1
|
Zhang J, Gao L, Zhang Y, Wang H, Sun S, Wu L. Involvement of microglial P2X7 receptor in pain modulation. CNS Neurosci Ther 2024; 30:e14496. [PMID: 37950524 PMCID: PMC10805404 DOI: 10.1111/cns.14496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 08/23/2023] [Accepted: 10/02/2023] [Indexed: 11/12/2023] Open
Abstract
BACKGROUND Pain is a rapid response mechanism that compels organisms to retreat from the harmful stimuli and triggers a repair response. Nonetheless, when pain persists for extended periods, it can lead to adverse changes into in the individual's brain, negatively impacting their emotional state and overall quality of life. Microglia, the resident immune cells in the central nervous system (CNS), play a pivotal role in regulating a variety of pain-related disorders. Specifically, recent studies have shed light on the central role that microglial purinergic ligand-gated ion channel 7 receptor (P2X7R) plays in regulating pain. In this respect, the P2X7R on microglial membranes represents a potential therapeutic target. AIMS To expound on the intricate link between microglial P2X7R and pain, offering insights into potential avenues for future research. METHODS We reviewed 140 literature and summarized the important role of microglial P2X7R in regulating pain, including the structure and function of P2X7R, the relationship between P2X7R and microglial polarization, P2X7R-related signaling pathways, and the effects of P2X7R antagonists on pain regulation. RESULTS P2X7R activation is related to M1 polarization of microglia, while suppressing P2X7R can transfer microglia from M1 into M2 phenotype. And targeting the P2X7R-mediated signaling pathways helps to explore new therapy for pain alleviation. P2X7R antagonists also hold potential for translational and clinical applications in pain management. CONCLUSIONS Microglial P2X7R holds promise as a potential novel pharmacological target for clinical treatments due to its distinctive structure, function, and the development of antagonists.
Collapse
Affiliation(s)
- Jing Zhang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Department of Pediatric Dentistry, School of StomatologyThe Fourth Military Medical UniversityXi'anShaanxiChina
| | - Lei Gao
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Department of Pediatric Dentistry, School of StomatologyThe Fourth Military Medical UniversityXi'anShaanxiChina
| | - Yaoyuan Zhang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Department of Pediatric Dentistry, School of StomatologyThe Fourth Military Medical UniversityXi'anShaanxiChina
| | - Haozhen Wang
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Department of Pediatric Dentistry, School of StomatologyThe Fourth Military Medical UniversityXi'anShaanxiChina
| | - Shukai Sun
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Department of Pediatric Dentistry, School of StomatologyThe Fourth Military Medical UniversityXi'anShaanxiChina
| | - Li‐an Wu
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Department of Pediatric Dentistry, School of StomatologyThe Fourth Military Medical UniversityXi'anShaanxiChina
| |
Collapse
|
2
|
Spekker E, Nagy-Grócz G, Vécsei L. Ion Channel Disturbances in Migraine Headache: Exploring the Potential Role of the Kynurenine System in the Context of the Trigeminovascular System. Int J Mol Sci 2023; 24:16574. [PMID: 38068897 PMCID: PMC10706278 DOI: 10.3390/ijms242316574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/13/2023] [Accepted: 11/16/2023] [Indexed: 12/18/2023] Open
Abstract
Migraine is a primary headache disorder, which is an enormous burden to the healthcare system. While some aspects of the pathomechanism of migraines remain unknown, the most accepted theory is that activation and sensitization of the trigeminovascular system are essential during migraine attacks. In recent decades, it has been suggested that ion channels may be important participants in the pathogenesis of migraine. Numerous ion channels are expressed in the peripheral and central nervous systems, including the trigeminovascular system, affecting neuron excitability, synaptic energy homeostasis, inflammatory signaling, and pain sensation. Dysfunction of ion channels could result in neuronal excitability and peripheral or central sensitization. This narrative review covers the current understanding of the biological mechanisms leading to activation and sensitization of the trigeminovascular pain pathway, with a focus on recent findings on ion channel activation and modulation. Furthermore, we focus on the kynurenine pathway since this system contains kynurenic acid, which is an endogenous glutamate receptor antagonist substance, and it has a role in migraine pathophysiology.
Collapse
Affiliation(s)
| | - Gábor Nagy-Grócz
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, H-6725 Szeged, Hungary;
- Faculty of Health Sciences and Social Studies, University of Szeged, H-6726 Szeged, Hungary
- Preventive Health Sciences Research Group, Incubation Competence Centre of the Centre of Excellence for Interdisciplinary Research, Development and Innovation of the University of Szeged, H-6725 Szeged, Hungary
| | - László Vécsei
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, H-6725 Szeged, Hungary;
- HUN-REN-SZTE Neuroscience Research Group, University of Szeged, H-6725 Szeged, Hungary
| |
Collapse
|
3
|
Neck Pain in Fibromyalgia: Treatment with Exercise and Mesotherapy. Biomedicines 2023; 11:biomedicines11030892. [PMID: 36979871 PMCID: PMC10045341 DOI: 10.3390/biomedicines11030892] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/16/2023] Open
Abstract
Background and Objectives: Fibromyalgia is a very common musculoskeletal disease. The purpose of this study is to assess, on a population of fibromyalgic patients, the clinical efficacy of antalgic mesotherapy with diclofenac and thiocolchicoside in the treatment of cervical pain reduction for improvement of the functional capacity and quality of life of these patients. Materials and Methods: We conducted an observational study of 78 fibromyalgia patients recruited using our hospital database. Based on the different types of treatment received, the patients were divided into two groups: the treatment group (TG), who received antalgic mesotherapy with diclofenac, thiococolchicoside, and mepivacaina; and the placebo group (PG), who received mesotherapy with sodium chloride solution. Patients in both groups also received the same rehabilitation protocol of 20 sessions. The primary outcome evaluated was the extent of pain. The secondary outcomes were the functional capacity and quality of life. Results: Pain improved both in the treatment group (7.4 ± 1.2 vs. 5.1 ± 1.1; p < 0.05) and placebo group (7.5 ± 1.4 vs. 6.1 ± 1.6; p < 0.05). The treatment group, compared to the placebo group, also showed significant statistical improvements in functional capacity (NDI: 35.6 ± 5.23 vs. 19.3 ± 3.41; p < 0.05) and quality of life (SF-12: 18.3 ± 4.11 vs. 33.1 ± 2.41; p < 0.05). Conclusions: Mesotherapy treatment with diclofenac and thiocolchicoside is a safe and effective procedure in the management of neck pain in fibromyalgia patients in the short term in terms of pain reduction, functional recovery and quality of life.
Collapse
|
4
|
Ren WJ, Illes P. Involvement of P2X7 receptors in chronic pain disorders. Purinergic Signal 2021; 18:83-92. [PMID: 34799827 PMCID: PMC8850523 DOI: 10.1007/s11302-021-09796-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 05/11/2021] [Indexed: 02/07/2023] Open
Abstract
Chronic pain is caused by cellular damage with an obligatory inflammatory component. In response to noxious stimuli, high levels of ATP leave according to their concentration gradient, the intracellular space through discontinuities generated in the plasma membrane or diffusion through pannexin-1 hemichannels, and activate P2X7Rs localized at peripheral and central immune cells. Because of the involvement of P2X7Rs in immune functions and especially the initiation of macrophage/microglial and astrocytic secretion of cytokines, chemokines, prostaglandins, proteases, reactive oxygen, and nitrogen species as well as the excitotoxic glutamate/ATP, this receptor type has a key role in chronic pain processes. Microglia are equipped with a battery of pattern recognition receptors that detect pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS) from bacterial infections or danger associated molecular patterns (DAMPs) such as ATP. The co-stimulation of these receptors leads to the activation of the NLRP3 inflammasome and interleukin-1β (IL-1β) release. In the present review, we invite you to a journey through inflammatory and neuropathic pain, primary headache, and regulation of morphine analgesic tolerance, in the pathophysiology of which P2X7Rs are centrally involved. P2X7R bearing microglia and astrocyte-like cells playing eminent roles in chronic pain will be also discussed.
Collapse
Affiliation(s)
- Wen-Jing Ren
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
| | - Peter Illes
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China.
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, 04109, Leipzig, Germany.
| |
Collapse
|
5
|
D’Amico R, Fusco R, Siracusa R, Impellizzeri D, Peritore AF, Gugliandolo E, Interdonato L, Sforza AM, Crupi R, Cuzzocrea S, Genovese T, Cordaro M, Di Paola R. Inhibition of P2X7 Purinergic Receptor Ameliorates Fibromyalgia Syndrome by Suppressing NLRP3 Pathway. Int J Mol Sci 2021; 22:ijms22126471. [PMID: 34208781 PMCID: PMC8234677 DOI: 10.3390/ijms22126471] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/11/2021] [Accepted: 06/14/2021] [Indexed: 12/12/2022] Open
Abstract
Fibromyalgia is a chronic condition characterized by persistent widespread pain that significantly reduces quality of life in patients. The purinergic P2X7 receptor (P2X7R) seems to be involved in different pain states and neuroinflammation. The purpose of this study is to investigate the positive effects of P2X7R inhibition by the antagonist Brilliant Blue G (BBG) in a rat model of reserpine-induced fibromyalgia. Sprague-Dawley male rats were injected with 1 mg/kg of reserpine for three consecutive days. Later, animals were administered BBG (50 mg/kg) intraperitoneally for seven days. Reserpine injections induced a significant increase in pain pro-inflammatory mediators as well as a significant increase in neuroinflammation. Chronic pain, in turn, led to depressive-like symptoms and reduced neurogenesis. Blockage of P2X7R by BBG administrations is able to attenuate the behavioral deficits, pain mediators and microglial activation induced by reserpine injection. Additionally, BBG prevents NLRP3 inflammasome activation and consequently the release of active interleukin (IL)-1 and IL-18, involved in the activation of nociceptors. In conclusion, these results suggest that inhibition of P2X7R should be further investigated to develop a potential approach for the management of fibromyalgia.
Collapse
Affiliation(s)
- Ramona D’Amico
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
| | - Roberta Fusco
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
| | - Rosalba Siracusa
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
| | - Daniela Impellizzeri
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
| | - Alessio Filippo Peritore
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
| | - Enrico Gugliandolo
- Department of Veterinary Sciences, University of Messina, 98168 Messina, Italy; (E.G.); (R.C.)
| | - Livia Interdonato
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
| | - Andrea Maria Sforza
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
| | - Rosalia Crupi
- Department of Veterinary Sciences, University of Messina, 98168 Messina, Italy; (E.G.); (R.C.)
| | - Salvatore Cuzzocrea
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
- Correspondence: (S.C.); (T.G.); Tel.: +39-090-676-5208 (S.C. & T.G.)
| | - Tiziana Genovese
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
- Correspondence: (S.C.); (T.G.); Tel.: +39-090-676-5208 (S.C. & T.G.)
| | - Marika Cordaro
- Department of Biomedical, Dental and Morphological and Functional Imaging, University of Messina, via Consolare Valeria, 98125 Messina, Italy;
| | - Rosanna Di Paola
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy; (R.D.); (R.F.); (R.S.); (D.I.); (A.F.P.); (L.I.); or (A.M.S.); (R.D.P.)
| |
Collapse
|
6
|
Inoue H, Kuroda H, Ofusa W, Oyama S, Kimura M, Ichinohe T, Shibukawa Y. Functional Coupling between the P2X 7 Receptor and Pannexin-1 Channel in Rat Trigeminal Ganglion Neurons. Int J Mol Sci 2021; 22:ijms22115978. [PMID: 34205953 PMCID: PMC8198496 DOI: 10.3390/ijms22115978] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/19/2021] [Accepted: 05/27/2021] [Indexed: 11/16/2022] Open
Abstract
The ionotropic P2X receptor, P2X7, is believed to regulate and/or generate nociceptive pain, and pain in several neuropathological diseases. Although there is a known relationship between P2X7 receptor activity and pain sensing, its detailed functional properties in trigeminal ganglion (TG) neurons remains unclear. We examined the electrophysiological and pharmacological characteristics of the P2X7 receptor and its functional coupling with other P2X receptors and pannexin-1 (PANX1) channels in primary cultured rat TG neurons, using whole-cell patch-clamp recordings. Application of ATP and Bz-ATP induced long-lasting biphasic inward currents that were more sensitive to extracellular Bz-ATP than ATP, indicating that the current was carried by P2X7 receptors. While the biphasic current densities of the first and second components were increased by Bz-ATP in a concentration dependent manner; current duration was only affected in the second component. These currents were significantly inhibited by P2X7 receptor antagonists, while only the second component was inhibited by P2X1, 3, and 4 receptor antagonists, PANX1 channel inhibitors, and extracellular ATPase. Taken together, our data suggests that autocrine or paracrine signaling via the P2X7-PANX1-P2X receptor/channel complex may play important roles in several pain sensing pathways via long-lasting neuronal activity driven by extracellular high-concentration ATP following tissue damage in the orofacial area.
Collapse
Affiliation(s)
- Hiroyuki Inoue
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
- Department of Dental Anesthesiology, Tokyo Dental College, Tokyo 101-0061, Japan;
| | - Hidetaka Kuroda
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
- Department of Dental Anesthesiology, Kanagawa Dental University, Kanagawa 238-8580, Japan
| | - Wataru Ofusa
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
| | - Sadao Oyama
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
| | - Tatsuya Ichinohe
- Department of Dental Anesthesiology, Tokyo Dental College, Tokyo 101-0061, Japan;
| | - Yoshiyuki Shibukawa
- Department of Physiology, Tokyo Dental College, Tokyo 101-0061, Japan; (H.I.); (H.K.); (W.O.); (S.O.); (M.K.)
- Correspondence:
| |
Collapse
|
7
|
Chen SP, Qin T, Seidel JL, Zheng Y, Eikermann M, Ferrari MD, van den Maagdenberg AMJM, Moskowitz MA, Ayata C, Eikermann-Haerter K. Inhibition of the P2X7-PANX1 complex suppresses spreading depolarization and neuroinflammation. Brain 2017; 140:1643-1656. [PMID: 28430869 DOI: 10.1093/brain/awx085] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 02/12/2017] [Indexed: 01/09/2023] Open
Abstract
Spreading depolarization is a wave of neuronal and glial depolarization. Within minutes after spreading depolarization, the neuronal hemichannel pannexin 1 (PANX1) opens and forms a pore complex with the ligand-gated cation channel P2X7, allowing the release of excitatory neurotransmitters to sustain spreading depolarization and activate neuroinflammation. Here, we explore the hypothesis that the P2X7-PANX1 pore complex is a critical determinant of spreading depolarization susceptibility with important consequences for neuroinflammation and trigeminovascular activation. We found that genetic loss of function or ablation of the P2x7 gene inhibits spreading depolarization. Moreover, pharmacological suppression of the P2X7-PANX1 pore complex inhibits spreading depolarization in mice carrying the human familial hemiplegic migraine type 1 R192Q missense mutation as well as in wild-type mice and rats. Pore inhibitors elevate the electrical threshold for spreading depolarization, and reduce spreading depolarization frequency and amplitude. Pore inhibitors also suppress downstream consequences of spreading depolarization such as upregulation of interleukin-1 beta, inducible nitric oxide synthase and cyclooxygenase-2 in the cortex after spreading depolarization. In addition, they inhibit surrogates for trigeminovascular activation, including expression of calcitonin gene-related peptide in the trigeminal ganglion and c-Fos in the trigeminal nucleus caudalis. Our results are consistent with the hypothesis that the P2X7-PANX1 pore complex is a critical determinant of spreading depolarization susceptibility and its downstream consequences, of potential relevance to its signature disorders such as migraine.
Collapse
Affiliation(s)
- Shih-Pin Chen
- Neurovascular Research Lab, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Tao Qin
- Neurovascular Research Lab, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Jessica L Seidel
- Neurovascular Research Lab, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Yi Zheng
- Neurovascular Research Lab, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Matthias Eikermann
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, MA and Universitaet Duisburg Essen, Essen, Germany
| | - Michel D Ferrari
- Department of Neurology, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands
| | - Arn M J M van den Maagdenberg
- Department of Neurology, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands.,Department of Human Genetics, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands
| | - Michael A Moskowitz
- Stroke and Neurovascular Regulation Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Cenk Ayata
- Neurovascular Research Lab, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Stroke Service and Neuroscience Intensive Care Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Katharina Eikermann-Haerter
- Neurovascular Research Lab, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| |
Collapse
|
8
|
Mittal R, Chan B, Grati M, Mittal J, Patel K, Debs LH, Patel AP, Yan D, Chapagain P, Liu XZ. Molecular Structure and Regulation of P2X Receptors With a Special Emphasis on the Role of P2X2 in the Auditory System. J Cell Physiol 2015; 231:1656-70. [PMID: 26627116 DOI: 10.1002/jcp.25274] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 12/01/2015] [Indexed: 12/23/2022]
Abstract
The P2X purinergic receptors are cation-selective channels gated by extracellular adenosine 5'-triphosphate (ATP). These purinergic receptors are found in virtually all mammalian cell types and facilitate a number of important physiological processes. Within the past few years, the characterization of crystal structures of the zebrafish P2X4 receptor in its closed and open states has provided critical insights into the mechanisms of ligand binding and channel activation. Understanding of this gating mechanism has facilitated to design and interpret new modeling and structure-function experiments to better elucidate how different agonists and antagonists can affect the receptor with differing levels of potency. This review summarizes the current knowledge on the structure, activation, allosteric modulators, function, and location of the different P2X receptors. Moreover, an emphasis on the P2X2 receptors has been placed in respect to its role in the auditory system. In particular, the discovery of three missense mutations in P2X2 receptors could become important areas of study in the field of gene therapy to treat progressive and noise-induced hearing loss. J. Cell. Physiol. 231: 1656-1670, 2016. © 2015 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Rahul Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Brandon Chan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - M'hamed Grati
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Jeenu Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Kunal Patel
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Luca H Debs
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Amit P Patel
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Prem Chapagain
- Department of Physics, Florida International University, Miami, Florida.,Biomolecular Science Institute, Florida International University, Miami, Florida
| | - Xue Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida.,Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida.,Department of Biochemistry, University of Miami Miller School of Medicine, Miami, Florida
| |
Collapse
|