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Valipour M, Naderi N, Heidarli E, Shaki F, Motafeghi F, Talebpour Amiri F, Emami S, Irannejad H. Design, synthesis and biological evaluation of naphthalene-derived (arylalkyl)azoles containing heterocyclic linkers as new anticonvulsants: A comprehensive in silico, in vitro, and in vivo study. Eur J Pharm Sci 2021; 166:105974. [PMID: 34390829 DOI: 10.1016/j.ejps.2021.105974] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 08/10/2021] [Accepted: 08/10/2021] [Indexed: 10/20/2022]
Abstract
In continuation of our research to find strong and safe anticonvulsant agents, a number of (arylalkyl)azoles (AAAs) containing naphthylthiazole and naphthyloxazole scaffolds were designed and synthesized. The in vivo anticonvulsant evaluations in BALB/c mice revealed that some of them had significant anticonvulsant activity in both maximal electroshock (MES) and pentylenetetrazole (PTZ) models of epilepsy. The best profile of activity was observed with compounds containing imidazole and triazole rings (C1, C6, G1, and G6). In particular, imidazolylmethyl-thiazole C1 with median effective dose (ED50)= 7.9 mg/kg in the MES test, ED50= 27.9 mg/kg in PTZ test, and without any sign of neurotoxicity (in the rotarod test, 100 mg/kg) was the most promising compound. The patch-clamp recording was performed to study the mechanism of action of the representative compound C1 on hippocampal dentate gyrus (DG) cells. The results did not confirm any modulatory effect of C1 on the voltage-gated ion channels (VGICs) or GABAA agonism, but suggested a significant reduction of excitatory postsynaptic currents (EPSCs) frequency on hippocampal DG neurons. Sub-acute toxicity studies revealed that administration of the most active compounds (C1, C6, G1, and G6) at 100 mg/kg bw/day for two weeks did not result in any mortality or significant toxicity as evaluated by assessment of biochemical markers such as lipid peroxidation, intracellular glutathione, total antioxidant capacity, histopathological changes, and mitochondrial functions. Other pharmacological aspects of compounds including mechanistic and ADME properties were investigated computationally and/or experimentally. Molecular docking on the NMDA and AMPA targets suggested that the introduction of the heterocyclic ring in the middle of AAAs significantly affects the affinity of the compounds. The obtained results totally demonstrated that the prototype compound C1 can be considered as a new lead for the development of anticonvulsant agents.
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Affiliation(s)
- Mehdi Valipour
- Department of Medicinal Chemistry, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Nima Naderi
- Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Neuroscience Research Center, Shahid Beheshti University of Medical Science, Tehran, Iran
| | - Elmira Heidarli
- Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fatemeh Shaki
- Department of Toxicology and Pharmacology, Mazandaran University of Medical Sciences, Sari, Iran
| | - Farzaneh Motafeghi
- Department of Toxicology and Pharmacology, Mazandaran University of Medical Sciences, Sari, Iran
| | - Fereshteh Talebpour Amiri
- Department of Anatomy, Faculty of Medicine, Molecular and Cell Biology Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Saeed Emami
- Department of Medicinal Chemistry, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran; Pharmaceutical Sciences Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
| | - Hamid Irannejad
- Department of Medicinal Chemistry, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran; Pharmaceutical Sciences Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
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Nakanishi-Koakutsu M, Takaki T, Miki K, Yoshida Y. Characterization of Ventricular and Atrial Cardiomyocyte Subtypes from Human-Induced Pluripotent Stem Cells. Methods Mol Biol 2021; 2320:135-49. [PMID: 34302655 DOI: 10.1007/978-1-0716-1484-6_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Human iPSC-derived cardiomyocytes (hiPSC-CMs) are expected to be used in regenerative therapies and drug discovery for heart failure. hiPSC-CMs are a mixture of mainly ventricular CMs (VCMs) and also of atrial CMs (ACMs) and pacemaker cells. Here we describe a method to enrich VCM and ACM differentiation and to characterize these subtypes by gene expression analysis using qRT-PCR and by electrophysiological properties using the patch-clamp method. The differentiated VCMs and ACMs highly express VCM and ACM marker genes, respectively. Furthermore, both subtypes show specific properties of action potentials.
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Bothe SN, Lampert A. The insecticide deltamethrin enhances sodium channel slow inactivation of human Nav1.9, Nav1.8 and Nav1.7. Toxicol Appl Pharmacol 2021; 428:115676. [PMID: 34389319 DOI: 10.1016/j.taap.2021.115676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/13/2021] [Accepted: 08/08/2021] [Indexed: 01/05/2023]
Abstract
The insecticide deltamethrin of the pyrethroid class mainly targets voltage-gated sodium channels (Navs). Deltamethrin prolongs the opening of Navs by slowing down fast inactivation and deactivation. Pyrethroids are supposedly safe for humans, however, they have also been linked to the gulf-war syndrome, a neuropathic pain condition that can develop following exposure to certain chemicals. Inherited neuropathic pain conditions have been linked to mutations in the Nav subtypes Nav1.7, Nav1.8, and Nav1.9. Here, we examined the effect of deltamethrin on the human isoforms Nav1.7, Nav1.8, and Nav1.9_C4 (chimera containing the C-terminus of rat Nav1.4) heterologously expressed in HEK293T and ND7/23 cells using whole-cell patch-clamp electrophysiology. For all three Nav subtypes, we observed increased persistent and tail currents that are typical for Nav channels modified by deltamethrin. The most surprising finding was an enhanced slow inactivation induced by deltamethrin in all three Nav subtypes. An enhanced slow inactivation is contrary to the prolonged opening caused by pyrethroids and has not been described for deltamethrin or any other pyrethroid before. Furthermore, we found that the fraction of deltamethrin-modified channels increased use-dependently. However, for Nav1.8, the use-dependent potentiation occurred only when the holding potential was increased to -90 mV, a potential at which the tail currents decay more slowly. This indicates that use-dependent modification is due to an accumulation of tail currents. In summary, our findings support a novel mechanism whereby deltamethrin enhances slow inactivation of voltage-gated sodium channels, which may, depending on the cellular resting membrane potential, reduce neuronal excitability and counteract the well-described pyrethroid effects of prolonging channel opening.
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Metzner K, Gross T, Balzulat A, Wack G, Lu R, Schmidtko A. Lack of efficacy of a partial adenosine A1 receptor agonist in neuropathic pain models in mice. Purinergic Signal 2021; 17:503-514. [PMID: 34313915 PMCID: PMC8410902 DOI: 10.1007/s11302-021-09806-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 12/19/2020] [Accepted: 06/28/2021] [Indexed: 12/25/2022] Open
Abstract
Previous studies suggest that adenosine A1 receptors (A1R) modulate the processing of pain. The aim of this study was to characterize the distribution of A1R in nociceptive tissues and to evaluate whether targeting A1R with the partial agonist capadenoson may reduce neuropathic pain in mice. The cellular distribution of A1R in dorsal root ganglia (DRG) and the spinal cord was analyzed using fluorescent in situ hybridization. In behavioral experiments, neuropathic pain was induced by spared nerve injury or intraperitoneal injection of paclitaxel, and tactile hypersensitivities were determined using a dynamic plantar aesthesiometer. Whole-cell patch-clamp recordings were performed to assess electrophysiological properties of dissociated DRG neurons. We found A1R to be expressed in populations of DRG neurons and dorsal horn neurons involved in the processing of pain. However, administration of capadenoson at established in vivo doses (0.03–1.0 mg/kg) did not alter mechanical hypersensitivity in the spared nerve injury and paclitaxel models of neuropathic pain, whereas the standard analgesic pregabalin significantly inhibited the pain behavior. Moreover, capadenoson failed to affect potassium currents in DRG neurons, in contrast to a full A1R agonist. Despite expression of A1R in nociceptive neurons, our data do not support the hypothesis that pharmacological intervention with partial A1R agonists might be a valuable approach for the treatment of neuropathic pain.
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Affiliation(s)
- Katharina Metzner
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany.
| | - Tilman Gross
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Annika Balzulat
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Gesine Wack
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Ruirui Lu
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Achim Schmidtko
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
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Landry CR, Yip MC, Kolb I, Stoy WA, Gonzalez MM, Forest CR. Method for Rapid Enzymatic Cleaning for Reuse of Patch Clamp Pipettes: Increasing Throughput by Eliminating Manual Pipette Replacement between Patch Clamp Attempts. Bio Protoc 2021; 11:e4085. [PMID: 34395724 PMCID: PMC8329470 DOI: 10.21769/bioprotoc.4085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/26/2021] [Accepted: 04/12/2021] [Indexed: 11/02/2022] Open
Abstract
The whole-cell patch-clamp method is a gold standard for single-cell analysis of electrical activity, cellular morphology, and gene expression. Prior to our discovery that patch-clamp pipettes could be cleaned and reused, experimental throughput and automation were limited by the need to replace pipettes manually after each experiment. This article presents an optimized protocol for pipette cleaning, which enables it to be performed quickly (< 30 s), resulting in a high yield of whole-cell recording success rate (> 90%) for over 100 reuses of a single pipette. For most patch-clamp experiments (< 30 whole-cell recordings per day), this method enables a single pipette to be used for an entire day of experiments. In addition, we describe easily implementable hardware and software as well as troubleshooting tips to help other labs implement this method in their own experiments. Pipette cleaning enables patch-clamp experiments to be performed with higher throughput, whether manually or in an automated fashion, by eliminating the tedious and skillful task of replacing pipettes. From our experience with numerous electrophysiology laboratories, pipette cleaning can be integrated into existing patch-clamp setups in approximately one day using the hardware and software described in this article. Graphic abstract: Rapid enzymatic cleaning for reuse of patch-clamp pipettes.
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Affiliation(s)
- Corey R. Landry
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, USA
| | - Mighten C. Yip
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, USA
| | - Ilya Kolb
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, USA
| | | | - Mercedes M. Gonzalez
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, USA
| | - Craig R. Forest
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, USA
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Gusic M, Benndorf K, Sattler C. Dissecting activation steps in P2X7 receptors. Biochem Biophys Res Commun 2021; 569:112-117. [PMID: 34243066 DOI: 10.1016/j.bbrc.2021.06.101] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 06/30/2021] [Indexed: 11/28/2022]
Abstract
P2X7 receptors are trimeric ion channels activated by extracellular ATP. Upon activation, they trigger cytolysis and apoptosis but also control cell proliferation. To shed more light on channel gating and the underlying function of the individual subunits, receptors of concatenated subunits were built containing a defined number of functional binding sites. The currents evoked by ATP were obtained in the outside-out configuration of the patch-clamp technique, and steady-state activation, as well as time courses, were analyzed. Our results show that each occupied binding site contributes to channel activation. While the occupation of a single binding site can already activate the channels, three bound ligands maximally stabilize the open state. Hence, P2X7 receptors can be described by a stepwise activation process.
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Affiliation(s)
- Milica Gusic
- Institute of Physiology II, Jena University Hospital, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Klaus Benndorf
- Institute of Physiology II, Jena University Hospital, Friedrich Schiller University Jena, 07743, Jena, Germany
| | - Christian Sattler
- Institute of Physiology II, Jena University Hospital, Friedrich Schiller University Jena, 07743, Jena, Germany.
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Russo ML, Molina-Campos E, Ybarra N, Rogalsky AE, Musial TF, Jimenez V, Haddad LG, Voskobiynyk Y, D'Souza GX, Carballo G, Neuman KM, Chetkovich DM, Oh MM, Disterhoft JF, Nicholson DA. Variability in sub-threshold signaling linked to Alzheimer's disease emerges with age and amyloid plaque deposition in mouse ventral CA1 pyramidal neurons. Neurobiol Aging 2021; 106:207-222. [PMID: 34303222 DOI: 10.1016/j.neurobiolaging.2021.06.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 10/15/2020] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 02/06/2023]
Abstract
The hippocampus is vulnerable to deterioration in Alzheimer's disease (AD). It is, however, a heterogeneous structure, which may contribute to the differential volumetric changes along its septotemporal axis during AD progression. Here, we investigated amyloid plaque deposition along the dorsoventral axis in two strains of transgenic AD (ADTg) mouse models. We also used patch-clamp physiology in these mice to probe for functional consequences of AD pathogenesis in ventral hippocampus, which we found bears significantly higher plaque burden in the aged ADTg group compared to corresponding dorsal regions. Despite dorsoventral differences in amyloid load, ventral CA1 pyramidal neurons of aged ADTg mice exhibited subthreshold physiological changes similar to those previously reported in dorsal neurons, indicative of an HCN channelopathy, but lacked exacerbated suprathreshold accommodation. Additionally, HCN channel function could be rescued by pharmacological manipulation of the endoplasmic reticulum. These observations suggest that an AD-linked HCN channelopathy emerges in both dorsal and ventral CA1 pyramidal neurons, but that the former encounter an additional integrative obstacle in the form of reduced intrinsic excitability.
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Affiliation(s)
- Matthew L Russo
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | | | - Natividad Ybarra
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | - Annalise E Rogalsky
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | - Timothy F Musial
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | - Viviana Jimenez
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | - Loreece G Haddad
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | - Yuliya Voskobiynyk
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | - Gary X D'Souza
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | - Gabriel Carballo
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | - Krystina M Neuman
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
| | | | - M Matthew Oh
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - John F Disterhoft
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Daniel A Nicholson
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA.
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Nagaeva E, Zubarev I, Korpi ER. Electrophysiological Properties of Neurons: Current-Clamp Recordings in Mouse Brain Slices and Firing-Pattern Analysis. Bio Protoc 2021; 11:e4061. [PMID: 34263004 DOI: 10.21769/bioprotoc.4061] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/24/2021] [Accepted: 04/12/2021] [Indexed: 11/02/2022] Open
Abstract
Characterization of an electrically active cell, such as a neuron, demands measurement of its electrical properties. Due to differences in gene activation, location, innervation patterns, and functions, the millions of neurons in the mammalian brain are tremendously diverse in their membrane characteristics and abilities to generate action potentials. These features can be measured with a patch-clamp technique in whole-cell current-clamp configuration followed by detailed post-hoc analysis of firing patterns. This analysis can be time-consuming, and different laboratories have their own methods to perform it, either manually or with custom-written scripts. Here, we describe in detail a protocol for firing-pattern registration in neurons of the ventral tegmental area (VTA) as an example and introduce a software for its fast and convenient analysis. With the help of this article, other research groups can easily apply this method and generate unified types of data that are comparable between brain regions and various studies. Graphic abstract: Workflow of the Protocol.
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Affiliation(s)
- Elina Nagaeva
- Department of Pharmacology, Faculty of Medicine, FI-00014 University of Helsinki, Helsinki, Finland
| | - Ivan Zubarev
- Department of Neuroscience and Biomedical Engineering, Aalto University, 11000 Espoo, Finland
| | - Esa R Korpi
- Department of Pharmacology, Faculty of Medicine, FI-00014 University of Helsinki, Helsinki, Finland
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Zhang Y, Gui H, Duan Z, Yu T, Zhang J, Liang X, Liu C. Dopamine D1 Receptor in the Nucleus Accumbens Modulates the Emergence from Propofol Anesthesia in Rat. Neurochem Res 2021; 46:1435-1446. [PMID: 33683630 DOI: 10.1007/s11064-021-03284-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 07/10/2020] [Revised: 01/26/2021] [Accepted: 02/23/2021] [Indexed: 01/04/2023]
Abstract
It has been reported that systemic activation of D1 receptors promotes emergence from isoflurane-induced unconsciousness, suggesting that the central dopaminergic system is involved in the process of recovering from general anesthesia. The nucleus accumbens (NAc) contains abundant GABAergic medium spiny neurons (MSNs) expressing the D1 receptor (D1R), which plays a key role in sleep-wake behavior. However, the role of NAc D1 receptors in the process of emergence from general anesthesia has not been identified. Here, using real-time in vivo fiber photometry, we found that neuronal activity in the NAc was markedly disinhibited during recovery from propofol anesthesia. Subsequently, microinjection of a D1R selective agonist (chloro-APB hydrobromide) into the NAc notably reduced the time to emerge from propofol anesthesia with a decrease in δ-band power and an increase in β-band power evident in the cortical electroencephalogram. These effects were prevented by pretreatment with a D1R antagonist (SCH-23390). Whole-cell patch clamp recordings were performed to further explore the cellular mechanism underlying the modulation of D1 receptors on MSNs under propofol anesthesia. Our data primarily demonstrated that propofol increased the frequency and prolonged the decay time of spontaneous inhibitory postsynaptic currents (sIPSCs) and miniature IPSCs (mIPSCs) of MSNs expressing D1 receptors. A D1R agonist attenuated the effect of propofol on the frequency of sIPSCs and mIPSCs, and the effects of the agonist were eliminated by preapplication of SCH-23390. Collectively, these results indicate that modulation of the D1 receptor on the activity of NAc MSNs is vital for emergence from propofol-induced unconsciousness.
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Affiliation(s)
- Yi Zhang
- Department of Anesthesiology, The Second Affiliated Hospital of Zunyi Medical University, Zunyi, China
- Department of Anesthesiology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
- Guizhou Key Laboratory of Brain Science, Guizhou Key Laboratory of Anesthesia and Organ Protection, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Huan Gui
- Guizhou Key Laboratory of Brain Science, Guizhou Key Laboratory of Anesthesia and Organ Protection, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Zikun Duan
- Guizhou Key Laboratory of Brain Science, Guizhou Key Laboratory of Anesthesia and Organ Protection, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Tian Yu
- Guizhou Key Laboratory of Brain Science, Guizhou Key Laboratory of Anesthesia and Organ Protection, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Jie Zhang
- Department of Anesthesiology, The Second Affiliated Hospital of Zunyi Medical University, Zunyi, China
- Guizhou Key Laboratory of Brain Science, Guizhou Key Laboratory of Anesthesia and Organ Protection, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Xiaoli Liang
- Department of Anesthesiology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
- Guizhou Key Laboratory of Brain Science, Guizhou Key Laboratory of Anesthesia and Organ Protection, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Chengxi Liu
- Department of Anesthesiology, The Second Affiliated Hospital of Zunyi Medical University, Zunyi, China.
- Guizhou Key Laboratory of Brain Science, Guizhou Key Laboratory of Anesthesia and Organ Protection, The Affiliated Hospital of Zunyi Medical University, Zunyi, China.
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Deng S, Zhang Y, Liao Z, Huang J, Huang R, Li Z. S100A4 plays a key role in TRPV3 ion channel expression and its electrophysiological function. Neurosci Lett 2021; 759:135999. [PMID: 34058292 DOI: 10.1016/j.neulet.2021.135999] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 04/27/2021] [Accepted: 05/25/2021] [Indexed: 01/07/2023]
Abstract
Transient receptor potential vanilloid 3 (TRPV3), a non-selective cation ion channel, is regulated by small molecules such as Ca2+ and calmodulin (CaM). Together with S100A4 (S100 calcium-binding protein family), is critical in cell proliferation and progression. Although TRPV3 has been proved to play a role in Ca2+ regulation and participate in Ca2+-related cellular processes, its molecular mechanism remains unclear. In this study, we found that TRPV3 and S100A4 were co-expressed in the same region of the cell, and surprisingly, the protein expression level of TRPV3 significantly increased with the overexpression of S100A4. Moreover, co-immunoprecipitation results showed that these two proteins could bind with each other. Functionally, we found that when S100A4 was simultaneously expressed in cells, more Ca2+ would be transferred into the cells through the TRPV3 ion channel. Consistent with Ca2+ regulation results, electrophysiological recordings demonstrated that S100A4 improved the function of TRPV3 in ions' flux, suggesting that the S100A4 could bind with TRPV3 and simultaneously promoted its expression, thus affecting its functions on related ions' flux. Our findings identified the link between S100A4 and TRPV3 and provided a novel molecular mechanism for TRPV3 regulation.
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Chrestia JF, Bruzzone A, Esandi MDC, Bouzat C. Tyrosine phosphorylation differentially fine-tunes ionotropic and metabotropic responses of human α7 nicotinic acetylcholine receptor. Cell Mol Life Sci 2021; 78:5381-5395. [PMID: 34028590 PMCID: PMC8142877 DOI: 10.1007/s00018-021-03853-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [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: 02/24/2021] [Revised: 04/23/2021] [Accepted: 05/08/2021] [Indexed: 12/29/2022]
Abstract
The α7 nicotinic acetylcholine receptor is involved in neurological, neurodegenerative, and inflammatory disorders. It operates both as a ligand-gated cationic channel and as a metabotropic receptor in neuronal and non-neuronal cells. As protein phosphorylation is an important cell function regulatory mechanism, deciphering how tyrosine phosphorylation modulates α7 dual ionotropic/metabotropic molecular function is required for understanding its integral role in physiological and pathological processes. α7 single-channel activity elicited by ACh appears as brief isolated openings and less often as episodes of few openings in quick succession. The reduction of phosphorylation by tyrosine kinase inhibition increases the duration and frequency of activation episodes, whereas the inhibition of phosphatases has the opposite effect. Removal of two tyrosine residues at the α7 intracellular domain recapitulates the effects mediated by tyrosine kinase inhibition. The tyrosine-free mutant receptor shows longer duration-activation episodes, reduced desensitization rate and significantly faster recovery from desensitization, indicating that phosphorylation decreases α7 channel activity by favoring the desensitized state. However, the mutant receptor is incapable of triggering ERK1/2 phosphorylation in response to the α7-agonist. Thus, while tyrosine phosphorylation is absolutely required for α7-triggered ERK pathway, it negatively modulates α7 ionotropic activity. Overall, phosphorylation/dephosphorylation events fine-tune the integrated cell response mediated by α7 activation, thus having a broad impact on α7 cholinergic signaling.
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Affiliation(s)
- Juan Facundo Chrestia
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía Blanca, Argentina
| | - Ariana Bruzzone
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía Blanca, Argentina
| | - María Del Carmen Esandi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía Blanca, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 8000, Bahía Blanca, Argentina.
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Francesconi W, Berton F, Olivera-Pasilio V, Dabrowska J. Oxytocin excites BNST interneurons and inhibits BNST output neurons to the central amygdala. Neuropharmacology 2021; 192:108601. [PMID: 33971215 DOI: 10.1016/j.neuropharm.2021.108601] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 11/25/2020] [Revised: 03/22/2021] [Accepted: 04/30/2021] [Indexed: 12/11/2022]
Abstract
The dorsolateral bed nucleus of the stria terminalis (BNSTDL) has high expression of oxytocin (OT) receptors (OTR), which were shown to facilitate cued fear. However, the role of OTR in the modulation of BNSTDL activity remains elusive. BNSTDL contains GABA-ergic neurons classified based on intrinsic membrane properties into three types. Using in vitro patch-clamp recordings in male rats, we demonstrate that OT selectively excites and increases spontaneous firing rate of Type I BNSTDL neurons. As a consequence, OT increases the frequency, but not amplitude, of spontaneous inhibitory post-synaptic currents (sIPSCs) selectively in Type II neurons, an effect abolished by OTR antagonist or tetrodotoxin, and reduces spontaneous firing rate in these neurons. These results suggest an indirect effect of OT in Type II neurons, which is mediated via OT-induced increase in firing of Type I interneurons. As Type II BNSTDL neurons were shown projecting to the central amygdala (CeA), we also recorded from retrogradely labeled BNST→CeA neurons and we show that OT increases the frequency of sIPSC in these Type II BNST→CeA output neurons. In contrast, in Type III neurons, OT reduces the amplitude, but not frequency, of both sIPSCs and evoked IPSCs via a postsynaptic mechanism without changing their intrinsic excitability. We present a model of fine-tuned modulation of BNSTDL activity by OT, which selectively excites BNSTDL interneurons and inhibits Type II BNST→CeA output neurons. These results suggest that OTR in the BNST might facilitate cued fear by inhibiting the BNST→CeA neurons.
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Affiliation(s)
- Walter Francesconi
- Center for the Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA; Discipline of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA
| | - Fulvia Berton
- Center for the Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA; Discipline of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA
| | - Valentina Olivera-Pasilio
- Center for the Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA; Discipline of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA; School of Graduate and Postdoctoral Studies, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA
| | - Joanna Dabrowska
- Center for the Neurobiology of Stress Resilience and Psychiatric Disorders, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA; Discipline of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA; School of Graduate and Postdoctoral Studies, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA.
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63
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Teisseyre A, Uryga A, Michalak K. Statins as inhibitors of voltage-gated potassium channels Kv1.3 in cancer cells. J Mol Struct 2021; 1230:129905. [PMID: 33437096 PMCID: PMC7789826 DOI: 10.1016/j.molstruc.2021.129905] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 10/01/2020] [Revised: 12/07/2020] [Accepted: 12/29/2020] [Indexed: 12/24/2022]
Abstract
Voltage-gated potassium channels are integral membrane proteins selectively permeable for potassium ions and activated upon change of membrane potential. Voltage-gated potassium channels of the Kv1.3 type were discovered both in plasma membrane and in inner mitochondrial membrane (mito Kv1.3 channels). For some time Kv1.3 channels located both in plasma membrane and in mitochondria are considered as a potentially new molecular target in several pathologies including some cancer disorders. Lipophilic nontoxic organic inhibitors of Kv1.3 channels may potentially find a clinical application to support therapy of some cancer diseases such as breast, pancreas and lung cancer, melanoma or chronic lymphocytic leukaemia (B-CLL). Inhibition of T lymphocyte Kv1.3 channels may be also important in treatment of chronic and acute respiratory diseases including severe pulmonary complication in corona virus disease Covid 19, however further studies are needed to confirm this supposition. Statins are small-molecule organic compounds, which are lipophilic and are widely used in treatment of hypercholesterolemia and atherosclerosis. Electrophysiological studies performed in our laboratory showed that statins: pravastatin, mevastatin and simvastatin are effective inhibitors of Kv1.3 channels in cancer cells of human T cell line Jurkat. We showed that application of the statins in the concentration range from 1.5 μM to 50 μM inhibited the channels in a concentration-dependent manner. The inhibitory effect was the most potent in case of simvastatin and the least potent in case of pravastatin. The inhibition was partially irreversible in case of simvastatin and fully reversible in case of pravastatin and mevastatin. It was accompanied by a significant acceleration of the current inactivation rate without any significant change of the activation rate. Mechanism of the inhibition is probably complex, including a direct interaction with the channel protein and perturbation of lipid bilayer structure, leading to stabilization of the inactivated state of the channels.
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Izumisawa Y, Ito K, Sugita K, Arai T, Kokudo H, Kitamura N, Shibuya I. Mechanisms of GABA-mediated inhibition of the angiotensin II-induced cytosolic Ca 2+ increase in rat subfornical organ neurons. Brain Res 2021; 1763:147451. [PMID: 33773979 DOI: 10.1016/j.brainres.2021.147451] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 10/21/2022]
Abstract
Neurons in the subfornical organ (SFO) sense both neurotransmitters and circulating humoral factors such as angiotensin II (AII) and atrial natriuretic peptide (ANP), and regulate multiple physiological functions including drinking behavior. We recently reported that AII at nanomolar concentrations induced a persistent [Ca2+]i increase in acutely dissociated SFO neurons and that this effect of AII was reversibly inhibited by GABA. In the present study, we studied the inhibitory mechanism of GABA using Ca2+ imaging and patch-clamp electrophysiology. The AII-induced persistent [Ca2+]i increase was inhibited by GABA in more than 90% of AII-responsive neurons and by other two SFO inhibitory ligands, ANP and galanin, in about 60 and 30% of neurons respectively. The inhibition by GABA was mimicked by the GABAA and GABAB receptor agonists muscimol and baclofen. The involvement of both GABA receptor subtypes was confirmed by reversal of the GABA-mediated inhibition only when the GABAA and GABAB receptors antagonists bicuculline methiodide and CGP55845 were both present. The GABAB agonist baclofen rapidly and reversibly inhibited voltage-gated Ca2+ channel (VGCC) currents recorded in response to depolarizing pulses in voltage-clamp electrophysiology using Ba2+ as a charge carrier (IBa). Baclofen inhibition of IBa was antagonized by CGP55845, confirming GABAB receptor involvement; was reduced by N-ethylmaleimide, suggesting downstream Gi-mediated actions; and was partially removed by a large prepulse, indicating voltage-dependency. The magnitude of IBa inhibition by baclofen was reduced by the application of selective blockers for N-, P/Q-, and L-type VGCCs (ω-conotoxin GVIA, ω-agatoxin IVA, and nifedipine respectively). Overall, our study indicates that GABA inhibition of the AII-induced [Ca2+]i increase is mediated by both GABAA and GABAB receptors, and that GABAB receptors associated with Gi proteins suppress Ca2+ entry through VGCCs in SFO neurons.
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Affiliation(s)
- Yu Izumisawa
- Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, Japan
| | - Kenji Ito
- Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, Japan
| | - Keisuke Sugita
- Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, Japan
| | - Tazuyo Arai
- Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, Japan
| | - Hina Kokudo
- Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, Japan
| | - Naoki Kitamura
- Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, Japan
| | - Izumi Shibuya
- Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, Japan.
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Saponara S, Fusi F, Iovinelli D, Ahmed A, Trezza A, Spiga O, Sgaragli G, Valoti M. Flavonoids and hERG channels: Friends or foes? Eur J Pharmacol 2021; 899:174030. [PMID: 33727059 DOI: 10.1016/j.ejphar.2021.174030] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [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: 10/08/2020] [Revised: 02/28/2021] [Accepted: 03/11/2021] [Indexed: 01/24/2023]
Abstract
The cardiac action potential is regulated by several ion channels. Drugs capable to block these channels, in particular the human ether-à-go-go-related gene (hERG) channel, also known as KV11.1 channel, may lead to a potentially lethal ventricular tachyarrhythmia called "Torsades de Pointes". Thus, evaluation of the hERG channel off-target activity of novel chemical entities is nowadays required to safeguard patients as well as to avoid attrition in drug development. Flavonoids, a large class of natural compounds abundantly present in food, beverages, herbal medicines, and dietary food supplements, generally escape this assessment, though consumed in consistent amounts. Continuously growing evidence indicates that these compounds may interact with the hERG channel and block it. The present review, by examining numerous studies, summarizes the state-of-the-art in this field, describing the most significant examples of direct and indirect inhibition of the hERG channel current operated by flavonoids. A description of the molecular interactions between a few of these natural molecules and the Rattus norvegicus channel protein, achieved by an in silico approach, is also presented.
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Affiliation(s)
- Simona Saponara
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Fabio Fusi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy.
| | - Daniele Iovinelli
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Amer Ahmed
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Alfonso Trezza
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Ottavia Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Giampietro Sgaragli
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy; Accademia Italiana della Vite e del Vino, via Logge degli Uffizi Corti 1, 50122, Florence, Italy
| | - Massimo Valoti
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
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Franceschi Biagioni A, Cellot G, Pati E, Lozano N, Ballesteros B, Casani R, Coimbra NC, Kostarelos K, Ballerini L. Graphene oxide prevents lateral amygdala dysfunctional synaptic plasticity and reverts long lasting anxiety behavior in rats. Biomaterials 2021; 271:120749. [PMID: 33714913 DOI: 10.1016/j.biomaterials.2021.120749] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [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: 11/30/2020] [Revised: 02/23/2021] [Accepted: 02/27/2021] [Indexed: 12/19/2022]
Abstract
Engineered small graphene oxide (s-GO) sheets were previously shown to reversibly down-regulate glutamatergic synapses in the hippocampus of juvenile rats, disclosing an unexpected translational potential of these nanomaterials to target selective synapses in vivo. Synapses are anatomical specializations acting in the Central Nervous System (CNS) as functional interfaces among neurons. Dynamic changes in synaptic function, named synaptic plasticity, are crucial to learning and memory. More recently, pathological mechanisms involving dysfunctional synaptic plasticity were implicated in several brain diseases, from dementia to anxiety disorders. Hyper-excitability of glutamatergic neurons in the lateral nucleus of the amygdala complex (LA) is substantially involved in the storage of aversive memory induced by stressful events enabling post-traumatic stress disorder (PTSD). Here we translated in PTSD animal model the ability of s-GO, when stereotaxically administered to hamper LA glutamatergic transmission and to prevent the behavioral response featured in long-term aversive memory. We propose that s-GO, by interference with glutamatergic plasticity, impair LA-dependent memory retrieval related to PTSD.
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Affiliation(s)
- Audrey Franceschi Biagioni
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Neuroscience, Via Bonomea 265, 34136, Trieste, Italy
| | - Giada Cellot
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Neuroscience, Via Bonomea 265, 34136, Trieste, Italy
| | - Elisa Pati
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Neuroscience, Via Bonomea 265, 34136, Trieste, Italy
| | - Neus Lozano
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193, Barcelona, Spain
| | - Belén Ballesteros
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193, Barcelona, Spain
| | - Raffaele Casani
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Neuroscience, Via Bonomea 265, 34136, Trieste, Italy
| | - Norberto Cysne Coimbra
- Laboratory of Neuroanatomy & Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes 3900, 14049-900, Ribeirão Preto, SP, Brazil
| | - Kostas Kostarelos
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193, Barcelona, Spain; Nanomedicine Lab, National Graphene Institute and Faculty of Biology, Medicine & Health, The University of Manchester, AV Hill Building, Oxford Rd, Manchester, M13 9PL, United Kingdom
| | - Laura Ballerini
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Neuroscience, Via Bonomea 265, 34136, Trieste, Italy.
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67
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Neginskaya MA, Pavlov EV, Sheu SS. Electrophysiological properties of the mitochondrial permeability transition pores: Channel diversity and disease implication. Biochim Biophys Acta Bioenerg 2021; 1862:148357. [PMID: 33359307 PMCID: PMC7954400 DOI: 10.1016/j.bbabio.2020.148357] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 11/26/2020] [Accepted: 12/15/2020] [Indexed: 02/07/2023]
Abstract
The mitochondrial permeability transition pore (mPTP) is a channel that, when open, is responsible for a dramatic increase in the permeability of the mitochondrial inner membrane, a process known as the mitochondrial permeability transition (mPT). mPTP activation during Ca2+ dyshomeostasis and oxidative stress disrupts normal mitochondrial function and induces cell death. mPTP opening has been implicated as a critical event in many diseases, including hypoxic injuries, neurodegeneration, and diabetes. Discoveries of recent years indicate that mPTP demonstrates very complicated behavior and regulation, and depending on specific induction or stress conditions, it can function as a high-conductance pore, a small channel, or a non-specific membrane leak. The focus of this review is to summarize the literature on the electrophysiological properties of the mPTP and to evaluate the evidence that it has multiple molecular identities. This review also provides perspective on how an electrophysiological approach can be used to quantitatively investigate the biophysical properties of the mPTP under physiological, pharmacological, pathophysiological, and disease conditions.
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Affiliation(s)
- M A Neginskaya
- Department of Molecular Pathobiology, New York University, New York, NY, USA.
| | - E V Pavlov
- Department of Molecular Pathobiology, New York University, New York, NY, USA
| | - S-S Sheu
- Department of Medicine, Center for Translational Medicine, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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68
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Montalbano A, Sala C, Abrardo C, Murciano N, Jahanfar F, D'Amico M, Bertoni F, Becchetti A, Arcangeli A. Data describing the effects of potassium channels modulators on outward currents measured in human lymphoma cell lines. Data Brief 2021; 34:106668. [PMID: 33385031 PMCID: PMC7772536 DOI: 10.1016/j.dib.2020.106668] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/07/2020] [Accepted: 12/14/2020] [Indexed: 12/01/2022] Open
Abstract
In the present work, applying the whole-cell patch-clamp technique in voltage clamp mode, we have investigated the effects of different drugs, such as riluzole, Psora-4 and Tram-34, on the potassium currents in four human lymphoma cell lines. We focused on outward currents mediated by two potassium channels (Kv1.3 and KCa3.1), which are known to play a key physiological role in lymphoid cells. The currents were evoked by voltage ramps ranging from -120 mV to +40 mV and the conductance of the two potassium channels was measured between +20 mV and +40 mV, both in the absence and in the presence of the specific blockers Psora-4 (Kv1.3; 1 µM) and Tram-34 (KCa3.1; 1 µM). The effect of the latter was tested after KCa3.1 channels were activated by riluzole 10 µM. Taken together, these data could be useful as an indication of the functional characteristics of the potassium channels in human lymphomas and represent a starting point for the study of potassium conductance in cellular models of these tumors.
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Affiliation(s)
- Alberto Montalbano
- Department of Experimental and Clinical Medicine, University of Florence, I‑50134 Florence, Italy
| | - Cesare Sala
- Department of Experimental and Clinical Medicine, University of Florence, I‑50134 Florence, Italy
| | - Chiara Abrardo
- Department of Experimental and Clinical Medicine, University of Florence, I‑50134 Florence, Italy
| | - Nicoletta Murciano
- Department of Experimental and Clinical Medicine, University of Florence, I‑50134 Florence, Italy
| | - Farhad Jahanfar
- DIVAL Toscana Srl, Via Madonna del Piano 6, Sesto Fiorentino, I-50119 Firenze, Italy.,Department of Medical Biotechnologies, University of Siena, I-53100 Siena, Italy
| | - Massimo D'Amico
- DIVAL Toscana Srl, Via Madonna del Piano 6, Sesto Fiorentino, I-50119 Firenze, Italy
| | - Francesco Bertoni
- Institute of Oncology Research, Faculty of Biomedical Sciences, USI, via Vela 6, CH-6500 Bellinzona, Switzerland.,Oncology Institute of Southern Switzerland (IOSI), Ospedale San Giovanni, CH-6500 Bellinzona, Switzerland
| | - Andrea Becchetti
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, I-20126 Milano, Italy
| | - Annarosa Arcangeli
- Department of Experimental and Clinical Medicine, University of Florence, I‑50134 Florence, Italy
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69
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Houy S, Martins JS, Mohrmann R, Sørensen JB. Measurements of Exocytosis by Capacitance Recordings and Calcium Uncaging in Mouse Adrenal Chromaffin Cells. Methods Mol Biol 2021; 2233:233-251. [PMID: 33222139 DOI: 10.1007/978-1-0716-1044-2_16] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Fusion of vesicles with the plasma membrane and liberation of their contents is a multistep process involving several proteins. Correctly assigning the role of specific proteins and reactions in this cascade requires a measurement method with high temporal resolution. Patch-clamp recordings of cell membrane capacitance in combination with calcium measurements, calcium uncaging, and carbon-fiber amperometry allow for the accurate determination of vesicle pool sizes, their fusion kinetics, and their secreted oxidizable content. Here, we will describe this method in a model system for neurosecretion, the adrenal chromaffin cells, which secrete adrenaline.
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Affiliation(s)
- Sébastien Houy
- Department of Neuroscience, University of Copenhagen, Copenhagen N, Denmark
| | - Joana S Martins
- Department of Neuroscience, University of Copenhagen, Copenhagen N, Denmark
| | - Ralf Mohrmann
- Institute for Physiology, Otto-von-Guericke University, Magdeburg, Germany
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70
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Bukiya AN, Dopico AM. Cholesterol antagonism of alcohol inhibition of smooth muscle BK channel requires cell integrity and involves a protein kinase C-dependent mechanism(s). Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1866:158874. [PMID: 33383194 DOI: 10.1016/j.bbalip.2020.158874] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 12/13/2020] [Accepted: 12/22/2020] [Indexed: 10/22/2022]
Abstract
Alcohol constricts cerebral arteries via inhibition of voltage/calcium-gated, large conductance potassium (BK) channels in vascular myocytes. Using a rat model of high-cholesterol (high-CLR) diet and CLR enrichment of cerebral arteries in vitro, we recently showed that CLR protected against alcohol-induced constriction of cerebral arteries. The subcellular mechanism(s) underlying CLR protection against alcohol-induced constriction of the artery is unclear. Here we use a rat model of high-CLR diet and patch-clamp recording of BK channels in inside-out patches from cerebral artery myocytes to demonstrate that this diet antagonizes inhibition of BK currents by 50 mM ethanol. High-CLR-driven protection against alcohol inhibition of BK currents is reversed following CLR depletion in vitro. Similar to CLR accumulation in vivo, pre-incubation of arterial myocytes from normocholesterolemic rats in CLR-enriching media in vitro protects against alcohol-induced inhibition of BK current. However, application of CLR-enriching media to cell-free membrane patches does not protect against the alcohol effect. These different outcomes point to the involvement of cell signaling in CLR-alcohol interaction on BK channels. Incubation of myocytes with the PKC activators phorbol 12-myristate 13-acetate or 1,2-dioctanoyl-sn-glycerol, but not with the PKC inhibitor Gouml 6983, prior to patch excision precludes CLR enrichment from antagonizing alcohol action. Thus, PKC activation either disables the CLR target(s) or competes with elevated CLR. Favoring the latter possibility, 1,2-dioctanoyl-sn-glycerol protects against alcohol-induced inhibition of BK currents in patches from myocytes with naïve CLR. Our findings document that CLR antagonism of alcohol-induced BK channel inhibition requires cell integrity and is enabled by a PKC-dependent mechanism(s).
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Affiliation(s)
- Anna N Bukiya
- Dept. Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, United States.
| | - Alex M Dopico
- Dept. Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, United States
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71
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Tang ZQ, Lu YG, Huang YN, Chen L. Cross-talk pattern between GABA A- and glycine-receptors in CNS neurons is shaped by their relative expression levels. Brain Res 2020; 1748:147071. [PMID: 32827550 DOI: 10.1016/j.brainres.2020.147071] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 08/03/2020] [Accepted: 08/17/2020] [Indexed: 11/17/2022]
Abstract
GABAA receptors (GABAARs) and glycine receptors (GlyRs) are two principal inhibitory chloride ion channels in the central nervous system. The two receptors do not function independently but cross-talk to each other, i.e., the activation of one receptor would inhibit the other. This cross-talk is present in different patterns across various regions in the central nervous system; however, the factor that determines these patterns is not understood. Here, we show that the pattern of cross-talk between the two receptors is shaped by their relative expression level in a neuron: a higher expression level correlates with louder talk. In line with a tendency of decrease in expression level of GlyRs and increase in expression level of GABAARs from the spinal cord, the brainstem to the neocortex, GlyRs talked much louder (i.e. produced greater inhibition) than GABAARs (one-way pattern) in spinal cord neurons, about equally loud as GABAARs (symmetric pattern) in inferior colliculus neurons and less loud (i.e. less inhibition) than GABAARs (asymmetric pattern) in auditory cortex neurons. Overexpression of GlyRs in inferior colliculus neurons produced an asymmetric pattern that should otherwise have been observed in spinal cord neurons. These expression level-dependent patterns of cross-talk between the two receptors may suggest how the central nervous system uses an alternative mechanism to maintain a delicate level of inhibition through adjusting the proportion of the two receptors in a neuron along its pathway.
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Affiliation(s)
- Zheng-Quan Tang
- School of Life Sciences, Anhui University, Hefei 230601, China; Key Laboratory of Human Microenvironment and Precision Medicine of Anhui Higher Education Institutes, Anhui University, Hefei 230601, China.
| | - Yun-Gang Lu
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China; Auditory Research Laboratory, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Yi-Na Huang
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China; Auditory Research Laboratory, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Lin Chen
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China; Auditory Research Laboratory, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China.
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Segura E, Mehta A, Marsolais M, Quan XR, Zhao J, Sauvé R, Spafford JD, Parent L. An ancestral MAGUK protein supports the modulation of mammalian voltage-gated Ca 2+ channels through a conserved Ca Vβ-like interface. Biochim Biophys Acta Biomembr 2020; 1862:183439. [PMID: 32814116 DOI: 10.1016/j.bbamem.2020.183439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/11/2020] [Accepted: 08/03/2020] [Indexed: 01/09/2023]
Abstract
Eukaryote voltage-gated Ca2+ channels of the CaV2 channel family are hetero-oligomers formed by the pore-forming CaVα1 protein assembled with auxiliary CaVα2δ and CaVβ subunits. CaVβ subunits are formed by a Src homology 3 (SH3) domain and a guanylate kinase (GK) domain connected through a HOOK domain. The GK domain binds a conserved cytoplasmic region of the pore-forming CaVα1 subunit referred as the "AID". Herein we explored the phylogenetic and functional relationship between CaV channel subunits in distant eukaryotic organisms by investigating the function of a MAGUK protein (XM_004990081) cloned from the choanoflagellate Salpingoeca rosetta (Sro). This MAGUK protein (Sroβ) features SH3 and GK structural domains with a 25% primary sequence identity to mammalian CaVβ. Recombinant expression of its cDNA with mammalian high-voltage activated Ca2+ channel CaV2.3 in mammalian HEK cells produced robust voltage-gated inward Ca2+ currents with typical activation and inactivation properties. Like CaVβ, Sroβ prevents fast degradation of total CaV2.3 proteins in cycloheximide assays. The three-dimensional homology model predicts an interaction between the GK domain of Sroβ and the AID motif of the pore-forming CaVα1 protein. Substitution of AID residues Trp (W386A) and Tyr (Y383A) significantly impaired co-immunoprecipitation of CaV2.3 with Sroβ and functional upregulation of CaV2.3 currents. Likewise, a 6-residue deletion within the GK domain of Sroβ, similar to the locus found in mammalian CaVβ, significantly reduced peak current density. Altogether our data demonstrate that an ancestor MAGUK protein reconstitutes the biophysical and molecular features responsible for channel upregulation by mammalian CaVβ through a minimally conserved molecular interface.
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Affiliation(s)
- Emilie Segura
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Canada; Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada
| | - Amrit Mehta
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Mireille Marsolais
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada
| | - Xin R Quan
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Juan Zhao
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada
| | - Rémy Sauvé
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Canada
| | - J David Spafford
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Lucie Parent
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Canada; Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada.
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73
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Seo MS, An JR, Jung HS, Kang M, Heo R, Han ET, Yang SR, Park H, Jung WK, Choi IW, Bae YM, Na SH, Park WS. Suppression of voltage-gated K + channels by darifenacin in coronary arterial smooth muscle cells. Eur J Pharmacol 2020; 891:173707. [PMID: 33137332 DOI: 10.1016/j.ejphar.2020.173707] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 10/22/2020] [Accepted: 10/29/2020] [Indexed: 10/23/2022]
Abstract
Darifenacin, an anticholinergic agent, has been used to treat overactive bladder syndrome. Despite its extensive clinical use, there is little information about the effect of darifenacin on vascular ion channels, specifically K+ channels. This study aimed to investigate the effect of the anti-muscarinic drug darifenacin on voltage-gated K+ (Kv) channels, vascular contractility, and coronary blood flow in rabbit coronary arteries. We used the whole-cell patch-clamp technique to evaluate the effect of darifenacin on Kv channels. Darifenacin inhibited the Kv current in a concentration-dependent manner. Applying 1 μM darifenacin shifted the activation and inactivation curves toward a more positive and negative potential, respectively. Darifenacin slowed the time constants of recovery from inactivation. Furthermore, blockade of the Kv current with darifenacin was increased gradually by applying a train of pulses, indicating that darifenacin inhibited Kv currents in a use- (state)-dependent manner. The darifenacin-mediated inhibition of Kv currents was associated with the Kv1.5 subtype, not the Kv2.1 or Kv7 subtype. Applying another anti-muscarinic drug atropine or ipratropium did not affect the Kv current or change the inhibitory effect of darifenacin. Isometric organ bath experiments using isolated coronary arteries were applied to evaluate whether darifenacin-induced inhibition of the Kv channel causes vasocontraction. Darifenacin substantially induced vasocontraction. Furthermore, darifenacin caused membrane depolarization and decreased coronary blood flow. From these results, we concluded that darifenacin inhibits the Kv currents in concentration- and use- (state)-dependent manners. Inhibition of the Kv current with darifenacin occurred by shifting the steady-state activation and inactivation curves regardless of its anti-muscarinic effect.
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Affiliation(s)
- Mi Seon Seo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Jin Ryeol An
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Hee Seok Jung
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Minji Kang
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Ryeon Heo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Se-Ran Yang
- Department of Thoracic and Cardiovascular Surgery, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Hongzoo Park
- Department of Urology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Won-Kyo Jung
- Department of Biomedical Engineering, and Center for Marine-Integrated Biomedical Technology (BK21 Plus), Pukyong National University, Busan, 48513, South Korea
| | - Il-Whan Choi
- Department of Microbiology, College of Medicine, Inje University, Busan, 48516, South Korea
| | - Young Min Bae
- Department of Physiology, Konkuk University School of Medicine, Chungju, 27478, South Korea
| | - Sung Hun Na
- Department of Obstetrics and Gynecology, Kangwon National University Hospital, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea.
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea.
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Kawai F, Ohkuma M, Horiguchi M, Ichinose H, Miyachi EI. A subset of cone bipolar cells expresses the Na + channel SCN2A in the human retina. Exp Eye Res 2020; 202:108299. [PMID: 33068627 DOI: 10.1016/j.exer.2020.108299] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 10/08/2020] [Accepted: 10/09/2020] [Indexed: 11/24/2022]
Abstract
Some bipolar cells in the human retina are known to express voltage-gated Na+ channels. However, it is unclear which types of channels are expressed, and whether Na+ channel expression is limited to specific types of bipolar cells. In the present study, we examined the types of voltage-gated Na+ channels expressed in human bipolar cells and the morphology of bipolar cells with voltage-gated Na+ currents. To investigate the expression of voltage-gated Na+ channels in human bipolar cells, we examined whether Na+ channel transcripts could be detected in single bipolar cells using the reverse transcription polymerase chain reaction (RT-PCR) technique. The voltage-gated Na+ current was recorded from isolated bipolar cells using the patch-clamp recording technique. Types of bipolar cells that have the Na+ currents were investigated by analyzing their morphology after staining with Lucifer yellow. Using RT-PCR, the SCN2A Na+ channel was detected in 5 of 6 isolated bipolar cells. This suggests that a subset of human bipolar cells expresses the SCN2A Na+ channel. Under voltage-clamp conditions, depolarizing voltage steps induced a fast transient inward current in cone bipolar cells with axon terminal boutons that stratified at the ON layer, which includes the stratum 3, 4, and 5 of the inner plexiform layer (IPL, n = 2/11 cells). The fast transient inward current of isolated bipolar cells was blocked by 1 μM of tetrodotoxin (TTX), a voltage-gated Na+ channel blocker. No fast transient inward current was recorded with axon terminals that stratify at the OFF layer, which includes stratum 1 and 2 of the IPL (n = 4). Thus, a subset of ON cone bipolar cells at least expresses the putative voltage-gated Na+ channel SCN2A in the human retina. The Na+ channels in the bipolar cells may serve to amplify the release of neurotransmitter, glutamate, when membrane potential is rapidly depolarized and thereby selectively accelerating light responses.
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Affiliation(s)
- Fusao Kawai
- Deptartment of Physiology, School of Medicine, Fujita Health University, Japan.
| | - Mahito Ohkuma
- Deptartment of Physiology, School of Medicine, Fujita Health University, Japan
| | - Masayuki Horiguchi
- Deptartment of Ophthalmology, School of Medicine, Fujita Health University, Japan
| | - Hiroshi Ichinose
- Institute for Comprehensive Medical Science, Fujita Health University, Japan; Present address:School of Life Science and Technology, Tokyo Institute of Technology, Japan
| | - Ei-Ichi Miyachi
- Deptartment of Physiology, School of Medicine, Fujita Health University, Japan
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75
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Fusi F, Mugnai P, Trezza A, Spiga O, Sgaragli G. Fine tuning by protein kinases of Ca V1.2 channel current in rat tail artery myocytes. Biochem Pharmacol 2020; 182:114263. [PMID: 33035505 DOI: 10.1016/j.bcp.2020.114263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [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: 09/22/2020] [Revised: 10/01/2020] [Accepted: 10/02/2020] [Indexed: 11/26/2022]
Abstract
Seventeen compounds, rather selective, direct or indirect inhibitors and activators of PKA, PKG, and PKC, were analysed for effects on vascular CaV1.2 channel current (ICa1.2) by using the patch-clamp technique in single rat tail artery myocytes. The aim was to investigate how PKs regulate ICa1.2 and disclose any unexpected modulation of CaV1.2 channel function by these agents. The cAMP analogues 8-Br-cAMP and 6-Bnz-cAMP partially reduced ICa1.2 in dialysed cells, while weakly increasing it under the perforated configuration. The β-adrenoceptor agonist isoproterenol and the adenylate cyclase activator forskolin concentration-dependently increased ICa1.2; this effect was reversed by PKA inhibitors H-89 and KT5720, but not by PKI 6-22. The cGMP analogue 8-Br-cGMP, similarly to the NO-donor SNP, moderately reduced ICa1.2, this effect being reversed to a slight stimulation under the perforated configuration. Among PKG inhibitors, Rp-8-Br-PET-cGMPS decreased current amplitude in a concentration-dependent manner while Rp-8-Br-cGMPS was ineffective. The non-specific phosphodiesterase inhibitor IBMX increased ICa1.2, while H-89, KT5720, and PKI 6-22 antagonized this effect. The PKC activator PMA, but not the diacylglycerol analogue OAG, stimulated ICa1.2 in a concentration-dependent manner; conversely, the PKCα inhibitor Gö6976 markedly reduced basal ICa1.2 and, similarly to the PKCδ (rottlerin) and PKCε translocation inhibitors antagonised PMA-induced current stimulation. The ensemble of findings indicates that the stimulation of cAMP/PKA, in spite of the paradoxical effect of both 8-Br-cAMP and 6-Bnz-cAMP, or PKC pathways enhanced, while that of cGMP/PKG weakly inhibited ICa1.2 in rat tail artery myocytes. Since Rp-8-Br-PET-cGMPS and Gö6976 appeared to block directly CaV1.2 channel, their docking to the channel protein was investigated. Both compounds appeared to bind the α1C subunit in a region involved in CaV1.2 channel inactivation, forming an interaction network comparable to that of CaV1.2 channel blockers. Therefore, caution should accompany the use of these agents as pharmacological tools to elucidate the mechanism of action of drugs on vascular preparations.
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Affiliation(s)
- F Fusi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - P Mugnai
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - A Trezza
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - O Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
| | - G Sgaragli
- Dipartimento di Scienze della Vita, Università degli Studi di Siena, via A. Moro 2, 53100 Siena, Italy
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76
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Hussein T, Bamann C. Charge Transport by Light-Activated Rhodopsins Determined by Electrophysiological Recordings. Methods Mol Biol 2021; 2191:67-84. [PMID: 32865739 DOI: 10.1007/978-1-0716-0830-2_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Electrophysiological experiments are required to determine the ion transport properties of light-activated currents from microbial rhodopsin expressing cells. The recordings set the quantitative basis for correlation with spectroscopic data and for understanding of channel gating, ion transport vectoriality, or ion selectivity. This chapter focuses on voltage-clamp recordings of channelrhodopsin-2-expressing cells, and it will describe different illumination protocols that reveal the kinetic properties of gating. While the opening and closing reaction is determined from a single turnover upon a short laser flash, desensitization of the light-gated currents is studied under continuous illumination. Recovery from the desensitized state is probed after prolonged illumination with a subsequent light activation upon different dark intervals. Compiling the experimental data will define a minimum number of states in kinetic schemes used to describe the light-gated currents in channelrhodopsins, and emphasis will be given on how to correlate the results with the different time-resolved spectroscopic experiments.
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77
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Martínez-Rojas VA, Jiménez-Garduño AM, Michelatti D, Tosatto L, Marchioretto M, Arosio D, Basso M, Pennuto M, Musio C. ClC-2-like Chloride Current Alterations in a Cell Model of Spinal and Bulbar Muscular Atrophy, a Polyglutamine Disease. J Mol Neurosci 2020; 71:662-674. [PMID: 32856205 DOI: 10.1007/s12031-020-01687-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [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: 05/18/2020] [Accepted: 08/14/2020] [Indexed: 12/21/2022]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by expansions of a polyglutamine (polyQ) tract in the androgen receptor (AR) gene. SBMA is associated with the progressive loss of lower motor neurons, together with muscle weakness and atrophy. PolyQ-AR is converted to a toxic species upon binding to its natural ligands, testosterone, and dihydrotestosterone (DHT). Our previous patch-clamp studies on a motor neuron-derived cell model of SBMA showed alterations in voltage-gated ion currents. Here, we identified and characterized chloride currents most likely belonging to the chloride channel-2 (ClC-2) subfamily, which showed significantly increased amplitudes in the SBMA cells. The treatment with the pituitary adenylyl cyclase-activating polypeptide (PACAP), a neuropeptide with a proven protective effect in a mouse model of SBMA, recovered chloride channel current alterations in SBMA cells. These observations suggest that the CIC-2 currents are affected in SBMA, an alteration that may contribute and potentially determine the pathophysiology of the disease.
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Affiliation(s)
- Vladimir A Martínez-Rojas
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Aura M Jiménez-Garduño
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy.,Departamento de Ciencias de la Salud, Escuela de Ciencias, Universidad de las Américas Puebla (UDLAP), San Andrés Cholula, Puebla, Mexico
| | - Daniela Michelatti
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy.,CIBIO Department, Laboratory of Chromatin Biology and Epigenetics, University of Trento, Trento, Italy
| | - Laura Tosatto
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Marta Marchioretto
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Daniele Arosio
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Manuela Basso
- CIBIO Department, Laboratory of Transcriptional Neurobiology, University of Trento, Trento, Italy
| | - Maria Pennuto
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Padova Neuroscience Center (PNC), University of Padova, Padova, Italy.,Veneto Institute of Molecular Medicine, Padova, Italy
| | - Carlo Musio
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy.
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78
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Vargas-Martínez EM, Gómez-Coronado KS, Espinosa-Luna R, Valdez-Morales EE, Barrios-García T, Barajas-Espinosa A, Ochoa-Cortes F, Montaño LM, Barajas-López C, Guerrero-Alba R. Functional expression of P2X1, P2X4 and P2X7 purinergic receptors in human monocyte-derived macrophages. Eur J Pharmacol 2020; 888:173460. [PMID: 32805257 DOI: 10.1016/j.ejphar.2020.173460] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/20/2020] [Accepted: 07/31/2020] [Indexed: 12/27/2022]
Abstract
This study sought to examine the co-expression of the following purinergic receptor subunits: P2X1, P2X1del, P2X4, and P2X7 and characterize the P2X response in human monocyte-derived macrophages (MDMs). Single-cell RT-PCR shows the presence of P2X1, P2X1del, P2X4, and P2X7 mRNA in 40%, 5%, 20%, and 90% of human MDMs, respectively. Of the studied human MDMs, 25% co-expressed P2X1 and P2X7 mRNA; 5% co-expressed P2X4 and P2X7; and 15% co-expressed P2X1, P2X4, and P2X7 mRNA. In whole-cell patch clamp recordings of human MDMs, rapid application of ATP (0.01 mM) evoked fast current activation and two different desensitization kinetics: 1. a rapid desensitizing current antagonized by PPADS (1 μM), reminiscent of the P2X1 receptor's current; 2. a slow desensitizing current, insensitive to PPADS but potentiated by ivermectin (3 μM), similar to the P2X4 receptor's current. Application of 5 mM ATP induced three current modalities: 1. slow current activation with no desensitization, similar to the P2X7 receptor current, present in 69% of human macrophages and antagonized by A-804598 (0.1 μM); 2. fast current activation and fast desensitization, present in 15% of human MDMs; 3. fast activation current followed by biphasic desensitization, observed in 15% of human MDMs. Both rapid and biphasic desensitization kinetics resemble those observed for the recombinant human P2X1 receptor expressed in oocytes. These data demonstrate, for the first time, the co-expression of P2X1, P2X4, and P2X7 transcripts and confirm the presence of functional P2X1, P2X4, and P2X7 receptors in human macrophages.
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Affiliation(s)
- Eydie M Vargas-Martínez
- División de Biología Molecular, Instituto Potosino Investigación Científica y Tecnológica, San Luis Potosí, SLP, México
| | - Karen S Gómez-Coronado
- División de Biología Molecular, Instituto Potosino Investigación Científica y Tecnológica, San Luis Potosí, SLP, México
| | - Rosa Espinosa-Luna
- División de Biología Molecular, Instituto Potosino Investigación Científica y Tecnológica, San Luis Potosí, SLP, México
| | - Eduardo E Valdez-Morales
- Catedras CONACYT, Departamento de Medicina, Centro de Ciencias de la Salud, Universidad Autónoma de Aguascalientes, Aguascalientes, México
| | - Tonatiuh Barrios-García
- Departamento de Fisiología y Farmacología, Centro de Ciencias Básicas, Universidad Autónoma de Aguascalientes, Aguascalientes, México
| | - Alma Barajas-Espinosa
- Licenciatura en Enfermería, Escuela Superior de Huejutla, Universidad Autónoma del Estado de Hidalgo, Huejutla de Reyes, Hidalgo, México
| | - Fernando Ochoa-Cortes
- Licenciatura en Enfermería, Escuela Superior de Huejutla, Universidad Autónoma del Estado de Hidalgo, Huejutla de Reyes, Hidalgo, México
| | - Luis M Montaño
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, CDMX, México
| | - Carlos Barajas-López
- División de Biología Molecular, Instituto Potosino Investigación Científica y Tecnológica, San Luis Potosí, SLP, México
| | - Raquel Guerrero-Alba
- Departamento de Fisiología y Farmacología, Centro de Ciencias Básicas, Universidad Autónoma de Aguascalientes, Aguascalientes, México.
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79
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Uzura R, Takahashi K, Saito S, Tominaga M, Ohta T. Reduction of extracellular sodium evokes nociceptive behaviors in the chicken via activation of TRPV1. Brain Res 2020; 1747:147052. [PMID: 32791143 DOI: 10.1016/j.brainres.2020.147052] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/03/2020] [Accepted: 08/07/2020] [Indexed: 10/23/2022]
Abstract
Transient receptor potential vanilloid 1 (TRPV1), a non-selective cation channel, is mainly expressed in nociceptive primary sensory neurons. Sensitivity of TRPV1 to several stimuli is known to vary among species, specifically, the avian orthologue is nearly insensitive to capsaicin. Extracellular sodium ions ([Na+]o) regulate TRPV1 activity in mammals, but their regulatory role on chicken TRPV1 (cTRPV1) is unknown. Here, we focused on the actions of capsaicin and low [Na+]o on cTRPV1 activity. In chicken dorsal root ganglion (cDRG) neurons, capsaicin elicited [Ca2+]i increases, but its effective concentration was much higher than those in mammals. Low [Na+]o evoked [Ca2+]i increases in cDRG neurons in a decreasing [Na+]o-dependent manner and the complete removal of [Na+]o (0Na) produced maximal effects. The population of 0Na-sensitive neurons was mostly overlapped with those of proton- and capsaicin-sensitive ones. Low [Na+]o synergistically potentiated the capsaicin- and proton-induced TRPV1 activation in cDRG neurons. In HEK293 cells expressing cTRPV1 (cTRPV1-HEK), capsaicin elicited [Ca2+]i increases with an EC50 of 11.8 µM, and low [Na+]o also did. Well-defined mammalian TRPV1 antagonists hardly suppressed cTRPV1 activation by low [Na+]o. 0Na evoked outwardly rectified currents in cTRPV1-HEK. Mutagenesis analyses revealed a possible interaction of [Na+]o with the proton-binding sites of cTRPV1. The administration of capsaicin and 0Na to chick eyes elicited pain-related behaviors. These results suggest that low [Na+]o is capable of activating cTRPV1 in vitro, resulting in pain in vivo. Our data demonstrate that characterization of the cTRPV1 function is important to understand activation mechanisms of TRPV1.
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Affiliation(s)
- R Uzura
- Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - K Takahashi
- Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - S Saito
- Division of Cell Signaling, National Institute for Physiological Sciences, National Institute of Natural Sciences, Aichi, Japan; Thermal Biology Group, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Sciences, Aichi, Japan
| | - M Tominaga
- Division of Cell Signaling, National Institute for Physiological Sciences, National Institute of Natural Sciences, Aichi, Japan; Thermal Biology Group, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Sciences, Aichi, Japan
| | - T Ohta
- Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, Tottori, Japan.
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80
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Chubinskiy-Nadezhdin VI, Vasileva VY, Negulyaev YA, Morachevskaya EA. Functional clustering and coupling of ion channels in cellular mechanosensing is independent on lipid raft integrity in plasma membrane. Biochim Biophys Acta Mol Cell Res 2020; 1867:118764. [PMID: 32479769 DOI: 10.1016/j.bbamcr.2020.118764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 05/23/2020] [Accepted: 05/27/2020] [Indexed: 10/24/2022]
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81
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Patel RN, Richards DP, Duce IR, Birkett MA, Sattelle DB, Mellor IR. Actions on mammalian and insect nicotinic acetylcholine receptors of harmonine-containing alkaloid extracts from the harlequin ladybird Harmonia axyridis. Pestic Biochem Physiol 2020; 166:104561. [PMID: 32448416 DOI: 10.1016/j.pestbp.2020.104561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/11/2020] [Accepted: 03/01/2020] [Indexed: 06/11/2023]
Abstract
The harlequin ladybird, Harmonia axyridis (H. axyridis), possesses a strong chemical defence that has contributed to its invasive success. Ladybird beetle defensive chemicals, secreted in response to stress and also found on the coating of laid eggs, are rich in alkaloids that are thought to be responsible for this beetle's toxicity to other species. Recent studies have shown that alkaloids from several species of ladybird beetle can target nicotinic acetylcholine receptors (nAChRs) acting as receptor antagonists, hence we have explored the actions of alkaloids of the ladybird H. axyridis on both mammalian and insect nAChRs. Electrophysiological studies on native and functionally expressed recombinant nAChRs were used to establish whether an alkaloid extract from H. axyridis (HAE) targeted nAChRs and whether any selectivity exists for insect over mammalian receptors of this type. HAE was found to be an inhibitor of all nAChRs tested with the voltage-dependence of inhibition and the effect on ACh EC50 differing between nAChR subtypes. Our finding that an HAE fraction consisting almost entirely of harmonine had a strong inhibitory effect points to this alkaloid as a key component of nAChR inhibitory actions. Comparison of HAE inhibition between the mammalian and insect nAChRs investigated indicates some preference for the insect nAChR supporting the view that investigation of ladybird alkaloids shows promise as a method for identifying natural product leads for future insecticide development.
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Affiliation(s)
- Rohit N Patel
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - David P Richards
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Ian R Duce
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Michael A Birkett
- Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK
| | - David B Sattelle
- Centre for Respiratory Biology, UCL Respiratory, University College London, Rayne Building, University Street, London WC1E 6JF, UK.
| | - Ian R Mellor
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
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Deng M, Jiang L, Luo X, Tao H, Liang S. Jingzhaotoxin-X, a gating modifier of Kv4.2 and Kv4.3 potassium channels purified from the venom of the Chinese tarantula Chilobrachys jingzhao. J Venom Anim Toxins Incl Trop Dis 2020; 26:e20190043. [PMID: 32536941 PMCID: PMC7269146 DOI: 10.1590/1678-9199-jvatitd-2019-0043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [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] [Indexed: 11/21/2022] Open
Abstract
Background The tarantula Chilobrachys jingzhao is one of the largest venomous spiders in China. In previous studies, we purified and characterized at least eight peptides from C. jingzhao venom. In this report, we describe the purification and characterization of Jingzhaotoxin-X (JZTX-X), which selectively blocks Kv4.2 and Kv4.3 potassium channels. Methods JZTX-X was purified using a combination of cation-exchange HPLC and reverse-phase HPLC. The amino-acid sequence was determined by automated Edman degradation and confirmed by mass spectrometry (MS). Voltage-gated ion channel currents were recorded in HEK293t cells transiently transfected with a variety of ion channel constructs. In addition, the hyperalgesic activity of JZTX-X and the toxin´s effect on motor function were assessed in mice. Results JZTX-X contained 31 amino acids, with six cysteine residues that formed three disulfide bonds within an inhibitory cysteine knot (ICK) topology. In whole-cell voltage-clamp experiments, JZTX-X inhibited Kv4.2 and Kv4.3 potassium channels in a concentration- and voltage-dependent manner, without affecting other ion channels (Kv1.1, 1.2, 1.3, 2.1, delayed rectifier potassium channels, high- and low-voltage-activated Ca2+ channels, and voltage-gated sodium channels Nav1.5 and 1.7). JZTX-X also shifted the voltage-dependent channel activation to more depolarized potentials, whereas extreme depolarization caused reversible toxin binding to Kv4.2 channels. JZTX-X shifted the Kv4.2 and Kv4.3 activities towards a resting state, since at the resting potential the toxin completely inhibited the channels, even in the absence of an applied physical stimulus. Intrathecal or intraplantar injection of JZTX-X caused a long-lasting decrease in the mechanical nociceptive threshold (hyperalgesia) but had no effect on motor function as assessed in the rotarod test. Conclusions JZTX-X selectively suppresses Kv4.2 and Kv4.3 potassium channel activity in a concentration- and voltage-dependent manner and causes long-lasting mechanical hyperalgesia.
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Affiliation(s)
- Meichun Deng
- Department of Biochemistry and Molecular Biology, School of Life Sciences, Central South University, Changsha, Hunan 410013, China
| | - Liping Jiang
- Department of Parasitology, Xiangya School of Medicine, Central South University, Changsha 410013, China
| | - Xuan Luo
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, 410081, China
| | - Huai Tao
- Department of Biochemistry and Molecular Biology, Hunan University of Chinese Medicine, Changsha 410208, Hunan, China
| | - Songping Liang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, 410081, China
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83
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Khazraei H, Mirkhani H, Shabbir W. Electrocardiological effects of ranolazine and lidocaine on normal and diabetic rat atrium. J Interv Card Electrophysiol 2020; 60:387-394. [PMID: 32328860 DOI: 10.1007/s10840-020-00742-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 03/30/2020] [Indexed: 12/19/2022]
Abstract
PURPOSE Cellular changes occurring in diabetic cardiomyopathy include disturbances of calcium and sodium homeostasis. Voltage-gated sodium channels are responsible for the initiation of cardiac action potentials, and the excitability would create relevance. The effect of ranolazine as a sodium channel blocker on atrium electromechanical parameters is investigated and compared with lidocaine in streptozocin-treated diabetic rats. METHODS After an 8-week induction of diabetes type I, the effect of cumulative concentrations of ranolazine and lidocaine on the electrophysiology of isolated atrium was studied. Ranolazine's effects were evaluated on cardiac sodium current in normal- and high-glucose medium, with whole-cell patch-clamp technique. RESULTS Ranolazine at therapeutic concentrations had no significant statistical effect on refractory period in normal and diabetic isolated heart. Ranolazine (10 μM) caused a hyperpolarizing shift of V1/2 for steady-state inactivation in normal media, while it significantly elicited a depolarizing shift in high-glucose media (p < 0.05). CONCLUSION It is concluded that in the isolated rat atrium preparation, ranolazine and lidocaine have no beneficial on diabetic cardiomyopathy. Although refractoriness and contractility were not much different in normal and diabetic atria, there was a definite effect of ranolazine and lidocaine on sodium current in varying concentrations. This may have significance in future therapeutics.
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Affiliation(s)
- Hajar Khazraei
- Colorectal research center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Hossein Mirkhani
- Department of pharmacology, Shiraz University of Medical Sciences, Shiraz, Iran.
| | - Waheed Shabbir
- Department of Pharmacology and Toxicology, University of Vienna, A-1090, Vienna, Austria
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84
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Desaphy JF, Farinato A, Altamura C, De Bellis M, Imbrici P, Tarantino N, Caccia C, Melloni E, Padoani G, Vailati S, Keywood C, Carratù MR, De Luca A, Conte D, Pierno S. Safinamide's potential in treating nondystrophic myotonias: Inhibition of skeletal muscle voltage-gated sodium channels and skeletal muscle hyperexcitability in vitro and in vivo. Exp Neurol 2020; 328:113287. [PMID: 32205118 DOI: 10.1016/j.expneurol.2020.113287] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [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: 10/29/2019] [Revised: 03/14/2020] [Accepted: 03/19/2020] [Indexed: 12/26/2022]
Abstract
The antiarrhythmic sodium-channel blocker mexiletine is used to treat patients with myotonia. However, around 30% of patients do not benefit from mexiletine due to poor tolerability or suboptimal response. Safinamide is an add-on therapy to levodopa for Parkinson's disease. In addition to MAOB inhibition, safinamide inhibits neuronal sodium channels, conferring anticonvulsant activity in models of epilepsy. Here, we investigated the effects of safinamide on skeletal muscle hNav1.4 sodium channels and in models of myotonia, in-vitro and in-vivo. Using patch-clamp, we showed that safinamide reversibly inhibited sodium currents in HEK293T cells transfected with hNav1.4. At the holding potential (hp) of -120 mV, the half-maximum inhibitory concentrations (IC50) were 160 and 33 μM at stimulation frequencies of 0.1 and 10 Hz, respectively. The calculated affinity constants of safinamide were dependent on channel state: 420 μM for closed channels and 9 μM for fast-inactivated channels. The p.F1586C mutation in hNav1.4 greatly impaired safinamide inhibition, suggesting that the drug binds to the local anesthetic receptor site in the channel pore. In a condition mimicking myotonia, i.e. hp. of -90 mV and 50-Hz stimulation, safinamide inhibited INa with an IC50 of 6 μM, being two-fold more potent than mexiletine. Using the two-intracellular microelectrodes current-clamp method, action potential firing was recorded in vitro in rat skeletal muscle fibers in presence of the chloride channel blocker, 9-anthracene carboxylic acid (9-AC), to increase excitability. Safinamide counteracted muscle fiber hyperexcitability with an IC50 of 13 μM. In vivo, oral safinamide was tested in the rat model of myotonia. In this model, intraperitoneal injection of 9-AC greatly increased the time of righting reflex (TRR) due to development of muscle stiffness. Safinamide counteracted 9-AC induced TRR increase with an ED50 of 1.2 mg/kg, which is 7 times lower than that previously determined for mexiletine. In conclusion, safinamide is a potent voltage and frequency dependent blocker of skeletal muscle sodium channels. Accordingly, the drug was able to counteract abnormal muscle hyperexcitability induced by 9-AC, both in vitro and in vivo. Thus, this study suggests that safinamide may have potential in treating myotonia and warrants further preclinical and human studies to fully evaluate this possibility.
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Affiliation(s)
- Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy.
| | - Alessandro Farinato
- Department of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Michela De Bellis
- Department of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Paola Imbrici
- Department of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Nancy Tarantino
- Department of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Carla Caccia
- Open R&D Department, Zambon S.p.A., Bresso, MI, Italy
| | - Elsa Melloni
- Open R&D Department, Zambon S.p.A., Bresso, MI, Italy
| | | | | | | | - Maria Rosaria Carratù
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Annamaria De Luca
- Department of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Diana Conte
- Department of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Sabata Pierno
- Department of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
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85
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Rauti R, Cellot G, D'Andrea P, Colliva A, Scaini D, Tongiorgi E, Ballerini L. BDNF impact on synaptic dynamics: extra or intracellular long-term release differently regulates cultured hippocampal synapses. Mol Brain 2020; 13:43. [PMID: 32183860 DOI: 10.1186/s13041-020-00582-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 03/09/2020] [Indexed: 01/21/2023] Open
Abstract
Brain Derived Neurotrophic Factor (BDNF) signalling contributes to the formation, maturation and plasticity of Central Nervous System (CNS) synapses. Acute exposure of cultured brain circuits to BDNF leads to up-regulation of glutamatergic neuro-transmission, by the accurate tuning of pre and post synaptic features, leading to structural and functional synaptic changes. Chronic BDNF treatment has been comparatively less investigated, besides it may represent a therapeutic option to obtain rescue of post-injury alterations of synaptic networks. In this study, we used a paradigm of BDNF long-term (4 days) incubation to assess in hippocampal neurons in culture, the ability of such a treatment to alter synapses. By patch clamp recordings we describe the augmented function of excitatory neurotransmission and we further explore by live imaging the presynaptic changes brought about by long-term BDNF. In our study, exogenous long-term BDNF exposure of post-natal neurons did not affect inhibitory neurotransmission. We further compare, by genetic manipulations of cultured neurons and BDNF release, intracellular overexpression of this neurotrophin at the same developmental age. We describe for the first-time differences in synaptic modulation by BDNF with respect to exogenous or intracellular release paradigms. Such a finding holds the potential of influencing the design of future therapeutic strategies.
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86
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Sciaccaluga M, Mazzocchetti P, Bastioli G, Ghiglieri V, Cardinale A, Mosci P, Caccia C, Keywood C, Melloni E, Padoani G, Vailati S, Picconi B, Calabresi P, Tozzi A. Effects of safinamide on the glutamatergic striatal network in experimental Parkinson's disease. Neuropharmacology 2020; 170:108024. [PMID: 32142791 DOI: 10.1016/j.neuropharm.2020.108024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [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: 10/25/2019] [Revised: 02/03/2020] [Accepted: 02/27/2020] [Indexed: 01/01/2023]
Abstract
OBJECTIVE The aim of the study was to evaluate electrophysiological effects of safinamide on the intrinsic and synaptic properties of striatal spiny projection neurons (SPNs) and to characterize the possible therapeutic antiparkinsonian effect of this drug in dopamine (DA) denervated rats before and during levodopa (l-DOPA) treatment. BACKGROUND Current therapeutic options in Parkinson's disease (PD) are primarily DA replacement strategies that usually cause progressive motor fluctuations and l-DOPA-induced dyskinesia (LIDs) as a consequence of SPNs glutamate-induced hyperactivity. As a reversible and use-dependent inhibitor of voltage-gated sodium channels, safinamide reduces the release of glutamate and possibly optimize the effect of l-DOPA therapy in PD. METHODS Electrophysiological effects of safinamide (1-100 μM) were investigated by patch-clamp recordings in striatal slices of naïve, 6-hydroxydopamine (6-OHDA)-lesioned DA-denervated rats and DA-denervated animals chronically treated with l-DOPA. LIDs were assessed in vivo with and without chronic safinamide treatment and measured by scoring the l-DOPA-induced abnormal involuntary movements (AIMs). Motor deficit was evaluated with the stepping test. RESULTS Safinamide reduced the SPNs firing rate and glutamatergic synaptic transmission in all groups, showing a dose-dependent effect with half maximal inhibitory concentration (IC50) values in the therapeutic range (3-5 μM). Chronic co-administration of safinamide plus l-DOPA in DA-denervated animals favored the recovery of corticostriatal long-term synaptic potentiation (LTP) and depotentiation of excitatory synaptic transmission also reducing motor deficits before the onset of LIDs. CONCLUSIONS Safinamide, at a clinically relevant dose, optimizes the effect of l-DOPA therapy in experimental PD reducing SPNs excitability and modulating synaptic transmission. Co-administration of safinamide and l-DOPA ameliorates motor deficits.
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Affiliation(s)
- Miriam Sciaccaluga
- Neurological Clinic, Department of Medicine, University of Perugia, Santa Maria della Misericordia Hospital, via Gambuli, 1, 06132, Perugia, Italy
| | - Petra Mazzocchetti
- Neurological Clinic, Department of Medicine, University of Perugia, Santa Maria della Misericordia Hospital, via Gambuli, 1, 06132, Perugia, Italy
| | - Guendalina Bastioli
- Neurological Clinic, Department of Medicine, University of Perugia, Santa Maria della Misericordia Hospital, via Gambuli, 1, 06132, Perugia, Italy
| | - Veronica Ghiglieri
- Department of Philosophy, Human, Social and Educational Sciences, University of Perugia, Piazza G. Ermini, 1, 06123, Perugia, Italy; Laboratory of Neurophysiology, Santa Lucia Foundation IRCCS, Via del Fosso di Fiorano, 64, 00143, Rome, Italy
| | - Antonella Cardinale
- Neurological Clinic, Department of Medicine, University of Perugia, Santa Maria della Misericordia Hospital, via Gambuli, 1, 06132, Perugia, Italy; Laboratory of Experimental Neurophysiology, IRCCS San Raffaele Pisana, Via Val Cannuta 247, 00166, Rome, Italy
| | - Paolo Mosci
- Department of Veterinary, University of Perugia, Via San Costanzo, 4, 06126, Perugia, Italy
| | - Carla Caccia
- Open R&D Department, Zambon SpA, Via Lillo del Duca, 10, 20091, Bresso, Milan, Italy
| | - Charlotte Keywood
- Open R&D Department, Zambon SpA, Via Lillo del Duca, 10, 20091, Bresso, Milan, Italy
| | - Elsa Melloni
- Open R&D Department, Zambon SpA, Via Lillo del Duca, 10, 20091, Bresso, Milan, Italy
| | - Gloria Padoani
- Open R&D Department, Zambon SpA, Via Lillo del Duca, 10, 20091, Bresso, Milan, Italy
| | - Silvia Vailati
- Open R&D Department, Zambon SpA, Via Lillo del Duca, 10, 20091, Bresso, Milan, Italy
| | - Barbara Picconi
- Laboratory of Experimental Neurophysiology, IRCCS San Raffaele Pisana, Via Val Cannuta 247, 00166, Rome, Italy; University San Raffaele, Via Val Cannuta, 247, 00166, Rome, Italy
| | - Paolo Calabresi
- Clinica Neurologica, Dipartimento di Neuroscienze, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Università Cattolica del Sacro Cuore, Largo Agostino Gemelli, 8, 00168, Roma, Italy
| | - Alessandro Tozzi
- Department of Experimental Medicine, Section of Physiology and Biochemistry, University of Perugia, via Gambuli, 1, 06132, Perugia, Italy.
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Pasierski M, Szulczyk B. Capsaicin inhibits sodium currents and epileptiform activity in prefrontal cortex pyramidal neurons. Neurochem Int 2020; 135:104709. [PMID: 32105721 DOI: 10.1016/j.neuint.2020.104709] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/31/2020] [Accepted: 02/20/2020] [Indexed: 11/19/2022]
Abstract
Capsaicin, a compound found in chili peppers, causes burning sensations by acting on the peripheral sensory system. However, it has also been reported to exert substantial effects on central neurons. The aim of this patch-clamp study was to test the antiepileptic potential of capsaicin in prefrontal cortical pyramidal neurons. Capsaicin at a concentration of 60 μM inhibited neuronal excitability. Moreover, later spikes in response to 50-s-long current steps were much smaller in amplitude in the presence of 60 μM capsaicin than in control solution. The tested compound did not influence the membrane potential. Voltage-clamp recordings showed that capsaicin markedly enhanced the use-dependent block of sodium channels (sodium currents were evoked at frequencies of 0,5 Hz and 10 Hz). The presence of the compound shifted the steady-state inactivation curve of sodium channels towards hyperpolarization, which suggests greater inactivation of sodium channels at rest in the presence of capsaicin. Moreover, capsaicin inhibited epileptiform events evoked in three different proepileptic solutions. Capsaicin abolished interictal-like events lasting less than 1 s recorded in zero magnesium solution with an increased potassium ion concentration. The drug also abolished long ictal events evoked in zero magnesium solution containing 4-AP. Moreover, ictal events recorded in zero magnesium solution containing picrotoxin were substantially shortened in the presence of capsaicin. We suggest that capsaicin exerts an antiepileptic effect. The important mechanism behind this phenomenon seems to be the inhibition of sodium channels, which is an effect of many antiepileptic drugs.
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Affiliation(s)
- Michał Pasierski
- Department of Pharmacodynamics, The Medical University of Warsaw, Warsaw, Banacha 1B, 02-097, Poland
| | - Bartłomiej Szulczyk
- Department of Pharmacodynamics, The Medical University of Warsaw, Warsaw, Banacha 1B, 02-097, Poland.
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88
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Mondragón-Rodríguez S, Ordaz B, Orta-Salazar E, Díaz-Cintra S, Peña-Ortega F, Perry G. Hippocampal Unicellular Recordings and Hippocampal-dependent Innate Behaviors in an Adolescent Mouse Model of Alzheimer's disease. Bio Protoc 2020; 10:e3529. [PMID: 33654753 PMCID: PMC7842348 DOI: 10.21769/bioprotoc.3529] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/27/2020] [Accepted: 01/28/2020] [Indexed: 11/02/2022] Open
Abstract
Transgenic mice have been used to make valuable contributions to the field of neuroscience and model neurological diseases. The simultaneous functional analysis of hippocampal cell activity combined with hippocampal dependent innate task evaluations provides a reliable experimental approach to detect fine changes during early phases of neurodegeneration. To this aim, we used a merge of patch-clamp with two hippocampal innate behavior tasks. With this experimental approach, whole-cell recordings of CA1 pyramidal cells, combined with hippocampal-dependent innate behaviors, have been crucial for evaluating the early mechanism of neurodegeneration and its consequences. Here, we present our protocol for ex vivo whole-cell recordings of CA1 pyramidal cells and hippocampal dependent innate behaviors in an adolescent (p30) mice.
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Affiliation(s)
- Siddhartha Mondragón-Rodríguez
- National Council for Science and Technology (CONACYT), México, México
- Developmental Neurobiology and Neurophysiology, Institute of Neurobiology, National Autonomous University of México (UNAM), Querétaro, México
| | - Benito Ordaz
- Developmental Neurobiology and Neurophysiology, Institute of Neurobiology, National Autonomous University of México (UNAM), Querétaro, México
| | - Erika Orta-Salazar
- Developmental Neurobiology and Neurophysiology, Institute of Neurobiology, National Autonomous University of México (UNAM), Querétaro, México
| | - Sofia Díaz-Cintra
- Developmental Neurobiology and Neurophysiology, Institute of Neurobiology, National Autonomous University of México (UNAM), Querétaro, México
| | - Fernando Peña-Ortega
- Developmental Neurobiology and Neurophysiology, Institute of Neurobiology, National Autonomous University of México (UNAM), Querétaro, México
| | - George Perry
- Neuroscience Institute and Department of Biology, College of Sciences, University of Texas at San Antonio (UTSA), San Antonio, Texas
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Zhou X, He D, Yan X, Chen X, Li R, Zhang G, Wang J. Moxonidine inhibits excitatory inputs to airway vagal preganglionic neurons via activation of both α 2-adrenoceptors and imidazoline I1 receptors. Brain Res 2020; 1732:146695. [PMID: 32007398 DOI: 10.1016/j.brainres.2020.146695] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 12/26/2019] [Accepted: 01/29/2020] [Indexed: 10/25/2022]
Abstract
As an imidazoline I1 receptor agonist with very weak binding affinity for α2-adrenoceptors, moxonidine is commonly used in the treatment of hypertension. Moxonidine also has been implicated to act centrally to reduce airway vagal outflow. However, it is unknown at which central sites moxonidine acts to affect airway vagal activity, and how moxonidine takes effect at synaptic and receptor levels. In this study, airway vagal preganglionic neurons (AVPNs) were retrogradely labeled in neonatal rats from the intrathoracic trachea; retrogradely labeled AVPNs in the external formation of the nucleus ambiguus (NA) were identified in rhythmically active medullary slices using whole-cell patch-clamp techniques; and the effects of moxonidine on the spontaneous excitatory postsynaptic currents (EPSCs) of AVPNs were observed at synaptic level. The results show that moxonidine (10 μmol·L-1) significantly inhibited the frequency of spontaneous EPSCs in both inspiratory-activated and inspiratory-inhibited AVPNs. This effect was partially blocked by SKF-86466 (10 μmol·L-1), a highly selective antagonist of α2-adrenoceptors, or AGN-192403, a selective antagonist of imidazoline I1 receptors, and was completely blocked by efaroxan (10 μmol·L-1), an antagonist of both α2-adrenoceptors and imidazoline I1 receptors. These results demonstrate that moxonidine inhibits the excitatory inputs to AVPNs via activation of both α2-adrenoceptors and imidazoline I1 receptors, and suggest that physiologically both of these two types of receptors are involved in the central regulation of airway vagal activity at preganglionic level. Moxonidine might be potentially useful in diseases with aberrant airway vagal activity such as asthma and chronic obstructive diseases.
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Affiliation(s)
- Xujiao Zhou
- Eye Institute in Eye & ENT Hospital, and NHC Key Laboratory of Myopia, Fudan University, China; Shanghai Key Laboratory of Visual Impairment and Restoration, China; Key Laboratory of Myopia, Chinese Academy of Medical Sciences, China
| | - Ding He
- Department of Physiology and Pathophysiology, Fudan University School of Basic Medical Sciences, China
| | - Xianxia Yan
- Department of Physiology and Pathophysiology, Fudan University School of Basic Medical Sciences, China
| | - Xingxin Chen
- Department of Physiology and Pathophysiology, Fudan University School of Basic Medical Sciences, China
| | - Rui Li
- Department of Nursing, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China
| | - Guangming Zhang
- Department of Anesthesiology, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200336, China.
| | - Jijiang Wang
- Department of Physiology and Pathophysiology, Fudan University School of Basic Medical Sciences, China.
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Abstract
Membrane fusion and fission are indispensable parts of intracellular membrane recycling and transport. Electrophysiological techniques have been instrumental in discovering and studying fusion and fission pores, the key intermediates shared by both processes. In cells, electrical admittance measurements are used to assess in real time the dynamics of the pore conductance, reflecting the nanoscale transformations of the pore, simultaneously with membrane leakage. Here, we described how this technique is adapted to in vitro mechanistic analyses of membrane fission by dynamin 1 (Dyn1), the protein orchestrating membrane fission in endocytosis. We reconstitute the fission reaction using purified Dyn1 and biomimetic lipid membrane nanotubes of defined geometry. We provide a comprehensive protocol describing simultaneous measurements of the ionic conductance through the nanotube lumen and across the nanotube wall, enabling spatiotemporal correlation between the nanotube constriction by Dyn1, leading to fission and membrane leakage. We present examples of "leaky" and "tight" fission reactions, specify the resolution limits of our method, and discuss how our results support the hemi-fission conjecture.
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Affiliation(s)
- Pavel V Bashkirov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, Russia
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
| | - Ksenia V Chekashkina
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, Russia
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
| | - Anna V Shnyrova
- Department of Biochemistry and Molecular Biology, Biophysics Institute (CSIC, UPV/EHU), University of the Basque Country, Leioa, Spain
| | - Vadim A Frolov
- Department of Biochemistry and Molecular Biology, Biophysics Institute (CSIC, UPV/EHU), University of the Basque Country, Leioa, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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91
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Casini S, Marchal GA, Kawasaki M, Nariswari FA, Portero V, van den Berg NWE, Guan K, Driessen AHG, Veldkamp MW, Mengarelli I, de Groot JR, Verkerk AO, Remme CA. Absence of Functional Na v1.8 Channels in Non-diseased Atrial and Ventricular Cardiomyocytes. Cardiovasc Drugs Ther 2019; 33:649-660. [PMID: 31916131 PMCID: PMC6994555 DOI: 10.1007/s10557-019-06925-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
PURPOSE Several studies have indicated a potential role for SCN10A/NaV1.8 in modulating cardiac electrophysiology and arrhythmia susceptibility. However, by which mechanism SCN10A/NaV1.8 impacts on cardiac electrical function is still a matter of debate. To address this, we here investigated the functional relevance of NaV1.8 in atrial and ventricular cardiomyocytes (CMs), focusing on the contribution of NaV1.8 to the peak and late sodium current (INa) under normal conditions in different species. METHODS The effects of the NaV1.8 blocker A-803467 were investigated through patch-clamp analysis in freshly isolated rabbit left ventricular CMs, human left atrial CMs and human-induced pluripotent stem cell-derived CMs (hiPSC-CMs). RESULTS A-803467 treatment caused a slight shortening of the action potential duration (APD) in rabbit CMs and hiPSC-CMs, while it had no effect on APD in human atrial cells. Resting membrane potential, action potential (AP) amplitude, and AP upstroke velocity were unaffected by A-803467 application. Similarly, INa density was unchanged after exposure to A-803467 and NaV1.8-based late INa was undetectable in all cell types analysed. Finally, low to absent expression levels of SCN10A were observed in human atrial tissue, rabbit ventricular tissue and hiPSC-CMs. CONCLUSION We here demonstrate the absence of functional NaV1.8 channels in non-diseased atrial and ventricular CMs. Hence, the association of SCN10A variants with cardiac electrophysiology observed in, e.g. genome wide association studies, is likely the result of indirect effects on SCN5A expression and/or NaV1.8 activity in cell types other than CMs.
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Affiliation(s)
- Simona Casini
- Department of Experimental Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands.
| | - Gerard A Marchal
- Department of Experimental Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
| | - Makiri Kawasaki
- Department of Experimental Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
| | - Fransisca A Nariswari
- Department of Experimental Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
| | - Vincent Portero
- Department of Experimental Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
| | | | - Kaomei Guan
- Institute of Pharmacology and Toxicology, Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
| | - Antoine H G Driessen
- Department of Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
| | - Marieke W Veldkamp
- Department of Experimental Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
| | - Isabella Mengarelli
- Department of Experimental Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
| | - Joris R de Groot
- Department of Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
| | - Arie O Verkerk
- Department of Experimental Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
- Department of Medical Biology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
| | - Carol Ann Remme
- Department of Experimental Cardiology, Amsterdam UMC, Meibergdreef 15, Amsterdam, 1105 AZ, The Netherlands
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92
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Bene L, Bagdány M, Damjanovich L. Adaptive threshold-stochastic resonance (AT-SR) in MHC clusters on the cell surface. Immunol Lett 2019; 217:65-71. [PMID: 31738956 DOI: 10.1016/j.imlet.2019.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 10/15/2019] [Accepted: 11/11/2019] [Indexed: 11/15/2022]
Abstract
Highly conserved 2D receptor clusters (membrane rafts) of immunological signaling molecules with MHCI and MHCII antigens as their cores have been observed in the past on the surface of T- and B-cell lines of lymphoid origin, as well as on cells from patients with colon tumor and Crohn's disease. Conservativity is related to the ever presence of MHCI molecules. Although they are suspected to play a role in maintaining these clusters and facilitating transmembrane signaling, their exact role has been left largely enigmatic. Here we are suggesting stochastic resonance (SR), or "noise-assisted signal detection", as a general organizing principle for transmembrane signaling events evoked by processes like immune recognition and cytokine binding taking place in these clusters. In the conceptual framework of SR, in immune recognition as a prototype of transmembrane signaling, the sea of self-peptide-MHC complexes around a nonself-peptide presenting MHC is conceived as a source of quickly fluctuating unspecific signal ("athermal noise") serving the extra energy for amplifying the weak sub-threshold specific signal of the nonself-peptide presenting MHC. This same noise is also utilized for a readjustment of the threshold - and also the sensitivity and specificity - of detection by a closed loop feedback control of the TcR-CD8 (CD4) proximity on the detecting T-cell. The weak sub threshold specific signal of nonself-peptide presenting MHC is amplified by the superposing unspecific signals of the neighboring self peptide-MHC complexes towards the T-cell receptor as the detector. Because in a successful detection event both self- and nonself-peptides are detected simultaneously, the principle of coincidence (or lock-in) detection is also realized. The ever presence of MHC islands gets a natural explanation as a source of extra power - in a form of "athermal noise" - needed for coincidence detection and frequency encoding the evoked downstream signals. The effect is quite general, because the actual type of molecules surrounding a chief signaling molecule - like nonself-peptide holding MHC, interleukin-2 and -15 cytokine receptors (IL-2R/15R) - as the fluctuating interaction energy sources is immaterial. The model applies also for other types of signaling, such as those evoked by cytokine binding. The phenomenon of SR can also be interpreted as sampling of a low frequency, specific signal with a high frequency unspecific signal, the "noise". Recipes for identifying other forms of SR in membrane clusters with biophysical tools are recommended.
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Affiliation(s)
- László Bene
- Department of Surgery, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
| | - Miklós Bagdány
- Department of Physiology, McGill University, Montreal, Canada
| | - László Damjanovich
- Department of Surgery, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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93
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Maroni M, Körner J, Schüttler J, Winner B, Lampert A, Eberhardt E. β1 and β3 subunits amplify mechanosensitivity of the cardiac voltage-gated sodium channel Nav1.5. Pflugers Arch 2019; 471:1481-1492. [PMID: 31728700 DOI: 10.1007/s00424-019-02324-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [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: 05/25/2019] [Revised: 09/25/2019] [Accepted: 10/21/2019] [Indexed: 12/19/2022]
Abstract
In cardiomyocytes, electrical activity is coupled to cellular contraction, thus exposing all proteins expressed in the sarcolemma to mechanical stress. The voltage-gated sodium channel Nav1.5 is the main contributor to the rising phase of the action potential in the heart. There is growing evidence that gating and kinetics of Nav1.5 are modulated by mechanical forces and pathogenic variants that affect mechanosensitivity have been linked to arrhythmias. Recently, the sodium channel β1 subunit has been described to stabilise gating against mechanical stress of Nav1.7 expressed in neurons. Here, we tested the effect of β1 and β3 subunits on mechanosensitivity of the cardiac Nav1.5. β1 amplifies stress-induced shifts of V1/2 of steady-state fast inactivation to hyperpolarised potentials (ΔV1/2: 6.2 mV without and 10.7 mV with β1 co-expression). β3, on the other hand, almost doubles stress-induced speeding of time to sodium current transient peak (Δtime to peak at - 30 mV: 0.19 ms without and 0.37 ms with β3 co-expression). Our findings may indicate that in cardiomyocytes, the interdependence of electrical activity and contraction is used as a means of fine tuning cardiac sodium channel function, allowing quicker but more strongly inactivating sodium currents under conditions of increased mechanical stress. This regulation may help to shorten action potential duration during tachycardia, to prevent re-entry phenomena and thus arrhythmias.
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Affiliation(s)
- Michele Maroni
- Department of Anaesthesiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany.,Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Jannis Körner
- Institute of Physiology, Medical Faculty, RWTH Aachen University, 52074, Aachen, Germany.,Department of Anaesthesiology, Medical Faculty, RWTH Aachen University, 52074, Aachen, Germany
| | - Jürgen Schüttler
- Department of Anaesthesiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Beate Winner
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Angelika Lampert
- Institute of Physiology, Medical Faculty, RWTH Aachen University, 52074, Aachen, Germany
| | - Esther Eberhardt
- Department of Anaesthesiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany.
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94
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Pastori V, D'Aloia A, Blasa S, Lecchi M. Serum-deprived differentiated neuroblastoma F-11 cells express functional dorsal root ganglion neuron properties. PeerJ 2019; 7:e7951. [PMID: 31687277 PMCID: PMC6825413 DOI: 10.7717/peerj.7951] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [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: 04/01/2019] [Accepted: 09/25/2019] [Indexed: 11/29/2022] Open
Abstract
The isolation and culture of dorsal root ganglion (DRG) neurons cause adaptive changes in the expression and regulation of ion channels, with consequences on neuronal excitability. Considering that not all neurons survive the isolation and that DRG neurons are heterogeneous, it is difficult to find the cellular subtype of interest. For this reason, researchers opt for DRG-derived immortal cell lines to investigate endogenous properties. The F-11 cell line is a hybridoma of embryonic rat DRG neurons fused with the mouse neuroblastoma line N18TG2. In the proliferative condition, F-11 cells do not display a gene expression profile correspondent with specific subclasses of sensory neurons, but the most significant differences when compared with DRGs are the reduction of voltage-gated sodium, potassium and calcium channels, and the small amounts of TRPV1 transcripts. To investigate if functional properties of mature F-11 cells showed more similarities with those of isolated DRG neurons, we differentiated them by serum deprivation. Potassium and sodium currents significantly increased with differentiation, and biophysical properties of tetrodotoxin (TTX)-sensitive currents were similar to those characterized in small DRG neurons. The analysis of the voltage-dependence of calcium currents demonstrated the lack of low threshold activated components. The exclusive expression of high threshold activated Ca2+ currents and of TTX-sensitive Na+ currents correlated with the generation of a regular tonic electrical activity, which was recorded in the majority of the cells (80%) and was closely related to the activity of afferent TTX-sensitive A fibers of the proximal urethra and the bladder. Responses to capsaicin and substance P were also recorded in ~20% and ~80% of cells, respectively. The percentage of cells responsive to acetylcholine was consistent with the percentage referred for rat DRG primary neurons and cell electrical activity was modified by activation of non-NMDA receptors as for embryonic DRG neurons. These properties and the algesic profile (responses to pH5 and sensitivity to both ATP and capsaicin), proposed in literature to define a sub-classification of acutely dissociated rat DRG neurons, suggest that differentiated F-11 cells express receptors and ion channels that are also present in sensory neurons.
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Affiliation(s)
- Valentina Pastori
- Department of Biotechnology and Biosciences and Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
| | - Alessia D'Aloia
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Stefania Blasa
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Marzia Lecchi
- Department of Biotechnology and Biosciences and Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
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95
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Bingor A, Yaka R. Using Toxins in Brain Slice Recordings. Methods Mol Biol 2020; 2068:269-74. [PMID: 31576533 DOI: 10.1007/978-1-4939-9845-6_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Use of biological toxins from different kinds is widely accepted in electrophysiological experiments. In particular, electrophysiological recordings from brain tissue slices are usually conducted with toxins to manipulate on different receptors or ion channels. Here we describe usage of toxins in electrophysiological experiments in acute brain slices.
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96
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Nielsen BE, Bermudez I, Bouzat C. Flavonoids as positive allosteric modulators of α7 nicotinic receptors. Neuropharmacology 2019; 160:107794. [PMID: 31560909 DOI: 10.1016/j.neuropharm.2019.107794] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [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: 05/09/2019] [Revised: 08/09/2019] [Accepted: 09/23/2019] [Indexed: 12/11/2022]
Abstract
The use of positive allosteric modulators (PAM) of α7 nicotinic receptors is a promising therapy for neurodegenerative, inflammatory and cognitive disorders. Flavonoids are polyphenolic compounds showing neuroprotective, anti-inflammatory and pro-cognitive actions. Besides their well-known antioxidant activity, flavonoids trigger intracellular pathways and interact with receptors, including α7. To reveal how the beneficial actions of flavonoids are linked to α7 function, we evaluated the effects of three representative flavonoids -genistein, quercetin and the neoflavonoid 5,7-dihydroxy-4-phenylcoumarin- on whole-cell and single-channel currents. All flavonoids increase the maximal currents elicited by acetylcholine with minimal effects on desensitization and do not reactivate desensitized receptors, a behaviour consistent with type I PAMs. At the single-channel level, they increase the duration of the open state and produce activation in long-duration episodes with a rank order of efficacy of genistein > quercetin ≥ neoflavonoid. By using mutant and chimeric α7 receptors, we demonstrated that flavonoids share transmembrane structural determinants with other PAMs. The α7-PAM activity of flavonoids results in decreased cell levels of reactive oxygen species. Thus, allosteric potentiation of α7 may be an additional mechanism underlying neuroprotective actions of flavonoids, which may be used as scaffolds for designing new therapeutic agents.
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Affiliation(s)
- Beatriz Elizabeth Nielsen
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Isabel Bermudez
- Department of Medical and Biological Sciences, Oxford Brookes University, Oxford, OX3 0BP, United Kingdom
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina.
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97
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Santori M, Gil R, Blanco-Verea A, Riuró H, Díaz-Castro Ó, López-Abel B, Brugada R, Carracedo Á, Pérez GJ, Scornik FS, Brion M. Sudden infant death as the most severe phenotype caused by genetic modulation in a family with atrial fibrillation. Forensic Sci Int Genet 2019; 43:102159. [PMID: 31522018 DOI: 10.1016/j.fsigen.2019.102159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [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: 07/04/2019] [Revised: 08/26/2019] [Accepted: 08/29/2019] [Indexed: 12/29/2022]
Abstract
AIMS To assess the functional impact of two combined KCNH2 variants involved in atrial fibrillation, syncope and sudden infant death syndrome. METHODS AND RESULTS Genetic testing of a 4-month old SIDS victim identified a rare missense heterozygous in KCNH2 variant (V483I) and a missense homozygous polymorphism (K897T) which is often described as a genetic modifier. Electrophysiological characterisation of heterologous HERG channels representing two different KCNH2 genotypes within the family, showed significant differences in both voltage and time dependence of activation and inactivation with a global gain-of-function effect of mutant versus wild type channels and, also, differences between both types of recombinant channels. CONCLUSIONS The rare variant V483I in combination with K897T produces a gain-of-function effect that represents a pathological substrate for atrial fibrillation, syncope and sudden infant death syndrome events in this family. Ascertaining the genotype-phenotype correlation of genetic variants is imperative for the correct assessment of genetic testing and counselling. TRANSLATIONAL PERSPECTIVE According to the current guidelines for clinical interpretation of sequence variants, functional studies are an essential tool for the ascertainment of variant pathogenicity. They are especially relevant in the context of sudden infant death syndrome and sudden cardiac death, where individuals cannot be clinically evaluated. The patch-clamp technique is a gold-standard for analysis of the biophysical mechanisms of ion channels.
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Affiliation(s)
- Montserrat Santori
- Xenética Cardiovascular, Instituto de Investigación Sanitaria de Santiago de Compostela, Spain; Grupo de Medicina Xenómica, Universidade de Santiago de Compostela, Spain.
| | - Rocío Gil
- Xenética Cardiovascular, Instituto de Investigación Sanitaria de Santiago de Compostela, Spain; Grupo de Medicina Xenómica, Universidade de Santiago de Compostela, Spain
| | - Alejandro Blanco-Verea
- Xenética Cardiovascular, Instituto de Investigación Sanitaria de Santiago de Compostela, Spain; Grupo de Medicina Xenómica, Universidade de Santiago de Compostela, Spain
| | - Helena Riuró
- Cardiovascular Genetics Center, Institut d'Investigació Biomèdica de Girona, Spain; Department of Medical Sciences, Medical School, Universitat de Girona, Spain
| | - Óscar Díaz-Castro
- Servizo de Cardioloxía, Hospital de Pontevedra, Servizo Galego de Saúde, Pontevedra, Spain
| | - Bernardo López-Abel
- Xenética Cardiovascular, Instituto de Investigación Sanitaria de Santiago de Compostela, Spain; Servizo de Pediatría, Hospital Clínico Universitario de Santiago de Compostela, Spain
| | - Ramón Brugada
- Cardiovascular Genetics Center, Institut d'Investigació Biomèdica de Girona, Spain; Department of Medical Sciences, Medical School, Universitat de Girona, Spain; Red de Enfermedades Cardiovasculares (CIBERCV), Spain
| | - Ángel Carracedo
- Grupo de Medicina Xenómica, Universidade de Santiago de Compostela, Spain; Fundación Pública Galega de Medicina Xenómica, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Santiago de Compostela, Spain
| | - Guillermo J Pérez
- Department of Medical Sciences, Medical School, Universitat de Girona, Spain; Red de Enfermedades Cardiovasculares (CIBERCV), Spain
| | - Fabiana S Scornik
- Department of Medical Sciences, Medical School, Universitat de Girona, Spain; Red de Enfermedades Cardiovasculares (CIBERCV), Spain
| | - María Brion
- Xenética Cardiovascular, Instituto de Investigación Sanitaria de Santiago de Compostela, Spain; Grupo de Medicina Xenómica, Universidade de Santiago de Compostela, Spain; Red de Enfermedades Cardiovasculares (CIBERCV), Spain
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98
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Benkerrou D, Minicozzi V, Gradogna A, Milenkovic S, Bodrenko IV, Festa M, Lagostena L, Cornara L, D'Amore A, Ceccarelli M, Filippini A, Carpaneto A. A perspective on the modulation of plant and animal two pore channels (TPCs) by the flavonoid naringenin. Biophys Chem 2019; 254:106246. [PMID: 31426023 DOI: 10.1016/j.bpc.2019.106246] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 08/03/2019] [Accepted: 08/03/2019] [Indexed: 12/17/2022]
Abstract
The inhibitory effect of the flavonoid naringenin on plant and human Two-Pore Channels (TPCs) was assessed by means of electrophysiological measurements. By acting on human TPC2, naringenin, was able to dampen intracellular calcium responses to VEGF in cultured human endothelial cells and to impair angiogenic activity in VEGF-containing matrigel plugs implanted in mice. Molecular docking predicts selective binding sites for naringenin in the TPC structure, thus suggesting a specific interaction between the flavonoid and the channel.
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99
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Löfgren M, Holmberg E, Bäckström T, Egecioglu E, Dickson SL. The additive effect of allopregnanolone on ghrelin's orexigenic effect in rats. Neuropeptides 2019; 76:101937. [PMID: 31253440 DOI: 10.1016/j.npep.2019.101937] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 06/08/2019] [Accepted: 06/12/2019] [Indexed: 11/20/2022]
Abstract
The progesterone metabolite, allopregnanolone (AlloP), is a GABAA receptor modulating steroid and is known to have orexigenic and pro-obesity effects. The neurobiological mechanisms underpinning these effects are most likely due to enhanced GABAergic signaling in the lateral arcuate nucleus (ARC) and medial paraventricular nucleus (PVN) of the hypothalamus. Inspired by the finding that GABAergic signaling is also important for the orexigenic effects of the circulating hormone, ghrelin, we sought to determine the extent to which AlloP (one of the most potent endogenous GABAA-receptor modulators) operates alongside ghrelin to enhance food intake. Male rats with ad libitum access to standard chow were injected intravenously with AlloP and/or ghrelin, alone or in combination. The intake of the standard chow was greater after AlloP 1 mg/kg together with ghrelin 30 μg/kg than with 30 μg/kg ghrelin alone. Food intake was also increased for the combined treatment of AlloP 0.5 mg/kg + ghrelin 10 μg/kg, AlloP 1 mg/kg + ghrelin 10 μg/kg, and AlloP 0.5 mg/kg + ghrelin 30 μg/kg. There was no significant difference in food intake between the two ghrelin doses or between the two doses of AlloP and the vehicle. In electrophysiological studies, physiologically relevant concentrations of AlloP prolonged the current decay time of spontaneous inhibitory post-synaptic current of dissociated cells of the ARC and PVN. We conclude that AlloP enhances the hyperphagic effect of ghrelin, findings of potential relevance for the hyperphagia associated with the luteal phase of the reproductive cycle.
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Affiliation(s)
- Magnus Löfgren
- Department of Clinical Sciences, Obstetrics and Gynaecology, Umeå University Hospital, SE-Building QA, 3rd floor, 901 85 Umeå, Sweden.
| | - Ellinor Holmberg
- Department of Clinical Sciences, Obstetrics and Gynaecology, Umeå University Hospital, SE-Building QA, 3rd floor, 901 85 Umeå, Sweden
| | - Torbjörn Bäckström
- Department of Clinical Sciences, Obstetrics and Gynaecology, Umeå University Hospital, SE-Building QA, 3rd floor, 901 85 Umeå, Sweden
| | - Emil Egecioglu
- Department of Experimental Medical Science, Appetite Regulation Unit, Faculty of Medicine, Lund University, 221 84 Lund, Sweden
| | - Suzanne L Dickson
- Institute for Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, P.O. Box 434, SE-405 30 Gothenburg, Sweden
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100
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Effraim PR, Huang J, Lampert A, Stamboulian S, Zhao P, Black JA, Dib-Hajj SD, Waxman SG. Fibroblast growth factor homologous factor 2 (FGF-13) associates with Nav1.7 in DRG neurons and alters its current properties in an isoform-dependent manner. Neurobiol Pain 2019; 6:100029. [PMID: 31223136 PMCID: PMC6565799 DOI: 10.1016/j.ynpai.2019.100029] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 03/22/2019] [Accepted: 03/22/2019] [Indexed: 11/29/2022]
Abstract
Fibroblast Growth Factor Homologous Factors (FHF) constitute a subfamily of FGF proteins with four prototypes (FHF1-4; also known as FGF11-14). FHF proteins have been shown to bind directly to the membrane-proximal segment of the C-terminus in voltage-gated sodium channels (Nav), and regulate current density, availability, and frequency-dependent inhibition of sodium currents. Members of the FHF2 subfamily, FHF2A and FHF2B, differ in the length and sequence of their N-termini, and, importantly, differentially regulate Nav1.6 gating properties. Using immunohistochemistry, we show that FHF2 isoforms are expressed in adult dorsal root ganglion (DRG) neurons where they co-localize with Nav1.6 and Nav1.7. FHF2A and FHF2B show differential localization in neuronal compartments in DRG neurons, and levels of expression of FHF2 factors are down-regulated following sciatic nerve axotomy. Because Nav1.7 in nociceptors plays a critical role in pain, we reasoned that its interaction with FHF2 isoforms might regulate its current properties. Using whole-cell patch clamp in heterologous expression systems, we show that the expression of FHF2A in HEK293 cell line stably expressing Nav1.7 channels causes no change in activation, whereas FHF2B depolarizes activation. Both FHF2 isoforms depolarize fast-inactivation. Additionally, FHF2A causes an accumulation of inactivated channels at all frequencies tested due to a slowing of recovery from inactivation, whereas FHF2B has little effect on these properties of Nav1.7. Measurements of the Nav1.7 current in DRG neurons in which FHF2 levels are knocked down confirmed the effects of FHF2A on repriming, and FHF2B on activation, however FHF2A and B did not have an effect on fast inactivation. Our data demonstrates that FHF2 does indeed regulate the current properties of Nav1.7 and does so in an isoform and cell-specific manner.
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Affiliation(s)
- Philip R. Effraim
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Jianying Huang
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Angelika Lampert
- Institute of Physiology, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Severine Stamboulian
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Peng Zhao
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Joel A. Black
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Sulayman D. Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Stephen G. Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
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