative diseases, such as SNHL, have been established. The hearing pathway is complex and depends on the comprehensive functions of many types of tissues and cells in auditory system. In this review, we discuss the roles of autophagy in promoting and inhibiting hearing, paying particular attention to specific cells in the auditory system, as discerned through research. Hence, our review provides enlightening ideas for the role of autophagy in hearing development and impairment.
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Affiliation(s)
- Huanzhi Wan
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- Research Institute of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yuanyuan Zhang
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- Research Institute of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- *Correspondence: Yuanyuan Zhang,
| | - Qingquan Hua
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- Research Institute of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
- Qingquan Hua,
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11
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Crozier RA, Wismer ZQ, Parra-Munevar J, Plummer MR, Davis RL. Amplification of input differences by dynamic heterogeneity in the spiral ganglion. J Neurophysiol 2022; 127:1317-1333. [PMID: 35389760 PMCID: PMC9054264 DOI: 10.1152/jn.00544.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/30/2022] [Accepted: 03/30/2022] [Indexed: 11/22/2022] Open
Abstract
A defining feature of type I primary auditory afferents that compose ∼95% of the spiral ganglion is their intrinsic electrophysiological heterogeneity. This diversity is evident both between and within unitary, rapid, and slow adaptation (UA, RA, and SA) classes indicative of specializations designed to shape sensory receptor input. But to what end? Our initial impulse is to expect the opposite: that auditory afferents fire uniformly to represent acoustic stimuli with accuracy and high fidelity. Yet this is clearly not the case. One explanation for this neural signaling strategy is to coordinate a system in which differences between input stimuli are amplified. If this is correct, then stimulus disparity enhancements within the primary afferents should be transmitted seamlessly into auditory processing pathways that utilize population coding for difference detection. Using sound localization as an example, one would expect to observe separately regulated differences in intensity level compared with timing or spectral cues within a graded tonotopic distribution. This possibility was evaluated by examining the neuromodulatory effects of cAMP on immature neurons with high excitability and slow membrane kinetics. We found that electrophysiological correlates of intensity and timing were indeed independently regulated and tonotopically distributed, depending on intracellular cAMP signaling level. These observations, therefore, are indicative of a system in which differences between signaling elements of individual stimulus attributes are systematically amplified according to auditory processing constraints. Thus, dynamic heterogeneity mediated by cAMP in the spiral ganglion has the potential to enhance the representations of stimulus input disparities transmitted into higher level difference detection circuitry.NEW & NOTEWORTHY Can changes in intracellular second messenger signaling within primary auditory afferents shift our perception of sound? Results presented herein lead to this conclusion. We found that intracellular cAMP signaling level systematically altered the kinetics and excitability of primary auditory afferents, exemplifying how dynamic heterogeneity can enhance differences between electrophysiological correlates of timing and intensity.
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Affiliation(s)
| | - Zachary Q Wismer
- AtlantiCare Regional Medical Center, Department of Family Medicine, Atlantic City, New Jersey
| | - Jeffrey Parra-Munevar
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
| | - Mark R Plummer
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
| | - Robin L Davis
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey
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12
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Metabotropic Glutamate Receptors at Ribbon Synapses in the Retina and Cochlea. Cells 2022; 11:cells11071097. [PMID: 35406660 PMCID: PMC8998116 DOI: 10.3390/cells11071097] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/17/2022] [Accepted: 03/22/2022] [Indexed: 02/01/2023] Open
Abstract
Our senses define our view of the world. They allow us to adapt to environmental stimuli and are essential for communication and social behaviour. For most humans, seeing and hearing are central senses for their daily life. Our eyes and ears respond to an extraordinary broad range of stimuli covering about 12 log units of light intensity or acoustic power, respectively. The cellular basis is represented by sensory cells (photoreceptors in the retina and inner hair cells in the cochlea) that convert sensory inputs into electrical signals. Photoreceptors and inner hair cells have developed a specific pre-synaptic structure, termed synaptic ribbon, that is decorated with numerous vesicles filled with the excitatory neurotransmitter glutamate. At these ribbon synapses, glutamatergic signal transduction is guided by distinct sets of metabotropic glutamate receptors (mGluRs). MGluRs belong to group II and III of the receptor classification can inhibit neuronal activity, thus protecting neurons from overstimulation and subsequent degeneration. Consequently, dysfunction of mGluRs is associated with vision and hearing disorders. In this review, we introduce the principle characteristics of ribbon synapses and describe group II and III mGluRs in these fascinating structures in the retina and cochlea.
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13
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Panganiban CH, Barth JL, Tan J, Noble KV, McClaskey CM, Howard BA, Jafri SH, Dias JW, Harris KC, Lang H. Two distinct types of nodes of Ranvier support auditory nerve function in the mouse cochlea. Glia 2021; 70:768-791. [DOI: 10.1002/glia.24138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 11/12/2021] [Accepted: 12/17/2021] [Indexed: 11/09/2022]
Affiliation(s)
- Clarisse H. Panganiban
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
- Wolfson Centre for Age‐Related Diseases King's College London London UK
| | - Jeremy L. Barth
- Department of Regenerative Medicine and Cell Biology Medical University of South Carolina Charleston South Carolina USA
| | - Junying Tan
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
| | - Kenyaria V. Noble
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
| | - Carolyn M. McClaskey
- Department of Otolaryngology & Head and Neck Surgery Medical University of South Carolina Charleston South Carolina USA
| | - Blake A. Howard
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
| | - Shabih H. Jafri
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
| | - James W. Dias
- Department of Otolaryngology & Head and Neck Surgery Medical University of South Carolina Charleston South Carolina USA
| | - Kelly C. Harris
- Department of Otolaryngology & Head and Neck Surgery Medical University of South Carolina Charleston South Carolina USA
| | - Hainan Lang
- Department of Pathology and Laboratory Medicine Medical University of South Carolina Charleston South Carolina USA
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14
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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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15
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Parra-Munevar J, Morse CE, Plummer MR, Davis RL. Dynamic Heterogeneity Shapes Patterns of Spiral Ganglion Activity. J Neurosci 2021; 41:8859-8875. [PMID: 34551939 PMCID: PMC8549539 DOI: 10.1523/jneurosci.0924-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 08/17/2021] [Accepted: 09/08/2021] [Indexed: 11/21/2022] Open
Abstract
Neural response properties that typify primary sensory afferents are critical to fully appreciate because they establish and, ultimately represent, the fundamental coding design used for higher-level processing. Studies illuminating the center-surround receptive fields of retinal ganglion cells, for example, were ground-breaking because they determined the foundation of visual form detection. For the auditory system, a basic organizing principle of the spiral ganglion afferents is their extensive electrophysiological heterogeneity establishing diverse intrinsic firing properties in neurons throughout the spiral ganglion. Moreover, these neurons display an impressively large array of neurotransmitter receptor types that are responsive to efferent feedback. Thus, electrophysiological diversity and its neuromodulation are a fundamental encoding mechanism contributed by the primary afferents in the auditory system. To place these features into context, we evaluated the effects of hyperpolarization and cAMP on threshold level as indicators of overall afferent responsiveness in CBA/CaJ mice of either sex. Hyperpolarization modified threshold gradients such that distinct voltage protocols could shift the relationship between sensitivity and stimulus input to reshape resolution. This resulted in an "accordion effect" that appeared to stretch, compress, or maintain responsivity across the gradient of afferent thresholds. cAMP targeted threshold and kinetic shifts to rapidly adapting neurons, thus revealing multiple cochleotopic properties that could potentially be independently regulated. These examples of dynamic heterogeneity in primary auditory afferents not only have the capacity to shift the range, sensitivity, and resolution, but to do so in a coordinated manner that appears to orchestrate changes with a seemingly unlimited repertoire.SIGNIFICANCE STATEMENT How do we discriminate the more nuanced qualities of the sound around us? Beyond the basics of pitch and loudness, aspects, such as pattern, distance, velocity, and location, are all attributes that must be used to encode acoustic sensations effectively. While higher-level processing is required for perception, it would not be unexpected if the primary auditory afferents optimized receptor input to expedite neural encoding. The findings reported herein are consistent with this design. Neuromodulation compressed, expanded, shifted, or realigned intrinsic electrophysiological heterogeneity to alter neuronal responses selectively and dynamically. This suggests that diverse spiral ganglion phenotypes provide a rich substrate to support an almost limitless array of coding strategies within the first neural element of the auditory pathway.
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Affiliation(s)
- Jeffrey Parra-Munevar
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Charles E Morse
- Department of Neurosurgery, Jefferson Hospital for Neuroscience, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania 19107
| | - Mark R Plummer
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Robin L Davis
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
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16
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Flook M, Escalera-Balsera A, Gallego-Martinez A, Espinosa-Sanchez JM, Aran I, Soto-Varela A, Lopez-Escamez JA. DNA Methylation Signature in Mononuclear Cells and Proinflammatory Cytokines May Define Molecular Subtypes in Sporadic Meniere Disease. Biomedicines 2021; 9:1530. [PMID: 34829759 PMCID: PMC8615058 DOI: 10.3390/biomedicines9111530] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 10/19/2021] [Accepted: 10/21/2021] [Indexed: 12/15/2022] Open
Abstract
Meniere Disease (MD) is a multifactorial disorder of the inner ear characterized by vertigo attacks associated with sensorineural hearing loss and tinnitus with a significant heritability. Although MD has been associated with several genes, no epigenetic studies have been performed on MD. Here we performed whole-genome bisulfite sequencing in 14 MD patients and six healthy controls, with the aim of identifying an MD methylation signature and potential disease mechanisms. We observed a high number of differentially methylated CpGs (DMC) when comparing MD patients to controls (n= 9545), several of them in hearing loss genes, such as PCDH15, ADGRV1 and CDH23. Bioinformatic analyses of DMCs and cis-regulatory regions predicted phenotypes related to abnormal excitatory postsynaptic currents, abnormal NMDA-mediated receptor currents and abnormal glutamate-mediated receptor currents when comparing MD to controls. Moreover, we identified various DMCs in genes previously associated with cochleovestibular phenotypes in mice. We have also found 12 undermethylated regions (UMR) that were exclusive to MD, including two UMR in an inter CpG island in the PHB gene. We suggest that the DNA methylation signature allows distinguishing between MD patients and controls. The enrichment analysis confirms previous findings of a chronic inflammatory process underlying MD.
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Affiliation(s)
- Marisa Flook
- Otology & Neurotology Group CTS495, Department of Genomic Medicine, GENYO, Centre for Genomics and Oncological Research, Pfizer University of Granada Andalusian Regional Government, PTS, 18016 Granada, Spain; (M.F.); (A.E.-B.); (A.G.-M.); (J.M.E.-S.)
- Sensorineural Pathology Programme, Centro de Investigación Biomédica en Red en Enfermedades Raras, CIBERER, 28029 Madrid, Spain
- Department of Otolaryngology, Instituto de Investigación Biosanitaria ibs.Granada, Hospital Universitario Virgen de las Nieves, Universidad de Granada, 18014 Granada, Spain
| | - Alba Escalera-Balsera
- Otology & Neurotology Group CTS495, Department of Genomic Medicine, GENYO, Centre for Genomics and Oncological Research, Pfizer University of Granada Andalusian Regional Government, PTS, 18016 Granada, Spain; (M.F.); (A.E.-B.); (A.G.-M.); (J.M.E.-S.)
- Sensorineural Pathology Programme, Centro de Investigación Biomédica en Red en Enfermedades Raras, CIBERER, 28029 Madrid, Spain
- Department of Otolaryngology, Instituto de Investigación Biosanitaria ibs.Granada, Hospital Universitario Virgen de las Nieves, Universidad de Granada, 18014 Granada, Spain
| | - Alvaro Gallego-Martinez
- Otology & Neurotology Group CTS495, Department of Genomic Medicine, GENYO, Centre for Genomics and Oncological Research, Pfizer University of Granada Andalusian Regional Government, PTS, 18016 Granada, Spain; (M.F.); (A.E.-B.); (A.G.-M.); (J.M.E.-S.)
- Sensorineural Pathology Programme, Centro de Investigación Biomédica en Red en Enfermedades Raras, CIBERER, 28029 Madrid, Spain
- Department of Otolaryngology, Instituto de Investigación Biosanitaria ibs.Granada, Hospital Universitario Virgen de las Nieves, Universidad de Granada, 18014 Granada, Spain
| | - Juan Manuel Espinosa-Sanchez
- Otology & Neurotology Group CTS495, Department of Genomic Medicine, GENYO, Centre for Genomics and Oncological Research, Pfizer University of Granada Andalusian Regional Government, PTS, 18016 Granada, Spain; (M.F.); (A.E.-B.); (A.G.-M.); (J.M.E.-S.)
- Sensorineural Pathology Programme, Centro de Investigación Biomédica en Red en Enfermedades Raras, CIBERER, 28029 Madrid, Spain
- Department of Otolaryngology, Instituto de Investigación Biosanitaria ibs.Granada, Hospital Universitario Virgen de las Nieves, Universidad de Granada, 18014 Granada, Spain
| | - Ismael Aran
- Department of Otolaryngology, Complexo Hospitalario de Pontevedra, 36071 Pontevedra, Spain;
| | - Andres Soto-Varela
- Division of Otoneurology, Department of Otorhinolaryngology, Complexo Hospitalario Universitario, 15706 Santiago de Compostela, Spain;
| | - Jose Antonio Lopez-Escamez
- Otology & Neurotology Group CTS495, Department of Genomic Medicine, GENYO, Centre for Genomics and Oncological Research, Pfizer University of Granada Andalusian Regional Government, PTS, 18016 Granada, Spain; (M.F.); (A.E.-B.); (A.G.-M.); (J.M.E.-S.)
- Sensorineural Pathology Programme, Centro de Investigación Biomédica en Red en Enfermedades Raras, CIBERER, 28029 Madrid, Spain
- Department of Otolaryngology, Instituto de Investigación Biosanitaria ibs.Granada, Hospital Universitario Virgen de las Nieves, Universidad de Granada, 18014 Granada, Spain
- Division of Otolaryngology, Department of Surgery, University of Granada, 18011 Granada, Spain
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17
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Voelker J, Voelker C, Engert J, Goemann N, Hagen R, Rak K. Spontaneous Calcium Oscillations through Differentiation: A Calcium Imaging Analysis of Rat Cochlear Nucleus Neural Stem Cells. Cells 2021; 10:2802. [PMID: 34685782 PMCID: PMC8534573 DOI: 10.3390/cells10102802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 09/14/2021] [Accepted: 10/14/2021] [Indexed: 11/28/2022] Open
Abstract
Causal therapies for the auditory-pathway and inner-ear diseases are still not yet available for clinical application. Regenerative medicine approaches are discussed and examined as possible therapy options. Neural stem cells could play a role in the regeneration of the auditory pathway. In recent years, neural stem and progenitor cells have been identified in the cochlear nucleus, the second nucleus of the auditory pathway. The current investigation aimed to analyze cell maturation concerning cellular calcium activity. Cochlear nuclei from PND9 CD rats were microscopically dissected and propagated as neurospheres in free-floating cultures in stem-cell medium (Neurobasal, B27, GlutaMAX, EGF, bFGF). After 30 days, the dissociation and plating of these cells took place under withdrawal of the growth factors and the addition of retinoic acid, which induces neural cell differentiation. Calcium imaging analysis with BAPTA-1/Oregon Green was carried out at different times during the differentiation phase. In addition, the influence of different voltage-dependent calcium channels was analyzed through the targeted application of inhibitors of the L-, N-, R- and T-type calcium channels. For this purpose, comparative examinations were performed on CN NSCs, and primary CN neurons. As the cells differentiated, a significant increase in spontaneous neuronal calcium activity was demonstrated. In the differentiation stage, specific frequencies of the spontaneous calcium oscillations were measured in different regions of the individual cells. Initially, the highest frequency of spontaneous calcium oscillations was ascertainable in the maturing somata. Over time, these were overtaken by calcium oscillations in the axons and dendrites. Additionally, in the area of the growth cones, an increasing activity was determined. By inhibiting voltage-dependent calcium channels, their expression and function in the differentiation process were confirmed. A comparable pattern of maturation of these channels was found in CN NSCs and primary CN neurons. The present results show that neural stem cells of the rat cochlear nucleus differentiated not only morphologically but also functionally. Spontaneous calcium activities are of great relevance in terms of neurogenesis and integration into existing neuronal structures. These functional aspects of neurogenesis within the auditory pathway could serve as future targets for the exogenous control of neuronal regeneration.
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Affiliation(s)
- Johannes Voelker
- Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, Department of Oto-Rhino-Laryngology, University of Wuerzburg Josef-Schneider-Strasse 11, D-97080 Wuerzburg, Germany; (C.V.); (J.E.); (N.G.); (R.H.); (K.R.)
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18
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Milon B, Shulman ED, So KS, Cederroth CR, Lipford EL, Sperber M, Sellon JB, Sarlus H, Pregernig G, Shuster B, Song Y, Mitra S, Orvis J, Margulies Z, Ogawa Y, Shults C, Depireux DA, Palermo AT, Canlon B, Burns J, Elkon R, Hertzano R. A cell-type-specific atlas of the inner ear transcriptional response to acoustic trauma. Cell Rep 2021; 36:109758. [PMID: 34592158 PMCID: PMC8709734 DOI: 10.1016/j.celrep.2021.109758] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/29/2021] [Accepted: 09/03/2021] [Indexed: 01/26/2023] Open
Abstract
Noise-induced hearing loss (NIHL) results from a complex interplay of damage to the sensory cells of the inner ear, dysfunction of its lateral wall, axonal retraction of type 1C spiral ganglion neurons, and activation of the immune response. We use RiboTag and single-cell RNA sequencing to survey the cell-type-specific molecular landscape of the mouse inner ear before and after noise trauma. We identify induction of the transcription factors STAT3 and IRF7 and immune-related genes across all cell-types. Yet, cell-type-specific transcriptomic changes dominate the response. The ATF3/ATF4 stress-response pathway is robustly induced in the type 1A noise-resilient neurons, potassium transport genes are downregulated in the lateral wall, mRNA metabolism genes are downregulated in outer hair cells, and deafness-associated genes are downregulated in most cell types. This transcriptomic resource is available via the Gene Expression Analysis Resource (gEAR; https://umgear.org/NIHL) and provides a blueprint for the rational development of drugs to prevent and treat NIHL.
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Affiliation(s)
- Beatrice Milon
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Eldad D Shulman
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Kathy S So
- Decibel Therapeutics, Boston, MA 02215, USA
| | - Christopher R Cederroth
- Laboratory of Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden; Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham NG7 2UH, UK
| | - Erika L Lipford
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Michal Sperber
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Heela Sarlus
- Laboratory of Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden; Applied Immunology & Immunotherapy, Neuroimmunology Unit, Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska University Hospital, 171 77 Stockholm, Sweden
| | | | - Benjamin Shuster
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yang Song
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Sunayana Mitra
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joshua Orvis
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Zachary Margulies
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yoko Ogawa
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Christopher Shults
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | | | | - Barbara Canlon
- Laboratory of Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden
| | - Joe Burns
- Decibel Therapeutics, Boston, MA 02215, USA
| | - Ran Elkon
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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19
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Stothert AR, Kaur T. Innate Immunity to Spiral Ganglion Neuron Loss: A Neuroprotective Role of Fractalkine Signaling in Injured Cochlea. Front Cell Neurosci 2021; 15:694292. [PMID: 34408629 PMCID: PMC8365835 DOI: 10.3389/fncel.2021.694292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 07/14/2021] [Indexed: 12/20/2022] Open
Abstract
Immune system dysregulation is increasingly being attributed to the development of a multitude of neurodegenerative diseases. This, in large part, is due to the delicate relationship that exists between neurons in the central nervous system (CNS) and peripheral nervous system (PNS), and the resident immune cells that aid in homeostasis and immune surveillance within a tissue. Classically, the inner ear was thought to be immune privileged due to the presence of a blood-labyrinth barrier. However, it is now well-established that both vestibular and auditory end organs in the inner ear contain a resident (local) population of macrophages which are the phagocytic cells of the innate-immune system. Upon cochlear sterile injury or infection, there is robust activation of these resident macrophages and a predominant increase in the numbers of macrophages as well as other types of leukocytes. Despite this, the source, nature, fate, and functions of these immune cells during cochlear physiology and pathology remains unclear. Migration of local macrophages and infiltration of bone-marrow-derived peripheral blood macrophages into the damaged cochlea occur through various signaling cascades, mediated by the release of specific chemical signals from damaged sensory and non-sensory cells of the cochlea. One such signaling pathway is CX3CL1-CX3CR1, or fractalkine (FKN) signaling, a direct line of communication between macrophages and sensory inner hair cells (IHCs) and spiral ganglion neurons (SGNs) of the cochlea. Despite the known importance of this neuron-immune axis in CNS function and pathology, until recently it was not clear whether this signaling axis played a role in macrophage chemotaxis and SGN survival following cochlear injury. In this review, we will explore the importance of innate immunity in neurodegenerative disease development, specifically focusing on the regulation of the CX3CL1-CX3CR1 axis, and present evidence for a role of FKN signaling in cochlear neuroprotection.
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Affiliation(s)
- Andrew Rigel Stothert
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States
| | - Tejbeer Kaur
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States
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20
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Martini FJ, Guillamón-Vivancos T, Moreno-Juan V, Valdeolmillos M, López-Bendito G. Spontaneous activity in developing thalamic and cortical sensory networks. Neuron 2021; 109:2519-2534. [PMID: 34293296 DOI: 10.1016/j.neuron.2021.06.026] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 05/05/2021] [Accepted: 06/23/2021] [Indexed: 11/19/2022]
Abstract
Developing sensory circuits exhibit different patterns of spontaneous activity, patterns that are related to the construction and refinement of functional networks. During the development of different sensory modalities, spontaneous activity originates in the immature peripheral sensory structures and in the higher-order central structures, such as the thalamus and cortex. Certainly, the perinatal thalamus exhibits spontaneous calcium waves, a pattern of activity that is fundamental for the formation of sensory maps and for circuit plasticity. Here, we review our current understanding of the maturation of early (including embryonic) patterns of spontaneous activity and their influence on the assembly of thalamic and cortical sensory networks. Overall, the data currently available suggest similarities between the developmental trajectory of brain activity in experimental models and humans, which in the future may help to improve the early diagnosis of developmental disorders.
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Affiliation(s)
- Francisco J Martini
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain.
| | - Teresa Guillamón-Vivancos
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain
| | - Verónica Moreno-Juan
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain
| | - Miguel Valdeolmillos
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain
| | - Guillermina López-Bendito
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain.
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21
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Kohrman D, Borges BC, Cassinotti L, Ji L, Corfas G. Axon-glia interactions in the ascending auditory system. Dev Neurobiol 2021; 81:546-567. [PMID: 33561889 PMCID: PMC9004231 DOI: 10.1002/dneu.22813] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/25/2020] [Accepted: 02/05/2021] [Indexed: 11/09/2022]
Abstract
The auditory system detects and encodes sound information with high precision to provide a high-fidelity representation of the environment and communication. In mammals, detection occurs in the peripheral sensory organ (the cochlea) containing specialized mechanosensory cells (hair cells) that initiate the conversion of sound-generated vibrations into action potentials in the auditory nerve. Neural activity in the auditory nerve encodes information regarding the intensity and frequency of sound stimuli, which is transmitted to the auditory cortex through the ascending neural pathways. Glial cells are critical for precise control of neural conduction and synaptic transmission throughout the pathway, allowing for the precise detection of the timing, frequency, and intensity of sound signals, including the sub-millisecond temporal fidelity is necessary for tasks such as sound localization, and in humans, for processing complex sounds including speech and music. In this review, we focus on glia and glia-like cells that interact with hair cells and neurons in the ascending auditory pathway and contribute to the development, maintenance, and modulation of neural circuits and transmission in the auditory system. We also discuss the molecular mechanisms of these interactions, their impact on hearing and on auditory dysfunction associated with pathologies of each cell type.
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Affiliation(s)
- David Kohrman
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Beatriz C. Borges
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Luis Cassinotti
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Lingchao Ji
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
| | - Gabriel Corfas
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109, USA
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22
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Ghosh S, Stansak K, Walters BJ. Cannabinoid Signaling in Auditory Function and Development. Front Mol Neurosci 2021; 14:678510. [PMID: 34079440 PMCID: PMC8165240 DOI: 10.3389/fnmol.2021.678510] [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: 03/09/2021] [Accepted: 04/15/2021] [Indexed: 12/20/2022] Open
Abstract
Plants of the genus Cannabis have been used by humans for millennia for a variety of purposes. Perhaps most notable is the use of certain Cannabis strains for their psychoactive effects. More recently, several biologically active molecules within the plants of these Cannabis strains, called phytocannabinoids or simply cannabinoids, have been identified. Furthermore, within human cells, endogenous cannabinoids, or endocannabinoids, as well as the receptors and secondary messengers that give rise to their neuromodulatory effects, have also been characterized. This endocannabinoid system (ECS) is composed of two primary ligands-anandamide and 2-arachidonyl glycerol; two primary receptors-cannabinoid receptors 1 and 2; and several enzymes involved in biosynthesis and degradation of endocannabinoid ligands including diacylglycerol lipase (DAGL) and monoacylglycerol lipase (MAGL). Here we briefly summarize cannabinoid signaling and review what has been discerned to date with regard to cannabinoid signaling in the auditory system and its roles in normal physiological function as well as pathological conditions. While much has been uncovered regarding cannabinoid signaling in the central nervous system, less attention has been paid to the auditory system specifically. Still, evidence is emerging to suggest that cannabinoid signaling is critical for the development, maturation, function, and survival of cochlear hair cells (HCs) and spiral ganglion neurons (SGNs). Furthermore, cannabinoid signaling can have profound effects on synaptic connectivity in CNS structures related to auditory processing. While clinical cases demonstrate that endogenous and exogenous cannabinoids impact auditory function, this review highlights several areas, such as SGN development, where more research is warranted.
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Affiliation(s)
- Sumana Ghosh
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, United States
| | - Kendra Stansak
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, United States
| | - Bradley J Walters
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, United States.,Department of Otolaryngology-Head and Neck Surgery, University of Mississippi Medical Center, Jackson, MS, United States
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23
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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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24
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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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25
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Conductive hearing loss during development does not appreciably alter the sharpness of cochlear tuning. Sci Rep 2021; 11:3955. [PMID: 33597563 PMCID: PMC7890061 DOI: 10.1038/s41598-021-83115-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/22/2021] [Indexed: 02/02/2023] Open
Abstract
An increasing number of studies show that listeners often have difficulty hearing in situations with background noise, despite normal tuning curves in quiet. One potential source of this difficulty could be sensorineural changes in the auditory periphery (the ear). Signal in noise detection deficits also arise in animals raised with developmental conductive hearing loss (CHL), a manipulation that induces acoustic attenuation to model how sound deprivation changes the central auditory system. This model attributes perceptual deficits to central changes by assuming that CHL does not affect sensorineural elements in the periphery that could raise masked thresholds. However, because of efferent feedback, altering the auditory system could affect cochlear elements. Indeed, recent studies show that adult-onset CHL can cause cochlear synapse loss, potentially calling into question the assumption of an intact periphery in early-onset CHL. To resolve this issue, we tested the long-term peripheral effects of CHL via developmental bilateral malleus displacement. Using forward masking tuning curves, we compared peripheral tuning in animals raised with CHL vs age-matched controls. Using compound action potential measurements from the round window, we assessed inner hair cell synapse integrity. Results indicate that developmental CHL can cause minor synaptopathy. However, developmental CHL does not appreciably alter peripheral frequency tuning.
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26
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Baumgartner JE, Baumgartner LS, Baumgartner ME, Moore EJ, Messina SA, Seidman MD, Shook DR. Progenitor cell therapy for acquired pediatric nervous system injury: Traumatic brain injury and acquired sensorineural hearing loss. Stem Cells Transl Med 2021; 10:164-180. [PMID: 33034162 PMCID: PMC7848325 DOI: 10.1002/sctm.20-0026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 08/18/2020] [Accepted: 08/24/2020] [Indexed: 12/16/2022] Open
Abstract
While cell therapies hold remarkable promise for replacing injured cells and repairing damaged tissues, cell replacement is not the only means by which these therapies can achieve therapeutic effect. For example, recent publications show that treatment with varieties of adult, multipotent stem cells can improve outcomes in patients with neurological conditions such as traumatic brain injury and hearing loss without directly replacing damaged or lost cells. As the immune system plays a central role in injury response and tissue repair, we here suggest that multipotent stem cell therapies achieve therapeutic effect by altering the immune response to injury, thereby limiting damage due to inflammation and possibly promoting repair. These findings argue for a broader understanding of the mechanisms by which cell therapies can benefit patients.
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Affiliation(s)
- James E. Baumgartner
- Advent Health for ChildrenOrlandoFloridaUSA
- Department of Neurological SurgeryUniversity of Central Florida College of MedicineOrlandoFloridaUSA
| | | | | | - Ernest J. Moore
- Department of Audiology and Speech Language PathologyUniversity of North TexasDentonTexasUSA
| | | | - Michael D. Seidman
- Advent Health CelebrationCelebrationFloridaUSA
- Department of OtorhinolaryngologyUniversity of Central FloridaOrlandoFloridaUSA
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27
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Phase-Locking Requires Efficient Ca 2+ Extrusion at the Auditory Hair Cell Ribbon Synapse. J Neurosci 2021; 41:1625-1635. [PMID: 33446517 DOI: 10.1523/jneurosci.1324-18.2020] [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: 05/17/2018] [Revised: 08/25/2020] [Accepted: 12/27/2020] [Indexed: 11/21/2022] Open
Abstract
Proper perception of sounds in the environment requires auditory signals to be encoded with extraordinary temporal precision up to tens of microseconds, but how it originates from the hearing organs in the periphery is poorly understood. In particular, sound-evoked spikes in auditory afferent fibers in vivo are phase-locked to sound frequencies up to 5 kHz, but it is not clear how hair cells can handle intracellular Ca2+ changes with such high speed and efficiency. In this study, we combined patch-clamp recording and two-photon Ca2+ imaging to examine Ca2+ dynamics in hair cell ribbon synapses in the bullfrog amphibian papilla of both sexes. We found that Ca2+ clearance from single synaptic ribbons followed a double exponential function, and the weight of the fast component, but not the two time constants, was significantly reduced for prolonged stimulation, and during inhibition of the plasma membrane Ca2+ ATPase (PMCA), the mitochondrial Ca2+ uptake (MCU), or the sarcolemma/endoplasmic reticulum Ca2+ ATPase (SERCA), but not the Na+/Ca2+ exchanger (NCX). Furthermore, we found that both the basal Ca2+ level and the Ca2+ rise during sinusoidal stimulation were significantly increased by inhibition of PMCA, MCU, or SERCA. Consistently, phase-locking of synaptic vesicle releases from hair cells was also significantly reduced by blocking PMCA, MCU, or SERCA, but not NCX. We conclude that, in addition to fast diffusion mediated by mobile Ca2+ buffer, multiple Ca2+ extrusion pumps are required for phase-locking at the auditory hair cell ribbon synapse.SIGNIFICANCE STATEMENT Hair cell synapses can transmit sound-driven signals precisely in the kHz range. However, previous studies of Ca2+ handling in auditory hair cells have often been conducted in immature hair cells, with elevated extracellular Ca2+ concentration, or through steady-state stimulation that may not be physiologically relevant. Here we examine Ca2+ clearance from hair cell synaptic ribbons in a fully mature preparation at physiological concentration of external Ca2+ and at physiological temperature. By stimulating hair cells with sinusoidal voltage commands that mimic pure sound tones, we recapitulated the phase-locking of hair cell exocytosis with an in vitro approach. This allowed us to reveal the Ca2+ extrusion mechanisms that are required for phase-locking at auditory hair cell ribbon synapses.
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28
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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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29
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Wood MB, Nowak N, Mull K, Goldring A, Lehar M, Fuchs PA. Acoustic Trauma Increases Ribbon Number and Size in Outer Hair Cells of the Mouse Cochlea. J Assoc Res Otolaryngol 2020; 22:19-31. [PMID: 33151428 PMCID: PMC7822997 DOI: 10.1007/s10162-020-00777-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/19/2020] [Indexed: 01/01/2023] Open
Abstract
Outer hair cells (OHCs) in the mouse cochlea are contacted by up to three type II afferent boutons. On average, only half of these are postsynaptic to presynaptic ribbons. Mice of both sexes were subjected to acoustic trauma that produced a threshold shift of 44.2 ± 9.1 dB 7 days after exposure. Ribbon synapses of OHCs were quantified in post-trauma and littermate controls using immunolabeling of CtBP2. Visualization with virtual reality was used to determine 3-D cytoplasmic localization of CtBP2 puncta to the synaptic pole of OHCs. Acoustic trauma was associated with a statistically significant increase in the number of synaptic ribbons per OHC. Serial section TEM was carried out on similarly treated mice. This also showed a significant increase in the number of ribbons in post-trauma OHCs, as well as a significant increase in ribbon volume compared to ribbons in control OHCs. An increase in OHC ribbon synapses after acoustic trauma is a novel observation that has implications for OHC:type II afferent signaling. A mathematical model showed that the observed increase in OHC ribbons considered alone could produce a significant increase in action potentials among type II afferent neurons during strong acoustic stimulation.
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Affiliation(s)
- Megan B Wood
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA.
| | - Nathaniel Nowak
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA
| | - Keira Mull
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA
| | - Adam Goldring
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA.,Sutter Instrument, Co. 1 Digital Drive, Novato, CA, 94949, USA
| | - Mohamed Lehar
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA
| | - Paul Albert Fuchs
- Department of Otolaryngology - Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD, 21205, USA
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Gao L, Kita T, Katsuno T, Yamamoto N, Omori K, Nakagawa T. Insulin-Like Growth Factor 1 on the Maintenance of Ribbon Synapses in Mouse Cochlear Explant Cultures. Front Cell Neurosci 2020; 14:571155. [PMID: 33132846 PMCID: PMC7579230 DOI: 10.3389/fncel.2020.571155] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/27/2020] [Indexed: 01/31/2023] Open
Abstract
Hearing loss has become one of the most common disabilities worldwide. The synaptic connections between inner hair cells (IHCs) and spiral ganglion neurons have specialized synaptic constructions, termed ribbon synapses, which are important for auditory function. The ribbon synapses in the cochlea are quite vulnerable to various insults. As such, the maintenance of ribbon synapses is important for ensuring hearing function. Insulin-like growth factor 1 (IGF1) plays a critical role in the development and maintenance of the cochlea and has the potential to protect cochlear hair cells from various insults. In this study, we examined the role of IGF1 in the maintenance of ribbon synapses in cochlear explants of postnatal day four mice. We cultured cochlear explants with an IGF1 receptor antagonist, JB1, which is an IGF1 peptide analog. Results showed that exposure to JB1 for 24 h resulted in the loss of ribbon synapses. After an additional 24-h culture without JB1, the number of ribbon synapses spontaneously recovered. The application of exogenous IGF1 showed two different aspects of ribbon synapses. Low doses of exogenous IGF1 promoted the recovery of ribbon synapses, while it compromised the spontaneous recovery of ribbon synapses at high doses. Altogether, these results indicate that the paracrine or autocrine release of IGF1 in the cochlea plays a crucial role in the maintenance of cochlear ribbon synapses.
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Affiliation(s)
- Li Gao
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tomoko Kita
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tatsuya Katsuno
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Norio Yamamoto
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Koichi Omori
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takayuki Nakagawa
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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The Purinergic Receptor P2rx3 is Required for Spiral Ganglion Neuron Branch Refinement during Development. eNeuro 2020; 7:ENEURO.0179-20.2020. [PMID: 32675174 PMCID: PMC7418533 DOI: 10.1523/eneuro.0179-20.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/03/2020] [Accepted: 07/08/2020] [Indexed: 12/18/2022] Open
Abstract
The mammalian cochlea undergoes a highly dynamic process of growth and innervation during development. This process includes spiral ganglion neuron (SGN) branch refinement, a process whereby Type I SGNs undergo a phase of “debranching” before forming unramified synaptic contacts with inner hair cells. Using Sox2CreERT2 and R26RtdTomato as a strategy to genetically label individual SGNs in mice of both sexes, we report on both a time course of SGN branch refinement and a role for P2rx3 in this process. P2rx3 is an ionotropic ATP receptor that was recently implicated in outer hair cell spontaneous activity and Type II SGN synapse development (Ceriani et al., 2019), but its function in Type I SGN development is unknown. Here, we demonstrate that P2rx3 is expressed by Type I SGNs and hair cells during developmental periods that coincide with SGN branching refinement. P2rx3 null mice show SGNs with more complex branching patterns on their peripheral synaptic terminals and near their cell bodies around the time of birth. Loss of P2rx3 does not appear to confer general changes in axon outgrowth or hair cell formation, and alterations in branching complexity appear to mostly recover by postnatal day (P)6. However, when we examined the distribution of Type I SGN subtypes using antibodies that bind Calb2, Calb1, and Pou4f1, we found that P2rx3 null mice showed an increased proportion of SGNs that express Calb2. These data suggest P2rx3 may be necessary for normal Type I SGN differentiation in addition to serving a role in branch refinement.
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Loss of Cochlear Ribbon Synapse Is a Critical Contributor to Chronic Salicylate Sodium Treatment-Induced Tinnitus without Change Hearing Threshold. Neural Plast 2020; 2020:3949161. [PMID: 32774354 PMCID: PMC7397434 DOI: 10.1155/2020/3949161] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 05/23/2020] [Accepted: 06/12/2020] [Indexed: 12/25/2022] Open
Abstract
Tinnitus is a common auditory disease worldwide; it is estimated that more than 10% of all individuals experience this hearing disorder during their lifetime. Tinnitus is sometimes accompanied by hearing loss. However, hearing loss is not acquired in some other tinnitus generations. In this study, we injected adult rats with salicylate sodium (SS) (200 mg/kg/day for 10 days) and found no significant hearing threshold changes at 2, 4, 8, 12, 14, 16, 20, or 24 kHz (all p > 0.05). Tinnitus was confirmed in the treated rats via Behaviour Testing of Acoustic Startle Response (ASR) and Gap Prepulse Inhibition Test of Acoustic Startle Reflex (GPIAS). A immunostaining study showed that there is significant loss of anti-CtBP2 puncta (a marker of cochlear inner hair cell (HC) ribbon synapses) in treated animals in apical, middle, and basal turns (all p < 0.05). The ABR wave I amplitudes were significantly reduced at 4, 8, 12, 14, 16, and 20 kHz (all p < 0.05). No significant losses of outer HCs, inner HCs, or HC cilia were observed (all p > 0.05). Thus, our study suggests that loss of cochlear inner HC ribbon synapse after SS exposure is a contributor to the development of tinnitus without changing hearing threshold.
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Peter MN, Paasche G, Reich U, Lenarz T, Warnecke A. Differential Effects of Low- and High-Dose Dexamethasone on Electrically Induced Damage of the Cultured Organ of Corti. Neurotox Res 2020; 38:487-497. [PMID: 32495312 PMCID: PMC7334252 DOI: 10.1007/s12640-020-00228-7] [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: 08/02/2019] [Revised: 05/02/2020] [Accepted: 05/19/2020] [Indexed: 12/29/2022]
Abstract
An increased number of patients with residual hearing are undergoing cochlear implantation. A subset of these experience delayed hearing loss post-implantation, and the aetiology of this loss is not well understood. Our previous studies suggest that electrical stimulation can induce damage to hair cells in organ of Corti (OC) organotypic cultures. Dexamethasone has the potential to protect residual hearing due to its multiple effects on cells and tissue (e.g., anti-inflammatory, free radical scavenger). We therefore hypothesized that dexamethasone treatment could prevent electrical stimulation induced changes in the OC. Organ of Corti explants from neonatal rats (P2–4) were cultured for 24 h with two different concentrations of dexamethasone. Thereafter, OC were subjected to a charge-balanced biphasic pulsed electrical stimulation (0.44–2 mA) for a further 24 h. Unstimulated dexamethasone-treated OC served as controls. Outcome analysis included immunohistochemical labelling of ribbon synapses, histochemical analysis of free reactive oxygen species and morphological analysis of stereocilia bundles. Overall, the protective effects of dexamethasone on electrically induced damage in cochlear explants were moderate. High-dose dexamethasone protected bundle integrity at higher current levels. Low-dose dexamethasone tended to increase ribbon density in the apical region.
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Affiliation(s)
- Marvin N Peter
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Gerrit Paasche
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Cluster of Excellence "Hearing4all" of the German Research Foundation, Hannover, Germany
| | - Uta Reich
- Department of Otorhinolaryngology, Head and Neck Surgery, Berlin Institute of Health, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Cluster of Excellence "Hearing4all" of the German Research Foundation, Hannover, Germany
| | - Athanasia Warnecke
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Cluster of Excellence "Hearing4all" of the German Research Foundation, Hannover, Germany.
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Brooks PM, Rose KP, MacRae ML, Rangoussis KM, Gurjar M, Hertzano R, Coate TM. Pou3f4-expressing otic mesenchyme cells promote spiral ganglion neuron survival in the postnatal mouse cochlea. J Comp Neurol 2020; 528:1967-1985. [PMID: 31994726 DOI: 10.1002/cne.24867] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 12/20/2022]
Abstract
During inner ear development, primary auditory neurons named spiral ganglion neurons (SGNs) are surrounded by otic mesenchyme cells, which express the transcription factor Pou3f4. Mutations in Pou3f4 are associated with DFNX2, the most common form of X-linked deafness and typically include developmental malformations of the middle ear and inner ear. It is known that interactions between Pou3f4-expressing mesenchyme cells and SGNs are important for proper axon bundling during development. However, Pou3f4 continues to be expressed through later phases of development, and potential interactions between Pou3f4 and SGNs during this period had not been explored. To address this, we documented Pou3f4 protein expression in the early postnatal mouse cochlea and compared SGNs in Pou3f4 knockout mice and littermate controls. In Pou3f4y/- mice, SGN density begins to decline by the end of the first postnatal week, with approximately 25% of SGNs ultimately lost. This period of SGN loss in Pou3f4y/- cochleae coincides with significant elevations in SGN apoptosis. Interestingly, this period also coincides with the presence of a transient population of Pou3f4-expressing cells around and within the spiral ganglion. To determine if Pou3f4 is normally required for SGN peripheral axon extension into the sensory domain, we used a genetic sparse labeling approach to track SGNs and found no differences compared with controls. We also found that Pou3f4 loss did not lead to changes in the proportions of Type I SGN subtypes. Overall, these data suggest that otic mesenchyme cells may play a role in maintaining SGN populations during the early postnatal period.
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Affiliation(s)
- Paige M Brooks
- Department of Biology, Georgetown University, Washington, District of Columbia
| | - Kevin P Rose
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, University of Maryland, Baltimore, Maryland
| | - Meaghan L MacRae
- Department of Biology, Georgetown University, Washington, District of Columbia
| | | | - Mansa Gurjar
- Department of Biology, Georgetown University, Washington, District of Columbia
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, University of Maryland, Baltimore, Maryland.,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, University of Maryland, Baltimore, Maryland.,Institute for Genome Sciences, University of Maryland School of Medicine, University of Maryland, Baltimore, Maryland
| | - Thomas M Coate
- Department of Biology, Georgetown University, Washington, District of Columbia
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Jung JS, Zhang KD, Wang Z, McMurray M, Tkaczuk A, Ogawa Y, Hertzano R, Coate TM. Semaphorin-5B Controls Spiral Ganglion Neuron Branch Refinement during Development. J Neurosci 2019; 39:6425-6438. [PMID: 31209173 PMCID: PMC6697390 DOI: 10.1523/jneurosci.0113-19.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 05/03/2019] [Accepted: 06/10/2019] [Indexed: 01/30/2023] Open
Abstract
During nervous system development, axons often undergo elaborate changes in branching patterns before circuits have achieved their mature patterns of innervation. In the auditory system, type I spiral ganglion neurons (SGNs) project their peripheral axons into the cochlear epithelium and then undergo a process of branch refinement before forming synapses with sensory hair cells. Here, we report that Semaphorin-5B (Sema5B) acts as an important mediator of this process. During cochlear development in mouse, immature hair cells express Sema5B, whereas the SGNs express both PlexinA1 and PlexinA3, which are known Sema5B receptors. In these studies, genetic sparse labeling and three-dimensional reconstruction techniques were leveraged to determine the morphologies of individual type I SGNs after manipulations of Sema5B signaling. Treating cultured mouse cochleae with Sema5B-Fc (to activate Plexin-As) led to type I SGNs with less numerous, but longer terminal branches. Conversely, cochleae from Sema5b knock-out mice showed type I SGNs with more numerous, but shorter terminal branches. In addition, conditional loss of Plxna1 in SGNs (using Bhlhb5Cre) led to increased type I SGN branching, suggesting that PlexinA1 normally responds to Sema5B in this process. In these studies, mice of either sex were used. The data presented here suggest that Sema5B-PlexinA1 signaling limits SGN terminal branch numbers without causing axonal repulsion, which is a role that distinguishes Sema5B from other Semaphorins in cochlear development.SIGNIFICANCE STATEMENT The sensorineural components of the cochlea include hair cells, which respond mechanically to sound waves, and afferent spiral ganglion neurons (SGNs), which respond to glutamate released by hair cells and transmit auditory information into the CNS. An important component of synapse formation in the cochlea is a process of SGN "debranching" whereby SGNs lose extraneous branches before developing unramified bouton endings that contact the hair cells. In this work, we have found that the transmembrane ligand Semaphorin-5B and its receptor PlexinA1 regulate the debranching process. The results in this report provide new knowledge regarding the molecular control of cochlear afferent innervation.
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Affiliation(s)
- Johnny S Jung
- Department of Biology, Georgetown University, Washington, DC 20007, and
| | - Kaidi D Zhang
- Department of Biology, Georgetown University, Washington, DC 20007, and
| | - Zhirong Wang
- Department of Biology, Georgetown University, Washington, DC 20007, and
| | - Mark McMurray
- Departments of Otorhinolaryngology Head and Neck Surgery
| | - Andrew Tkaczuk
- Departments of Otorhinolaryngology Head and Neck Surgery
| | - Yoko Ogawa
- Departments of Otorhinolaryngology Head and Neck Surgery
| | - Ronna Hertzano
- Departments of Otorhinolaryngology Head and Neck Surgery
- Anatomy and Neurobiology, and
- Institute for Genome Sciences, University of Maryland School of Medicine, University of Maryland, Baltimore, Maryland 21201
| | - Thomas M Coate
- Department of Biology, Georgetown University, Washington, DC 20007, and
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How to Build a Fast and Highly Sensitive Sound Detector That Remains Robust to Temperature Shifts. J Neurosci 2019; 39:7260-7276. [PMID: 31315946 DOI: 10.1523/jneurosci.2510-18.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 06/13/2019] [Accepted: 07/09/2019] [Indexed: 12/26/2022] Open
Abstract
Frogs must have sharp hearing abilities during the warm summer months to successfully find mating partners. This study aims to understand how frog hair cell ribbon-type synapses preserve both sensitivity and temporal precision during temperature changes. Under room (∼24°C) and high (∼32°C) temperature, we performed in vitro patch-clamp recordings of hair cells and their afferent fibers in amphibian papillae of either male or female bullfrogs. Afferent fibers exhibited a wide heterogeneity in membrane input resistance (Rin) from 100 mΩ to 1000 mΩ, which may contribute to variations in spike threshold and firing frequency. At higher temperatures, most fibers increased their frequency of spike firing due to an increase in spontaneous EPSC frequencies. Hair cell resting membrane potential (Vrest) remained surprisingly stable during temperature increases, because Ca2+ influx and K+ outflux increased simultaneously. This increase in Ca2+ current likely enhanced spontaneous EPSC frequencies. These larger "leak currents" at Vrest also lowered Rin and produced higher electrical resonant frequencies. Lowering Rin will reduce the hair cells receptor potential and presumably moderate the systems sensitivity. Using membrane capacitance measurements, we suggest that hair cells can partially compensate for this reduced sensitivity by increasing exocytosis efficiency and the size of the readily releasable pool of synaptic vesicles. Furthermore, paired recordings of hair cells and their afferent fibers showed that synaptic delays shortened and multivesicular release becomes more synchronous at higher temperatures, which should improve temporal precision. Together, our results explain many previous in vivo observations on the temperature dependence of spikes in auditory nerves.SIGNIFICANCE STATEMENT The vertebrate inner ear detects and transmits auditory information over a broad dynamic range of sound frequency and intensity. It achieves remarkable sensitivity to soft sounds and precise frequency selectivity. How does the ear of cold-blooded vertebrates maintain its performance level as temperature changes? More specifically, how does the hair cell to afferent fiber synapse in bullfrog amphibian papilla adjust to a wide range of physiological temperatures without losing its sensitivity and temporal fidelity to sound signals? This study uses in vitro experiments to reveal the biophysical mechanisms that explain many observations made from in vivo auditory nerve fiber recordings. We find that higher temperature facilitates vesicle exocytosis and electrical tuning to higher sound frequencies, which benefits sensitivity and selectivity.
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