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Trus M, Atlas D. Non-ionotropic voltage-gated calcium channel signaling. Channels (Austin) 2024; 18:2341077. [PMID: 38601983 PMCID: PMC11017947 DOI: 10.1080/19336950.2024.2341077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 04/04/2024] [Indexed: 04/12/2024] Open
Abstract
Voltage-gated calcium channels (VGCCs) are the major conduits for calcium ions (Ca2+) within excitable cells. Recent studies have highlighted the non-ionotropic functionality of VGCCs, revealing their capacity to activate intracellular pathways independently of ion flow. This non-ionotropic signaling mode plays a pivotal role in excitation-coupling processes, including gene transcription through excitation-transcription (ET), synaptic transmission via excitation-secretion (ES), and cardiac contraction through excitation-contraction (EC). However, it is noteworthy that these excitation-coupling processes require extracellular calcium (Ca2+) and Ca2+ occupancy of the channel ion pore. Analogous to the "non-canonical" characterization of the non-ionotropic signaling exhibited by the N-methyl-D-aspartate receptor (NMDA), which requires extracellular Ca2+ without the influx of ions, VGCC activation requires depolarization-triggered conformational change(s) concomitant with Ca2+ binding to the open channel. Here, we discuss the contributions of VGCCs to ES, ET, and EC coupling as Ca2+ binding macromolecules that transduces external stimuli to intracellular input prior to elevating intracellular Ca2+. We emphasize the recognition of calcium ion occupancy within the open ion-pore and its contribution to the excitation coupling processes that precede the influx of calcium. The non-ionotropic activation of VGCCs, triggered by the upstroke of an action potential, provides a conceptual framework to elucidate the mechanistic aspects underlying the microseconds nature of synaptic transmission, cardiac contractility, and the rapid induction of first-wave genes.
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Affiliation(s)
- Michael Trus
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Daphne Atlas
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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2
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Li L, Wang J, Chen L, Ren Q, Akhtar MF, Liu W, Wang C, Cao S, Liu W, Zhao Q, Li Y, Wang T. Diltiazem HCl suppresses porcine reproductive and respiratory syndrome virus infection in susceptible cells and in swine. Vet Microbiol 2024; 292:110054. [PMID: 38507832 DOI: 10.1016/j.vetmic.2024.110054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/03/2024] [Accepted: 03/11/2024] [Indexed: 03/22/2024]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is a pathogen for swine, resulting in substantial economic losses to the swine industry. However, there has been little success in developing effective vaccines or drugs for PRRSV control. In the present study, we discovered that Diltiazem HCl, an inhibitor of L-type Ca2+ channel, effectively suppresses PRRSV replication in MARC-145, PK-15CD163 and PAM cells in dose-dependent manner. Furthermore, it demonstrates a broad-spectrum activity against both PRRSV-1 and PRRSV-2 strains. Additionally, we explored the underlying mechanisms and found that Diltiazem HCl -induced inhibition of PRRSV associated with regulation of calcium ion homeostasis in susceptible cells. Moreover, we evaluated the antiviral effects of Diltiazem HCl in PRRSV-challenged piglets, assessing rectal temperature, viremia, and gross and microscopic lung lesions. Our results indicate that Diltiazem HCl treatment alleviates PRRSV-induced rectal temperature spikes, pulmonary pathological changes, and serum viral load. In conclusion, our data suggest that Diltiazem HCl could serve as a novel therapeutic drug against PRRSV infection.
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Affiliation(s)
- Liangliang Li
- College of Agronomy, Liaocheng University, Liaocheng, China
| | - Jiayu Wang
- College of Agronomy, Liaocheng University, Liaocheng, China
| | - Li Chen
- College of Agronomy, Liaocheng University, Liaocheng, China
| | - Qinghai Ren
- College of Agronomy, Liaocheng University, Liaocheng, China
| | | | - Wenhua Liu
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
| | - Changfa Wang
- College of Agronomy, Liaocheng University, Liaocheng, China
| | - Shengliang Cao
- College of Agronomy, Liaocheng University, Liaocheng, China
| | - Wenqiang Liu
- College of Agronomy, Liaocheng University, Liaocheng, China
| | - Qin Zhao
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China.
| | - Yubao Li
- College of Agronomy, Liaocheng University, Liaocheng, China.
| | - Tongtong Wang
- College of Agronomy, Liaocheng University, Liaocheng, China.
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3
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Yang Q, Perfitt TL, Quay J, Hu L, Lawson-Qureshi D, Colbran RJ. Clustering of Ca V 1.3 L-type calcium channels by Shank3. J Neurochem 2023; 167:16-37. [PMID: 37392026 PMCID: PMC10543641 DOI: 10.1111/jnc.15880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 05/19/2023] [Accepted: 05/28/2023] [Indexed: 07/02/2023]
Abstract
Clustering of L-type voltage-gated Ca2+ channels (LTCCs) in the plasma membrane is increasingly implicated in creating highly localized Ca2+ signaling nanodomains. For example, neuronal LTCC activation can increase phosphorylation of the nuclear CREB transcription factor by increasing Ca2+ concentrations within a nanodomain close to the channel, without requiring bulk Ca2+ increases in the cytosol or nucleus. However, the molecular basis for LTCC clustering is poorly understood. The postsynaptic scaffolding protein Shank3 specifically associates with one of the major neuronal LTCCs, the CaV 1.3 calcium channel, and is required for optimal LTCC-dependent excitation-transcription coupling. Here, we co-expressed CaV 1.3 α1 subunits with two distinct epitope-tags with or without Shank3 in HEK cells. Co-immunoprecipitation studies using the cell lysates revealed that Shank3 can assemble complexes containing multiple CaV 1.3 α1 subunits under basal conditions. Moreover, CaV 1.3 LTCC complex formation was facilitated by CaV β subunits (β3 and β2a), which also interact with Shank3. Shank3 interactions with CaV 1.3 LTCCs and multimeric CaV 1.3 LTCC complex assembly were disrupted following the addition of Ca2+ to cell lysates, perhaps simulating conditions within an activated CaV 1.3 LTCC nanodomain. In intact HEK293T cells, co-expression of Shank3 enhanced the intensity of membrane-localized CaV 1.3 LTCC clusters under basal conditions, but not after Ca2+ channel activation. Live cell imaging studies also revealed that Ca2+ influx through LTCCs disassociated Shank3 from CaV 1.3 LTCCs clusters and reduced the CaV 1.3 cluster intensity. Deletion of the Shank3 PDZ domain prevented both binding to CaV 1.3 and the changes in multimeric CaV 1.3 LTCC complex assembly in vitro and in HEK293 cells. Finally, we found that shRNA knock-down of Shank3 expression in cultured rat primary hippocampal neurons reduced the intensity of surface-localized CaV 1.3 LTCC clusters in dendrites. Taken together, our findings reveal a novel molecular mechanism contributing to neuronal LTCC clustering under basal conditions.
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Affiliation(s)
- Qian Yang
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA 37232-0615
| | - Tyler L. Perfitt
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA 37232-0615
- Current address: Rare Disease Research Unit, Pfizer Inc
| | - Juliana Quay
- Chemical and Physical Biology, Vanderbilt University School of Medicine, Nashville, TN, USA 37232-0615
| | - Lan Hu
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA 37232-0615
| | - Dorian Lawson-Qureshi
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA 37232-0615
| | - Roger J. Colbran
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA 37232-0615
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA 37232-0615
- Vanderbilt-Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA 37232-0615
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4
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Atlas D. Revisiting the molecular basis of synaptic transmission. Prog Neurobiol 2022; 216:102312. [PMID: 35760141 DOI: 10.1016/j.pneurobio.2022.102312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 06/12/2022] [Accepted: 06/20/2022] [Indexed: 10/17/2022]
Abstract
Measurements of the time elapsed during synaptic transmission has shown that synaptic vesicle (SV) fusion lags behind Ca2+-influx by approximately 60 microseconds (µsec). The conventional model cannot explain this extreme rapidity of the release event. Synaptic transmission occurs at the active zone (AZ), which comprises of two pools of SV, non-releasable "tethered" vesicles, and a readily-releasable pool of channel-associated Ca2+-primed vesicles, "RRP". A recent TIRF study at cerebellar-mossy fiber-terminal, showed that subsequent to an action potential, newly "tethered" vesicles, became fusion-competent in a Ca2+-dependent manner, 300-400 milliseconds after tethering, but were not fused. This time resolution may correspond to priming of tethered vesicles through Ca2+-binding to Syt1/Munc13-1/complexin. It confirms that Ca2+-priming and Ca2+-influx-independent fusion, are two distinct events. Notably, we have established that Ca2+ channel signals evoked-release in an ion flux-independent manner, demonstrated by Ca2+-impermeable channel, or a Ca2+ channel in which Ca2+ is replaced by impermeable La3+. Thus, conformational changes in a channel coupled to RRP appear to directly activate the release machinery and account for a µsec Ca2+-influx-independent vesicle fusion. Rapid vesicle fusion driven by non-ionotropic channel signaling strengthens a conformational-coupling mechanism of synaptic transmission, and contributes to better understanding of neuronal communication vital for brain function.
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Affiliation(s)
- Daphne Atlas
- Dept. of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904 Israel.
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Đukanović Đ, Gajic Bojic M, Marinkovic S, Trailovic SM, Stojiljković MP, Škrbić R. Vasorelaxant effect of monoterpene carvacrol on isolated human umbilical artery. Can J Physiol Pharmacol 2022; 100:755-762. [PMID: 35507953 DOI: 10.1139/cjpp-2021-0736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Carvacrol is the main compound of essential oils extracted primarily from Thymus and Origanum species. Its various biological activities were confirmed: antioxidant, anti-inflammatory, antibacterial, antifungal, anti-tumour, antinematodal and vasorelaxant action. Although vasodilation mediated by carvacrol was previously described, the exact mechanism of its action has not yet been established. Hence, the aim of this study was to investigate carvacrol vasoactivity on human umbilical arteries (HUA) and different pathways involved in its mechanism of action using tissue bath methodology. Carvacrol caused a significant decrease in vascular tension of 5-HT-pre-contracted umbilical arteries, with EC50 of 442.13 ± 33.8 µM (mean ± standard error of the mean - SEM). At 300 µM, carvacrol shifted downward the 5-HT concentration-response curve with statistical significance of p < 0.001 obtained for the four highest concentrations. At concentration of 1 mM, carvacrol completely abolished BaCl2-induced contraction in Ca2+-free Krebs-Ringer bicarbonate solution (p < 0.001). Isopentenyl pyrophosphate, the antagonist of TRPV3 channel, was able to decrease the efficacy of carvacrol (p < 0.001). The vasorelaxant effect of carvacrol seems to involve the blocking of L-type of Ca2+ channels on smooth muscle cells. However, the role of TRPV3 channels in carvacrol-induced vasodilation of HUA cannot be excluded either.
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Affiliation(s)
- Đorđe Đukanović
- University of Banja Luka Faculty of Medicine, 469576, Centre for Biomedical Research, Banja Luka, Bosnia and Herzegovina;
| | - Milica Gajic Bojic
- University of Banja Luka Faculty of Medicine, 469576, Centre for Biomedical Research, Banja Luka, Bosnia and Herzegovina;
| | - Sonja Marinkovic
- University of Banja Luka Faculty of Medicine, 469576, Centre for Biomedical Research, Banja Luka, Bosnia and Herzegovina;
| | - Sasa M Trailovic
- University of Belgrade, 54801, Pharmacology and Toxicology, Bulevar oslobodjenja 18, Beograd, Serbia, 11000;
| | - Miloš P Stojiljković
- University of Banja Luka Faculty of Medicine, 469576, Department of Pharmacology, Toxicology and Clinical Pharmacology, Banja Luka, Bosnia and Herzegovina, 78000;
| | - Ranko Škrbić
- University of Banja Luka Faculty of Medicine, 469576, Banja Luka, Bosnia and Herzegovina, 78000;
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Estrada-Soto S, Rendón-Vallejo P, Villalobos-Molina R, Millán-Pacheco C, Vázquez M, Hernández-Borja F, Hernández-Núñez E. 6-Amino-3-Methyl-4-(2-nitrophenyl)-1,4-Dihydropyrano[2,3-c]Pyrazole-5-Carbonitrile Shows Antihypertensive and Vasorelaxant Action via Calcium Channel Blockade. Drug Res (Stuttg) 2021; 72:53-60. [PMID: 34662917 DOI: 10.1055/a-1616-0156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Several 4H-pyran derivatives were designed and synthesized previously as vasorelaxant agents for potential antihypertensive drugs. In this context, the objective of the present investigation was to determine the functional mechanism of vasorelaxant action of 6-amino-3-methyl-4-(2-nitrophenyl)-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (1: ) and its in vivo antihypertensive effect. Thus, compound 1: showed significant vasorelaxant action on isolated aorta rat rings pre-contracted with serotonin or noradrenaline, and the effect was not endothelium-dependent. Compound 1: induced a significant relaxant effect when aortic rings were contracted with KCl (80 mM), indicating that the main mechanism of action is related to L-type calcium channel blockade. Last was corroborated since compound 1: induced a significant concentration-dependent lowering of contraction provoked by cumulative CaCl2 adding. Moreover, compound 1: was capable to block the contraction induced by FPL 64176, a specific L-type calcium channel agonist, in a concentration-dependent manner. On the other hand, docking studies revealed that compound 1: interacts on two possible sites of the L-type calcium channel and it had better affinity energy (-7.80+/-0.00 kcal/mol on the best poses) than nifedipine (-6.86+/-0.14 kcal/mol). Finally, compound 1: (50 mg/kg) showed significant antihypertensive activity, lowering the systolic and diastolic blood pressure on spontaneously hypertensive rats (SHR) without modifying heart rate.
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Affiliation(s)
- Samuel Estrada-Soto
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - Priscila Rendón-Vallejo
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - Rafael Villalobos-Molina
- Unidad de Biomedicina, Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla, Estado de México, México
| | - César Millán-Pacheco
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - MiguelA Vázquez
- Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, México
| | - Fernando Hernández-Borja
- Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, México
| | - Emanuel Hernández-Núñez
- Cátedra CONACyT, Departamento de Recursos del Mar, Centro de Investigación y de Estudios Avanzados del IPN, Unidad Mérida, Yucatán, Mexico
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Lima CC, de Holanda-Angelin-Alves CM, Pereira-Gonçalves Á, Kennedy-Feitosa E, Evangelista-Costa E, Bezerra MAC, Coelho-de-Souza AN, Leal-Cardoso JH. Antispasmodic effects of the essential oil of Croton zehnteneri, anethole, and estragole, on tracheal smooth muscle. Heliyon 2020; 6:e05445. [PMID: 33251351 PMCID: PMC7679260 DOI: 10.1016/j.heliyon.2020.e05445] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/23/2020] [Accepted: 11/03/2020] [Indexed: 11/28/2022] Open
Abstract
Croton zehntneri is a plant well adapted to the semi-arid climate of northeastern region of Brazil. The essential oil of C. zehntneri (EOCz) has been described to have several pharmacologic properties, including effect on airflow resistance of in vivo respiratory system. For this reason, we investigated the hypothesis that EOCz and its major constituents, anethole and estragole, have antispasmodic activity on tracheal muscle. In tracheal rings of Wistar rats, maintained in Krebs-Henseleit's solution, EOCz, anethole and estragole inhibited contractions induced by 60mM [K+], ACh (10μM), Ba2+ and Phorbol dibutirate (1 μM). For EOCz, anethole and estragole, the IC50 for inhibition of KCl-induced contractions were 145.8 ± 14.8, 89.9 ± 7.4 and 181.0 ± 23.3 μg/mL, respectively, and for ACh-induced contraction, they were 606.1 ± 122.0, 160.5 ± 33.0 and 358.6 ± 49.2 μg/mL. Pharmacodynamic efficacy was maximal in all cases. These data in Ba2+-induced contraction and the differential IC50 suggested that blockade of Voltage Dependent Calcium Channels (VDCC) is a component of the mechanism of action of the three agents. Evaluation of the direct effect of anethole, on VDCC, showed inhibition of the Ca2+ current through this type of channel. These results show that EOCz and the constituents have antispasmodic activity and the mechanism includes blockade of VDCC channels.
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Affiliation(s)
- Crystianne Calado Lima
- Laboratory of Pulmonary Physiology, Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil
| | | | - Átila Pereira-Gonçalves
- Laboratory of Electrophysiology, Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil
| | - Emanuel Kennedy-Feitosa
- Department of Health Sciences, Federal Rural University of Semi-Arid, Mossorró, Rio Grande do Norte, Brazil
| | - Eder Evangelista-Costa
- Laboratory of Electrophysiology, Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil
| | | | | | - José Henrique Leal-Cardoso
- Laboratory of Electrophysiology, Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil
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Abstract
The neurotrophic factor BDNF is an important regulator for the development of brain circuits, for synaptic and neuronal network plasticity, as well as for neuroregeneration and neuroprotection. Up- and downregulations of BDNF levels in human blood and tissue are associated with, e.g., neurodegenerative, neurological, or even cardiovascular diseases. The changes in BDNF concentration are caused by altered dynamics in BDNF expression and release. To understand the relevance of major variations of BDNF levels, detailed knowledge regarding physiological and pathophysiological stimuli affecting intra- and extracellular BDNF concentration is important. Most work addressing the molecular and cellular regulation of BDNF expression and release have been performed in neuronal preparations. Therefore, this review will summarize the stimuli inducing release of BDNF, as well as molecular mechanisms regulating the efficacy of BDNF release, with a focus on cells originating from the brain. Further, we will discuss the current knowledge about the distinct stimuli eliciting regulated release of BDNF under physiological conditions.
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Affiliation(s)
- Tanja Brigadski
- Department of Informatics and Microsystem Technology, University of Applied Sciences Kaiserslautern, D-66482, Zweibrücken, Germany.
| | - Volkmar Leßmann
- Institute of Physiology, Otto-von-Guericke University, D-39120, Magdeburg, Germany.
- Center for Behavioral Brain Sciences, Magdeburg, Germany.
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Maldifassi MC, Momboisse F, Guerra MJ, Vielma AH, Maripillán J, Báez-Matus X, Flores-Muñoz C, Cádiz B, Schmachtenberg O, Martínez AD, Cárdenas AM. The interplay between α7 nicotinic acetylcholine receptors, pannexin-1 channels and P2X7 receptors elicit exocytosis in chromaffin cells. J Neurochem 2020; 157:1789-1808. [PMID: 32931038 DOI: 10.1111/jnc.15186] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 08/18/2020] [Accepted: 09/04/2020] [Indexed: 12/20/2022]
Abstract
Pannexin-1 (Panx1) forms plasma membrane channels that allow the exchange of small molecules between the intracellular and extracellular compartments, and are involved in diverse physiological and pathological responses in the nervous system. However, the signaling mechanisms that induce their opening still remain elusive. Here, we propose a new mechanism for Panx1 channel activation through a functional crosstalk with the highly Ca2+ permeable α7 nicotinic acetylcholine receptor (nAChR). Consistent with this hypothesis, we found that activation of α7 nAChRs induces Panx1-mediated dye uptake and ATP release in the neuroblastoma cell line SH-SY5Y-α7. Using membrane permeant Ca2+ chelators, total internal reflection fluorescence microscopy in SH-SY5Y-α7 cells expressing a membrane-tethered GCAMP3, and Src kinase inhibitors, we further demonstrated that Panx1 channel opening depends on Ca2+ signals localized in submembrane areas, as well as on Src kinases. In turn, Panx1 channels amplify cytosolic Ca2+ signals induced by the activation of α7 nAChRs, by a mechanism that seems to involve ATP release and P2X7 receptor activation, as hydrolysis of extracellular ATP with apyrase or blockage of P2X7 receptors with oxidized ATP significantly reduces the α7 nAChR-Ca2+ signal. The physiological relevance of this crosstalk was also demonstrated in neuroendocrine chromaffin cells, wherein Panx1 channels and P2X7 receptors contribute to the exocytotic release of catecholamines triggered by α7 nAChRs, as measured by amperometry. Together these findings point to a functional coupling between α7 nAChRs, Panx1 channels and P2X7 receptors with physiological relevance in neurosecretion.
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Affiliation(s)
- María C Maldifassi
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | | | - María J Guerra
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Alex H Vielma
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Jaime Maripillán
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Ximena Báez-Matus
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Carolina Flores-Muñoz
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Programa de Doctorado en Ciencias, Universidad de Valparaíso, Chile
| | - Bárbara Cádiz
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Programa de Magister en Ciencias Biológicas, Universidad de Valparaíso, Chile
| | - Oliver Schmachtenberg
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Agustín D Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Ana M Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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10
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Evaristo Rodrigues da Silva R, de Alencar Silva A, Pereira-de-Morais L, de Sousa Almeida N, Iriti M, Kerntopf MR, de Menezes IRA, Coutinho HDM, Barbosa R. Relaxant Effect of Monoterpene (-)-Carveol on Isolated Human Umbilical Cord Arteries and the Involvement of Ion Channels. Molecules 2020; 25:molecules25112681. [PMID: 32527034 PMCID: PMC7321233 DOI: 10.3390/molecules25112681] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/29/2020] [Accepted: 06/01/2020] [Indexed: 01/11/2023] Open
Abstract
Carveol is a monoterpene present in the structure of many plant products. It has a variety of biological activities: antioxidant, anticancer and vasorelaxation. However, studies investigating the effect of monoterpenoids on human vessels have not yet been described. Thus, the present study aimed to characterize the effect of (−)-carveol on human umbilical arteries (HUAs). HUA ring preparations were isolated and subjected to isometric tension recordings of umbilical artery smooth muscle contractions. (−)-Carveol exhibited a significant vasorelaxant effect on KCl and 5-HT-induced contractions, obtaining EC50 values of 344.25 ± 8.4 and 175.82 ± 4.05 µM, respectively. The participation of calcium channels in the relaxation produced by (−)-carveol was analyzed using vessels pre-incubated with (−)-carveol (2000 µM) in a calcium-free medium, where the induction of contractions was abolished. The vasorelaxant effect of (−)-carveol on HUAs was reduced by tetraethylammonium (TEA), which increased the (−)-carveol EC50 to 484.87 ± 6.55 µM. The present study revealed that (−)-carveol possesses a vasorelaxant activity in HUAs, which was dependent on the opening of calcium and potassium channels. These results pave the way for further studies involving the use of monoterpenoids for the vasodilatation of HUAs. These molecules have the potential to treat diseases such as pre-eclampsia, which is characterized by resistance in umbilical arteries.
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Affiliation(s)
- Renata Evaristo Rodrigues da Silva
- Department of Biological Chemistry, Regional University of Cariri, Crato 63105-000, CE, Brazil; (R.E.R.d.S.); (N.d.S.A.); (M.R.K.); (I.R.A.d.M.); (H.D.M.C.); (R.B.)
| | - Andressa de Alencar Silva
- PhD student Graduate Program in Physiological Sciences, Higher Institute of Biomedical Sciences State University of Ceará–UECE, Fortaleza 60714-903, CE, Brazil;
| | - Luís Pereira-de-Morais
- PhD student in Biotechnology by the Northeastern Biotechnology Network - RENORBIO, State University of Ceará-UECE, Fortaleza 60714-903, CE, Brazil;
| | - Nayane de Sousa Almeida
- Department of Biological Chemistry, Regional University of Cariri, Crato 63105-000, CE, Brazil; (R.E.R.d.S.); (N.d.S.A.); (M.R.K.); (I.R.A.d.M.); (H.D.M.C.); (R.B.)
| | - Marcello Iriti
- Department of Agricultural and Environmental Sciences, Milan State University, via G. Celoria 2, 20133 Milan, Italy
- Correspondence: ; Tel.: +390-250316766
| | - Marta Regina Kerntopf
- Department of Biological Chemistry, Regional University of Cariri, Crato 63105-000, CE, Brazil; (R.E.R.d.S.); (N.d.S.A.); (M.R.K.); (I.R.A.d.M.); (H.D.M.C.); (R.B.)
| | - Irwin Rose Alencar de Menezes
- Department of Biological Chemistry, Regional University of Cariri, Crato 63105-000, CE, Brazil; (R.E.R.d.S.); (N.d.S.A.); (M.R.K.); (I.R.A.d.M.); (H.D.M.C.); (R.B.)
| | - Henrique Douglas Melo Coutinho
- Department of Biological Chemistry, Regional University of Cariri, Crato 63105-000, CE, Brazil; (R.E.R.d.S.); (N.d.S.A.); (M.R.K.); (I.R.A.d.M.); (H.D.M.C.); (R.B.)
| | - Roseli Barbosa
- Department of Biological Chemistry, Regional University of Cariri, Crato 63105-000, CE, Brazil; (R.E.R.d.S.); (N.d.S.A.); (M.R.K.); (I.R.A.d.M.); (H.D.M.C.); (R.B.)
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11
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Servili E, Trus M, Sajman J, Sherman E, Atlas D. Elevated basal transcription can underlie timothy channel association with autism related disorders. Prog Neurobiol 2020; 191:101820. [PMID: 32437834 DOI: 10.1016/j.pneurobio.2020.101820] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Revised: 03/18/2020] [Accepted: 04/28/2020] [Indexed: 01/08/2023]
Abstract
Timothy syndrome (TS) is a neurodevelopmental disorder caused by mutations in the pore-forming subunit α11.2 of the L-type voltage-gated Ca2+-channel Cav1.2, at positions G406R or G402S. Although both mutations cause cardiac arrhythmias, only Cav1.2G406R is associated with the autism-spectrum-disorder (ASD). We show that transcriptional activation by Cav1.2G406R and Cav1.2G402S is driven by membrane depolarization through the Ras/ERK/CREB pathway in a process called excitation-transcription (ET) coupling, as previously shown for wt Cav1.2. This process requires the presence of the intracellular β-subunit of the channel. We found that only the autism-associated mutant Cav1.2G406R, as opposed to the non-autistic mutated channel Cav1.2G402S, exhibits a depolarization-independent CREB phosphorylation, and spontaneous transcription of cFos and MeCP2. A leftward voltage-shift typical of Cav1.2G406R activation, increases channel opening at subthreshold potentials, resulting in an enhanced channel activity, as opposed to a rightward shift in Cav1.2G402S. We suggest that the enhanced spontaneous Cav1.2G406R activity accounts for the increase in basal transcriptional activation. This uncontroled transcriptional activation may result in the manifestation of long-term dysregulations such as autism. Thus, gating changes provide a mechanistic framework for understanding the molecular events underlying the autistic phenomena caused by the G406R Timothy mutation. They might clarify whether a constitutive transcriptional activation accompanies other VGCC that exhibit a leftward voltage-shift of activation and are also associated with long-term cognitive disorders.
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Affiliation(s)
- Evrim Servili
- Dept. of Biological Chemistry, Institute of Life Sciences, Israel
| | - Michael Trus
- Dept. of Biological Chemistry, Institute of Life Sciences, Israel
| | - Julia Sajman
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Eilon Sherman
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Daphne Atlas
- Dept. of Biological Chemistry, Institute of Life Sciences, Israel.
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12
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Servili E, Trus M, Atlas D. Ion occupancy of the channel pore is critical for triggering excitation-transcription (ET) coupling. Cell Calcium 2019; 84:102102. [DOI: 10.1016/j.ceca.2019.102102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 10/07/2019] [Accepted: 10/07/2019] [Indexed: 11/28/2022]
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13
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β-Subunit of the voltage-gated Ca 2+ channel Cav1.2 drives signaling to the nucleus via H-Ras. Proc Natl Acad Sci U S A 2018; 115:E8624-E8633. [PMID: 30150369 DOI: 10.1073/pnas.1805380115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Depolarization-induced signaling to the nucleus by the L-type voltage-gated calcium channel Cav1.2 is widely assumed to proceed by elevating intracellular calcium. The apparent lack of quantitative correlation between Ca2+ influx and gene activation suggests an alternative activation pathway. Here, we demonstrate that membrane depolarization of HEK293 cells transfected with α11.2/β2b/α2δ subunits (Cav1.2) triggers c-Fos and MeCP2 activation via the Ras/ERK/CREB pathway. Nuclear signaling is lost either by absence of the intracellular β2 subunit or by transfecting the cells with the channel mutant α11.2W440A/β2b/α2δ, a mutation that disrupts the interaction between α11.2 and β2 subunits. Pulldown assays in neuronal SH-SY5Y cells and in vitro binding of recombinant H-Ras and β2 confirmed the importance of the intracellular β2 subunit for depolarization-induced gene activation. Using a Ca2+-impermeable mutant channel α11.2L745P/β2b/α2δ or disrupting Ca2+/calmodulin binding to the channel using the channel mutant α11.2I1624A/β2b/α2δ, we demonstrate that depolarization-induced c-Fos and MeCP2 activation does not depend on Ca2+ transport by the channel. Thus, in contrast to the paradigm that elevated intracellular Ca2+ drives nuclear signaling, we show that Cav1.2-triggered c-Fos or MeCP2 is dependent on extracellular Ca2+ and Ca2+ occupancy of the open channel pore, but is Ca2+-influx independent. An indispensable β-subunit interaction with H-Ras, which is triggered by conformational changes at α11.2 independently of Ca2+ flux, brings to light a master regulatory role of β2 in transcriptional activation via the ERK/CREB pathway. This mode of H-Ras activation could have broad implications for understanding the coupling of membrane depolarization to the rapid induction of gene transcription.
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14
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Hydroxyl Group and Vasorelaxant Effects of Perillyl Alcohol, Carveol, Limonene on Aorta Smooth Muscle of Rats. Molecules 2018; 23:molecules23061430. [PMID: 29899230 PMCID: PMC6099955 DOI: 10.3390/molecules23061430] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/02/2018] [Accepted: 06/03/2018] [Indexed: 01/11/2023] Open
Abstract
The present study used isometric tension recording to investigate the vasorelaxant effect of limonene (LM), carveol (CV), and perillyl alcohol (POH) on contractility parameters of the rat aorta, focusing in particular on the structure-activity relationship. LM, CV, and POH showed a reversible inhibitory effect on the contraction induced by electromechanical and pharmacomechanical coupling. In the case of LM, but not CV and POH, this effect was influenced by preservation of the endothelium. POH and CV but not LM exhibited greater pharmacological potency on BayK-8644-induced contraction and on electromechanical coupling than on pharmacomechanical coupling. In endothelium-denuded preparations, the order of pharmacological potency on electrochemical coupling was LM < CV < POH. These compounds inhibited also, with grossly similar pharmacological potency, the contraction induced by phorbol ester dibutyrate. The present results suggest that LM, CV and POH induced relaxant effect on vascular smooth muscle by means of different mechanisms likely to include inhibition of PKC and IP3 pathway. For CV and POH, hydroxylated compounds, it was in electromechanical coupling that the greater pharmacological potency was observed, thus suggesting a relative specificity for a mechanism likely to be important in electromechanical coupling, for example, blockade of voltage-dependent calcium channel.
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15
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Chapochnikov N, Takago H, Huang CH, Pangršič T, Khimich D, Neef J, Auge E, Göttfert F, Hell S, Wichmann C, Wolf F, Moser T. Uniquantal Release through a Dynamic Fusion Pore Is a Candidate Mechanism of Hair Cell Exocytosis. Neuron 2014; 83:1389-403. [DOI: 10.1016/j.neuron.2014.08.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2014] [Indexed: 01/19/2023]
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16
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Bachnoff N, Cohen-Kutner M, Trus M, Atlas D. Intra-membrane signaling between the voltage-gated Ca2+-channel and cysteine residues of syntaxin 1A coordinates synchronous release. Sci Rep 2014; 3:1620. [PMID: 23567899 PMCID: PMC3621091 DOI: 10.1038/srep01620] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 03/26/2013] [Indexed: 11/28/2022] Open
Abstract
The interaction of syntaxin 1A (Sx1A) with voltage-gated calcium channels (VGCC) is required for depolarization-evoked release. However, it is unclear how the signal is transferred from the channel to the exocytotic machinery and whether assembly of Sx1A and the calcium channel is conformationally linked to triggering synchronous release. Here we demonstrate that depolarization-evoked catecholamine release was decreased in chromaffin cells infected with semliki forest viral vectors encoding Sx1A mutants, Sx1AC271V, or Sx1AC272V, or by direct oxidation of these Sx1A transmembrane (TM) cysteine residues. Mutating or oxidizing these highly conserved Sx1A Cys271 and Cys272 equally disrupted the Sx1A interaction with the channel. The results highlight the functional link between the VGCC and the exocytotic machinery, and attribute the redox sensitivity of the release process to the Sx1A TM C271 and C272. This unique intra-membrane signal-transduction pathway enables fast signaling, and triggers synchronous release by conformational-coupling of the channel with Sx1A.
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Affiliation(s)
- Niv Bachnoff
- The Hebrew University of Jerusalem, Institute of Life Sciences, Department of Biological Chemistry, Givat-Ram, Jerusalem, Israel
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17
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Simms BA, Zamponi GW. Neuronal voltage-gated calcium channels: structure, function, and dysfunction. Neuron 2014; 82:24-45. [PMID: 24698266 DOI: 10.1016/j.neuron.2014.03.016] [Citation(s) in RCA: 420] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Voltage-gated calcium channels are the primary mediators of depolarization-induced calcium entry into neurons. There is great diversity of calcium channel subtypes due to multiple genes that encode calcium channel α1 subunits, coassembly with a variety of ancillary calcium channel subunits, and alternative splicing. This allows these channels to fulfill highly specialized roles in specific neuronal subtypes and at particular subcellular loci. While calcium channels are of critical importance to brain function, their inappropriate expression or dysfunction gives rise to a variety of neurological disorders, including, pain, epilepsy, migraine, and ataxia. This Review discusses salient aspects of voltage-gated calcium channel function, physiology, and pathophysiology.
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Affiliation(s)
- Brett A Simms
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
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18
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Atlas D. The Voltage-Gated Calcium Channel Functions as the Molecular Switch of Synaptic Transmission. Annu Rev Biochem 2013; 82:607-35. [DOI: 10.1146/annurev-biochem-080411-121438] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Daphne Atlas
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel;
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19
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Identification of a sphingosine-sensitive Ca2+ channel in the plasma membrane of Leishmania mexicana. Biochem Biophys Res Commun 2013; 430:1091-6. [DOI: 10.1016/j.bbrc.2012.12.033] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 12/06/2012] [Indexed: 11/18/2022]
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20
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Gez LS, Hagalili Y, Shainberg A, Atlas D. Voltage-driven Ca(2+) binding at the L-type Ca(2+) channel triggers cardiac excitation-contraction coupling prior to Ca(2+) influx. Biochemistry 2012; 51:9658-66. [PMID: 23145875 DOI: 10.1021/bi301124a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The activation of the ryanodine Ca(2+) release channels (RyR2) by the entry of Ca(2+) through the L-type Ca(2+) channels (Cav1.2) is believed to be the primary mechanism of excitation-contraction (EC) coupling in cardiac cells. This proposed mechanism of Ca(2+)-induced Ca(2+) release (CICR) cannot fully account for the lack of a termination signal for this positive feedback process. Using Cav1.2 channel mutants, we demonstrate that the Ca(2+)-impermeable α(1)1.2/L775P/T1066Y mutant introduced through lentiviral infection into neonate cardiomyocytes triggers Ca(2+) transients in a manner independent of Ca(2+) influx. In contrast, the α(1)1.2/L775P/T1066Y/4A mutant, in which the Ca(2+)-binding site of the channel was destroyed, supports neither the spontaneous nor the electrically evoked contractions. Ca(2+) bound at the channel selectivity filter appears to initiate a signal that is conveyed directly from the channel pore to RyR2, triggering contraction of cardiomyocytes prior to Ca(2+) influx. Thus, RyR2 is activated in response to a conformational change in the L-type channel during membrane depolarization and not through interaction with Ca(2+) ions diffusing in the junctional gap space. Accordingly, termination of the RyR2 activity is achieved when the signal stops upon the return of the L-channel to the resting state. We propose a new model in which the physical link between Cav1.2 and RyR2 allows propagation of a conformational change induced at the open pore of the channel to directly activate RyR2. These results highlight Cav1.2 as a signaling protein and provide a mechanism for terminating the release of Ca(2+) from RyR2 through protein-protein interactions. In this model, the L-type channel is a master regulator of both initiation and termination of EC coupling in neonate cardiomyocytes.
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Affiliation(s)
- Liron S Gez
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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21
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Control of low-threshold exocytosis by T-type calcium channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1579-86. [PMID: 22885170 DOI: 10.1016/j.bbamem.2012.07.031] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 07/30/2012] [Accepted: 07/30/2012] [Indexed: 12/11/2022]
Abstract
Low-voltage-activated (LVA) T-type Ca²⁺ channels differ from their high-voltage-activated (HVA) homologues by unique biophysical properties. Hence, whereas HVA channels convert action potentials into intracellular Ca²⁺ elevations, T-type channels control Ca²⁺ entry during small depolarizations around the resting membrane potential. They play an important role in electrical activities by generating low-threshold burst discharges that occur during various physiological and pathological forms of neuronal rhythmogenesis. In addition, they mediate a previously unrecognized function in the control of synaptic transmission where they directly trigger the release of neurotransmitters at rest. In this review, we summarize our present knowledge of the role of T-type Ca²⁺ channels in vesicular exocytosis, and emphasize the critical importance of localizing the exocytosis machinery close to the Ca²⁺ source for reliable synaptic transmission. This article is part of a Special Issue entitled: Calcium channels.
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22
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Regulation of voltage-gated calcium channels by synaptic proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:759-75. [PMID: 22453968 DOI: 10.1007/978-94-007-2888-2_33] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Calcium entry through neuronal voltage-gated calcium channels into presynaptic nerve terminal is a key step in synaptic exocytosis. In order to receive the calcium signal and trigger fast, efficient and spatially delimited neurotransmitter release, the vesicle-docking/release machinery must be located near the calcium source. In many cases, this close localization is achieved by a direct interaction of several members of the vesicle release machinery with the calcium channels. In turn, the binding of synaptic proteins to presynaptic calcium channels modulates channel activity to provide fine control over calcium entry, and thus modulates synaptic strength. In this chapter we summarize our present knowledge of the molecular mechanisms by which synaptic proteins regulate presynaptic calcium channel activity.
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23
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Marom M, Birnbaumer L, Atlas D. Membrane depolarization combined with Gq-activated G-protein-coupled receptors induce transient receptor potential channel 1 (TRPC1)- dependent potentiation of catecholamine release. Neuroscience 2011; 189:132-45. [DOI: 10.1016/j.neuroscience.2011.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 05/02/2011] [Accepted: 05/02/2011] [Indexed: 10/18/2022]
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Bannister RA, Beam KG. Properties of Na+ currents conducted by a skeletal muscle L-type Ca2+ channel pore mutant (SkEIIIK). Channels (Austin) 2011; 5:262-8. [PMID: 21406961 DOI: 10.4161/chan.5.3.15269] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Four glutamate residues residing at corresponding positions within the four conserved membrane-spanning repeats of L-type Ca(2+) channels are important structural determinants for the passage of Ca(2+) across the selectivity filter. Mutation of the critical glutamate in Repeat III in the a 1S subunit of the skeletal L-type channel (Ca(v)1.1) to lysine virtually eliminates passage of Ca(2+) during step depolarizations. In this study, we examined the ability of this mutant Ca(v)1.1 channel (SkEIIIK) to conduct inward Na(+) current. When 150 mM Na(+) was present as the sole monovalent cation in the bath solution, dysgenic (Ca(v)1.1 null) myotubes expressing SkEIIIK displayed slowly-activating, non-inactivating, nifedipine-sensitive inward currents with a reversal potential (45.6 ± 2.5 mV) near that expected for Na(+). Ca(2+) block of SkEIIIK-mediated Na(+) current was revealed by the substantial enhancement of Na(+) current amplitude after reduction of Ca(2+) in the external recording solution from 10 mM to near physiological 1 mM. Inward SkEIIIK-mediated currents were potentiated by either ±Bay K 8644 (10 mM) or 200-ms depolarizing prepulses to +90 mV. In contrast, outward monovalent currents were reduced by ±Bay K 8644 and were unaffected by strong depolarization, indicating a preferential potentiation of inward Na(+) currents through the mutant Ca(v)1.1 channel. Taken together, our results show that SkEIIIK functions as a non-inactivating, junctionally-targeted Na(+) channel when Na(+) is the sole monvalent cation present and urge caution when interpreting the impact of mutations designed to ablate Ca(2+) permeability mediated by Ca(v) channels on physiological processes that extend beyond channel gating and permeability.
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Affiliation(s)
- Roger A Bannister
- Department of Physiology and Biophysics, University of Colorado-Anschutz Medical Campus, Aurora, CO, USA.
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25
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Weiss N. Control of depolarization-evoked presynaptic neurotransmitter release by Cav2.1 calcium channel: old story, new insights. Channels (Austin) 2010; 4:431-3. [PMID: 20935476 DOI: 10.4161/chan.4.6.13613] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Affiliation(s)
- Norbert Weiss
- INSERM U836, Grenoble Institut des Neurosciences, Grenoble, France.
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Friedrich R, Ashery U. From spike to graph--a complete automated single-spike analysis. J Neurosci Methods 2010; 193:271-80. [PMID: 20869399 DOI: 10.1016/j.jneumeth.2010.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 09/06/2010] [Accepted: 09/13/2010] [Indexed: 11/16/2022]
Abstract
Amperometry is a commonly used technique for detecting the kinetics of single-vesicle exocytosis with excellent temporal and spatial resolution. However, different methods of analyzing the amperometric signals can produce conflicting conclusions. We developed an efficient automated method for kinetics analysis of single spikes that does not filter the data and therefore prevents distortion of the results. The algorithm assesses the signal-to-noise ratios (SNRs) and accordingly, separates the signals using an adjustable two-threshold calculation. This enables comparing data with different SNRs from different setups. The software also includes a complete statistical analysis, with an automated selection of the most appropriate statistical tests and a graphical representation. The algorithms can be used for any other experimental results requiring the separation of signals from noise, making this method useful for many applications.
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Affiliation(s)
- Reut Friedrich
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel.
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