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Fisch KM, Rosenthal SB, Mark A, Sasik R, Nasamran CA, Clifford R, Derebery MJ, Boussaty E, Jepsen K, Harris J, Friedman RA. The genomic landscape of Ménière's disease: a path to endolymphatic hydrops. BMC Genomics 2024; 25:646. [PMID: 38943082 PMCID: PMC11212243 DOI: 10.1186/s12864-024-10552-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Accepted: 06/21/2024] [Indexed: 07/01/2024] Open
Abstract
BACKGROUND Ménière's disease (MD) is a disorder of the inner ear that causes episodic bouts of severe dizziness, roaring tinnitus, and fluctuating hearing loss. To date, no targeted therapy exists. As such, we have undertaken a large whole genome sequencing study on carefully phenotyped unilateral MD patients with the goal of gene/pathway discovery and a move towards targeted intervention. This study was a retrospective review of patients with a history of Ménière's disease. Genomic DNA, acquired from saliva samples, was purified and subjected to whole genome sequencing. RESULTS Stringent variant calling, performed on 511 samples passing quality checks, followed by gene-based filtering by recurrence and proximity in molecular interaction networks, led to 481 high priority MD genes. These high priority genes, including MPHOSPH8, MYO18A, TRIOBP, OTOGL, TNC, and MYO6, were previously implicated in hearing loss, balance, and cochlear function, and were significantly enriched in common variant studies of hearing loss. Validation in an independent MD cohort confirmed 82 recurrent genes. Pathway analysis pointed to cell-cell adhesion, extracellular matrix, and cellular energy maintenance as key mediators of MD. Furthermore, the MD-prioritized genes were highly expressed in human inner ear hair cells and dark/vestibular cells, and were differentially expressed in a mouse model of hearing loss. CONCLUSION By enabling the development of model systems that may lead to targeted therapies and MD screening panels, the genes and variants identified in this study will inform diagnosis and treatment of MD.
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Affiliation(s)
- Kathleen M Fisch
- Center for Computational Biology & Bioinformatics, University of California, San Diego, La Jolla, CA, USA.
- Department of Obstetrics, Gynecology & Reproductive Sciences, University of California, San Diego, La Jolla, CA, USA.
| | - Sara Brin Rosenthal
- Center for Computational Biology & Bioinformatics, University of California, San Diego, La Jolla, CA, USA
| | - Adam Mark
- Center for Computational Biology & Bioinformatics, University of California, San Diego, La Jolla, CA, USA
| | - Roman Sasik
- Center for Computational Biology & Bioinformatics, University of California, San Diego, La Jolla, CA, USA
| | - Chanond A Nasamran
- Center for Computational Biology & Bioinformatics, University of California, San Diego, La Jolla, CA, USA
| | - Royce Clifford
- Department of Otolaryngology, Head & Neck Surgery, University of California, San Diego, La Jolla, CA, USA
- Research Department, VA Hospitals, San Diego, CA, USA
| | | | - Ely Boussaty
- Department of Otolaryngology, Head & Neck Surgery, University of California, San Diego, La Jolla, CA, USA
| | - Kristen Jepsen
- Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Jeffrey Harris
- Department of Otolaryngology, Head & Neck Surgery, University of California, San Diego, La Jolla, CA, USA
| | - Rick A Friedman
- Department of Otolaryngology, Head & Neck Surgery, University of California, San Diego, La Jolla, CA, USA.
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2
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Gardner EC, Tramont C, Bachanová P, Wang C, Do H, Boutz DR, Kar S, Zemelman BV, Gollihar JD, Ellington AD. Engineering a human P2X2 receptor with altered ligand selectivity in yeast. J Biol Chem 2024; 300:107248. [PMID: 38556082 PMCID: PMC11063903 DOI: 10.1016/j.jbc.2024.107248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 03/14/2024] [Accepted: 03/23/2024] [Indexed: 04/02/2024] Open
Abstract
P2X receptors are a family of ligand gated ion channels found in a range of eukaryotic species including humans but are not naturally present in the yeast Saccharomyces cerevisiae. We demonstrate the first recombinant expression and functional gating of the P2X2 receptor in baker's yeast. We leverage the yeast host for facile genetic screens of mutant P2X2 by performing site saturation mutagenesis at residues of interest, including SNPs implicated in deafness and at residues involved in native binding. Deep mutational analysis and rounds of genetic engineering yield mutant P2X2 F303Y A304W, which has altered ligand selectivity toward the ATP analog AMP-PNP. The F303Y A304W variant shows over 100-fold increased intracellular calcium amplitudes with AMP-PNP compared to the WT receptor and has a much lower desensitization rate. Since AMP-PNP does not naturally activate P2X receptors, the F303Y A304W P2X2 may be a starting point for downstream applications in chemogenetic cellular control. Interestingly, the A304W mutation selectively destabilizes the desensitized state, which may provide a mechanistic basis for receptor opening with suboptimal agonists. The yeast system represents an inexpensive, scalable platform for ion channel characterization and engineering by circumventing the more expensive and time-consuming methodologies involving mammalian hosts.
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Affiliation(s)
- Elizabeth C Gardner
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Caitlin Tramont
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Petra Bachanová
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Chad Wang
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Hannah Do
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Daniel R Boutz
- Antibody Discovery and Accelerated Protein Therapeutics, Department of Pathology & Genomic Medicine, Houston Methodist Research Institute, Houston, Texas, USA
| | - Shaunak Kar
- Antibody Discovery and Accelerated Protein Therapeutics, Department of Pathology & Genomic Medicine, Houston Methodist Research Institute, Houston, Texas, USA
| | - Boris V Zemelman
- Department of Neuroscience, Center for Learning and Memory, The University of Texas at Austin, Austin, Texas, USA.
| | - Jimmy D Gollihar
- Antibody Discovery and Accelerated Protein Therapeutics, Department of Pathology & Genomic Medicine, Houston Methodist Research Institute, Houston, Texas, USA.
| | - Andrew D Ellington
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA.
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3
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Liu Z, Sun M, Liu W, Feng F, Li X, Jin C, Zhang Y, Wang J. Deficiency of purinergic P2X4 receptor alleviates experimental autoimmune hepatitis in mice. Biochem Pharmacol 2024; 221:116033. [PMID: 38301964 DOI: 10.1016/j.bcp.2024.116033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 12/29/2023] [Accepted: 01/25/2024] [Indexed: 02/03/2024]
Abstract
Purinergic P2X4 receptor (P2X4R) has been shown to have immunomodulatory properties in infection, inflammation, and organ damage including liver regeneration and fibrosis. However, the mechanisms and pathophysiology associated with P2X4R during acute liver injury remain unknown. We used P2X4R-/- mice to explore the role of P2X4R in three different models of acute liver injury caused by concanavalin A (ConA), carbon tetrachloride, and acetaminophen. ConA treatment results in an increased expression of P2X4R in the liver of mice, which was positively correlated with higher levels of aspartate aminotransferase and alanine aminotransferase in the serum. However, P2X4R gene ablation significantly reduced the severity of acute hepatitis in mice caused by ConA, but not by carbon tetrachloride or acetaminophen. The protective benefits against immune-mediated acute hepatitis were achieved via modulating inflammation (Interleukin (IL)-1β, IL-6, IL-17A, interferon-γ, tumor necrosis factor-α), oxidative stress (malondialdehyde, superoxide dismutase, glutathione peroxidase, and catalase), apoptosis markers (Bax, Bcl-2, and Caspase-3), autophagy biomarkers (LC3, Beclin-1, and p62), and nucleotide oligomerization domain-likereceptorprotein 3(NLRP3) inflammasome-activated pyroptosis markers (NLRP3, Gasdermin D, Caspase-1, ASC, IL-1β). Additionally, administration of P2X4R antagonist (5-BDBD) or agonist (cytidine 5'-triphosphate) either improved or worsened ConA-induced autoimmune hepatitis, respectively. This study is the first to reveal that the absence of the P2X4 receptor may mitigate immune-mediated liver damage, potentially by restraining inflammation, oxidation, and programmed cell death mechanisms. And highlight P2X4 receptor is essential for ConA-induced acute hepatitis.
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Affiliation(s)
- Zejin Liu
- Infection and Immunity Institute and Translational Medical Center of Huaihe Hospital, Henan University, Kaifeng 475000, China
| | - Mengyang Sun
- Infection and Immunity Institute and Translational Medical Center of Huaihe Hospital, Henan University, Kaifeng 475000, China
| | - Wenhua Liu
- Infection and Immunity Institute and Translational Medical Center of Huaihe Hospital, Henan University, Kaifeng 475000, China
| | - Fangyu Feng
- Infection and Immunity Institute and Translational Medical Center of Huaihe Hospital, Henan University, Kaifeng 475000, China
| | - Xinyu Li
- Infection and Immunity Institute and Translational Medical Center of Huaihe Hospital, Henan University, Kaifeng 475000, China
| | - Chaolei Jin
- Infection and Immunity Institute and Translational Medical Center of Huaihe Hospital, Henan University, Kaifeng 475000, China
| | - Yijie Zhang
- Infection and Immunity Institute and Translational Medical Center of Huaihe Hospital, Henan University, Kaifeng 475000, China
| | - Junpeng Wang
- Infection and Immunity Institute and Translational Medical Center of Huaihe Hospital, Henan University, Kaifeng 475000, China.
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4
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Chen Y, Mu W, Wu Y, Xu J, Li X, Hu H, Wang S, Wang D, Hui B, Wang L, Dong Y, Chen W. Optogenetically modified human embryonic stem cell-derived otic neurons establish functional synaptic connection with cochlear nuclei. J Tissue Eng 2024; 15:20417314241265198. [PMID: 39092452 PMCID: PMC11292720 DOI: 10.1177/20417314241265198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Accepted: 06/14/2024] [Indexed: 08/04/2024] Open
Abstract
Spiral ganglia neurons (SGNs) impairment can cause deafness. One important therapeutic approach involves utilizing stem cells to restore impaired auditory circuitry. Nevertheless, the inadequate implementation of research methodologies poses a challenge in accurately assessing the functionality of derived cells within the circuit. Here, we describe a novel method for converting human embryonic stem cells (hESCs) into otic neurons (ONs) and assess their functional connectivity using an optogenetic approach with cells or an organotypic slice of rat cochlear nucleus (CN) in coculture. Embryonic stem cell-derived otic neurons (eONs) exhibited SGN marker expression and generated functional synaptic connection when cocultured with cochlear nucleus neurons (CNNs). Synapsin 1 and VGLUT expression are found in the cochlear nucleus of brain slices, where eONs projected processes during the coculture of eONs and CN brain slices. Action potential spikes and INa+/IK+ of CNNs increased in tandem with light stimulations to eONs. These findings provide further evidence that eONs may be a candidate source to treat SGN-deafness.
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Affiliation(s)
- Yanni Chen
- Institute of Translational Medicine, and Children’s Hospital Affiliated and Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
- College of Public Health, Shanghai University of Medicine & Health Sciences, Shanghai China
- Institute of Wound Prevention and Treatment, Shanghai University of Medicine & Health Sciences, Shanghai, China
- Institute of Translational Medicine, School of Medicine, Zhejiang University, Hangzhou, China
| | - Wenbo Mu
- Institute of Translational Medicine, and Children’s Hospital Affiliated and Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
- College of Public Health, Shanghai University of Medicine & Health Sciences, Shanghai China
- Institute of Wound Prevention and Treatment, Shanghai University of Medicine & Health Sciences, Shanghai, China
- Institute of Translational Medicine, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yongkang Wu
- Key Laboratory of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, School of Physical Education & Health Care, East China Normal University, Shanghai, China
| | - Jiake Xu
- Chongqing Key Laboratory of Translational Research for Cancer Metastasis and Individualized Treatment, Chongqing University Cancer Hospital, Chongqing, China
| | - Xiaofang Li
- Department of Neurology of the First Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China
| | - Hui Hu
- School of Laboratory Medicine and Bioengineering, Hangzhou Medical College, Hangzhou, China
| | - Siqi Wang
- College of Public Health, Shanghai University of Medicine & Health Sciences, Shanghai China
| | - Dali Wang
- Center for Clinical and Translational Medicine, Shanghai University of Medicine and Health Sciences, Shanghai, China
| | - Bin Hui
- College of Pharmacy, Shanghai University of Medical & Health Sciences, Shanghai, China
| | - Lang Wang
- Department of Neurology of the First Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China
| | - Yi Dong
- Key Laboratory of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, School of Physical Education & Health Care, East China Normal University, Shanghai, China
| | - Wei Chen
- Institute of Translational Medicine, and Children’s Hospital Affiliated and Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
- College of Public Health, Shanghai University of Medicine & Health Sciences, Shanghai China
- Institute of Wound Prevention and Treatment, Shanghai University of Medicine & Health Sciences, Shanghai, China
- Institute of Translational Medicine, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji, China
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5
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Ai Y, Wang H, Liu L, Qi Y, Tang S, Tang J, Chen N. Purine and purinergic receptors in health and disease. MedComm (Beijing) 2023; 4:e359. [PMID: 37692109 PMCID: PMC10484181 DOI: 10.1002/mco2.359] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 08/07/2023] [Accepted: 08/10/2023] [Indexed: 09/12/2023] Open
Abstract
Purines and purinergic receptors are widely distributed throughout the human body. Purine molecules within cells play crucial roles in regulating energy metabolism and other cellular processes, while extracellular purines transmit signals through specific purinergic receptors. The ubiquitous purinergic signaling maintains normal neural excitability, digestion and absorption, respiratory movement, and other complex physiological activities, and participates in cell proliferation, differentiation, migration, and death. Pathological dysregulation of purinergic signaling can result in the development of various diseases, including neurodegeneration, inflammatory reactions, and malignant tumors. The dysregulation or dysfunction of purines and purinergic receptors has been demonstrated to be closely associated with tumor progression. Compared with other subtypes of purinergic receptors, the P2X7 receptor (P2X7R) exhibits distinct characteristics (i.e., a low affinity for ATP, dual functionality upon activation, the mediation of ion channels, and nonselective pores formation) and is considered a promising target for antitumor therapy, particularly in patients with poor response to immunotherapy This review summarizes the physiological and pathological significance of purinergic signaling and purinergic receptors, analyzes their complex relationship with tumors, and proposes potential antitumor immunotherapy strategies from tumor P2X7R inhibition, tumor P2X7R overactivation, and host P2X7R activation. This review provides a reference for clinical immunotherapy and mechanism investigation.
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Affiliation(s)
- Yanling Ai
- Department of OncologyHospital of Chengdu University of Traditional Chinese MedicineChengduChina
| | - Hengyi Wang
- Department of Infectious DiseasesHospital of Chengdu University of Traditional Chinese MedicineChengduChina
| | - Lu Liu
- School of PharmacyChengdu University of Traditional Chinese MedicineChengduChina
| | - Yulin Qi
- Department of OphthalmologyThe First Affiliated Hospital of Guangzhou University of Chinese MedicineGuangzhou University of Chinese MedicineGuangzhouChina
- Postdoctoral Research Station of Guangzhou University of Chinese MedicineGuangzhouChina
| | - Shiyun Tang
- Hospital of Chengdu University of Traditional Chinese MedicineChengduChina
| | - Jianyuan Tang
- TCM Regulating Metabolic Diseases Key Laboratory of Sichuan ProvinceHospital of Chengdu University of Traditional Chinese MedicineChengduChina
| | - Nianzhi Chen
- State Key Laboratory of Ultrasound in Medicine and EngineeringCollege of Biomedical EngineeringChongqing Medical UniversityChongqingChina
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6
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Sivcev S, Kudova E, Zemkova H. Neurosteroids as positive and negative allosteric modulators of ligand-gated ion channels: P2X receptor perspective. Neuropharmacology 2023; 234:109542. [PMID: 37040816 DOI: 10.1016/j.neuropharm.2023.109542] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 03/06/2023] [Accepted: 04/07/2023] [Indexed: 04/13/2023]
Abstract
Neurosteroids are steroids synthesized de novo in the brain from cholesterol in an independent manner from peripheral steroid sources. The term "neuroactive steroid" includes all steroids independent of their origin, and newly synthesized analogs of neurosteroids that modify neuronal activities. In vivo application of neuroactive steroids induces potent anxiolytic, antidepressant, anticonvulsant, sedative, analgesic and amnesic effects, mainly through interaction with the γ-aminobutyric acid type-A receptor (GABAAR). However, neuroactive steroids also act as positive or negative allosteric regulators on several ligand-gated channels including N-methyl-d-aspartate receptors (NMDARs), nicotinic acetylcholine receptors (nAChRs) and ATP-gated purinergic P2X receptors. Seven different P2X subunits (P2X1-7) can assemble to form homotrimeric or heterotrimeric ion channels permeable for monovalent cations and calcium. Among them, P2X2, P2X4, and P2X7 are the most abundant within the brain and can be regulated by neurosteroids. Transmembrane domains are necessary for neurosteroid binding, however, no generic motif of amino acids can accurately predict the neurosteroid binding site for any of the ligand-gated ion channels including P2X. Here, we will review what is currently known about the modulation of rat and human P2X by neuroactive steroids and the possible structural determinants underlying neurosteroid-induced potentiation and inhibition of the P2X2 and P2X4 receptors.
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Affiliation(s)
- Sonja Sivcev
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic; Faculty of Science, Charles University, Prague, Czech Republic
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Hana Zemkova
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
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7
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Tam SW, Huffer K, Li M, Swartz KJ. Ion permeation pathway within the internal pore of P2X receptor channels. eLife 2023; 12:84796. [PMID: 36940138 PMCID: PMC10027316 DOI: 10.7554/elife.84796] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 03/07/2023] [Indexed: 03/21/2023] Open
Abstract
P2X receptor channels are trimeric ATP-activated ion channels expressed in neuronal and non-neuronal cells that are attractive therapeutic targets for human disorders. Seven subtypes of P2X receptor channels have been identified in mammals that can form both homomeric and heteromeric channels. P2X1-4 and P2X7 receptor channels are cation-selective, whereas P2X5 has been reported to have both cation and anion permeability. P2X receptor channel structures reveal that each subunit is comprised of two transmembrane helices, with both N-and C-termini on the intracellular side of the membrane and a large extracellular domain that contains the ATP binding sites at subunit interfaces. Recent structures of ATP-bound P2X receptors with the activation gate open reveal the unanticipated presence of a cytoplasmic cap over the central ion permeation pathway, leaving lateral fenestrations that may be largely buried within the membrane as potential pathways for ions to permeate the intracellular end of the pore. In the present study, we identify a critical residue within the intracellular lateral fenestrations that is readily accessible to thiol-reactive compounds from both sides of the membrane and where substitutions influence the relative permeability of the channel to cations and anions. Taken together, our results demonstrate that ions can enter or exit the internal pore through lateral fenestrations that play a critical role in determining the ion selectivity of P2X receptor channels.
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Affiliation(s)
- Stephanie W Tam
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Kate Huffer
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - Mufeng Li
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Kenton J Swartz
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
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8
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Vlajkovic SM, Thorne PR. Purinergic Signalling in the Cochlea. Int J Mol Sci 2022; 23:ijms232314874. [PMID: 36499200 PMCID: PMC9741428 DOI: 10.3390/ijms232314874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
The mammalian cochlea is the sensory organ of hearing with a delicate, highly organised structure that supports unique operating mechanisms. ATP release from the secretory tissues of the cochlear lateral wall (stria vascularis) triggers numerous physiological responses by activating P2 receptors in sensory, supporting and neural tissues. Two families of P2 receptors, ATP-gated ion channels (P2X receptors) and G protein-coupled P2Y receptors, activate intracellular signalling pathways that regulate cochlear development, homeostasis, sensory transduction, auditory neurotransmission and response to stress. Of particular interest is a purinergic hearing adaptation, which reflects the critical role of the P2X2 receptor in adaptive cochlear response to elevated sound levels. Other P2 receptors are involved in the maturation of neural processes and frequency selectivity refinement in the developing cochlea. Extracellular ATP signalling is regulated by a family of surface-located enzymes collectively known as "ectonucleotidases" that hydrolyse ATP to adenosine. Adenosine is a constitutive cell metabolite with an established role in tissue protection and regeneration. The differential activation of A1 and A2A adenosine receptors defines the cochlear response to injury caused by oxidative stress, inflammation, and activation of apoptotic pathways. A1 receptor agonism, A2A receptor antagonism, and increasing adenosine levels in cochlear fluids all represent promising therapeutic tools for cochlear rescue from injury and prevention of hearing loss.
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Affiliation(s)
- Srdjan M. Vlajkovic
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Correspondence: ; Tel.: +64-9-9239782
| | - Peter R. Thorne
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Section of Audiology, School of Population Health, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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9
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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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10
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Kim SH, Choi JY. Purinergic signaling in the peripheral vestibular system. Purinergic Signal 2022; 18:165-176. [PMID: 35344126 DOI: 10.1007/s11302-022-09855-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 02/19/2022] [Indexed: 11/25/2022] Open
Abstract
The inner ear comprises the cochlea and vestibular system, which detect sound and acceleration stimulation, respectively. The function of the inner ear is regulated by ion transport activity among sensory epithelial cells, neuronal cells, non-sensory epithelial cells, and luminal fluid with a unique ionic composition of high [K+] and low [Na+], which enables normal hearing and balance maintenance. One of the important mechanisms regulating ion transport in the inner ear is purinergic signaling. Various purinergic receptors are distributed throughout inner ear epithelial cells and neuronal cells. To date, most studies have focused on the role of purinergic receptors in the cochlea, and few studies have examined these receptors in the vestibular system. As purinergic receptors play an important role in the cochlea, they would likely do the same in the vestibular system, which is fairly similar to the cochlea in cellular structure and function. Based on available studies performed to date, purinergic signaling is postulated to be involved in the regulation of ion homeostasis, protection of hair cells, otoconia formation, and regulation of electrical signaling from the sensory epithelium to vestibular neurons. In this review, the distribution and roles of purinergic receptors in the peripheral vestibular system are summarized and discussed.
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Affiliation(s)
- Sung Huhn Kim
- Department of Otorhinolaryngology, Yonsei University College of Medicine, 50-1 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, Republic of Korea
| | - Jae Young Choi
- Department of Otorhinolaryngology, Yonsei University College of Medicine, 50-1 Yonsei-Ro, Seodaemun-Gu, Seoul, 03722, Republic of Korea.
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Gasparri F, Sarkar D, Bielickaite S, Poulsen MH, Hauser AS, Pless SA. P2X2 receptor subunit interfaces are missense variant hotspots where mutations tend to increase apparent ATP affinity. Br J Pharmacol 2022; 179:3859-3874. [PMID: 35285517 PMCID: PMC9314836 DOI: 10.1111/bph.15830] [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: 03/27/2021] [Revised: 01/31/2022] [Accepted: 02/09/2022] [Indexed: 11/30/2022] Open
Abstract
Background and Purpose P2X receptors are trimeric ligand‐gated ion channels that open a cation‐selective pore in response to ATP binding to their large extracellular domain. The seven known P2X subtypes can assemble as homotrimeric or heterotrimeric complexes and contribute to numerous physiological functions, including nociception, inflammation and hearing. The overall structure of P2X receptors is well established, but little is known about the range and prevalence of human genetic variations and the functional implications of specific domains. Experimental Approach Here, we examine the impact of P2X2 receptor inter‐subunit interface missense variants identified in the human population or by structural predictions. We test both single and double mutants through electrophysiological and biochemical approaches. Key Results We demonstrate that predicted extracellular domain inter‐subunit interfaces display a higher‐than‐expected density of missense variations and that the majority of mutations that disrupt putative inter‐subunit interactions result in channels with higher apparent ATP affinity. Lastly, we show that double mutants at the subunit interface show significant energetic coupling, especially if located in close proximity. Conclusion and Implications We provide the first structural mapping of the mutational distribution across the human population in a ligand‐gated ion channel and show that the density of missense mutations is constrained between protein domains, indicating evolutionary selection at the domain level. Our data may indicate that, unlike other ligand‐gated ion channels, P2X2 receptors have evolved an intrinsically high threshold for activation, possibly to allow for additional modulation or as a cellular protection mechanism against overstimulation.
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Affiliation(s)
- Federica Gasparri
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Debayan Sarkar
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Sarune Bielickaite
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Mette Homann Poulsen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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Chen X, Abad C, Chen ZY, Young JI, Gurumurthy CB, Walz K, Liu XZ. Generation and characterization of a P2rx2 V60L mouse model for DFNA41. Hum Mol Genet 2021; 30:985-995. [PMID: 33791800 DOI: 10.1093/hmg/ddab077] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 03/06/2021] [Accepted: 03/12/2021] [Indexed: 11/13/2022] Open
Abstract
P2RX2 encodes the P2X2 receptor, which is an adenosine triphosphate (ATP) gated (purinoreceptor) ion channel. P2RX2 c. 178G > T (p.V60L) mutation was previously identified in two unrelated Chinese families, as the cause of human DFNA41, a form of dominant, early-onset and progressive sensorineural hearing loss. We generated and characterized a knock-in mouse model based on human p.V60L mutation that recapitulates the human phenotype. Heterozygous KI mice started to exhibit hearing loss at 21-day-old and progressed to deafness by 6-month-old. Vestibular dysfunction was also observed in mutant mice. Abnormal morphology of the inner hair cells and ribbon synapses was progressively observed in KI animals suggesting that P2rx2 plays a role in the membrane spatial location of the ribbon synapses. These results suggest that P2rx2 is essential for acoustic information transfer, which can be the molecular mechanism related to hearing loss.
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Affiliation(s)
- Xiaoya Chen
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Clemer Abad
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Zheng-Yi Chen
- Department of Otolaryngology and Program in Neuroscience, Harvard Medical School and Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, USA
| | - Juan I Young
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Channabasavaiah B Gurumurthy
- Mouse Genome Engineering Core Facility, Vice Chancellor for Research Office, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Katherina Walz
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Xue Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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Illes P, Müller CE, Jacobson KA, Grutter T, Nicke A, Fountain SJ, Kennedy C, Schmalzing G, Jarvis MF, Stojilkovic SS, King BF, Di Virgilio F. Update of P2X receptor properties and their pharmacology: IUPHAR Review 30. Br J Pharmacol 2020; 178:489-514. [PMID: 33125712 PMCID: PMC8199792 DOI: 10.1111/bph.15299] [Citation(s) in RCA: 164] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 12/20/2022] Open
Abstract
The known seven mammalian receptor subunits (P2X1–7) form cationic channels gated by ATP. Three subunits compose a receptor channel. Each subunit is a polypeptide consisting of two transmembrane regions (TM1 and TM2), intracellular N- and C-termini, and a bulky extracellular loop. Crystallization allowed the identification of the 3D structure and gating cycle of P2X receptors. The agonist-binding pocket is located at the intersection of two neighbouring subunits. In addition to the mammalian P2X receptors, their primitive ligand-gated counterparts with little structural similarity have also been cloned. Selective agonists for P2X receptor subtypes are not available, but medicinal chemistry supplied a range of subtype-selective antagonists, as well as positive and negative allosteric modulators. Knockout mice and selective antagonists helped to identify pathological functions due to defective P2X receptors, such as male infertility (P2X1), hearing loss (P2X2), pain/cough (P2X3), neuropathic pain (P2X4), inflammatory bone loss (P2X5), and faulty immune reactions (P2X7).
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Affiliation(s)
- Peter Illes
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany.,International Collaborative Centre on Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Thomas Grutter
- University of Strasbourg, Centre National de la Recherche Scientifique, CAMB UMR 7199, Strasbourg, France
| | - Annette Nicke
- Walther Straub Institute for Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Charles Kennedy
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Günther Schmalzing
- Institute of Clinical Pharmacology, RWTH Aachen University, Aachen, Germany
| | | | - Stanko S Stojilkovic
- Section on Cellular Signaling, The Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Brian F King
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Francesco Di Virgilio
- Department of Medical Sciences, Section of Experimental Medicine, University of Ferrara, Ferrara, Italy
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Cochlear homeostasis: a molecular physiological perspective on maintenance of sound transduction and auditory neurotransmission with noise and ageing. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.09.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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