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Johns JD, Olszewski R, Strepay D, Lopez IA, Ishiyama A, Hoa M. Emerging Mechanisms in the Pathogenesis of Menière's Disease: Evidence for the Involvement of Ion Homeostatic or Blood-Labyrinthine Barrier Dysfunction in Human Temporal Bones. Otol Neurotol 2023; 44:1057-1065. [PMID: 37733989 PMCID: PMC10840868 DOI: 10.1097/mao.0000000000004016] [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] [Indexed: 09/23/2023]
Abstract
HYPOTHESIS Analysis of human temporal bone specimens of patients with Menière's disease (MD) may demonstrate altered expression of gene products related to barrier formation and ionic homeostasis within cochlear structures compared with control specimens. BACKGROUND MD represents a challenging otologic disorder for investigation. Despite attempts to define the pathogenesis of MD, there remain many gaps in our understanding, including differences in protein expression within the inner ear. Understanding these changes may facilitate the identification of more targeted therapies for MD. METHODS Human temporal bones from patients with MD (n = 8) and age-matched control patients (n = 8) were processed with immunohistochemistry stains to detect known protein expression related to ionic homeostasis and barrier function in the cochlea, including CLDN11, CLU, KCNJ10, and SLC12A2. Immunofluorescence intensity analysis was performed to quantify protein expression in the stria vascularis, organ of Corti, and spiral ganglion neuron (SGN). RESULTS Expression of KCNJ10 was significantly reduced in all cochlear regions, including the stria vascularis (9.23 vs 17.52, p = 0.011), OC (14.93 vs 29.16, p = 0.014), and SGN (7.69 vs 18.85, p = 0.0048) in human temporal bone specimens from patients with MD compared with control, respectively. CLDN11 (7.40 vs 10.88, p = 0.049) and CLU (7.80 vs 17.51, p = 0.0051) expression was significantly reduced in the SGN. CONCLUSION The results of this study support that there may be differences in the expression of proteins related to ionic homeostasis and barrier function within the cochlea, potentially supporting the role of targeted therapies to treat MD.
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Affiliation(s)
- J. Dixon Johns
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
- Department of Otolaryngology, Georgetown University School of Medicine, Washington DC, USA
| | - Rafal Olszewski
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Dillon Strepay
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Ivan A. Lopez
- Department of Head & Neck Surgery, University of California School of Medicine, Los Angeles, CA, USA
| | - Akira Ishiyama
- Department of Head & Neck Surgery, University of California School of Medicine, Los Angeles, CA, USA
| | - Michael Hoa
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
- Department of Otolaryngology, Georgetown University School of Medicine, Washington DC, USA
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2
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Zhao L, Huang W, Yi S. Cellular complexity of the peripheral nervous system: Insights from single-cell resolution. Front Neurosci 2023; 17:1098612. [PMID: 36998728 PMCID: PMC10043217 DOI: 10.3389/fnins.2023.1098612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 02/21/2023] [Indexed: 03/15/2023] Open
Abstract
Single-cell RNA sequencing allows the division of cell populations, offers precise transcriptional profiling of individual cells, and fundamentally advances the comprehension of cellular diversity. In the peripheral nervous system (PNS), the application of single-cell RNA sequencing identifies multiple types of cells, including neurons, glial cells, ependymal cells, immune cells, and vascular cells. Sub-types of neurons and glial cells have further been recognized in nerve tissues, especially tissues in different physiological and pathological states. In the current article, we compile the heterogeneities of cells that have been reported in the PNS and describe cellular variability during development and regeneration. The discovery of the architecture of peripheral nerves benefits the understanding of the cellular complexity of the PNS and provides a considerable cellular basis for future genetic manipulation.
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Affiliation(s)
- Lili Zhao
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
- NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, Jiangsu, China
| | - Weixiao Huang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
- NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, Jiangsu, China
- School of Medicine and Life Sciences, Nanjing University of Chinese Medicine, Nanjing, China
| | - Sheng Yi
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
- NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, Jiangsu, China
- *Correspondence: Sheng Yi,
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3
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Li YK, Zhang YY, Lin J, Liu YJ, Li YL, Feng YH, Zhao JS, Zhou C, Liu F, Shen JF. Metabotropic glutamate receptor 5-mediated inhibition of inward-rectifying K + channel 4.1 contributes to orofacial ectopic mechanical allodynia following inferior alveolar nerve transection in male mice. J Neurosci Res 2023; 101:1170-1187. [PMID: 36807930 DOI: 10.1002/jnr.25181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 01/20/2023] [Accepted: 01/31/2023] [Indexed: 02/20/2023]
Abstract
Inward-rectifying K+ channel 4.1 (Kir4.1), which regulates the electrophysiological properties of neurons and glia by affecting K+ homeostasis, plays a critical role in neuropathic pain. Metabotropic glutamate receptor 5 (mGluR5) regulates the expression of Kir4.1 in retinal Müller cells. However, the role of Kir4.1 and its expressional regulatory mechanisms underlying orofacial ectopic allodynia remain unclear. This study aimed to investigate the biological roles of Kir4.1 and mGluR5 in the trigeminal ganglion (TG) in orofacial ectopic mechanical allodynia and the role of mGluR5 in Kir4.1 regulation. An animal model of nerve injury was established via inferior alveolar nerve transection (IANX) in male C57BL/6J mice. Behavioral tests indicated that mechanical allodynia in the ipsilateral whisker pad lasted at least 14 days after IANX surgery and was alleviated by the overexpression of Kir4.1 in the TG, as well as intraganglionic injection of an mGluR5 antagonist (MPEP hydrochloride) or a protein kinase C (PKC) inhibitor (chelerythrine chloride); Conditional knockdown of the Kir4.1 gene downregulated mechanical thresholds in the whisker pad. Double immunostaining revealed that Kir4.1 and mGluR5 were co-expressed in satellite glial cells in the TG. IANX downregulated Kir4.1 and upregulated mGluR5 and phosphorylated PKC (p-PKC) in the TG; Inhibition of mGluR5 reversed the changes in Kir4.1 and p-PKC that were induced by IANX; Inhibition of PKC activation reversed the downregulation of Kir4.1 expression caused by IANX (p < .05). In conclusion, activation of mGluR5 in the TG after IANX contributed to orofacial ectopic mechanical allodynia by suppressing Kir4.1 via the PKC signaling pathway.
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Affiliation(s)
- Yi-Ke Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yan-Yan Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jiu Lin
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ya-Jing Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yue-Ling Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yu-Heng Feng
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jia-Shuo Zhao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Cheng Zhou
- Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, China
| | - Fei Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jie-Fei Shen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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4
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Jang MW, Lim J, Park MG, Lee JH, Lee CJ. Active role of glia-like supporting cells in the organ of Corti: Membrane proteins and their roles in hearing. Glia 2022; 70:1799-1825. [PMID: 35713516 DOI: 10.1002/glia.24229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 05/23/2022] [Accepted: 05/30/2022] [Indexed: 12/13/2022]
Abstract
The organ of Corti, located in the cochlea in the inner ear, is one of the major sensory organs involved in hearing. The organ of Corti consists of hair cells, glia-like supporting cells, and the cochlear nerve, which work in harmony to receive sound from the outer ear and transmit auditory signals to the cochlear nucleus in the auditory ascending pathway. In this process, maintenance of the endocochlear potential, with a high potassium gradient and clearance of electrolytes and biochemicals in the inner ear, is critical for normal sound transduction. There is an emerging need for a thorough understanding of each cell type involved in this process to understand the sophisticated mechanisms of the organ of Corti. Hair cells have long been thought to be active, playing a primary role in the cochlea in actively detecting and transmitting signals. In contrast, supporting cells are thought to be silent and function to support hair cells. However, growing lines of evidence regarding the membrane proteins that mediate ionic movement in supporting cells have demonstrated that supporting cells are not silent, but actively play important roles in normal signal transduction. In this review, we summarize studies that characterize diverse membrane proteins according to the supporting cell subtypes involved in cochlear physiology and hearing. This review contributes to a better understanding of supporting cell functions and facilitates the development of potential therapeutic tools for hearing loss.
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Affiliation(s)
- Minwoo Wendy Jang
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jiwoon Lim
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Mingu Gordon Park
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jae-Hun Lee
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - C Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
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5
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Bryant D, Pauzuolyte V, Ingham NJ, Patel A, Pagarkar W, Anderson LA, Smith KE, Moulding DA, Leong YC, Jafree DJ, Long DA, Al-Yassin A, Steel KP, Jagger DJ, Forge A, Berger W, Sowden JC, Bitner-Glindzicz M. The timing of auditory sensory deficits in Norrie disease has implications for therapeutic intervention. JCI Insight 2022; 7:148586. [PMID: 35132964 PMCID: PMC8855802 DOI: 10.1172/jci.insight.148586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 12/10/2021] [Indexed: 11/29/2022] Open
Abstract
Norrie disease is caused by mutation of the NDP gene, presenting as congenital blindness followed by later onset of hearing loss. Protecting patients from hearing loss is critical for maintaining their quality of life. This study aimed to understand the onset of pathology in cochlear structure and function. By investigating patients and juvenile Ndp-mutant mice, we elucidated the sequence of onset of physiological changes (in auditory brainstem responses, distortion product otoacoustic emissions, endocochlear potential, blood-labyrinth barrier integrity) and determined the cellular, histological, and ultrastructural events leading to hearing loss. We found that cochlear vascular pathology occurs earlier than previously reported and precedes sensorineural hearing loss. The work defines a disease mechanism whereby early malformation of the cochlear microvasculature precedes loss of vessel integrity and decline of endocochlear potential, leading to hearing loss and hair cell death while sparing spiral ganglion cells. This provides essential information on events defining the optimal therapeutic window and indicates that early intervention is needed. In an era of advancing gene therapy and small-molecule technologies, this study establishes Ndp-mutant mice as a platform to test such interventions and has important implications for understanding the progression of hearing loss in Norrie disease.
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Affiliation(s)
- Dale Bryant
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - Valda Pauzuolyte
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - Neil J Ingham
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Aara Patel
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - Waheeda Pagarkar
- Great Ormond Street Hospital, Great Ormond Street, London, United Kingdom
| | - Lucy A Anderson
- UCL Ear Institute, University College London, London, United Kingdom
| | - Katie E Smith
- UCL Ear Institute, University College London, London, United Kingdom
| | - Dale A Moulding
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - Yeh C Leong
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - Daniyal J Jafree
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom.,UCL MB/PhD Programme, Faculty of Medical Sciences, University College London, London, United Kingdom
| | - David A Long
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - Amina Al-Yassin
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - Karen P Steel
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Daniel J Jagger
- UCL Ear Institute, University College London, London, United Kingdom
| | - Andrew Forge
- UCL Ear Institute, University College London, London, United Kingdom
| | - Wolfgang Berger
- Institute of Medical Molecular Genetics, University of Zürich, Schlieren, Switzerland.,Neuroscience Center Zurich, University and ETH Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Jane C Sowden
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - Maria Bitner-Glindzicz
- UCL Great Ormond Street Institute of Child Health, University College London, and NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
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6
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Tasdemir-Yilmaz OE, Druckenbrod NR, Olukoya OO, Dong W, Yung AR, Bastille I, Pazyra-Murphy MF, Sitko AA, Hale EB, Vigneau S, Gimelbrant AA, Kharchenko PV, Goodrich LV, Segal RA. Diversity of developing peripheral glia revealed by single-cell RNA sequencing. Dev Cell 2021; 56:2516-2535.e8. [PMID: 34469751 DOI: 10.1016/j.devcel.2021.08.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 05/31/2021] [Accepted: 08/06/2021] [Indexed: 12/22/2022]
Abstract
The peripheral nervous system responds to a wide variety of sensory stimuli, a process that requires great neuronal diversity. These diverse neurons are closely associated with glial cells originating from the neural crest. However, the molecular nature and diversity among peripheral glia are not understood. Here, we used single-cell RNA sequencing to profile developing and mature glia from somatosensory dorsal root ganglia and auditory spiral ganglia. We found that glial precursors (GPs) in these two systems differ in their transcriptional profiles. Despite their unique features, somatosensory and auditory GPs undergo convergent differentiation to generate molecularly uniform myelinating and non-myelinating Schwann cells. By contrast, somatosensory and auditory satellite glial cells retain system-specific features. Lastly, we identified a glial signature gene set, providing new insights into commonalities among glia across the nervous system. This survey of gene expression in peripheral glia constitutes a resource for understanding functions of glia across different sensory modalities.
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Affiliation(s)
- Ozge E Tasdemir-Yilmaz
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Noah R Druckenbrod
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Weixiu Dong
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Andrea R Yung
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Isle Bastille
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Maria F Pazyra-Murphy
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Austen A Sitko
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Evan B Hale
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Sébastien Vigneau
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | | | - Peter V Kharchenko
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Lisa V Goodrich
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Rosalind A Segal
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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7
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Bazard P, Frisina RD, Acosta AA, Dasgupta S, Bauer MA, Zhu X, Ding B. Roles of Key Ion Channels and Transport Proteins in Age-Related Hearing Loss. Int J Mol Sci 2021; 22:6158. [PMID: 34200434 PMCID: PMC8201059 DOI: 10.3390/ijms22116158] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/30/2021] [Accepted: 05/31/2021] [Indexed: 12/25/2022] Open
Abstract
The auditory system is a fascinating sensory organ that overall, converts sound signals to electrical signals of the nervous system. Initially, sound energy is converted to mechanical energy via amplification processes in the middle ear, followed by transduction of mechanical movements of the oval window into electrochemical signals in the cochlear hair cells, and finally, neural signals travel to the central auditory system, via the auditory division of the 8th cranial nerve. The majority of people above 60 years have some form of age-related hearing loss, also known as presbycusis. However, the biological mechanisms of presbycusis are complex and not yet fully delineated. In the present article, we highlight ion channels and transport proteins, which are integral for the proper functioning of the auditory system, facilitating the diffusion of various ions across auditory structures for signal transduction and processing. Like most other physiological systems, hearing abilities decline with age, hence, it is imperative to fully understand inner ear aging changes, so ion channel functions should be further investigated in the aging cochlea. In this review article, we discuss key various ion channels in the auditory system and how their functions change with age. Understanding the roles of ion channels in auditory processing could enhance the development of potential biotherapies for age-related hearing loss.
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Affiliation(s)
- Parveen Bazard
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Robert D. Frisina
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
- Department Communication Sciences and Disorders, College of Behavioral & Communication Sciences, Tampa, FL 33620, USA
| | - Alejandro A. Acosta
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Sneha Dasgupta
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Mark A. Bauer
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Xiaoxia Zhu
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Bo Ding
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
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8
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Smith KE, Murphy P, Jagger DJ. Divergent membrane properties of mouse cochlear glial cells around hearing onset. J Neurosci Res 2020; 99:679-698. [PMID: 33099767 DOI: 10.1002/jnr.24744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/21/2020] [Accepted: 10/05/2020] [Indexed: 11/11/2022]
Abstract
Spiral ganglion neurons (SGNs) are the primary afferent neurons of the auditory system, and together with their attendant glia, form the auditory nerve. Within the cochlea, satellite glial cells (SGCs) encapsulate the cell body of SGNs, whereas Schwann cells (SCs) wrap their peripherally- and centrally-directed neurites. Despite their likely importance in auditory nerve function and homeostasis, the physiological properties of auditory glial cells have evaded description. Here, we characterized the voltage-activated membrane currents of glial cells from the mouse cochlea. We identified a prominent weak inwardly rectifying current in SGCs within cochlear slice preparations (postnatal day P5-P6), which was also present in presumptive SGCs within dissociated cultures prepared from the cochleae of hearing mice (P14-P15). Pharmacological block by Ba2+ and desipramine suggested that channels belonging to the Kir4 family mediated the weak inwardly rectifying current, and post hoc immunofluorescence implicated the involvement of Kir4.1 subunits. Additional electrophysiological profiles were identified for glial cells within dissociated cultures, suggesting that glial subtypes may have specific membrane properties to support distinct physiological roles. Immunofluorescence using fixed cochlear sections revealed that although Kir4.1 is restricted to SGCs after the onset of hearing, these channels are more widely distributed within the glial population earlier in postnatal development (i.e., within both SGCs and SCs). The decrease in Kir4.1 immunofluorescence during SC maturation was coincident with a reduction of Sox2 expression and advancing neurite myelination. The data suggest a diversification of glial properties occurs in preparation for sound-driven activity in the auditory nerve.
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Affiliation(s)
- Katie E Smith
- UCL Ear Institute, University College London, London, UK
| | - Phoebe Murphy
- UCL Ear Institute, University College London, London, UK
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9
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Smith KE, Whitcroft K, Law S, Andrews P, Choi D, Jagger DJ. Olfactory ensheathing cells from the nasal mucosa and olfactory bulb have distinct membrane properties. J Neurosci Res 2019; 98:888-901. [PMID: 31797433 DOI: 10.1002/jnr.24566] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/14/2019] [Accepted: 11/14/2019] [Indexed: 12/15/2022]
Abstract
Transplantation of olfactory ensheathing cells (OECs) is a potential therapy for the regeneration of damaged neurons. While they maintain tissue homeostasis in the olfactory mucosa (OM) and olfactory bulb (OB), their regenerative properties also support the normal sense of smell by enabling continual turnover and axonal regrowth of olfactory sensory neurons (OSNs). However, the molecular physiology of OECs is not fully understood, especially that of OECs from the mucosa. Here, we carried out whole-cell patch-clamp recordings from individual OECs cultured from the OM and OB of the adult rat, and from the human OM. A subset of OECs from the rat OM cultured 1-3 days in vitro had large weakly rectifying K+ currents, which were sensitive to Ba2+ and desipramine, blockers of Kir4-family channels. Kir4.1 immunofluorescence was detectable in cultured OM cells colabeled for the OEC marker S100, and in S100-labeled cells found adjacent to OSN axons in mucosal sections. OECs cultured from rat OB had distinct properties though, displaying strongly rectifying inward currents at hyperpolarized membrane potentials and strongly rectifying outward currents at depolarized potentials. Kir4.1 immunofluorescence was not evident in OECs adjacent to axons of OSNs in the OB. A subset of human OECs cultured from the OM of adults had membrane properties comparable to those of the rat OM that is dominated by Ba2+ -sensitive weak inwardly rectifying currents. The membrane properties of peripheral OECs are different to those of central OECs, suggesting they may play distinct roles during olfaction.
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Affiliation(s)
- Katie E Smith
- UCL Ear Institute, University College London, London, UK
| | - Katherine Whitcroft
- UCL Ear Institute, University College London, London, UK.,Royal National Throat Nose & Ear Hospital, London, UK
| | - Stuart Law
- Institute of Neurology, University College London, London, UK
| | - Peter Andrews
- UCL Ear Institute, University College London, London, UK.,Royal National Throat Nose & Ear Hospital, London, UK
| | - David Choi
- Institute of Neurology, University College London, London, UK
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10
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Pannese E. Biology and Pathology of Perineuronal Satellite Cells in Sensory Ganglia. BIOLOGY AND PATHOLOGY OF PERINEURONAL SATELLITE CELLS IN SENSORY GANGLIA 2018. [DOI: 10.1007/978-3-319-60140-3_1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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11
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Kim YR, Kim KH, Lee S, Oh SK, Park JW, Lee KY, Baek JI, Kim UK. Expression patterns of members of the isocitrate dehydrogenase gene family in murine inner ear. Biotech Histochem 2017; 92:536-544. [PMID: 28925723 DOI: 10.1080/10520295.2017.1367034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Age-related hearing loss (ARHL) is characterized by an age-dependent decline of auditory function characterized by with loss of sensory hair cells, spiral ganglion neurons, and stria vascularis (SV) cells in the cochlea of the inner ear. Aging and age-related diseases result from accumulated oxidative damage caused by reactive oxygen species (ROS) generated by mitochondria. The isocitrate dehydrogenase (IDH) family includes three enzymes in human cells: IDH1, IDH2, and IDH3. Although all three enzymes catalyze the same enzymatic reaction, that is, oxidative decarboxylation of isocitrate to produce α-ketoglutarate, each IDH enzyme has unique features. We identified and characterized IDH expression in the cochlea and vestibule of the murine inner ear. We examined the mRNA expression levels of Idh family members in the cochlea and vestibule using reverse transcription-PCR (RT-PCR) and detected expression of IDH family members in both tissues. We also used immunohistochemistry to localize IDH family members within the cochlea and vestibule of the adult mouse inner ear. IDH1 was detected throughout the cochlea. IDH2 was expressed specifically in the hair cells, spiral ganglion, and stria vascularis. IDH3α was found in the cell bodies of neurons of the spiral ganglion, the stria vascularis, and in types II, IV, and V cells of the spiral ligament in a pattern that resembled the location of the Na+, K+-ATPase ion channel. We postulate that the IDH family participates in transporting K+ ions in the cochlea. In the vestibule, all IDH family members were detected in both hair cells and the vestibular ganglion. We hypothesize that IDH1, IDH2, and IDH3 function to protect proteins in the inner ear from oxidative stress during K+ recycling.
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Affiliation(s)
- Y-R Kim
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
| | - K-H Kim
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
| | - S Lee
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
| | - S-K Oh
- c Laboratory Animal Center, Daegu-Gyeonbuk Medical Innovation Foundation
| | - J-W Park
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
| | - K-Y Lee
- d Department of Otorhinolaryngology-Head and Neck Surgery , Kyungpook National University Hospital, Kyungpook National University School of Medicine
| | - J-I Baek
- e Department of Aroma Applied Industry , College of Herbal Bio-industry, Daegu Haany University , Daegu , Republic of Korea
| | - U-K Kim
- a Department of Biology, College of Natural Sciences , Kyungpook National University.,b School of Life Sciences, KNU Creative BioResearch Group (BK21 plus project) , Kyungpook National University
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12
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Xie AX, Lee JJ, McCarthy KD. Ganglionic GFAP + glial Gq-GPCR signaling enhances heart functions in vivo. JCI Insight 2017; 2:e90565. [PMID: 28138563 DOI: 10.1172/jci.insight.90565] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The sympathetic nervous system (SNS) accelerates heart rate, increases cardiac contractility, and constricts resistance vessels. The activity of SNS efferent nerves is generated by a complex neural network containing neurons and glia. Gq G protein-coupled receptor (Gq-GPCR) signaling in glial fibrillary acidic protein-expressing (GFAP+) glia in the central nervous system supports neuronal function and regulates neuronal activity. It is unclear how Gq-GPCR signaling in GFAP+ glia affects the activity of sympathetic neurons or contributes to SNS-regulated cardiovascular functions. In this study, we investigated whether Gq-GPCR activation in GFAP+ glia modulates the regulatory effect of the SNS on the heart; transgenic mice expressing Gq-coupled DREADD (designer receptors exclusively activated by designer drugs) (hM3Dq) selectively in GFAP+ glia were used to address this question in vivo. We found that acute Gq-GPCR activation in peripheral GFAP+ glia significantly accelerated heart rate and increased left ventricle contraction. Pharmacological experiments suggest that the glial-induced cardiac changes were due to Gq-GPCR activation in satellite glial cells within the sympathetic ganglion; this activation led to increased norepinephrine (NE) release and beta-1 adrenergic receptor activation within the heart. Chronic glial Gq-GPCR activation led to hypotension in female Gfap-hM3Dq mice. This study provides direct evidence that Gq-GPCR activation in peripheral GFAP+ glia regulates cardiovascular functions in vivo.
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13
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Schwieger J, Esser KH, Lenarz T, Scheper V. Establishment of a long-term spiral ganglion neuron culture with reduced glial cell number: Effects of AraC on cell composition and neurons. J Neurosci Methods 2016; 268:106-16. [DOI: 10.1016/j.jneumeth.2016.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 04/29/2016] [Accepted: 05/02/2016] [Indexed: 01/13/2023]
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14
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Eckhard A, Dos Santos A, Liu W, Bassiouni M, Arnold H, Gleiser C, Hirt B, Harteneck C, Müller M, Rask-Andersen H, Löwenheim H. Regulation of the perilymphatic-endolymphatic water shunt in the cochlea by membrane translocation of aquaporin-5. Pflugers Arch 2015; 467:2571-88. [PMID: 26208470 PMCID: PMC4646919 DOI: 10.1007/s00424-015-1720-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 07/01/2015] [Accepted: 07/04/2015] [Indexed: 12/02/2022]
Abstract
Volume homeostasis of the cochlear endolymph depends on radial and longitudinal endolymph movements (LEMs). LEMs measured in vivo have been exclusively recognized under physiologically challenging conditions, such as experimentally induced alterations of perilymph osmolarity or endolymph volume. The regulatory mechanisms that adjust LEMs to the physiological requirements of endolymph volume homeostasis remain unknown. Here, we describe the formation of an aquaporin (AQP)-based "water shunt" during the postnatal development of the mouse cochlea and its regulation by different triggers. The final complementary expression pattern of AQP5 (apical membrane) and AQP4 (basolateral membrane) in outer sulcus cells (OSCs) of the cochlear apex is acquired at the onset of hearing function (postnatal day (p)8-p12). In vitro, hyperosmolar perfusion of the perilymphatic fluid spaces or the administration of the muscarinic agonist pilocarpine in cochlear explants (p14) induced the translocation of AQP5 channel proteins into the apical membranes of OSCs. AQP5 membrane translocation was blocked by the muscarinic antagonist atropine. The muscarinic M3 acetylcholine (ACh) receptor (M3R) was identified in murine OSCs via mRNA expression, immunolabeling, and in vitro binding studies using an M3R-specific fluorescent ligand. Finally, the water shunt elements AQP4, AQP5, and M3R were also demonstrated in OSCs of the human cochlea. The regulation of the AQP4/AQP5 water shunt in OSCs of the cochlear apex provides a molecular basis for regulated endolymphatic volume homeostasis. Moreover, its dysregulation or disruption may have pathophysiologic implications for clinical conditions related to endolymphatic hydrops, such as Ménière's disease.
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Affiliation(s)
- A Eckhard
- Department of Otorhinolaryngology-Head & Neck Surgery, University of Tübingen Medical Centre, Tübingen, Germany
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA
| | - A Dos Santos
- Department of Otorhinolaryngology-Head & Neck Surgery, University of Tübingen Medical Centre, Tübingen, Germany
| | - W Liu
- Department of Surgical Sciences, Section of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden
| | - M Bassiouni
- Department of Otorhinolaryngology-Head & Neck Surgery, University of Tübingen Medical Centre, Tübingen, Germany
| | - H Arnold
- Department of Otorhinolaryngology-Head & Neck Surgery, University of Tübingen Medical Centre, Tübingen, Germany
| | - C Gleiser
- Institute of Anatomy, University of Tübingen, Tübingen, Germany
| | - B Hirt
- Institute of Anatomy, University of Tübingen, Tübingen, Germany
| | - C Harteneck
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Interfaculty Center of Pharmacogenomics and Pharmaceutical Research (ICePhA), University of Tübingen, Tübingen, Germany
| | - M Müller
- School of Medicine and Health Sciences - European Medical School, University Hospital of Otorhinolaryngology, Medical Campus University of Oldenburg, Steinweg 13-17, 26122, Oldenburg, Germany
- Research Center of Neurosensory Science, University of Oldenburg, 26111, Oldenburg, Germany
- Cluster of Excellence Hearing4all, University of Oldenburg, 26111, Oldenburg, Germany
| | - H Rask-Andersen
- Department of Surgical Sciences, Section of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden
| | - H Löwenheim
- School of Medicine and Health Sciences - European Medical School, University Hospital of Otorhinolaryngology, Medical Campus University of Oldenburg, Steinweg 13-17, 26122, Oldenburg, Germany.
- Research Center of Neurosensory Science, University of Oldenburg, 26111, Oldenburg, Germany.
- Cluster of Excellence Hearing4all, University of Oldenburg, 26111, Oldenburg, Germany.
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15
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Sepúlveda FV, Pablo Cid L, Teulon J, Niemeyer MI. Molecular aspects of structure, gating, and physiology of pH-sensitive background K2P and Kir K+-transport channels. Physiol Rev 2015; 95:179-217. [PMID: 25540142 DOI: 10.1152/physrev.00016.2014] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
K(+) channels fulfill roles spanning from the control of excitability to the regulation of transepithelial transport. Here we review two groups of K(+) channels, pH-regulated K2P channels and the transport group of Kir channels. After considering advances in the molecular aspects of their gating based on structural and functional studies, we examine their participation in certain chosen physiological and pathophysiological scenarios. Crystal structures of K2P and Kir channels reveal rather unique features with important consequences for the gating mechanisms. Important tasks of these channels are discussed in kidney physiology and disease, K(+) homeostasis in the brain by Kir channel-equipped glia, and central functions in the hearing mechanism in the inner ear and in acid secretion by parietal cells in the stomach. K2P channels fulfill a crucial part in central chemoreception probably by virtue of their pH sensitivity and are central to adrenal secretion of aldosterone. Finally, some unorthodox behaviors of the selectivity filters of K2P channels might explain their normal and pathological functions. Although a great deal has been learned about structure, molecular details of gating, and physiological functions of K2P and Kir K(+)-transport channels, this has been only scratching at the surface. More molecular and animal studies are clearly needed to deepen our knowledge.
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Affiliation(s)
- Francisco V Sepúlveda
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
| | - L Pablo Cid
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
| | - Jacques Teulon
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
| | - María Isabel Niemeyer
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
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16
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Davis RL, Crozier RA. Dynamic firing properties of type I spiral ganglion neurons. Cell Tissue Res 2015; 361:115-27. [PMID: 25567109 DOI: 10.1007/s00441-014-2071-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 11/17/2014] [Indexed: 10/24/2022]
Abstract
Spiral ganglion neurons, the first neural element in the auditory system, possess complex intrinsic properties, possibly required to process frequency-specific sensory input that is integrated with extensive efferent regulation. Together with their tonotopically-graded sizes, the somata of these neurons reveal a sophisticated electrophysiological profile. Type I neurons, which make up ~95 % of the ganglion, have myriad voltage-gated ion channels that not only vary along the frequency contour of the cochlea, but also can be modulated by regulators such as voltage, calcium, and second messengers. The resultant developmentally- and tonotopically-regulated neuronal firing patterns conform to three distinct response modes (unitary, rapid, and slow) based on threshold and accommodation. This phenotype, however, is not static for any individual type I neuron. Recent observations have shown that, as neurons become less excitable with age, they demonstrate enhanced plasticity enabling them to change from one response mode to another depending upon resting membrane potential and the presence of neurotrophin-3. Thus, the primary auditory afferents utilized to encode dynamic acoustic stimuli possess the intrinsic specializations that allow them dynamically to alter their firing pattern.
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Affiliation(s)
- Robin L Davis
- Department of Cell Biology and Neuroscience, Nelson Laboratories, Rutgers University, 604 Allison Road, Piscataway, NJ 08854, USA,
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17
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Expression and localization of aquaporin-4 in sensory ganglia. Biochem Biophys Res Commun 2014; 451:562-7. [DOI: 10.1016/j.bbrc.2014.08.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 08/05/2014] [Indexed: 12/20/2022]
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18
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Chen J, Zhao HB. The role of an inwardly rectifying K(+) channel (Kir4.1) in the inner ear and hearing loss. Neuroscience 2014; 265:137-46. [PMID: 24480364 DOI: 10.1016/j.neuroscience.2014.01.036] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/16/2014] [Accepted: 01/18/2014] [Indexed: 11/18/2022]
Abstract
The KCNJ10 gene which encodes an inwardly rectifying K(+) channel Kir4.1 subunit plays an essential role in the inner ear and hearing. Mutations or deficiency of KCNJ10 can cause hearing loss with EAST or SeSAME syndromes. This review mainly focuses on the expression and function of Kir4.1 potassium channels in the inner ear and hearing. We first introduce general information about inwardly rectifying potassium (Kir) channels. Then, we review the expression and function of Kir4.1 channels in the inner ear, especially in endocochlear potential (EP) generation. Finally, we review KCNJ10 mutation-induced hearing loss and functional impairments. Kir4.1 is strongly expressed on the apical membrane of intermediate cells in the stria vascularis and in the satellite cells of cochlear ganglia. Functionally, Kir4.1 has critical roles in cochlear development and hearing through two distinct aspects of extracellular K(+) homeostasis: First, it participates in the generation and maintenance of EP and high K(+) concentration in the endolymph inside the scala media. Second, Kir4.1 is the major K(+) channel in satellite glial cells surrounding spiral ganglion neurons to sink K(+) ions expelled by the ganglion neurons during excitation. Kir4.1 deficiency leads to hearing loss with the absence of EP and spiral ganglion neuron degeneration. Deafness mutants show loss-of-function and reduced channel membrane-targeting and currents, which can be rescued upon by co-expression with wild-type Kir4.1. This review provides insights for further understanding Kir potassium channel function in the inner ear and the pathogenesis of deafness due to KCNJ10 deficiency, and also provides insights for developing therapeutic strategies targeting this deafness.
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Affiliation(s)
- J Chen
- Department of Morphology, Medical College of China Three Gorges University, Yichang, Hubei 443002, PR China; Department of Otolaryngology, University of Kentucky Medical Center, Lexington, KY 40536-0293, USA
| | - H-B Zhao
- Department of Otolaryngology, University of Kentucky Medical Center, Lexington, KY 40536-0293, USA.
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19
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Mahmood F, Mozere M, Zdebik AA, Stanescu HC, Tobin J, Beales PL, Kleta R, Bockenhauer D, Russell C. Generation and validation of a zebrafish model of EAST (epilepsy, ataxia, sensorineural deafness and tubulopathy) syndrome. Dis Model Mech 2013; 6:652-60. [PMID: 23471908 PMCID: PMC3634649 DOI: 10.1242/dmm.009480] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recessive mutations in KCNJ10, which encodes an inwardly rectifying potassium channel, were recently identified as the cause of EAST syndrome, a severe and disabling multi-organ disorder consisting of epilepsy, ataxia, sensorineural deafness and tubulopathy that becomes clinically apparent with seizures in infancy. A Kcnj10 knockout mouse shows postnatal mortality and is therefore not suitable for drug discovery. Because zebrafish are ideal for in vivo screening for potential therapeutics, we tested whether kcnj10 knockdown in zebrafish would fill this need. We cloned zebrafish kcnj10 and demonstrated that its function is equivalent to that of human KCNJ10. We next injected splice- and translation-blocking kcnj10 antisense morpholino oligonucleotides and reproduced the cardinal symptoms of EAST syndrome – ataxia, epilepsy and renal tubular defects. Several of these phenotypes could be assayed in an automated manner. We could rescue the morphant phenotype with complementary RNA (cRNA) encoding human wild-type KCNJ10, but not with cRNA encoding a KCNJ10 mutation identified in individuals with EAST syndrome. Our results suggest that zebrafish will be a valuable tool to screen for compounds that are potentially therapeutic for EAST syndrome or its individual symptoms. Knockdown of kcnj10 represents the first zebrafish model of a salt-losing tubulopathy, which has relevance for blood pressure control.
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Affiliation(s)
- Fahad Mahmood
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
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20
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Inwardly rectifying potassium channel Kir4.1 is localized at the calyx endings of vestibular afferents. Neuroscience 2012; 215:209-16. [PMID: 22546335 DOI: 10.1016/j.neuroscience.2012.04.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 04/03/2012] [Accepted: 04/06/2012] [Indexed: 12/13/2022]
Abstract
Inwardly rectifying potassium (Kir) channel Kir4.1 (also called Kcnj10) is expressed in various cells such as satellite glial cells. It is suggested that these cells would absorb excess accumulated K(+) from intercellular space which is surrounded by these cell membranes expressing Kir4.1. In the vestibular system, loss of Kir4.1 results in selective degeneration of type I hair cells despite normal development of type II hair cells. The mechanisms underlying this developmental disorder have been unclear, because it was thought that Kir4.1 is only expressed in glial cells throughout the entire nervous system. Here, we show that Kir4.1 is expressed not only in glial cells but also in neurons of the mouse vestibular system. In the vestibular ganglion, Kir4.1 mRNA is transcribed in both satellite cells and neuronal somata, whereas Kir4.1 protein is expressed only in satellite cells. On the other hand, in the vestibular sensory epithelia, Kir4.1 protein is localized at the calyx endings of vestibular afferents, which surround type I hair cells. Kir4.1 protein expression in the vestibular sensory epithelia is detected beginning after birth, and its localization gradually adopts a calyceal shape until type I hair cells are mature. Kir4.1 localized at the calyx endings may play a role in the K(+)-buffering action of vestibular afferents surrounding type I hair cells.
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21
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Covasala O, Stirn SL, Albrecht S, De Col R, Messlinger K. Calcitonin gene-related peptide receptors in rat trigeminal ganglion do not control spinal trigeminal activity. J Neurophysiol 2012; 108:431-40. [PMID: 22539824 DOI: 10.1152/jn.00167.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Calcitonin gene-related peptide (CGRP) is regarded as a key mediator in the generation of primary headaches. CGRP receptor antagonists reduce migraine pain in clinical trials and spinal trigeminal activity in animal experiments. The site of CGRP receptor inhibition causing these effects is debated. Activation and inhibition of CGRP receptors in the trigeminal ganglion may influence the activity of trigeminal afferents and hence of spinal trigeminal neurons. In anesthetized rats extracellular activity was recorded from neurons with meningeal afferent input in the spinal trigeminal nucleus caudalis. Mechanical stimuli were applied at regular intervals to receptive fields located in the exposed cranial dura mater. α-CGRP (10(-5) M), the CGRP receptor antagonist olcegepant (10(-3) M), or vehicle was injected through the infraorbital canal into the trigeminal ganglion. The injection of volumes caused transient discharges, but vehicle, CGRP, or olcegepant injection was not followed by significant changes in ongoing or mechanically evoked activity. In animals pretreated intravenously with the nitric oxide donor glyceryl trinitrate (GTN, 250 μg/kg) the mechanically evoked activity decreased after injection of CGRP and increased after injection of olcegepant. In conclusion, the activity of spinal trigeminal neurons with meningeal afferent input is normally not controlled by CGRP receptor activation or inhibition in the trigeminal ganglion. CGRP receptors in the trigeminal ganglion may influence neuronal activity evoked by mechanical stimulation of meningeal afferents only after pretreatment with GTN. Since it has previously been shown that olcegepant applied to the cranial dura mater is ineffective, trigeminal activity driven by meningeal afferent input is more likely to be controlled by CGRP receptors located centrally to the trigeminal ganglion.
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Affiliation(s)
- Oana Covasala
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
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22
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cGMP-Prkg1 signaling and Pde5 inhibition shelter cochlear hair cells and hearing function. Nat Med 2012; 18:252-9. [PMID: 22270721 DOI: 10.1038/nm.2634] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 12/07/2011] [Indexed: 02/07/2023]
Abstract
Noise-induced hearing loss (NIHL) is a global health hazard with considerable pathophysiological and social consequences that has no effective treatment. In the heart, lung and other organs, cyclic guanosine monophosphate (cGMP) facilitates protective processes in response to traumatic events. We therefore analyzed NIHL in mice with a genetic deletion of the gene encoding cGMP-dependent protein kinase type I (Prkg1) and found a greater vulnerability to and markedly less recovery from NIHL in these mice as compared to mice without the deletion. Prkg1 was expressed in the sensory cells and neurons of the inner ear of wild-type mice, and its expression partly overlapped with the expression profile of cGMP-hydrolyzing phosphodiesterase 5 (Pde5). Treatment of rats and wild-type mice with the Pde5 inhibitor vardenafil almost completely prevented NIHL and caused a Prkg1-dependent upregulation of poly (ADP-ribose) in hair cells and the spiral ganglion, suggesting an endogenous protective cGMP-Prkg1 signaling pathway that culminates in the activation of poly (ADP-ribose) polymerase. These data suggest vardenafil or related drugs as possible candidates for the treatment of NIHL.
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23
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The structure of the perineuronal sheath of satellite glial cells (SGCs) in sensory ganglia. ACTA ACUST UNITED AC 2010; 6:3-10. [DOI: 10.1017/s1740925x10000037] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In sensory ganglia each nerve cell body is usually enveloped by a satellite glial cell (SGC) sheath, sharply separated from sheaths encircling adjacent neurons by connective tissue. However, following axon injury SGCs may form bridges connecting previously separate perineuronal sheaths. Each sheath consists of one or several layers of cells that overlap in a more or less complex fashion; sometimes SGCs form a perineuronal myelin sheath. SGCs are flattened mononucleate cells containing the usual cell organelles. Several ion channels, receptors and adhesion molecules have been identified in these cells. SGCs of the same sheath are usually linked by adherent and gap junctions, and are functionally coupled. Following axon injury, both the number of gap junctions and the coupling of SGCs increase markedly. The apposed plasma membranes of adjacent cells are separated by 15–20 nm gaps, which form a potential pathway, usually long and tortuous, between connective tissue and neuronal surface. The boundary between neuron and SGC sheath is usually complicated, mainly by many projections arising from the neuron. The outer surface of the SGC sheath is covered by a basal lamina. The number of SGCs enveloping a nerve cell body is proportional to the cell body volume; the volume of the SGC sheath is proportional to the volume and surface area of the nerve cell body. In old animals, both the number of SGCs and the mean volume of the SGC sheaths are significantly lower than in young adults. Furthermore, extensive portions of the neuronal surface are not covered by SGCs, exposing neurons of aged animals to damage by harmful substances.
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Jagger DJ, Nevill G, Forge A. The Membrane Properties of Cochlear Root Cells are Consistent with Roles in Potassium Recirculation and Spatial Buffering. J Assoc Res Otolaryngol 2010; 11:435-48. [PMID: 20393778 DOI: 10.1007/s10162-010-0218-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 03/24/2010] [Indexed: 11/27/2022] Open
Abstract
Auditory transduction, amplification, and hair cell survival depend on the regulation of extracellular [K(+)] in the cochlea. K(+) is removed from the vicinity of sensory hair cells by epithelial cells, and may be distributed through the epithelial cell syncytium, reminiscent of "spatial buffering" in glia. Hypothetically, K(+) is then transferred from the epithelial syncytium into the connective tissue syncytium within the cochlear lateral wall, enabling recirculation of K(+) back into endolymph. This may involve secretion of K(+) from epithelial root cells, and its re-uptake via transporters into spiral ligament fibrocytes. The molecular basis of this secretion is not known. Using a combination of approaches we demonstrated that the resting conductance in guinea pig root cells was dominated by K(+) channels, most likely composed of the Kir4.1 subunit. Dye injections revealed extensive intercellular gap junctional coupling, and delineated the root cell processes that penetrated the spiral ligament. Following uncoupling using 1-octanol, individual cells had Ba(2+)-sensitive weakly rectifying currents. In the basal (high-frequency encoding) cochlear region K(+) loads are predicted to be the highest, and root cells in this region had the largest surface area and the highest current density, consistent with their role in K(+) secretion. Kir4.1 was localized within root cells by immunofluorescence, and specifically to root cell process membranes by immunogold labeling. These results support a role for root cells in cochlear K(+) regulation, and suggest that channels composed of Kir4.1 subunits may mediate K(+) secretion from the epithelial gap junction network.
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Affiliation(s)
- Daniel J Jagger
- Centre for Auditory Research, UCL Ear Institute, University College London, 332 Gray's Inn Road, London, WC1X 8EE UK
| | - Graham Nevill
- Centre for Auditory Research, UCL Ear Institute, University College London, 332 Gray's Inn Road, London, WC1X 8EE UK
| | - Andrew Forge
- Centre for Auditory Research, UCL Ear Institute, University College London, 332 Gray's Inn Road, London, WC1X 8EE UK
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Hibino H, Inanobe A, Furutani K, Murakami S, Findlay I, Kurachi Y. Inwardly rectifying potassium channels: their structure, function, and physiological roles. Physiol Rev 2010; 90:291-366. [PMID: 20086079 DOI: 10.1152/physrev.00021.2009] [Citation(s) in RCA: 1081] [Impact Index Per Article: 77.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Inwardly rectifying K(+) (Kir) channels allow K(+) to move more easily into rather than out of the cell. They have diverse physiological functions depending on their type and their location. There are seven Kir channel subfamilies that can be classified into four functional groups: classical Kir channels (Kir2.x) are constitutively active, G protein-gated Kir channels (Kir3.x) are regulated by G protein-coupled receptors, ATP-sensitive K(+) channels (Kir6.x) are tightly linked to cellular metabolism, and K(+) transport channels (Kir1.x, Kir4.x, Kir5.x, and Kir7.x). Inward rectification results from pore block by intracellular substances such as Mg(2+) and polyamines. Kir channel activity can be modulated by ions, phospholipids, and binding proteins. The basic building block of a Kir channel is made up of two transmembrane helices with cytoplasmic NH(2) and COOH termini and an extracellular loop which folds back to form the pore-lining ion selectivity filter. In vivo, functional Kir channels are composed of four such subunits which are either homo- or heterotetramers. Gene targeting and genetic analysis have linked Kir channel dysfunction to diverse pathologies. The crystal structure of different Kir channels is opening the way to understanding the structure-function relationships of this simple but diverse ion channel family.
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Affiliation(s)
- Hiroshi Hibino
- Department of Pharmacology, Graduate School of Medicine and The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka 565-0871, Japan
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Tang X, Schmidt TM, Perez-Leighton CE, Kofuji P. Inwardly rectifying potassium channel Kir4.1 is responsible for the native inward potassium conductance of satellite glial cells in sensory ganglia. Neuroscience 2010; 166:397-407. [PMID: 20074622 DOI: 10.1016/j.neuroscience.2010.01.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 01/05/2010] [Indexed: 12/31/2022]
Abstract
Satellite glial cells (SGCs) surround primary afferent neurons in sensory ganglia, and increasing evidence has implicated the K(+) channels of SGCs in affecting or regulating sensory ganglion excitability. The inwardly rectifying K(+) (Kir) channel Kir4.1 is highly expressed in several types of glial cells in the central nervous system (CNS) where it has been implicated in extracellular K(+) concentration buffering. Upon neuronal activity, the extracellular K(+) concentration increases, and if not corrected, causes neuronal depolarization and uncontrolled changes in neuronal excitability. Recently, it has been demonstrated that knockdown of Kir4.1 expression in trigeminal ganglia leads to neuronal hyperexcitability in this ganglia and heightened nociception. Thus, we investigated the contribution of Kir4.1 to the membrane K(+) conductance of SGCs in neonatal and adult mouse trigeminal and dorsal root ganglia. Whole cell patch clamp recordings were performed in conjunction with immunocytochemistry and quantitative transcript analysis in various mouse lines. We found that in wild-type mice, the inward K(+) conductance of SGCs is blocked almost completely with extracellular barium, cesium and desipramine, consistent with a conductance mediated by Kir channels. We then utilized mouse lines in which genetic ablation led to partial or complete loss of Kir4.1 expression to assess the role of this channel subunit in SGCs. The inward K(+) currents of SGCs in Kir4.1+/- mice were decreased by about half while these currents were almost completely absent in Kir4.1-/- mice. These findings in combination with previous reports support the notion that Kir4.1 is the principal Kir channel type in SGCs. Therefore Kir4.1 emerges as a key regulator of SGC function and possibly neuronal excitability in sensory ganglia.
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Affiliation(s)
- X Tang
- Department of Neuroscience, University of Minnesota, 6-145 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455, USA
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Seizures, sensorineural deafness, ataxia, mental retardation, and electrolyte imbalance (SeSAME syndrome) caused by mutations in KCNJ10. Proc Natl Acad Sci U S A 2009; 106:5842-7. [PMID: 19289823 DOI: 10.1073/pnas.0901749106] [Citation(s) in RCA: 337] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We describe members of 4 kindreds with a previously unrecognized syndrome characterized by seizures, sensorineural deafness, ataxia, mental retardation, and electrolyte imbalance (hypokalemia, metabolic alkalosis, and hypomagnesemia). By analysis of linkage we localize the putative causative gene to a 2.5-Mb segment of chromosome 1q23.2-23.3. Direct DNA sequencing of KCNJ10, which encodes an inwardly rectifying K(+) channel, identifies previously unidentified missense or nonsense mutations on both alleles in all affected subjects. These mutations alter highly conserved amino acids and are absent among control chromosomes. Many of these mutations have been shown to cause loss of function in related K(+) channels. These findings demonstrate that loss-of-function mutations in KCNJ10 cause this syndrome, which we name SeSAME. KCNJ10 is expressed in glia in the brain and spinal cord, where it is believed to take up K(+) released by neuronal repolarization, in cochlea, where it is involved in the generation of endolymph, and on the basolateral membrane in the distal nephron. We propose that KCNJ10 is required in the kidney for normal salt reabsorption in the distal convoluted tubule because of the need for K(+) recycling across the basolateral membrane to enable normal activity of the Na(+)-K(+)-ATPase; loss of this function accounts for the observed electrolyte defects. Mice deficient for KCNJ10 show a related phenotype with seizures, ataxia, and hearing loss, further supporting KCNJ10's role in this syndrome. These findings define a unique human syndrome, and establish the essential role of basolateral K(+) channels in renal electrolyte homeostasis.
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Zou J, Zhang Y, Yin S, Wu H, Pyykkö I. Mitochondrial dysfunction disrupts trafficking of Kir4.1 in spiral ganglion satellite cells. J Neurosci Res 2009; 87:141-9. [DOI: 10.1002/jnr.21842] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Jin Z, Liang GH, Cooper EC, Jarlebark L. Expression and localization of K channels KCNQ2 and KCNQ3 in the mammalian cochlea. Audiol Neurootol 2008; 14:98-105. [PMID: 18827480 DOI: 10.1159/000158538] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Accepted: 07/23/2008] [Indexed: 11/19/2022] Open
Abstract
KCNQ1 and KCNQ4 voltage-gated potassium channel subunits play key roles in hearing. Other members of the KCNQ family also encode slow, low voltage-activated K(+) M currents. We have previously reported the presence of M-like K(+) currents in sensory hair cells, and expression of Kcnq family genes in the cochlea. Here, we describe Kcnq2/3 gene expression and distribution of M channel subunits KCNQ2 and 3 in the cochlea. By using RT-PCR, we found expression of Kcnq2 in the modiolus and organ of Corti, while Kcnq3 expression was also detected in the cochlear lateral wall. Five alternative splice variants of the Kcnq2 gene, one of which has not been reported previously, were identified in the rat cochlea. KCNQ2 and KCNQ3 immunoreactivities were observed in spiral ganglion auditory neurons. In addition, the unmyelinated parts of the nerve fibers innervating hair cells and synaptic regions under hair cells showed KCNQ2 immunoreactivity. KCNQ3 immunoreactivity was also prominent in spiral ganglion satellite cells. These findings suggest that cochlear M channels play important roles in regulation of cellular excitability and maintenance of cochlear K(+) homeostasis in the auditory system.
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Affiliation(s)
- Zhe Jin
- Center for Hearing and Communication Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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Rusznák Z, Szucs G. Spiral ganglion neurones: an overview of morphology, firing behaviour, ionic channels and function. Pflugers Arch 2008; 457:1303-25. [PMID: 18777041 DOI: 10.1007/s00424-008-0586-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 08/22/2008] [Accepted: 08/26/2008] [Indexed: 11/29/2022]
Abstract
The spiral ganglion cells provide the afferent innervation of the hair cells of the organ of Corti. Ninety-five percent of these cells (termed type I spiral ganglion neurones) are in synaptic contact with the inner hair cells, whereas about 5% of them are type II cells, which are responsible for the sensory innervation of the outer hair cells. To understand the function of the spiral ganglion neurones, it is important to explore their membrane properties, understand their activity patterns and describe the variety of ionic channels determining their behaviour. In this review, a brief description is given of the various experimental methods that allow the investigation of the spiral ganglion cells, followed by the discussion of their action potential firing patterns and ionic conductances. The presence, distribution and significance of the K(+) currents of the spiral ganglion cells are specifically addressed, along with the introduction of the putative subunit compositions of the relevant voltage-gated K(+) channels.
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Affiliation(s)
- Zoltán Rusznák
- Department of Physiology, Medical and Health Science Centre, University of Debrecen, Debrecen, P O Box 22, H-4012, Hungary.
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Vit JP, Ohara PT, Bhargava A, Kelley K, Jasmin L. Silencing the Kir4.1 potassium channel subunit in satellite glial cells of the rat trigeminal ganglion results in pain-like behavior in the absence of nerve injury. J Neurosci 2008; 28:4161-71. [PMID: 18417695 PMCID: PMC2533133 DOI: 10.1523/jneurosci.5053-07.2008] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 02/25/2008] [Accepted: 02/26/2008] [Indexed: 12/21/2022] Open
Abstract
Growing evidence suggests that changes in the ion buffering capacity of glial cells can give rise to neuropathic pain. In the CNS, potassium ion (K+) buffering is dependent on the glia-specific inward rectifying K+ channel Kir4.1. We recently reported that the satellite glial cells that surround primary sensory neurons located in sensory ganglia of the peripheral nervous system also express Kir4.1, whereas the neurons do not. In the present study, we show that, in the rat trigeminal ganglion, the location of the primary sensory neurons for face sensation, specific silencing of Kir4.1 using RNA interference leads to spontaneous and evoked facial pain-like behavior in freely moving rats. We also show that Kir4.1 in the trigeminal ganglion is reduced after chronic constriction injury of the infraorbital nerve. These findings suggests that neuropathic pain can result from a change in expression of a single K+ channel in peripheral glial cells, raising the possibility of targeting Kir4.1 to treat pain in general and particularly neuropathic pain that occurs in the absence of nerve injury.
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Affiliation(s)
- Jean-Philippe Vit
- Department of Neurosurgery and Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048, and
| | | | - Aditi Bhargava
- Surgery, University of California, San Francisco, San Francisco, California 94143
| | - Kanwar Kelley
- Department of Neurosurgery and Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048, and
| | - Luc Jasmin
- Department of Neurosurgery and Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048, and
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Rojas A, Su J, Yang L, Lee M, Cui N, Zhang X, Fountain D, Jiang C. Modulation of the heteromeric Kir4.1-Kir5.1 channel by multiple neurotransmitters via Galphaq-coupled receptors. J Cell Physiol 2007; 214:84-95. [PMID: 17559083 PMCID: PMC4132838 DOI: 10.1002/jcp.21169] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The heteromeric Kir4.1-Kir5.1 channel is a candidate sensing molecule for central CO(2) chemoreception. Since central CO(2) chemoreception is subject to neural modulations, we performed studies to test the hypothesis that the Kir4.1-Kir5.1 channel is modulated by the neurotransmitters critical for respiratory control, including serotonin (5-HT), substance-P (SP), and thyrotropin releasing hormone (TRH). The heteromeric Kir4.1-Kir5.1 channel was strongly inhibited by SP, TRH, and 5-HT when expressed in Xenopus oocytes, whereas these neurotransmitters had no effect on the homomeric Kir4.1 channel. Such an inhibition was dose-dependent and relied on specific G(alphaq)-protein-coupled receptors and protein kinase C (PKC). No direct interaction of the channel with G-proteins was found. Channel sensitivity to CO(2)/pH was not compromised with the inhibition by these neurotransmitters, as the channel remained to be inhibited by acidic pH following an exposure to the neurotransmitters. The firing rate of CO(2)-sensitive brainstem neurons cultured in microelectrode arrays was augmented by SP or a 5-HT2A receptor agonist, which was blocked by PKC inhibitors suggesting that PKC underscores the inhibitory effect of SP and 5-HT in cultured brainstem neurons as well. Immunostaining showed that both Kir4.1 and Kir5.1 proteins were co-localized in the cultured brainstem neurons. These results therefore indicate that the heteromeric Kir4.1-Kir5.1 channel is modulated by the neurotransmitters critical for respiratory control, suggesting a novel neuromodulatory mechanism for the chemosensitivity of brainstem neurons to elevated PCO(2) and acidic pH.
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Affiliation(s)
| | | | | | | | | | | | | | - Chun Jiang
- Correspondence to: Dr. Chun Jiang, Department of Biology, Georgia State University, 24 Peachtree Center Avenue, Atlanta, GA 30302-4010, Phone: 404-651-0913, Fax: 404-651-2509,
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Rojas A, Cui N, Su J, Yang L, Muhumuza JP, Jiang C. Protein kinase C dependent inhibition of the heteromeric Kir4.1-Kir5.1 channel. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1768:2030-42. [PMID: 17585871 PMCID: PMC2228331 DOI: 10.1016/j.bbamem.2007.04.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 03/22/2007] [Accepted: 04/04/2007] [Indexed: 11/13/2022]
Abstract
Heteromultimerization of Kir4.1 and Kir5.1 leads to a channel with distinct functional properties. The heteromeric Kir4.1-Kir5.1 channel is expressed in the eye, kidney and brainstem and has CO(2)/pH sensitivity in the physiological range, suggesting a candidate molecule for the regulation of K(+) homeostasis and central CO(2) chemoreception. It is known that K(+) transport in renal epithelium and brainstem CO(2) chemosensitivity are subject to modulation by hormones and neurotransmitters that activate distinct intracellular signaling pathways. If the Kir4.1-Kir5.1 channel is involved in pH-dependent regulation of cellular functions, it may also be regulated by some of the intracellular signaling systems. Therefore, we undertook studies to determine whether PKC modulates the heteromeric Kir4.1-Kir5.1 channel. The channel expressed using a Kir4.1-Kir5.1 tandem dimer construct was inhibited by the PKC activator PMA in a dose-dependent manner. The channel inhibition was produced via reduction of the P(open). The effect of PMA was abolished by specific PKC inhibitors. In contrast, exposure of oocytes to forskolin (a PKA activator) had no significant effect on Kir4.1-Kir5.1 currents. The channel inhibition appeared to be independent of PIP(2) depletion and PKC-dependent internalization. Several consensus sequences of potential PKC phosphorylation sites were identified in the Kir4.1 and Kir5.1 subunits by sequence scan. Although the C-terminal peptides of both Kir4.1 and Kir5.1 were phosphorylated in vitro, site-directed mutagenesis of individual residues failed to reveal the PKC phosphorylation sites suggesting that the channel may have multiple phosphorylation sites. Taken together, these results suggest that the Kir4.1-Kir5.1 but not the homomeric Kir4.1 channel is strongly inhibited by PKC activation.
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Affiliation(s)
- Asheebo Rojas
- Department of Biology, Georgia State University, 24 Peachtree Center Avenue Atlanta, GA 30302-4010
| | - Ningren Cui
- Department of Biology, Georgia State University, 24 Peachtree Center Avenue Atlanta, GA 30302-4010
| | - Junda Su
- Department of Biology, Georgia State University, 24 Peachtree Center Avenue Atlanta, GA 30302-4010
| | - Liang Yang
- Department of Biology, Georgia State University, 24 Peachtree Center Avenue Atlanta, GA 30302-4010
| | - Jean-Pierre Muhumuza
- Department of Biology, Georgia State University, 24 Peachtree Center Avenue Atlanta, GA 30302-4010
| | - Chun Jiang
- Department of Biology, Georgia State University, 24 Peachtree Center Avenue Atlanta, GA 30302-4010
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Jin Z, Wei D, Järlebark L. Developmental expression and localization of KCNJ10 K+ channels in the guinea pig inner ear. Neuroreport 2006; 17:475-9. [PMID: 16543810 DOI: 10.1097/01.wnr.0000208999.25234.91] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The inward rectifier Kir4.1, composed of KCNJ10 K channel subunits, plays an essential role in inner ear K homeostasis. We have investigated the developmental expression and localization of KCNJ10 (Kir4.1) in the guinea pig inner ear using semi-quantitative reverse transcription polymerase chain reaction and immunohistochemistry. Kcnj10 was expressed at low levels from embryonic day 30 (E30), increased from E45, and persisted from E50 to adulthood. KCNJ10 channel protein was detected in spiral ganglion satellite cells of the basal turn at E40, and at E45 its expression proceeded with a base-to-apex gradient along the cochlear spiral. KCNJ10 protein was enriched in the myelin sheath around the cochlear nerve between E40 and E45 and disappeared gradually with age. In the strial intermediate cells, KCNJ10 channel expression was first observed at E50, and lagged behind that of the spiral ganglion. In addition, KCNJ10 channel protein was expressed and localized in vestibular transitional cells. Differential expression of KCNJ10 channel protein suggests roles for KCNJ10 channels in inner ear development and onset of auditory function.
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Affiliation(s)
- Zhe Jin
- Center for Hearing and Communication Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Abstract
Current information indicates that glial cells participate in all the normal and pathological processes of the central nervous system. Although much less is known about satellite glial cells (SGCs) in sensory ganglia, it appears that these cells share many characteristics with their central counterparts. This review presents information that has been accumulated recently on the physiology and pharmacology of SGCs. It appears that SGCs carry receptors for numerous neuroactive agents (e.g., ATP, bradykinin) and can therefore receive signals from other cells and respond to changes in their environment. Activation of SGCs might in turn influence neighboring neurons. Thus SGCs are likely to participate in signal processing and transmission in sensory ganglia. Damage to the axons of sensory ganglia is known to contribute to neuropathic pain. Such damage also affects SGCs, and it can be proposed that these cells have a role in pathological changes in the ganglia.
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Affiliation(s)
- Menachem Hanani
- Laboratory of Experimental Surgery, Hadassah University Hospital, Mount Scopus, Jerusalem 91240, Israel
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Hibino H, Higashi-Shingai K, Fujita A, Iwai K, Ishii M, Kurachi Y. Expression of an inwardly rectifying K+ channel, Kir5.1, in specific types of fibrocytes in the cochlear lateral wall suggests its functional importance in the establishment of endocochlear potential. Eur J Neurosci 2004; 19:76-84. [PMID: 14750965 DOI: 10.1111/j.1460-9568.2004.03092.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Cochlear endolymph contains 150 mm K+ and has a highly positive potential of approximately +80 mV. The specialized ionic composition and high potential in endolymph are essential for hearing and maintained by circulation of K+ from perilymph to endolymph through the cochlear lateral wall. Various types of K+ channel such as Kir4.1 and KCNQ1/KCNE1 are expressed in stria vascularis of the lateral wall and play essential roles in K+ circulation. In this study, we examined a distribution of another K+ channel, Kir5.1, and found it specifically expressed in the spiral ligament of the cochlear lateral wall. Specific immunoreactivity for Kir5.1 was detected in type II, IV and V fibrocytes of the ligament and spiral limbus, all of which are directly involved in K+ circulation. Kir5.1 was not found in either type I or III fibrocytes. Although Kir5.1 assembles with Kir4.1 to form a functional Kir channel in renal epithelia and retinal Müller cells, double-immunolabelling revealed that they were expressed in distinct regions in the cochlea lateral wall, i.e. Kir4.1 only in stria vascularis vs. Kir5.1 in spiral ligament. During development, the expression of Kir5.1 subunits started significantly later than Kir4.1 and was correlated with the 'rapid' phase of the elevation of endocochlear potential (EP). Kir5.1 and Kir4.1 channel-subunits may therefore play distinct functional roles in K+ circulation in the cochlear lateral wall.
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Affiliation(s)
- Hiroshi Hibino
- Department of Pharmacology II, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan
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Hurley PA, Clarke M, Crook JM, Wise AK, Shepherd RK. Cochlear immunochemistry--a new technique based on gelatin embedding. J Neurosci Methods 2003; 129:81-6. [PMID: 12951235 DOI: 10.1016/s0165-0270(03)00211-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Histological processing of the cochlea for immunochemistry is often a compromise between good anatomical resolution and preservation of antigenicity. Techniques able to preserve tissue architecture invariably demand elevated temperatures and harsh chemicals or a combination of both. The likely result is reduced antigenicity, enzyme activity and nucleic acid integrity. We have modified an existing embedding medium for use in the cochlea that operates at physiological temperature and avoids denaturing agents and organic solvents. Tissue antigenicity is maximised and anatomical detail preserved, normally two mutually exclusive goals. The method is attractive because of its simplicity, speed and transparency for easy cochlear orientation. It is also likely to be adaptable for the infiltration of other heterogeneous structures prone to distortion during frozen sectioning.
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Affiliation(s)
- Patricia A Hurley
- Department of Otolaryngology, Royal Victorian Eye and Ear Hospital, University of Melbourne, 32, Gisborne Street, East Melbourne, Melbourne 3002, Vic., Australia
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Rozengurt N, Lopez I, Chiu CS, Kofuji P, Lester HA, Neusch C. Time course of inner ear degeneration and deafness in mice lacking the Kir4.1 potassium channel subunit. Hear Res 2003; 177:71-80. [PMID: 12618319 DOI: 10.1016/s0378-5955(02)00799-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The Kir4.1 gene (KCNJ10) encodes an inwardly rectifying K(+) channel subunit abundantly expressed in the CNS. Its expression in the mammalian inner ear has been suggested but its function in vivo in the inner ear is unknown. Because diverse human hereditary deafness syndromes are associated with mutations in K(+) channels, we examined auditory function and inner ear structure in mice with a genetically inactivated Kir4.1 K(+) channel subunit. Startle response experiments suggest that Kir4.1-/- mice are profoundly deaf, whereas Kir4.1+/- mice react like wild-type mice to acoustic stimuli. In Kir4.1-/- mice, the Reissner membrane is collapsed, the tectorial membrane is swollen, and type I hair cells and spiral ganglion neurons as well as their central processes degenerate over the first postnatal weeks. In the vestibular ganglia, neuronal cell death with apoptotic features is also observed. Immunostaining reveals that Kir4.1 is strongly expressed in stria vascularis of wild-type but not Kir4.1-/- mice. Within the spiral ganglion, Kir4.1 labeling was detected on satellite cells surrounding spiral ganglion neurons and axons. We conclude that Kir4.1 is crucial for normal development of the cochlea and hearing, via two distinct aspects of extracellular K(+) homeostasis: (1). in stria vascularis, Kir4.1 helps to generate the cochlear endolymph; and (2). in spiral and vestibular ganglia, Kir4.1 in surrounding glial cells helps to support the spiral and vestibular ganglion neurons and their projecting axons.
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Affiliation(s)
- Nora Rozengurt
- Department of Pathology, UCLA School of Medicine, Los Angeles, CA 90095, USA
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Inanobe A, Fujita A, Ito M, Tomoike H, Inageda K, Kurachi Y. Inward rectifier K+ channel Kir2.3 is localized at the postsynaptic membrane of excitatory synapses. Am J Physiol Cell Physiol 2002; 282:C1396-403. [PMID: 11997254 DOI: 10.1152/ajpcell.00615.2001] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Classical inwardly rectifying K+ channels (Kir2.0) are responsible for maintaining the resting membrane potential near the K+ equilibrium potential in various cells, including neurons. Although Kir2.3 is known to be expressed abundantly in the forebrain, its precise localization has not been identified. Using an antibody specific to Kir2.3, we examined the subcellular localization of Kir2.3 in mouse brain. Kir2.3 immunoreactivity was detected in a granular pattern in restricted areas of the brain, including the olfactory bulb (OB). Immunoelectron microscopy of the OB revealed that Kir2.3 immunoreactivity was specifically clustered on the postsynaptic membrane of asymmetric synapses between granule cells and mitral/tufted cells. The immunoprecipitants for Kir2.3 obtained from brain contained PSD-95 and chapsyn-110, PDZ domain-containing anchoring proteins. In vitro binding assay further revealed that the COOH-terminal end of Kir2.3 is responsible for the association with these anchoring proteins. Therefore, the Kir channel may be involved in formation of the resting membrane potential of the spines and, thus, would affect the response of N-methyl-D-aspartic acid receptor channels at the excitatory postsynaptic membrane.
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Affiliation(s)
- Atsushi Inanobe
- Department of Pharmacology II, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
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Horio Y. Potassium channels of glial cells: distribution and function. JAPANESE JOURNAL OF PHARMACOLOGY 2001; 87:1-6. [PMID: 11676192 DOI: 10.1254/jjp.87.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Firing of neurons changes the extracellular concentration of K+ ions ([K+]o). Glial cells have the ability to maintain [K+]o at a constant level. This function has been called "K+-spatial buffering". K+ channels are believed to be involved in K+-spatial buffering. Kir4.1 in retinal glial cells and Kir2.1, Kir2.3 and Kv1.5 in Schwann cells have been identified. All of these K+ channels show polarized distribution, which enables the channels to transport K+ ions to appropriate regions such as blood vessels and the vitreous body. These channels have a consensus C-terminal sequence that can bind a protein containing PDZ (PSD-95/dlg/ZO1) domains, which may regulate the distribution of the channels. Kir4.1 is predominantly expressed in membranes adjacent to basement membranes. Laminin, a component of basement membranes, is necessary for the surface expression of Kir4.1 in cultured retinal glial cells, suggesting that an extracellular signal regulates the function of glial cells. In some cases, K+ buffering has been considered to couple tightly with water flux. Actually the aquaporin-4 water channel has been found to colocalize with Kir4.1 in retinal glial cells. Recent studies of K+ channels have elucidated the mechanisms of old well-known phenomena and present new unknown roles of glial cells.
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Affiliation(s)
- Y Horio
- Department of Pharmacology, Sapporo Medical School, School of Medicine, Japan.
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Higashi K, Fujita A, Inanobe A, Tanemoto M, Doi K, Kubo T, Kurachi Y. An inwardly rectifying K(+) channel, Kir4.1, expressed in astrocytes surrounds synapses and blood vessels in brain. Am J Physiol Cell Physiol 2001; 281:C922-31. [PMID: 11502569 DOI: 10.1152/ajpcell.2001.281.3.c922] [Citation(s) in RCA: 243] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glial cells express inwardly rectifying K(+) (Kir) channels, which play a critical role in the buffering of extracellular K(+). Kir4.1 is the only Kir channel so far shown to be expressed in brain glial cells. We examined the distribution of Kir4.1 in rat brain with a specific antibody. The Kir4.1 immunostaining distributed broadly but not diffusely in the brain. It was strong in some regions such as the glomerular layer of the olfactory bulb, the Bergmann glia in the cerebellum, the ependyma, and pia mater, while little activity was detected in white matter of the corpus callosum or cerebellar peduncle. In the olfactory bulb, Kir4.1 immunoreactivity was detected in a scattered manner in about one-half of the glial fibrillary acidic protein-positive astrocytes. Immunoelectron microscopic examination revealed that Kir4.1 channels were enriched on the processes of astrocytes wrapping synapses and blood vessels. These data suggest that Kir4.1 is expressed in a limited population of brain astrocytes and may play a specific role in the glial K(+)-buffering action.
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Affiliation(s)
- K Higashi
- Department of Pharmacology II, Osaka University, Suita, Japan
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42
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Kilpeläinen P, Rybnikova E, Hietala O, Pelto-Huikko M. Expression of ODC and its regulatory protein antizyme in the adult rat brain. J Neurosci Res 2000; 62:675-85. [PMID: 11104505 DOI: 10.1002/1097-4547(20001201)62:5<675::aid-jnr6>3.0.co;2-s] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Ornithine decarboxylase and its inhibitor protein, antizyme are key regulators of polyamine biosynthesis. We examined their expression in the adult rat brain using in situ hybridization and immunocytochemistry. Both genes were widely expressed and their expression patterns were mostly overlapping and relatively similar. The levels of antizyme mRNA were always higher than those of ornithine decarboxylase mRNA. The highest expression for both genes was detected in the cerebellar cortex, hippocampus, hypothalamic paraventricular and supraoptic nuclei, locus coeruleus, olfactory bulb, piriform cortex and pontine nuclei. Ornithine decarboxylase and antizyme mRNAs appeared to be localized in the nerve cells. ODC antibody displayed mainly cytoplasmic staining in all brain areas. Antizyme antibody staining was mainly cytoplasmic in the most brain areas, although predominantly nuclear staining was detected in some areas, most notably in the cerebellar cortex, anterior olfactory nucleus and frontal cortex. Our study is the first detailed and comparative analysis of ornithine decarboxylase and antizyme expression in the adult mammalian brain.
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Affiliation(s)
- P Kilpeläinen
- Department of Biochemistry, University of Oulu, Oulu, Finland
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Perillán PR, Li X, Potts EA, Chen M, Bredt DS, Simard JM. Inward rectifier K(+) channel Kir2.3 (IRK3) in reactive astrocytes from adult rat brain. Glia 2000; 31:181-92. [PMID: 10878604 DOI: 10.1002/1098-1136(200008)31:2<181::aid-glia90>3.0.co;2-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Astrocytic inward rectifying K(+) channels that participate in K(+) spatial buffering in the central nervous system have been extensively investigated, but specific gene products have not been fully identified. We studied primary cultured reactive astrocytes of stellate and polygonal morphology from adult rat brains, as well as stellate astrocytes from neonatal rat brains. Single-channel recordings of cell-attached patches revealed that polygonal reactive astrocytes expressed only one hyperpolarization-activated single-channel conductance of 11-15 pS whose open probability was independent of voltage, whereas stellate reactive and stellate neonatal astrocytes exhibited two conductances, 11-15 pS and 24-27 pS. All three subtypes of astrocytes exhibited a hyperpolarization-activated macroscopic inward K(+) current that was strongly rectifying and was abrogated by 1 mM intracellular Mg(2+) introduced during conventional but not perforated patch whole-cell recording. This Mg(2+)-sensitive current comprised the total inward rectifier current in polygonal reactive astrocytes, but only a fraction of the inward rectifier current in stellate reactive and stellate neonatal astrocytes. Because a strongly rectifying, inward rectifier K(+) channel with a single-channel conductance of 11-15 pS that is voltage independent is consistent with features of Kir2.3 (IRK3), we performed immunofluorescence experiments with anti-Kir2.3 and anti-glial fibrillary acidic protein antibodies. Both antibodies co-localized to all three subtypes of astrocytes in primary culture and to reactive astrocytes in situ within brain and gelatin sponge implants. Our data indicate that astrocytes of both polygonal and stellate morphology, from both adult and neonatal rat brain, express Kir2.3 both in vivo and in vitro. Constitutive expression of Kir2.3 regardless of cell morphology or age of origin of the source tissue suggests an important functional role for this channel in astrocytes.
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Affiliation(s)
- P R Perillán
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201-1595, USA
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