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Knezic A, Budusan E, Saez NJ, Broughton BRS, Rash LD, King GF, Widdop RE, McCarthy CA. Hi1a Improves Sensorimotor Deficit following Endothelin-1-Induced Stroke in Rats but Does Not Improve Functional Outcomes following Filament-Induced Stroke in Mice. ACS Pharmacol Transl Sci 2024; 7:1043-1054. [PMID: 38638162 PMCID: PMC11022283 DOI: 10.1021/acsptsci.3c00328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 02/07/2024] [Accepted: 03/04/2024] [Indexed: 04/20/2024]
Abstract
Activation of acid-sensing ion channel 1a (ASIC1a) plays a major role in mediating acidosis-induced neuronal injury following a stroke. Therefore, the inhibition of ASIC1a is a potential therapeutic avenue for the treatment of stroke. Venom-peptide Hi1a, a selective and highly potent ASIC1a inhibitor, reduces the infarct size and functional deficits when injected into the brain after stroke in rodents. However, its efficacy when administered using a clinically relevant route of administration remains to be established. Therefore, the current investigation aims to examine the efficacy of systemically administered Hi1a, using two different models of stroke in different species. Mice were subjected to the filament model of middle cerebral artery occlusion (MCAO) and treated with Hi1a systemically using either a single- or multiple-dosing regimen. 24 h poststroke, mice underwent functional testing, and the brain infarct size was assessed. Rats were subjected to endothelin-1 (ET-1)-induced MCAO and treated with Hi1a intravenously 2 h poststroke. Rats underwent functional tests prior to and for 3 days poststroke, when infarct volume was assessed. Mice receiving Hi1a did not show any improvements in functional outcomes, despite a trend toward reduced infarct size. This trend for reduced infarct size in mice was consistent regardless of the dosing regimen. There was also a trend toward lower infarct size in rats treated with Hi1a. More specifically, Hi1a reduced the amount of damage occurring within the somatosensory cortex, which was associated with an improved sensorimotor function in Hi1a-treated rats. Thus, this study suggests that Hi1a or more brain-permeable ASIC1a inhibitors are a potential stroke treatment.
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Affiliation(s)
- Adriana Knezic
- Cardiovascular Disease Program, Monash Biomedicine
Discovery Institute (BDI), Department of Pharmacology, Monash
University, Clayton, VIC 3800, Australia
| | - Elena Budusan
- School of Biomedical Sciences, Faculty of Medicine,
The University of Queensland, St Lucia, QLD 4072,
Australia
| | - Natalie J. Saez
- Institute for Molecular Bioscience, The
University of Queensland, St Lucia, QLD 4072,
Australia
- Australian Research Council Centre of Excellence for
Innovations in Peptide and Protein Science, The University of
Queensland, St Lucia, QLD 4072, Australia
| | - Brad R. S. Broughton
- Cardiovascular Disease Program, Monash Biomedicine
Discovery Institute (BDI), Department of Pharmacology, Monash
University, Clayton, VIC 3800, Australia
| | - Lachlan D. Rash
- School of Biomedical Sciences, Faculty of Medicine,
The University of Queensland, St Lucia, QLD 4072,
Australia
| | - Glenn F. King
- Institute for Molecular Bioscience, The
University of Queensland, St Lucia, QLD 4072,
Australia
- Australian Research Council Centre of Excellence for
Innovations in Peptide and Protein Science, The University of
Queensland, St Lucia, QLD 4072, Australia
| | - Robert E. Widdop
- Cardiovascular Disease Program, Monash Biomedicine
Discovery Institute (BDI), Department of Pharmacology, Monash
University, Clayton, VIC 3800, Australia
| | - Claudia A. McCarthy
- Cardiovascular Disease Program, Monash Biomedicine
Discovery Institute (BDI), Department of Pharmacology, Monash
University, Clayton, VIC 3800, Australia
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Wang H, Li Z, Cao G, Tang L, Zhou R, Li C, Zhang J, Wu H, Li X, Yang H. Targeted Energy Metabolomics Combined with Spatial Metabolomics Study on the Efficacy of Guhong Injection Against Cerebral Ischemia Reperfusion. Mol Neurobiol 2023; 60:5533-5547. [PMID: 37328677 DOI: 10.1007/s12035-023-03403-x] [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: 02/05/2023] [Accepted: 05/23/2023] [Indexed: 06/18/2023]
Abstract
Optimizing the metabolic phenotype to improve cerebral function is critical for treatment of cerebral ischemia-reperfusion (I/R) injury. Guhong injection (GHI), which comprised safflower extract and aceglutamide, is widely prescribed in Chinese medicine for the treatment of cerebrovascular diseases. In this study, a combination of LC-QQQ-MS and MALDI-MSI were utilized to explore tissue-specific metabolic alterations in the brain of I/R, as well as to evaluate the therapeutic effect of GHI. Pharmacological evaluation demonstrated that GHI can significantly improve infarction rate, neurological deficit, cerebral blood flow, and neuronal damage in I/R rats. Based on LC-QQQ-MS, 23 energy metabolites were found to be significantly altered in the I/R group compared to the sham group (P < 0.05). After GHI treatment, 12 metabolites, including G6P, TPP, NAD, citrate, succinate, malate, ATP, GTP, GDP, ADP, NADP, and FMN showed a significant tendency of returning to baseline values (P < 0.05). Based on MALDI-MSI, 4 metabolites in glycolysis and TCA, 4 metabolites in nucleic acid metabolism, 4 amino acid metabolites, and 6 metabolites were discovered and compared between the different groups in the four special regions of cortex, hippocampus, hypothalamus, and striatum. Parts of these were found to have significant changes after I/R in the special brain region, and were regulated by GHI. The study provides comprehensive and detailed information for specific metabolic reprogramming of brain tissue in rats with I/R, and the therapeutic effect of GHI. Schema describing the discovery strategies of integrated LC-MS and MALDI-MSI to identify cerebral ischemia reperfusion metabolic reprogramming and GHI therapeutic effects.
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Affiliation(s)
- Huanhuan Wang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Dong Nei Nan Xiao Jie 16, Beijing, 100700, China
| | - Zhenkun Li
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Dong Nei Nan Xiao Jie 16, Beijing, 100700, China
| | - Guangzhao Cao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Dong Nei Nan Xiao Jie 16, Beijing, 100700, China
| | - Liying Tang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Dong Nei Nan Xiao Jie 16, Beijing, 100700, China.
| | - Rui Zhou
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Dong Nei Nan Xiao Jie 16, Beijing, 100700, China
| | - Caifeng Li
- Experimental Research Centre, China Academy of Chinese Medical Sciences, Beijing, 100700, China
| | - Jingjing Zhang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Dong Nei Nan Xiao Jie 16, Beijing, 100700, China.
- Chinese Institute for Brain Research, Beijing, 102206, China.
| | - Hongwei Wu
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Dong Nei Nan Xiao Jie 16, Beijing, 100700, China.
| | - Xianyu Li
- Experimental Research Centre, China Academy of Chinese Medical Sciences, Beijing, 100700, China
| | - Hongjun Yang
- Experimental Research Centre, China Academy of Chinese Medical Sciences, Beijing, 100700, China
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3
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Cao Y, Redd MA, Fang C, Mizikovsky D, Li X, Macdonald PS, King GF, Palpant NJ. New Drug Targets and Preclinical Modelling Recommendations for Treating Acute Myocardial Infarction. Heart Lung Circ 2023:S1443-9506(23)00139-7. [PMID: 37230806 DOI: 10.1016/j.hlc.2022.12.015] [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: 09/05/2022] [Revised: 11/28/2022] [Accepted: 12/15/2022] [Indexed: 05/27/2023]
Abstract
Acute myocardial infarction (AMI) is the leading cause of morbidity and mortality worldwide and the primary underlying risk factor for heart failure. Despite decades of research and clinical trials, there are no drugs currently available to prevent organ damage from acute ischaemic injuries of the heart. In order to address the increasing global burden of heart failure, drug, gene, and cell-based regeneration technologies are advancing into clinical testing. In this review we highlight the burden of disease associated with AMI and the therapeutic landscape based on market analyses. New studies revealing the role of acid-sensitive cardiac ion channels and other proton-gated ion channels in cardiac ischaemia are providing renewed interest in pre- and post-conditioning agents with novel mechanisms of action that may also have implications for gene- and cell-based therapeutics. Furthermore, we present guidelines that couple new cell technologies and data resources with traditional animal modelling pipelines to help de-risk drug candidates aimed at treating AMI. We propose that improved preclinical pipelines and increased investment in drug target identification for AMI is critical to stem the increasing global health burden of heart failure.
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Affiliation(s)
- Yuanzhao Cao
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld, Australia
| | - Meredith A Redd
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld, Australia
| | - Chen Fang
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld, Australia
| | - Dalia Mizikovsky
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld, Australia
| | - Xichun Li
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld, Australia
| | - Peter S Macdonald
- Cardiopulmonary Transplant Unit, St Vincent's Hospital, Sydney, NSW, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld, Australia; Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Qld, Australia
| | - Nathan J Palpant
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld, Australia.
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Shedenkova MO, Stelmashook EV, Isaev NK. Toxic Effect of Zinc Ions Is Accompanied by Acidification of the Cytoplasm in Cultured Rat Cerebellar Granule Neurons. Bull Exp Biol Med 2022; 173:539-543. [DOI: 10.1007/s10517-022-05578-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Indexed: 10/14/2022]
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Duggan NM, Saez NJ, Clayton D, Budusan E, Watson EE, Tucker IJ, Rash LD, King GF, Payne RJ. Total Synthesis of the Spider-Venom Peptide Hi1a. Org Lett 2021; 23:8375-8379. [PMID: 34632783 DOI: 10.1021/acs.orglett.1c03112] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Hi1a is a venom peptide from the Australian funnel-web spider Hadronyche infensa with a complex tertiary structure. Hi1a has neuroprotective and cardioprotective properties due to its potent inhibition of acid-sensing ion channel 1a (ASIC1a) and is currently being pursued as a novel therapy for acute ischemic events. Herein, we describe the total synthesis of Hi1a using native chemical ligation. The synthetic peptide was successfully folded and exhibited similar inhibitory activity on ASIC1a to recombinant Hi1a.
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Affiliation(s)
- Nisharnthi M Duggan
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW 2006, Australia
| | - Natalie J Saez
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Daniel Clayton
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW 2006, Australia
| | - Elena Budusan
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Emma E Watson
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW 2006, Australia
| | - Isaac J Tucker
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Lachlan D Rash
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Richard J Payne
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, NSW 2006, Australia
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6
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Abstract
Cardiac arrest results from a broad range of etiologies that can be broadly grouped as sudden and asphyxial. Animal studies point to differences in injury pathways invoked in the heart and brain that drive injury and outcome after these different forms of cardiac arrest. Present guidelines largely ignore etiology in their management recommendations. Existing clinical data reveal significant heterogeneity in the utility of presently employed resuscitation and postresuscitation strategies based on etiology. The development of future neuroprotective and cardioprotective therapies should also take etiology into consideration to optimize the chances for successful translation.
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William M, Turnadzic S, Chu XP. Commentary: Therapeutic Potential of Targeting the Auto-Inhibition of ASIC1a for Neuroprotection Against Ischemic Brain Injury. Front Pharmacol 2020; 11:604892. [PMID: 33390995 PMCID: PMC7774517 DOI: 10.3389/fphar.2020.604892] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 10/08/2020] [Indexed: 01/28/2023] Open
Affiliation(s)
- Matthew William
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Sejla Turnadzic
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Xiang-Ping Chu
- Department of Biomedical Sciences, School of Medicine, University of Missouri-Kansas City, Kansas City, MO, United States
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Kozin SV, Kravtsov AA, Zlischeva EI, Shurygina LV, Malyshko VV, Moiseev AV, Elkina AA, Baryshev MG. The Influence of a Deuterium Depleted Drinking Diet on the Functional State of the Central Nervous System of Animals in Hypoxia. Biophysics (Nagoya-shi) 2020. [DOI: 10.1134/s0006350920060093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Extracellular mild acidosis decreases the Ca 2+ permeability of the human NMDA receptors. Cell Calcium 2019; 80:63-70. [PMID: 30978540 DOI: 10.1016/j.ceca.2019.04.001] [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: 01/07/2019] [Revised: 03/20/2019] [Accepted: 04/03/2019] [Indexed: 11/20/2022]
Abstract
NMDA receptors (NMDARs) are glutamate-gated ion channels involved in excitatory synaptic transmission and in others physiological processes such as synaptic plasticity and development. The overload of Ca2+ ions through NMDARs, caused by an excessive activation of receptors, leads to excitotoxic neuronal cell death. For this reason, the reduction of Ca2+ flux through NMDARs has been a central focus in finding therapeutic strategies to prevent neuronal cell damage. Extracellular H+ are allosteric modulators of NMDARs. Starting from previous studies showing that extracellular mild acidosis reduces NMDA-evoked whole cell currents, we analyzed the effects of this condition on the NMDARs Ca2+ permeability, measured as "fractional calcium current" (Pf, i.e. the percentage of the total current carried by Ca2+ ions), of human NMDARs NR1/NR2A and NR1/NR2B transiently transfected in HeLa cells. Extracellular mild acidosis significantly reduces Pf of both human NR1/NR2A and NR1/NR2B NMDARs, also decreasing single channel conductance in outside out patches for NR1/NR2A receptor. Reduction of Ca2+ flux through NMDARs was also confirmed in cortical neurons in culture. A comparative analysis of both NMDA evoked Ca2+ transients and whole cell currents showed that extracellular H+ differentially modulate the permeation of Na+ and Ca2+ through NMDARs. Our data highlight the synergy of two distinct neuroprotective mechanisms during acidosis: Ca2+ entry through NMDARs is lowered due to the modulation of both open probability and Ca2+ permeability. Furthermore, this study provides the proof of concept that it is possible to reduce Ca2+ overload in neurons modulating the NMDAR Ca2+ permeability.
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Potent neuroprotection after stroke afforded by a double-knot spider-venom peptide that inhibits acid-sensing ion channel 1a. Proc Natl Acad Sci U S A 2017; 114:3750-3755. [PMID: 28320941 DOI: 10.1073/pnas.1614728114] [Citation(s) in RCA: 146] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Stroke is the second-leading cause of death worldwide, yet there are no drugs available to protect the brain from stroke-induced neuronal injury. Acid-sensing ion channel 1a (ASIC1a) is the primary acid sensor in mammalian brain and a key mediator of acidosis-induced neuronal damage following cerebral ischemia. Genetic ablation and selective pharmacologic inhibition of ASIC1a reduces neuronal death following ischemic stroke in rodents. Here, we demonstrate that Hi1a, a disulfide-rich spider venom peptide, is highly neuroprotective in a focal model of ischemic stroke. Nuclear magnetic resonance structural studies reveal that Hi1a comprises two homologous inhibitor cystine knot domains separated by a short, structurally well-defined linker. In contrast with known ASIC1a inhibitors, Hi1a incompletely inhibits ASIC1a activation in a pH-independent and slowly reversible manner. Whole-cell, macropatch, and single-channel electrophysiological recordings indicate that Hi1a binds to and stabilizes the closed state of the channel, thereby impeding the transition into a conducting state. Intracerebroventricular administration to rats of a single small dose of Hi1a (2 ng/kg) up to 8 h after stroke induction by occlusion of the middle cerebral artery markedly reduced infarct size, and this correlated with improved neurological and motor function, as well as with preservation of neuronal architecture. Thus, Hi1a is a powerful pharmacological tool for probing the role of ASIC1a in acid-mediated neuronal injury and various neurological disorders, and a promising lead for the development of therapeutics to protect the brain from ischemic injury.
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Purification of serine protease from polychaeta, Lumbrineris nipponica, and assessment of its fibrinolytic activity. In Vitro Cell Dev Biol Anim 2017; 53:494-501. [PMID: 28283876 DOI: 10.1007/s11626-017-0137-2] [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] [Received: 07/17/2016] [Accepted: 01/24/2017] [Indexed: 10/20/2022]
Abstract
Ischemic stroke and cardiovascular disease can occur from blockage of blood vessels by fibrin clots formed naturally in the body. Therapeutic drugs of anticoagulant or thrombolytic agents have been studied; however, various problems have been reported such as side effects and low efficacy. Thus, development of new candidates that are more effective and safe is necessary. The objective of this study is to evaluate fibrinolytic activity, anti-coagulation, and characterization of serine protease purified from Lumbrineris nipponica, polychaeta, for new thrombolytic agents. In the present study, we isolated and identified a new fibrinolytic serine protease from L. nipponica. The N-terminal sequence of the identified serine protease was EAMMDLADQLEQSLN, which is not homologous with any known serine protease. The size of the purified serine protease was 28 kDa, and the protein purification yield was 12.7%. The optimal enzyme activity was observed at 50°C and pH 2.0. A fibrin plate assay confirmed that indirect fibrinolytic activity of the purified serine protease was higher than that of urokinase-PA, whereas direct fibrinolytic activity, which causes bleeding side effects, was relatively low. The serine protease did not induce any cytotoxicity toward the endothelial cell line. In addition, anticoagulant activity was verified by an in vivo DVT animal model system. These results suggest that serine protease purified from L. nipponica has the potential to be an alternative fibrinolytic agent for the treatment of thrombosis and use in various biomedical applications.
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Identification of a new serine protease from polychaeta, Marphysa sanguinea, for its thrombolytic and anticoagulant activity. KOREAN J CHEM ENG 2017. [DOI: 10.1007/s11814-016-0331-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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13
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Wang YC, Li WZ, Wu Y, Yin YY, Dong LY, Chen ZW, Wu WN. Acid-sensing ion channel 1a contributes to the effect of extracellular acidosis on NLRP1 inflammasome activation in cortical neurons. J Neuroinflammation 2015; 12:246. [PMID: 26715049 PMCID: PMC4696203 DOI: 10.1186/s12974-015-0465-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 12/20/2015] [Indexed: 12/23/2022] Open
Abstract
Background Acid-sensing ion channels (ASICs) are cation channels which were activated by extracellular acidosis and involved in various physiological and pathological processes in the nervous system. Inflammasome is a key component of the innate immune response in host against harmful and irritable stimuli. As the first discovered molecular platform, NLRP1 (nucleotide-binding oligomerization domain (NOD)-like receptor protein 1) inflammasome is expressed in neurons and implicated in many nervous system diseases such as brain injury, nociception and epilepsy. However, little is known about the effect of ASICs on NLRP1 inflammasome activation under acidosis. Methods The expression of inflammasome complex protein (NLRP1, ASC (apoptosis-associated speck-like protein containing a caspase-activating recruitment domain) and caspase-1), inflammatory cytokines (IL-1β and IL-18), and apoptosis-related protein (Bax, Bcl-2, and activated caspase-3) was detected by Western blot. Large-conductance Ca2+ and voltage-activated K+ (BK) channel currents were recorded by whole-cell patch-clamp technology. Measurement of [K+]i was performed by fluorescent ion imaging system. Co-expression of ASICs and BK channels was determined by dual immunofluorescence. Cell viability was assessed by MTT and LDH kit. Results ASICs and BK channels were co-expressed in primary cultured cortical neurons. Extracellular acidosis increased the expression of NLRP1, ASC, caspase-1, IL-1β, and IL-18. Further mechanistic studies revealed that acidosis-induced ASIC1a activation results in the increase of BK channel currents, with the subsequent K+ efflux and a low concentration of intracellular K+, which activated NLRP1 inflammasome. Furthermore, these effects of acidosis could be blocked by specific ASIC1a inhibitor PcTX1 and BK channel inhibitor IbTX. The data also demonstrated neutralization of NLRP1-protected cortical neurons against injury induced by extracellular acidosis. Conclusions Our data showed that NLRP1 inflammasome could be activated by extracellular acidosis though ASIC-BK channel K+ signal pathway and was involved in extracellular acidosis-induced cortical neuronal injury. Electronic supplementary material The online version of this article (doi:10.1186/s12974-015-0465-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yu-Chan Wang
- Department of Pharmacology, Key Laboratory of Anti-inflammatory and Immunopharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, China.
| | - Wei-Zu Li
- Department of Pharmacology, Key Laboratory of Anti-inflammatory and Immunopharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, China.
| | - Yu Wu
- Department of Pharmacology, Key Laboratory of Anti-inflammatory and Immunopharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, China.
| | - Yan-Yan Yin
- Department of Pharmacology, Key Laboratory of Anti-inflammatory and Immunopharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, China.
| | - Liu-Yi Dong
- Department of Pharmacology, Key Laboratory of Anti-inflammatory and Immunopharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, China.
| | - Zhi-Wu Chen
- Department of Pharmacology, Key Laboratory of Anti-inflammatory and Immunopharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, China.
| | - Wen-Ning Wu
- Department of Pharmacology, Key Laboratory of Anti-inflammatory and Immunopharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, China.
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McCarthy CA, Rash LD, Chassagnon IR, King GF, Widdop RE. PcTx1 affords neuroprotection in a conscious model of stroke in hypertensive rats via selective inhibition of ASIC1a. Neuropharmacology 2015; 99:650-7. [DOI: 10.1016/j.neuropharm.2015.08.040] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/18/2015] [Accepted: 08/24/2015] [Indexed: 12/18/2022]
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15
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Abstract
Over a period of more than 300 million years, spiders have evolved complex venoms containing an extraordinary array of toxins for prey capture and defense against predators. The major components of most spider venoms are small disulfide-bridged peptides that are highly stable and resistant to proteolytic degradation. Moreover, many of these peptides have high specificity and potency toward molecular targets of therapeutic importance. This unique combination of bioactivity and stability has made spider-venom peptides valuable both as pharmacological tools and as leads for drug development. This review describes recent advances in spider-venom-based drug discovery pipelines. We discuss spider-venom-derived peptides that are currently under investigation for treatment of a diverse range of pathologies including pain, stroke and cancer.
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Marchesi A, Arcangeletti M, Mazzolini M, Torre V. Proton transfer unlocks inactivation in cyclic nucleotide-gated A1 channels. J Physiol 2015; 593:857-70. [PMID: 25480799 DOI: 10.1113/jphysiol.2014.284216] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 11/28/2014] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS Desensitization and inactivation provide a form of short-term memory controlling the firing patterns of excitable cells and adaptation in sensory systems. Unlike many of their cousin K(+) channels, cyclic nucleotide-gated (CNG) channels are thought not to desensitize or inactivate. Here we report that CNG channels do inactivate and that inactivation is controlled by extracellular protons. Titration of a glutamate residue within the selectivity filter destabilizes the pore architecture, which collapses towards a non-conductive, inactivated state in a process reminiscent of the usual C-type inactivation observed in many K(+) channels. These results indicate that inactivation in CNG channels represents a regulatory mechanism that has been neglected thus far, with possible implications in several physiological processes ranging from signal transduction to growth cone navigation. ABSTRACT Ion channels control ionic fluxes across biological membranes by residing in any of three functionally distinct states: deactivated (closed), activated (open) or inactivated (closed). Unlike many of their cousin K(+) channels, cyclic nucleotide-gated (CNG) channels do not desensitize or inactivate. Using patch recording techniques, we show that when extracellular pH (pHo ) is decreased from 7.4 to 6 or lower, wild-type CNGA1 channels inactivate in a voltage-dependent manner. pHo titration experiments show that at pHo < 7 the I-V relationships are outwardly rectifying and that inactivation is coupled to current rectification. Single-channel recordings indicate that a fast mechanism of proton blockage underlines current rectification while inactivation arises from conformational changes downstream from protonation. Furthermore, mutagenesis and ionic substitution experiments highlight the role of the selectivity filter in current decline, suggesting analogies with the C-type inactivation observed in K(+) channels. Analysis with Markovian models indicates that the non-independent binding of two protons within the transmembrane electrical field explains both the voltage-dependent blockage and the inactivation. Low pH, by inhibiting the CNGA1 channels in a state-dependent manner, may represent an unrecognized endogenous signal regulating CNG physiological functions in diverse tissues.
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Affiliation(s)
- Arin Marchesi
- Neurobiology Sector, International School for Advanced Studies (SISSA), Trieste, Italy
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17
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Zhang Y, Li CS, Wu CJ, Yang J, Hang CC. Neuroprotective effect of Shenfu Injection () following cardiac arrest in pig correlates with improved mitochondrial function and cerebral glucose uptake. Chin J Integr Med 2014; 20:835-43. [PMID: 25411019 DOI: 10.1007/s11655-014-1890-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Indexed: 01/03/2023]
Abstract
OBJECTIVE To test whether Shenfu Injection (, SFI) might attenuate the impact of cerebral energy dysfunction after resuscitation in a pig model of cardiac arrest (CA). METHODS Thirty-four Wuzhishan miniature inbred pigs were randomly divided into three groups: the SFI group (n=12), the saline group (SA group, n=12), and the sham-operated group (sham group, n=10). Following successful return of spontaneous circulation (ROSC) from 8-min untreated ventricular fibrillation, animals received a continuous infusion of either SFI (0.2 mL/min) or saline for 6 h. Cerebral performance category score was evaluated at 24 and 48 h after ROSC, followed by positron emission tomography and computed tomography scans of cerebral glucose uptake. Surviving pigs were euthanized 48 h after ROSC, and the brains were removed for detecting mitochondrial function. RESULTS Compared with the SA group, SFI treatment produced a better neurologic outcome 48 h after ROSC (P<0.05). However, there was no significant difference of survival rate between the SA and SFI groups (83.3% vs. 81.8%, P>0.05). After ROSC, the SA group showed a decrease in the maximum standardized uptake value of different regions in the brain tissue, where SFI treatment can ameliorate these decreases (P<0.01 or P<0.05). Improved mitochondrial respiratory properties and higher mitochondrial membrane potential were also found following SFI treatment compared with the SA group at 48 h after ROSC (P<0.05 or P<0.01). CONCLUSION SFI treatment after resuscitation has significant neuroprotective effects against disruption of cerebral energy metabolism from CA by improving glucose uptake and by normalizing mitochondrial function.
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Affiliation(s)
- Yi Zhang
- Department of Hyperbaric Oxygen, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, 100020, China
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18
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Pekun TG, Hrynevich SV, Waseem TV, Fedorovich SV. Role of iron, zinc and reduced glutathione in oxidative stress induction by low pH in rat brain synaptosomes. SPRINGERPLUS 2014; 3:560. [PMID: 25332861 PMCID: PMC4190190 DOI: 10.1186/2193-1801-3-560] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 09/23/2014] [Indexed: 01/01/2023]
Abstract
Brain ischemia leads to a decrease in pHo. We have shown previously in synaptosomes that the extracellular acidification induces depolarization of mitochondria followed by synthesis of superoxide anions and oxidative stress. Here, we investigated the effects of lowered pHo on oxidative stress and membrane potentials in synaptosomes treated by the iron chelator deferoxamine and zinc chelator TPEN. We demonstrated that chelating of metals has no impact on superoxide anion synthesis and intrasynaptosomal mitochondria depolarization. Meanwhile, deferoxamine was able to inhibit oxidative stress induced by low pHo and hydrogen peroxide application. Compared to deferoxamine, TPEN was less effective but it decreased the DCF fluorescence induced by pHo 6.0 which had no effects in other oxidative stress models. We found that the chelators were able to inhibit slightly plasma membrane depolarization. Synaptosomes preincubation at low pHo caused no effects on the reduced glutathione level. Depletion of glutathione by CDNB produced no additional increase in the DCF fluorescence induced by pHo 7.0. Our results suggest that free iron is crucial for the development of oxidative stress elicited by acidification in synaptosomes. Chelating of this metal seems to be a promising strategy for protecting the neuronal presynaptic terminals against oxidative stress developed at stroke.
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Affiliation(s)
- Tatyana G Pekun
- Laboratory of Biophysics and Engineering of Cell, Institute of Biophysics and Cell Engineering, Akademicheskaya St., 27, Minsk, 220072 Belarus
| | - Sviatlana V Hrynevich
- Laboratory of Biophysics and Engineering of Cell, Institute of Biophysics and Cell Engineering, Akademicheskaya St., 27, Minsk, 220072 Belarus
| | - Tatyana V Waseem
- INSERM UMR1106, Institut de Neurosciences des Systems, Aix-Marseille University, Marseille, France
| | - Sergei V Fedorovich
- Laboratory of Biophysics and Engineering of Cell, Institute of Biophysics and Cell Engineering, Akademicheskaya St., 27, Minsk, 220072 Belarus
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Zhao L, Li H, Guo R, Ma T, Hou R, Ma X, Du Y. miR-137, a new target for post-stroke depression? Neural Regen Res 2014; 8:2441-8. [PMID: 25206554 PMCID: PMC4146110 DOI: 10.3969/j.issn.1673-5374.2013.26.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 07/11/2013] [Indexed: 12/17/2022] Open
Abstract
Expression of miR-137 is downregulated in brain tissue from patients with depression and suicidal behavior, and is also downregulated in peripheral blood from stroke patients. However, it is not yet known if miR-137 acts as a bridge between stroke and depression. To test this, we used middle cerebral artery occlusion and chronic mild stress to establish a post-stroke depression model in rats. Compared with controls, we found significantly lower miR-137 levels in the brain and peripheral blood from post-stroke depression rats. Injection of a miR-137 antagonist into the brain ventricles upregulated miR-137 levels, and improved behavioral changes in post-stroke depression rats. Luciferase assays showed miR-137 bound to the 3’UTR of Grin2A, regulating Grin2A expression in a neuronal cell line. Grin2A gene overexpression in the brain of post-stroke depression rats, noticeably suppressed the inhibitory effect of miR-137 on post-stroke depression. Overall, our results show that miR-137 suppresses Grin2A protein expression through binding to Grin2A mRNA, thereby exerting an inhibitory effect on post-stroke depression. Our results offer a new therapeutic direction for post-stroke depression.
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Affiliation(s)
- Lixia Zhao
- Department of Neurology, Shandong Provincial Hospital, Jinan 250021, Shandong Province, China ; Department of Neurology, Haici Hospital Affiliated to Medical College of Qingdao University, Qingdao 266033, Shandong Province, China
| | - Huazi Li
- Department of Medical Imaging, Haici Hospital Affiliated to Medical College of Qingdao University, Qingdao 266033, Shandong Province, China
| | - Ruiyou Guo
- Department of Neurology, Haici Hospital Affiliated to Medical College of Qingdao University, Qingdao 266033, Shandong Province, China
| | - Teng Ma
- Department of Neurology, Haici Hospital Affiliated to Medical College of Qingdao University, Qingdao 266033, Shandong Province, China
| | - Rongyao Hou
- Department of Neurology, Haici Hospital Affiliated to Medical College of Qingdao University, Qingdao 266033, Shandong Province, China
| | - Xiaowei Ma
- Department of Neurology, Haici Hospital Affiliated to Medical College of Qingdao University, Qingdao 266033, Shandong Province, China
| | - Yifeng Du
- Department of Neurology, Shandong Provincial Hospital, Jinan 250021, Shandong Province, China
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Stelmashook EV, Novikova SV, Amelkina GA, Genrikhs EE, Khaspekov LG, Isaev NK. The mechanism of the neurocytotoxic effect of the Na+/H+ exchange inhibitor 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) in the rat cerebellum cultured granule neurons. NEUROCHEM J+ 2014. [DOI: 10.1134/s181971241402010x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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21
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Abstract
Why do neurons sense extracellular acid? In large part, this question has driven increasing investigation on acid-sensing ion channels (ASICs) in the CNS and the peripheral nervous system for the past two decades. Significant progress has been made in understanding the structure and function of ASICs at the molecular level. Studies aimed at clarifying their physiological importance have suggested roles for ASICs in pain, neurological and psychiatric disease. This Review highlights recent findings linking these channels to physiology and disease. In addition, it discusses some of the implications for therapy and points out questions that remain unanswered.
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22
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Zha XM. Acid-sensing ion channels: trafficking and synaptic function. Mol Brain 2013; 6:1. [PMID: 23281934 PMCID: PMC3562204 DOI: 10.1186/1756-6606-6-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 12/20/2012] [Indexed: 01/05/2023] Open
Abstract
Extracellular acidification occurs in the brain with elevated neural activity, increased metabolism, and neuronal injury. This reduction in pH can have profound effects on brain function because pH regulates essentially every single biochemical reaction. Therefore, it is not surprising to see that Nature evolves a family of proteins, the acid-sensing ion channels (ASICs), to sense extracellular pH reduction. ASICs are proton-gated cation channels that are mainly expressed in the nervous system. In recent years, a growing body of literature has shown that acidosis, through activating ASICs, contributes to multiple diseases, including ischemia, multiple sclerosis, and seizures. In addition, ASICs play a key role in fear and anxiety related psychiatric disorders. Several recent reviews have summarized the importance and therapeutic potential of ASICs in neurological diseases, as well as the structure-function relationship of ASICs. However, there is little focused coverage on either the basic biology of ASICs or their contribution to neural plasticity. This review will center on these topics, with an emphasis on the synaptic role of ASICs and molecular mechanisms regulating the spatial distribution and function of these ion channels.
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Affiliation(s)
- Xiang-ming Zha
- Department of Cell Biology and Neuroscience, College of Medicine, University of South Alabama, 307 University Blvd, MSB1201, Mobile, AL 36688, USA.
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23
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Weilinger NL, Maslieieva V, Bialecki J, Sridharan SS, Tang PL, Thompson RJ. Ionotropic receptors and ion channels in ischemic neuronal death and dysfunction. Acta Pharmacol Sin 2013; 34:39-48. [PMID: 22864302 DOI: 10.1038/aps.2012.95] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Loss of energy supply to neurons during stroke induces a rapid loss of membrane potential that is called the anoxic depolarization. Anoxic depolarizations result in tremendous physiological stress on the neurons because of the dysregulation of ionic fluxes and the loss of ATP to drive ion pumps that maintain electrochemical gradients. In this review, we present an overview of some of the ionotropic receptors and ion channels that are thought to contribute to the anoxic depolarization of neurons and subsequently, to cell death. The ionotropic receptors for glutamate and ATP that function as ligand-gated cation channels are critical in the death and dysfunction of neurons. Interestingly, two of these receptors (P2X7 and NMDAR) have been shown to couple to the pannexin-1 (Panx1) ion channel. We also discuss the important roles of transient receptor potential (TRP) channels and acid-sensing ion channels (ASICs) in responses to ischemia. The central challenge that emerges from our current understanding of the anoxic depolarization is the need to elucidate the mechanistic and temporal interrelations of these ion channels to fully appreciate their impact on neurons during stroke.
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Pekun TG, Lemeshchenko VV, Lyskova TI, Waseem TV, Fedorovich SV. Influence of intra- and extracellular acidification on free radical formation and mitochondria membrane potential in rat brain synaptosomes. J Mol Neurosci 2012; 49:211-22. [PMID: 23124485 DOI: 10.1007/s12031-012-9913-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 10/21/2012] [Indexed: 11/25/2022]
Abstract
Brain ischemia is accompanied by lowering of intra- and extracellular pH. Stroke often leads to irreversible damage of synaptic transmission by unknown mechanism. We investigated an influence of lowering of pH(i) and pH(o) on free radical formation in synaptosomes. Three models of acidosis were used: (1) pH(o) 6.0 corresponding to pH(i) decrease down to 6.04; (2) pH(o) 7.0 corresponding to the lowering of pH(i) down to 6.92: (3) 1 mM amiloride corresponding to pH(i) decrease down to 6.65. We have shown that both types of extracellular acidification, but not intracellular acidification, increase 2',7'-dichlorodihydrofluorescein diacetate fluorescence that reflects free radical formation. These three treatments induce the rise of the dihydroethidium fluorescence that reports synthesis of superoxide anion. However, the impact of amiloride on superoxide anion synthesis was less than that induced by moderate extracellular acidification. Superoxide anion synthesis at pH(o) 7.0 was almost completely eliminated by mitochondrial uncoupler carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone. Furthermore, using fluorescent dyes JC-1 and rhodamine-123, we confirmed that pH(o) lowering, but not intracellular acidification, led to depolarization of intrasynaptosomal mitochondria. We have shown that pH(o) but not pH(i) lowering led to oxidative stress in neuronal presynaptic endings that might underlie the long-term irreversible changing in synaptic transmission.
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Affiliation(s)
- Tatyana G Pekun
- Laboratory of Biophysics and Engineering of Cell, Institute of Biophysics and Cell Engineering, Akademicheskaya St., 27, Minsk 220072, Belarus
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25
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Potential implication of the chemical properties and bioactivity of nitrone spin traps for therapeutics. Future Med Chem 2012; 4:1171-207. [PMID: 22709256 DOI: 10.4155/fmc.12.74] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Nitrone therapeutics has been employed in the treatment of oxidative stress-related diseases such as neurodegeneration, cardiovascular disease and cancer. The nitrone-based compound NXY-059, which is the first drug to reach clinical trials for the treatment of acute ischemic stroke, has provided promise for the development of more robust pharmacological agents. However, the specific mechanism of nitrone bioactivity remains unclear. In this review, we present a variety of nitrone chemistry and biological activity that could be implicated for the nitrone's pharmacological activity. The chemistries of spin trapping and spin adduct reveal insights on the possible roles of nitrones for altering cellular redox status through radical scavenging or nitric oxide donation, and their biological effects are presented. An interdisciplinary approach towards the development of novel synthetic antioxidants with improved pharmacological properties encompassing theoretical, synthetic, biochemical and in vitro/in vivo studies is covered.
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Stelmashook EV, Isaev NK, Lozier ER, Goryacheva ES, Khaspekov LG. Role of Glutamine in Neuronal Survival and Death During Brain Ischemia and Hypoglycemia. Int J Neurosci 2011; 121:415-22. [DOI: 10.3109/00207454.2011.570464] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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27
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Wang Y, Xu T. Ion channels in neuronal survival. SCIENCE CHINA-LIFE SCIENCES 2010; 53:342-347. [DOI: 10.1007/s11427-010-0060-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Accepted: 01/19/2010] [Indexed: 02/06/2023]
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Isaev NK, Stelmashook EV, Lukin SV, Freyer D, Mergenthaler P, Zorov DB. Acidosis-induced zinc-dependent death of cultured cerebellar granule neurons. Cell Mol Neurobiol 2010; 30:877-83. [PMID: 20373017 DOI: 10.1007/s10571-010-9516-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 03/18/2010] [Indexed: 12/16/2022]
Abstract
Severe acidosis caused death of cultured cerebellar granule neurons (CGNs). Acidosis was accompanied by a progressive increase of the intracellular zinc ions ([Zn(2+)](i)) and decrease of [Ca(2+)](i). Zn(2+) chelator, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), prevented the increase of [Zn(2+)](i) and acidosis-induced neuronal death. However, neuronal death was insensitive to blockade of ASIC1 channels with amiloride, as CGNs display considerably lower expression of ASIC1a than other neurons. The antioxidant trolox and menadione significantly protected neurons from acidotic death. Earlier, we demonstrated that menadione rescues neurons from the deleterious effect of inhibition of mitochondrial complex I (Isaev et al. Neuroreport 15:2227-2231, 2004). We speculate that excessive Zn(2+)-dependent production of reactive oxygen species by mitochondrial complex I may be a general motive for the induction of cell death in CGNs under acidotic conditions.
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Affiliation(s)
- Nikolay K Isaev
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia, 119992.
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29
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Starkus JG, Fleig A, Penner R. The calcium-permeable non-selective cation channel TRPM2 is modulated by cellular acidification. J Physiol 2010; 588:1227-40. [PMID: 20194125 DOI: 10.1113/jphysiol.2010.187476] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
TRPM2 is a calcium-permeable non-selective cation channel expressed in the plasma membrane and in lysosomes that is critically involved in aggravating reactive oxygen species (ROS)-induced inflammatory processes and has been implicated in cell death. TRPM2 is gated by ADP-ribose (ADPR) and modulated by physiological processes that produce peroxide, cyclic ADP-ribose (cADPR), nicotinamide adenine dinucleotide phosphate (NAADP) and Ca(2+). We investigated the role of extra- and intracellular acidification on heterologously expressed TRPM2 in HEK293 cells. Our results show that TRPM2 is inhibited by external acidification with an IC(50) of pH 6.5 and is completely suppressed by internal pH of 6. Current inhibition requires channel opening and is strongly voltage dependent, being most effective at negative potentials. In addition, increased cytosolic pH buffering capacity or elevated [Ca(2+)](i) reduces the rate of current inactivation elicited by extracellular acidification, and Na(+) and Ca(2+) influence the efficacy of proton-induced inactivation. Together, these results suggest that external protons permeate TRPM2 channels to gain access to an intracellular site that regulates channel activity. Consistent with this notion, single-channel measurements in HEK293 cells reveal that internal protons induce channel closure without affecting single-channel conductance, whereas external protons affect channel open probability as well as single-channel conductance of native TRPM2 in neutrophils. We conclude that protons compete with Na(+) and Ca(2+) for channel permeation and channel closure results from a competitive antagonism of protons at an intracellular Ca(2+) binding site.
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Affiliation(s)
- John G Starkus
- University of Hawaii, Pacific Biosciences Research Center, Queens Medical Center, University Tower, 814, 1356 Lusitania Street, Honolulu, HI 96813, USA.
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Evaluation of the role of nitric oxide in acid sensing ion channel mediated cell death. Nitric Oxide 2010; 22:213-9. [PMID: 20045740 DOI: 10.1016/j.niox.2009.12.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 12/24/2009] [Accepted: 12/29/2009] [Indexed: 11/22/2022]
Abstract
Acid sensing ion channels (ASICs) are widely expressed in central and peripheral nervous system. They are involved in a variety of physiological and pathophysiological processes: synaptic transmission, learning and memory, pain perception, ischemia, etc. During ischemia, metabolic acidosis causes the drop of extracellular pH (pHe) which in turn activates ASICs. Activation of calcium permeable ASIC1a has been implicated in neuronal death. ASICs are modulated by several redox reagents, divalent cations and nitric oxide (NO). Although NO potentiates ASIC mediated currents, the physiological significance of such modulation has not been studied in detail. We have evaluated the role of endogenous NO in cell death at different pH, mediated by the activation of ASICs. At pH 6.1, death rates of ASIC1 expressing Neuro2A (N2A) cells are significantly higher in comparison to the cells that do not express ASICs. Amiloride, a blocker of ASICs protects the cell from acid-injury. Sodium nitroprusside, a potent NO donor not only increases the ASIC mediated currents but also increases cell death at low pH. L-Arg, the precursor of NO also potentiates ASICs in a pH dependent manner. L-Arg-induced NO production and potentiation of ASICs were observed at pHs 7.4, 7.2, 7.0 and 6.8. Lowering the pH below 6.8 did not result in significant production of NO or potentiation of ASICs upon L-Arg stimulation. Our results suggest that potentiation of ASICs by NO and subsequent cell death in vivo depends on the severity of acidosis. During mild and moderate acidosis, NO promotes cell death by potentiating ASICs, whereas this potentiation subsides in severe acidosis due to inhibition of NO synthase.
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Cho GS, Choi IY, Choi YK, Kim SK, Cai Y, Nho K, Lee JC. Attenuated Cerebral Ischemic Injury by Polyethylene Glycol-Conjugated Hemoglobin. Biomol Ther (Seoul) 2009. [DOI: 10.4062/biomolther.2009.17.3.270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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