1
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Kysilov B, Kuchtiak V, Hrcka Krausova B, Balik A, Korinek M, Fili K, Dobrovolski M, Abramova V, Chodounska H, Kudova E, Bozikova P, Cerny J, Smejkalova T, Vyklicky L. Disease-associated nonsense and frame-shift variants resulting in the truncation of the GluN2A or GluN2B C-terminal domain decrease NMDAR surface expression and reduce potentiating effects of neurosteroids. Cell Mol Life Sci 2024; 81:36. [PMID: 38214768 PMCID: PMC10786987 DOI: 10.1007/s00018-023-05062-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 11/16/2023] [Accepted: 11/21/2023] [Indexed: 01/13/2024]
Abstract
N-methyl-D-aspartate receptors (NMDARs) play a critical role in normal brain function, and variants in genes encoding NMDAR subunits have been described in individuals with various neuropsychiatric disorders. We have used whole-cell patch-clamp electrophysiology, fluorescence microscopy and in-silico modeling to explore the functional consequences of disease-associated nonsense and frame-shift variants resulting in the truncation of GluN2A or GluN2B C-terminal domain (CTD). This study characterizes variant NMDARs and shows their reduced surface expression and synaptic localization, altered agonist affinity, increased desensitization, and reduced probability of channel opening. We also show that naturally occurring and synthetic steroids pregnenolone sulfate and epipregnanolone butanoic acid, respectively, enhance NMDAR function in a way that is dependent on the length of the truncated CTD and, further, is steroid-specific, GluN2A/B subunit-specific, and GluN1 splice variant-specific. Adding to the previously described effects of disease-associated NMDAR variants on the receptor biogenesis and function, our results improve the understanding of the molecular consequences of NMDAR CTD truncations and provide an opportunity for the development of new therapeutic neurosteroid-based ligands.
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Affiliation(s)
- Bohdan Kysilov
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic
- Stony Brook University, Stony Brook, 100 Nicolls Road, NY, 11794, USA
| | - Viktor Kuchtiak
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic
- Faculty of Science, Charles University, Albertov 2038, 12800, Prague 2, Czech Republic
| | - Barbora Hrcka Krausova
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic
| | - Ales Balik
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic
| | - Miloslav Korinek
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic
| | - Klevinda Fili
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic
- Third Faculty of Medicine, Charles University, Ruska 87, 10000, Prague 10, Czech Republic
| | - Mark Dobrovolski
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic
- Third Faculty of Medicine, Charles University, Ruska 87, 10000, Prague 10, Czech Republic
| | - Vera Abramova
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic
- Third Faculty of Medicine, Charles University, Ruska 87, 10000, Prague 10, Czech Republic
| | - Hana Chodounska
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo Nam. 2, 16610, Prague 6, Czech Republic
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo Nam. 2, 16610, Prague 6, Czech Republic
| | - Paulina Bozikova
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 25250, Vestec, Czech Republic
| | - Jiri Cerny
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic
| | - Tereza Smejkalova
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic.
| | - Ladislav Vyklicky
- Laboratory of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, 14200, Prague 4, Czech Republic.
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2
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Abramova V, Leal Alvarado V, Hill M, Smejkalova T, Maly M, Vales K, Dittert I, Bozikova P, Kysilov B, Hrcka Krausova B, Vyklicky V, Balik A, Fili K, Korinek M, Chodounska H, Kudova E, Ciz D, Martinovic J, Cerny J, Bartunek P, Vyklicky L. Effects of Pregnanolone Glutamate and Its Metabolites on GABA A and NMDA Receptors and Zebrafish Behavior. ACS Chem Neurosci 2023; 14:1870-1883. [PMID: 37126803 PMCID: PMC10198160 DOI: 10.1021/acschemneuro.3c00131] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 04/11/2023] [Indexed: 05/03/2023] Open
Abstract
Multiple molecular targets have been identified to mediate membrane-delimited and nongenomic effects of natural and synthetic steroids, but the influence of steroid metabolism on neuroactive steroid signaling is not well understood. To begin to address this question, we set out to identify major metabolites of a neuroprotective synthetic steroid 20-oxo-5β-pregnan-3α-yl l-glutamyl 1-ester (pregnanolone glutamate, PAG) and characterize their effects on GABAA and NMDA receptors (GABARs, NMDARs) and their influence on zebrafish behavior. Gas chromatography-mass spectrometry was used to assess concentrations of PAG and its metabolites in the hippocampal tissue of juvenile rats following intraperitoneal PAG injection. PAG is metabolized in the peripheral organs and nervous tissue to 20-oxo-17α-hydroxy-5β-pregnan-3α-yl l-glutamyl 1-ester (17-hydroxypregnanolone glutamate, 17-OH-PAG), 3α-hydroxy-5β-pregnan-20-one (pregnanolone, PA), and 3α,17α-dihydroxy-5β-pregnan-20-one (17-hydroxypregnanolone, 17-OH-PA). Patch-clamp electrophysiology experiments in cultured hippocampal neurons demonstrate that PA and 17-OH-PA are potent positive modulators of GABARs, while PAG and 17-OH-PA have a moderate inhibitory effect at NMDARs. PAG, 17-OH-PA, and PA diminished the locomotor activity of zebrafish larvae in a dose-dependent manner. Our results show that PAG and its metabolites are potent modulators of neurotransmitter receptors with behavioral consequences and indicate that neurosteroid-based ligands may have therapeutic potential.
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Affiliation(s)
- Vera Abramova
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
- Charles
University, Third Faculty of Medicine, Ruska 87, 100 00 Prague 10,Czech Republic
| | - Vanessa Leal Alvarado
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Martin Hill
- Institute
of Endocrinology, Narodni
8, 116 94 Prague
1, Czech Republic
| | - Tereza Smejkalova
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Michal Maly
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Karel Vales
- Institute
of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
- National
Institute of Mental Health, Topolova 748, 250 67 Klecany, Czech Republic
| | - Ivan Dittert
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Paulina Bozikova
- Institute
of Biotechnology CAS, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Bohdan Kysilov
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Barbora Hrcka Krausova
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Vojtech Vyklicky
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Ales Balik
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Klevinda Fili
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
- Charles
University, Third Faculty of Medicine, Ruska 87, 100 00 Prague 10,Czech Republic
| | - Miloslav Korinek
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Hana Chodounska
- Institute
of Organic Chemistry and Biochemistry CAS, Flemingovo nam. 2, 166 10 Prague 2, Czech Republic
| | - Eva Kudova
- Institute
of Organic Chemistry and Biochemistry CAS, Flemingovo nam. 2, 166 10 Prague 2, Czech Republic
| | - David Ciz
- IT4Innovations
National Supercomputing Center, Studentska 6231/1B, 708 00 Ostrava-Poruba, Czech Republic
| | - Jan Martinovic
- IT4Innovations
National Supercomputing Center, Studentska 6231/1B, 708 00 Ostrava-Poruba, Czech Republic
| | - Jiri Cerny
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Petr Bartunek
- Institute
of Molecular Genetics CAS, Videnska 1083, 142 20 Prague, Czech Republic
- CZ-OPENSCREEN, Institute of
Molecular Genetics CAS, Videnska 1083, 142
20 Prague 4, Czech Republic
| | - Ladislav Vyklicky
- Laboratory
of Cellular Neurophysiology, Institute of
Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
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Kysilov B, Hrcka Krausova B, Vyklicky V, Smejkalova T, Korinek M, Horak M, Chodounska H, Kudova E, Cerny J, Vyklicky L. Pregnane-based steroids are novel positive NMDA receptor modulators that may compensate for the effect of loss-of-function disease-associated GRIN mutations. Br J Pharmacol 2022; 179:3970-3990. [PMID: 35318645 DOI: 10.1111/bph.15841] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 02/24/2022] [Accepted: 03/04/2022] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND AND PURPOSE N-methyl-D-aspartate receptors (NMDARs) play a critical role in synaptic plasticity, and mutations in human genes encoding NMDAR subunits have been described in individuals with various neuropsychiatric disorders. Compounds with a positive allosteric effect are thought to compensate for reduced receptor function. EXPERIMENTAL APPROACH We have used whole-cell patch-clamp electrophysiology on recombinant rat NMDARs and human variants found in individuals with neuropsychiatric disorders, in combination with in silico modelling, to explore the site of action of novel epipregnanolone-based NMDAR modulators. KEY RESULTS Analysis of the action of 4-(20-oxo-5β-pregnan-3β-yl) butanoic acid (EPA-But) at the NMDAR indicates that the effect of this steroid with a "bent" structure is different from that of cholesterol and oxysterols and shares a disuse-dependent mechanism of NMDAR potentiation with the "planar" steroid 20-oxo-pregn-5-en-3β-yl sulfate (PE-S). The potentiating effects of EPA-But and PE-S are additive. Alanine scan mutagenesis identified residues that reduce the potentiating effect of EPA-But. No correlation was found between the effects of EPA-But and PE-S at mutated receptors that were less sensitive to either steroid. The relative degree of potentiation induced by the two steroids also differed in human NMDARs carrying rare variants of hGluN1 or hGluN2B subunits found in individuals with neuropsychiatric disorders, including intellectual disability, epilepsy, developmental delay, and autism spectrum disorder. CONCLUSION AND IMPLICATIONS Our results show novel sites of action for pregnanolones at the NMDAR and provide an opportunity for the development of new therapeutic neurosteroid-based ligands to treat diseases associated with glutamatergic system hypofunction.
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Affiliation(s)
- Bohdan Kysilov
- Institute of Physiology CAS, Prague 4, Czech Republic.,Third Faculty of Medicine, Charles University in Prague, Prague 10, Czech Republic
| | | | | | | | | | - Martin Horak
- Institute of Physiology CAS, Prague 4, Czech Republic
| | - Hana Chodounska
- Institute of Organic Chemistry and Biochemistry CAS, Prague 6, Czech Republic
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry CAS, Prague 6, Czech Republic
| | - Jiri Cerny
- Institute of Physiology CAS, Prague 4, Czech Republic
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4
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Smejkalova T, Korinek M, Krusek J, Hrcka Krausova B, Candelas Serra M, Hajdukovic D, Kudova E, Chodounska H, Vyklicky L. Endogenous neurosteroids pregnanolone and pregnanolone sulfate potentiate presynaptic glutamate release through distinct mechanisms. Br J Pharmacol 2021; 178:3888-3904. [PMID: 33988248 PMCID: PMC8518729 DOI: 10.1111/bph.15529] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 03/23/2021] [Accepted: 05/06/2021] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Neurosteroids influence neuronal function and have multiple promising clinical applications. Direct modulation of postsynaptic neurotransmitter receptors by neurosteroids is well characterized, but presynaptic effects remain poorly understood. Here, we report presynaptic glutamate release potentiation by neurosteroids pregnanolone and pregnanolone sulfate and compare their mechanisms of action to phorbol 12,13-dibutyrate (PDBu), a mimic of the second messenger DAG. EXPERIMENTAL APPROACH We use whole-cell patch-clamp electrophysiology and pharmacology in rat hippocampal microisland cultures and total internal reflection fluorescence (TIRF) microscopy in HEK293 cells expressing GFP-tagged vesicle priming protein Munc13-1, to explore the mechanisms of neurosteroid presynaptic modulation. KEY RESULTS Pregnanolone sulfate and pregnanolone potentiate glutamate release downstream of presynaptic Ca2+ influx, resembling the action of a phorbol ester PDBu. PDBu partially occludes the effect of pregnanolone, but not of pregnanolone sulfate. Calphostin C, an inhibitor that disrupts DAG binding to its targets, reduces the effect PDBu and pregnanolone, but not of pregnanolone sulfate, suggesting that pregnanolone might interact with a well-known DAG/phorbol ester target Munc13-1. However, TIRF microscopy experiments found no evidence of pregnanolone-induced membrane translocation of GFP-tagged Munc13-1, suggesting that pregnanolone may regulate Munc13-1 indirectly or interact with other DAG targets. CONCLUSION AND IMPLICATIONS We describe a novel presynaptic effect of neurosteroids pregnanolone and pregnanolone sulfate to potentiate glutamate release downstream of presynaptic Ca2+ influx. The mechanism of action of pregnanolone, but not of pregnanolone sulfate, partly overlaps with that of PDBu. Presynaptic effects of neurosteroids may contribute to their therapeutic potential in the treatment of disorders of the glutamate system.
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Affiliation(s)
- Tereza Smejkalova
- Institute of PhysiologyCzech Academy of SciencesPragueCzech Republic
| | - Miloslav Korinek
- Institute of PhysiologyCzech Academy of SciencesPragueCzech Republic
| | - Jan Krusek
- Institute of PhysiologyCzech Academy of SciencesPragueCzech Republic
| | | | | | | | - Eva Kudova
- Institute of Organic Chemistry and BiochemistryCzech Academy of SciencesPragueCzech Republic
| | - Hana Chodounska
- Institute of Organic Chemistry and BiochemistryCzech Academy of SciencesPragueCzech Republic
| | - Ladislav Vyklicky
- Institute of PhysiologyCzech Academy of SciencesPragueCzech Republic
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Korinek M, Gonzalez-Gonzalez IM, Smejkalova T, Hajdukovic D, Skrenkova K, Krusek J, Horak M, Vyklicky L. Cholesterol modulates presynaptic and postsynaptic properties of excitatory synaptic transmission. Sci Rep 2020; 10:12651. [PMID: 32724221 PMCID: PMC7387334 DOI: 10.1038/s41598-020-69454-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 07/10/2020] [Indexed: 12/22/2022] Open
Abstract
Cholesterol is a structural component of cellular membranes particularly enriched in synapses but its role in synaptic transmission remains poorly understood. We used rat hippocampal cultures and their acute cholesterol depletion by methyl-β-cyclodextrin as a tool to describe the physiological role of cholesterol in glutamatergic synaptic transmission. Cholesterol proved to be a key molecule for the function of synapses as its depletion resulted in a significant reduction of both NMDA receptor (NMDAR) and AMPA/kainate receptor-mediated evoked excitatory postsynaptic currents (eEPSCs), by 94% and 72%, respectively. We identified two presynaptic and two postsynaptic steps of synaptic transmission which are modulated by cholesterol and explain together the above-mentioned reduction of eEPSCs. In the postsynapse, we show that physiological levels of cholesterol are important for maintaining the normal probability of opening of NMDARs and for keeping NMDARs localized in synapses. In the presynapse, our results favour the hypothesis of a role of cholesterol in the propagation of axonal action potentials. Finally, cholesterol is a negative modulator of spontaneous presynaptic glutamate release. Our study identifies cholesterol as an important endogenous regulator of synaptic transmission and provides insight into molecular mechanisms underlying the neurological manifestation of diseases associated with impaired cholesterol synthesis or decomposition.
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Affiliation(s)
- Miloslav Korinek
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic.
| | | | - Tereza Smejkalova
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Dragana Hajdukovic
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Kristyna Skrenkova
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Jan Krusek
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Martin Horak
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Ladislav Vyklicky
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
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Krusek J, Dittert I, Smejkalova T, Korinek M, Gottftriedova K, Freislebenova H, Neuhoferova E, Taylor A, Mortet V, Petrak V, Benson V, Petrakova V. Surface Functionalization of Nanocrystalline and Nanostructured Diamond to Form Interface with Newborn and Adult Neurons. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.706.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jan Krusek
- Institute of Physiology CASPragueCzech Republic
| | | | | | | | | | | | | | | | | | - Vaclav Petrak
- Faculty of Biomedical Engineering CTUKladnoCzech Republic
| | - Veronika Benson
- Institute of Microbiology CASPragueCzech Republic
- Faculty of Biomedical Engineering CTUKladnoCzech Republic
| | - Vladimira Petrakova
- Faculty of Biomedical Engineering CTUKladnoCzech Republic
- Institute of Experimental Physics & Institute of Chemistry and BiochemistryFUBBerlinGermany
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7
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Kaniakova M, Kleteckova L, Lichnerova K, Holubova K, Skrenkova K, Korinek M, Krusek J, Smejkalova T, Korabecny J, Vales K, Soukup O, Horak M. 7-Methoxyderivative of tacrine is a ‘foot-in-the-door’ open-channel blocker of GluN1/GluN2 and GluN1/GluN3 NMDA receptors with neuroprotective activity in vivo. Neuropharmacology 2018; 140:217-232. [DOI: 10.1016/j.neuropharm.2018.08.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/17/2018] [Accepted: 08/07/2018] [Indexed: 10/28/2022]
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Vyklicky V, Krausova B, Cerny J, Ladislav M, Smejkalova T, Kysilov B, Korinek M, Danacikova S, Horak M, Chodounska H, Kudova E, Vyklicky L. Surface Expression, Function, and Pharmacology of Disease-Associated Mutations in the Membrane Domain of the Human GluN2B Subunit. Front Mol Neurosci 2018; 11:110. [PMID: 29681796 PMCID: PMC5897658 DOI: 10.3389/fnmol.2018.00110] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/20/2018] [Indexed: 12/20/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs), glutamate-gated ion channels, mediate signaling at the majority of excitatory synapses in the nervous system. Recent sequencing data for neurological and psychiatric patients have indicated numerous mutations in genes encoding for NMDAR subunits. Here, we present surface expression, functional, and pharmacological analysis of 11 de novo missense mutations of the human hGluN2B subunit (P553L; V558I; W607C; N615I; V618G; S628F; E657G; G820E; G820A; M824R; L825V) located in the pre-M1, M1, M2, M3, and M4 membrane regions. These variants were identified in patients with intellectual disability, developmental delay, epileptic symptomatology, and autism spectrum disorder. Immunofluorescence microscopy indicated that the ratio of surface-to-total NMDAR expression was reduced for hGluN1/hGluN2B(S628F) receptors and increased for for hGluN1/hGluN2B(G820E) receptors. Electrophysiological recordings revealed that agonist potency was altered in hGluN1/hGluN2B(W607C; N615I; and E657G) receptors and desensitization was increased in hGluN1/hGluN2B(V558I) receptors. The probability of channel opening of hGluN1/hGluN2B (V558I; W607C; V618G; and L825V) receptors was diminished ~10-fold when compared to non-mutated receptors. Finally, the sensitivity of mutant receptors to positive allosteric modulators of the steroid origin showed that glutamate responses induced in hGluN1/hGluN2B(V558I; W607C; V618G; and G820A) receptors were potentiated by 59–96% and 406-685% when recorded in the presence of 20-oxo-pregn-5-en-3β-yl sulfate (PE-S) and androst-5-en-3β-yl hemisuccinate (AND-hSuc), respectively. Surprisingly hGluN1/hGluN2B(L825V) receptors were strongly potentiated, by 197 and 1647%, respectively, by PE-S and AND-hSuc. Synaptic-like responses induced by brief glutamate application were also potentiated and the deactivation decelerated. Further, we have used homology modeling based on the available crystal structures of GluN1/GluN2B NMDA receptor followed by molecular dynamics simulations to try to relate the functional consequences of mutations to structural changes. Overall, these data suggest that de novo missense mutations of the hGluN2B subunit located in membrane domains lead to multiple defects that manifest by the NMDAR loss of function that can be rectified by steroids. Our results provide an opportunity for the development of new therapeutic neurosteroid-based ligands to treat diseases associated with hypofunction of the glutamatergic system.
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Affiliation(s)
- Vojtech Vyklicky
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia
| | - Barbora Krausova
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia
| | - Jiri Cerny
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia
| | - Marek Ladislav
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia.,Department of Physiology, Faculty of Science, Charles University, Prague, Czechia
| | - Tereza Smejkalova
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia
| | - Bohdan Kysilov
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia
| | - Miloslav Korinek
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia
| | - Sarka Danacikova
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia.,Department of Physiology, Faculty of Science, Charles University, Prague, Czechia
| | - Martin Horak
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia
| | - Hana Chodounska
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences (CAS), Prague, Czechia
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences (CAS), Prague, Czechia
| | - Ladislav Vyklicky
- Department of Cellular Neurophysiology, Institute of Physiology of the Czech Academy of Sciences (CAS), Prague, Czechia
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9
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Korinek M, El-Shazly M, Tsai YC, Wang LC, Yu ML, Wu YC, Chen BH, Chang FR. Screening for Anti-allergic Activity of Natural Products. Am J Transl Res 2017. [DOI: 10.1055/s-0037-1608097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- M Korinek
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - M El-Shazly
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, Ain-Shams University, Cairo, Egypt
| | - YC Tsai
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - LC Wang
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - ML Yu
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - YC Wu
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
- Research Center for Natural Products & Drug Development, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - BH Chen
- Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - FR Chang
- Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
- Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
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Vyklicky V, Krausova B, Cerny J, Balik A, Zapotocky M, Novotny M, Lichnerova K, Smejkalova T, Kaniakova M, Korinek M, Petrovic M, Kacer P, Horak M, Chodounska H, Vyklicky L. Block of NMDA receptor channels by endogenous neurosteroids: implications for the agonist induced conformational states of the channel vestibule. Sci Rep 2015; 5:10935. [PMID: 26086919 PMCID: PMC4471902 DOI: 10.1038/srep10935] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 05/08/2015] [Indexed: 11/10/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) mediate synaptic plasticity, and their dysfunction is implicated in multiple brain disorders. NMDARs can be allosterically modulated by numerous compounds, including endogenous neurosteroid pregnanolone sulfate. Here, we identify the molecular basis of the use-dependent and voltage-independent inhibitory effect of neurosteroids on NMDAR responses. The site of action is located at the extracellular vestibule of the receptor's ion channel pore and is accessible after receptor activation. Mutations in the extracellular vestibule in the SYTANLAAF motif disrupt the inhibitory effect of negatively charged steroids. In contrast, positively charged steroids inhibit mutated NMDAR responses in a voltage-dependent manner. These results, in combination with molecular modeling, characterize structure details of the open configuration of the NMDAR channel. Our results provide a unique opportunity for the development of new therapeutic neurosteroid-based ligands to treat diseases associated with dysfunction of the glutamate system.
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Affiliation(s)
- Vojtech Vyklicky
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Barbora Krausova
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Jiri Cerny
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Ales Balik
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Martin Zapotocky
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Marian Novotny
- Charles University in Prague, Faculty of Science, Albertov 6, 128 43 Prague 2, Czech Republic
| | | | - Tereza Smejkalova
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Martina Kaniakova
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Miloslav Korinek
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Milos Petrovic
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston, PR1 2HE, UK
- Institute of Medical Physiology, School of Medicine, University of Belgrade, Visegradska 26/II, 11000 Beograd, Srbija
| | - Petr Kacer
- Institute of Chemical Technology—Prague, Technicka 5, 166 28 Prague, Czech Republic
| | - Martin Horak
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Hana Chodounska
- Institute of Organic Chemistry and Biochemistry CAS, Flemingovo nam. 2, 166 10 Prague 2, Czech Republic
| | - Ladislav Vyklicky
- Institute of Physiology CAS, Videnska 1083, 142 20 Prague 4, Czech Republic
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Korinek M, Vyklicky V, Borovska J, Lichnerova K, Kaniakova M, Krausova B, Krusek J, Balik A, Smejkalova T, Horak M, Vyklicky L. Cholesterol modulates open probability and desensitization of NMDA receptors. J Physiol 2015; 593:2279-93. [PMID: 25651798 DOI: 10.1113/jphysiol.2014.288209] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 01/30/2015] [Indexed: 01/14/2023] Open
Abstract
NMDA receptors (NMDARs) are glutamate-gated ion channels that mediate excitatory neurotransmission in the CNS. Although these receptors are in direct contact with plasma membrane, lipid-NMDAR interactions are little understood. In the present study, we aimed at characterizing the effect of cholesterol on the ionotropic glutamate receptors. Whole-cell current responses induced by fast application of NMDA in cultured rat cerebellar granule cells (CGCs) were almost abolished (reduced to 3%) and the relative degree of receptor desensitization was increased (by seven-fold) after acute cholesterol depletion by methyl-β-cyclodextrin. Both of these effects were fully reversible by cholesterol repletion. By contrast, the responses mediated by AMPA/kainate receptors were not affected by cholesterol depletion. Similar results were obtained in CGCs after chronic inhibition of cholesterol biosynthesis by simvastatin and acute enzymatic cholesterol degradation to 4-cholesten-3-one by cholesterol oxidase. Fluorescence anisotropy measurements showed that membrane fluidity increased after methyl-β-cyclodextrin pretreatment. However, no change in fluidity was observed after cholesterol enzymatic degradation, suggesting that the effect of cholesterol on NMDARs is not mediated by changes in membrane fluidity. Our data show that diminution of NMDAR responses by cholesterol depletion is the result of a reduction of the open probability, whereas the increase in receptor desensitization is the result of an increase in the rate constant of entry into the desensitized state. Surface NMDAR population, agonist affinity, single-channel conductance and open time were not altered in cholesterol-depleted CGCs. The results of our experiments show that cholesterol is a strong endogenous modulator of NMDARs.
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Affiliation(s)
| | | | - Jirina Borovska
- Institute of Physiology AS CR, v.v.i, Prague, Czech Republic
| | - Katarina Lichnerova
- Institute of Physiology AS CR, v.v.i, Prague, Czech Republic.,Department of Physiology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | | | - Barbora Krausova
- Institute of Physiology AS CR, v.v.i, Prague, Czech Republic.,Second Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - Jan Krusek
- Institute of Physiology AS CR, v.v.i, Prague, Czech Republic
| | - Ales Balik
- Institute of Physiology AS CR, v.v.i, Prague, Czech Republic
| | | | - Martin Horak
- Institute of Physiology AS CR, v.v.i, Prague, Czech Republic
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Vyklicky V, Korinek M, Smejkalova T, Balik A, Krausova B, Kaniakova M, Lichnerova K, Cerny J, Krusek J, Dittert I, Horak M, Vyklicky L. Structure, function, and pharmacology of NMDA receptor channels. Physiol Res 2014; 63:S191-203. [PMID: 24564659 DOI: 10.33549/physiolres.932678] [Citation(s) in RCA: 166] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
NMDA receptors have received much attention over the last few decades, due to their role in many types of neural plasticity on the one hand, and their involvement in excitotoxicity on the other hand. There is great interest in developing clinically relevant NMDA receptor antagonists that would block excitotoxic NMDA receptor activation, without interfering with NMDA receptor function needed for normal synaptic transmission and plasticity. This review summarizes current understanding of the structure of NMDA receptors and the mechanisms of NMDA receptor activation and modulation, with special attention given to data describing the properties of various types of NMDA receptor inhibition. Our recent analyses point to certain neurosteroids as NMDA receptor inhibitors with desirable properties. Specifically, these compounds show use-dependent but voltage-independent block, that is predicted to preferentially target excessive tonic NMDA receptor activation. Importantly, neurosteroids are also characterized by use-independent unblock, compatible with minimal disruption of normal synaptic transmission. Thus, neurosteroids are a promising class of NMDA receptor modulators that may lead to the development of neuroprotective drugs with optimal therapeutic profiles.
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Affiliation(s)
- V Vyklicky
- Department of Cellular Neurophysiology, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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Kaniakova M, Krausova B, Vyklicky V, Korinek M, Lichnerova K, Vyklicky L, Horak M. Key amino acid residues within the third membrane domains of NR1 and NR2 subunits contribute to the regulation of the surface delivery of N-methyl-D-aspartate receptors. J Biol Chem 2012; 287:26423-34. [PMID: 22711533 DOI: 10.1074/jbc.m112.339085] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
N-methyl-d-aspartate (NMDA) receptors are glutamate ionotropic receptors that play critical roles in synaptic transmission, plasticity, and excitotoxicity. The functional NMDA receptors, heterotetramers composed mainly of two NR1 and two NR2 subunits, likely pass endoplasmic reticulum quality control before they are released from the endoplasmic reticulum and trafficked to the cell surface. However, the mechanism underlying this process is not clear. Using truncated and mutated NMDA receptor subunits expressed in heterologous cells, we found that the M3 domains of both NR1 and NR2 subunits contain key amino acid residues that contribute to the regulation of the number of surface functional NMDA receptors. These key residues are critical neither for the interaction between the NR1 and NR2 subunits nor for the formation of the functional receptors, but rather they regulate the early trafficking of the receptors. We also found that the identified key amino acid residues within both NR1 and NR2 M3 domains contribute to the regulation of the surface expression of unassembled NR1 and NR2 subunits. Thus, our data identify the unique role of the membrane domains in the regulation of the number of surface NMDA receptors.
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Affiliation(s)
- Martina Kaniakova
- Institute of Physiology, Academy of Sciences of the Czech Republic v.v.i., Videnska 1083, 14220 Prague 4, Czech Republic
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Korinek M, Kapras V, Vyklicky V, Adamusova E, Borovska J, Vales K, Stuchlik A, Horak M, Chodounska H, Vyklicky L. Neurosteroid modulation of N-methyl-D-aspartate receptors: molecular mechanism and behavioral effects. Steroids 2011; 76:1409-18. [PMID: 21925193 DOI: 10.1016/j.steroids.2011.09.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/31/2011] [Accepted: 09/01/2011] [Indexed: 12/12/2022]
Abstract
Glutamate is the main neurotransmitter released at synapses in the central nervous system of vertebrates. Its excitatory role is mediated through activation of specific glutamatergic ionotropic receptors, among which the N-methyl-D-aspartate (NMDA) receptor subtype has attracted considerable attention in recent years. Substantial progress has been made in elucidating the roles these receptors play under physiological and pathological conditions and in our understanding of the functional, structural, and pharmacological properties of NMDA receptors. Many pharmacological compounds have been identified that affect the activity of NMDA receptors, including neurosteroids. This review summarizes our knowledge about molecular mechanisms underlying the neurosteroid action at NMDA receptors as well as about the action of neurosteroids in animal models of human diseases.
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Affiliation(s)
- Miloslav Korinek
- Institute of Physiology, Academy of Sciences of the Czech Republic, vvi Videnska 1083, 142 20 Prague 4, Czech Republic
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Korinek M, Sedlacek M, Cais O, Dittert I, Vyklicky L. Temperature dependence of N-methyl-D-aspartate receptor channels and N-methyl-D-aspartate receptor excitatory postsynaptic currents. Neuroscience 2009; 165:736-48. [PMID: 19883737 DOI: 10.1016/j.neuroscience.2009.10.058] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 10/27/2009] [Accepted: 10/27/2009] [Indexed: 11/18/2022]
Abstract
N-methyl-d-aspartate (NMDA) receptors (NMDARs) are highly expressed in the CNS and mediate the slow component of excitatory transmission. The present study was aimed at characterizing the temperature dependence of the kinetic properties of native NMDARs, with special emphasis on the deactivation of synaptic NMDARs. We used patch-clamp recordings to study synaptic NMDARs at layer II/III pyramidal neurons of the rat cortex, recombinant GluN1/GluN2B receptors expressed in human embryonic kidney (HEK293) cells, and NMDARs in cultured hippocampal neurons. We found that time constants characterizing the deactivation of NMDAR-mediated excitatory postsynaptic currents (EPSCs) were similar to those of the deactivation of responses to a brief application of glutamate recorded under conditions of low NMDAR desensitization (whole-cell recording from cultured hippocampal neurons). In contrast, the deactivation of NMDAR-mediated responses exhibiting a high degree of desensitization (outside-out recording) was substantially faster than that of synaptic NMDA receptors. The time constants characterizing the deactivation of synaptic NMDARs and native NMDARs activated by exogenous glutamate application were only weakly temperature sensitive (Q(10)=1.7-2.2), in contrast to those of recombinant GluN1/GluN2B receptors, which are highly temperature sensitive (Q(10)=2.7-3.7). Ifenprodil reduced the amplitude of NMDAR-mediated EPSCs by approximately 50% but had no effect on the time course of deactivation. Analysis of GluN1/GluN2B responses indicated that the double exponential time course of deactivation reflects mainly agonist dissociation and receptor desensitization. We conclude that the temperature dependences of native and recombinant NMDAR are different; in addition, we contribute to a better understanding of the molecular mechanism that controls the time course of NMDAR-mediated EPSCs.
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Affiliation(s)
- M Korinek
- Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
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Tauber E, Kollaritsch H, Korinek M, Rendi-Wagner P, Jilma B, Firbas C, Schranz S, Jong E, Klingler A, Dewasthaly S, Klade CS. Safety and immunogenicity of a Vero-cell-derived, inactivated Japanese encephalitis vaccine: a non-inferiority, phase III, randomised controlled trial. Lancet 2007; 370:1847-53. [PMID: 18061060 DOI: 10.1016/s0140-6736(07)61780-2] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis in southeast Asia. Although no treatment is currently available, vaccination effectively prevents the disease. In a non-inferiority study, we aimed to compare the safety and immunogenicity of a novel, second-generation, inactivated candidate vaccine for JEV with a licensed, mouse-brain-derived vaccine. METHODS We included 867 adults in a multicentre, multinational, observer-blinded, randomised controlled phase III trial. Study sites were located in the USA, Germany, and Austria. Volunteers received either the JEV test vaccine intramuscularly on a two-dose schedule (on days 0 and 28; n=430) or the licensed vaccine subcutaneously according to its recommended three-dose schedule (on days 0, 7, and 28; n=437). The primary endpoint was immunogenicity, with respect to neutralising JEV-specific antibodies assessed by a plaque-reduction neutralisation test, which was assessable in 725 patients in the per-protocol population. This trial is registered as a clinical trial, EudraCT number 2004-002474-36. FINDINGS The safety profile of the test vaccine was good, and its local tolerability profile was more favourable than that of the licensed vaccine. Frequency of adverse events was similar between treatment groups, and vaccine-related adverse events were generally mild. The seroconversion rate of the test vaccine was 98% compared with 95% for the licensed vaccine on day 56 (95% CI for the difference -1.33 to 3.43). Geometric mean titre for recipients of the test vaccine was 244 (range 5-19 783), compared with 102 (5-1864) for the licensed vaccine (ratio 2.3 [95% CI 1.967-2.75]). INTERPRETATION The test JEV vaccine has a promising immunogenicity and safety profile.
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Affiliation(s)
- E Tauber
- Institute of Specific Prophylaxis and Tropical Medicine, Centre for Physiology and Pathophysiology, Medical University of Vienna, Vienna, Austria
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Abstract
The research in the field of the photodynamic therapy of cancer (PDT) is focused on a development of photosensitizers exhibiting high quantum yield of singlet oxygen production. Direct time-resolved spectroscopic observation of singlet oxygen phosphorescence can provide time constants of its population and depopulation as well as photosensitizer phosphorescence lifetime and relative quantum yields. In our contribution, a study of time and spectral resolved phosphorescence of singlet oxygen photosensitized by meso-tetraphenylporphine in acetone together with the photosensitizer phosphorescence is presented. Time constants of singlet oxygen population and depopulation were determined at wide range of photosensitizer concentrations. The time constant of singlet oxygen generation (0.28 +/- 0.01) micros is slightly shorter then the lifetime of photosensitizer's triplet state (0.32 +/- 0.01) micros. It is caused by lower ability of TPP aggregates to transfer excitation energy to oxygen. The lifetime of singlet oxygen (approximately 50 micros) decreases with increasing photosensitizer concentration. Therefore, the photosensitizer acts also as a quencher of oxygen singlet state, similarly to the effects observed in [A. A. Krasnovsky, P. Cheng, R. E. Blankenship, T. A. Moore, and D. Gust (1993). Photochem. Photobiol. 57, 324-330; H. Küpper, R. Dedic, A. Svoboda, J. Hála, and P. M. H. Kroneck (2002). Biochim. Biophys. Acta Gen. Subj. 1572, 107-113]. Moreover, the increasing concentration of the photosensitizer causes a slight hypsochromic shift of the singlet oxygen luminescence maximum.
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Affiliation(s)
- Miloslav Korinek
- Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Czech Republic.
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