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Davis MJ, Earley S, Li YS, Chien S. Vascular mechanotransduction. Physiol Rev 2023; 103:1247-1421. [PMID: 36603156 PMCID: PMC9942936 DOI: 10.1152/physrev.00053.2021] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 09/26/2022] [Accepted: 10/04/2022] [Indexed: 01/07/2023] Open
Abstract
This review aims to survey the current state of mechanotransduction in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), including their sensing of mechanical stimuli and transduction of mechanical signals that result in the acute functional modulation and longer-term transcriptomic and epigenetic regulation of blood vessels. The mechanosensors discussed include ion channels, plasma membrane-associated structures and receptors, and junction proteins. The mechanosignaling pathways presented include the cytoskeleton, integrins, extracellular matrix, and intracellular signaling molecules. These are followed by discussions on mechanical regulation of transcriptome and epigenetics, relevance of mechanotransduction to health and disease, and interactions between VSMCs and ECs. Throughout this review, we offer suggestions for specific topics that require further understanding. In the closing section on conclusions and perspectives, we summarize what is known and point out the need to treat the vasculature as a system, including not only VSMCs and ECs but also the extracellular matrix and other types of cells such as resident macrophages and pericytes, so that we can fully understand the physiology and pathophysiology of the blood vessel as a whole, thus enhancing the comprehension, diagnosis, treatment, and prevention of vascular diseases.
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Affiliation(s)
- Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Scott Earley
- Department of Pharmacology, University of Nevada, Reno, Nevada
| | - Yi-Shuan Li
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
| | - Shu Chien
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
- Department of Medicine, University of California, San Diego, California
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2
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Desjardins K, Khadra M, Caron A, Ponton DE, Rosabal M, Amyot M. Significance of chemical affinity on metal subcellular distribution in yellow perch (Perca flavescens) livers from Lake Saint-Pierre (QUEBEC, Canada). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 312:120077. [PMID: 36057325 DOI: 10.1016/j.envpol.2022.120077] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 08/26/2022] [Accepted: 08/27/2022] [Indexed: 06/15/2023]
Abstract
The subcellular partitioning approach provides useful information on the location of metals within cells and is often used on organisms with high levels of bioaccumulation to establish relationships between the internal concentration and the potential toxicity of metals. Relatively little is known about the subcellular partitioning of metals in wild fish with low bioaccumulation levels in comparison with those from higher contaminated areas. This study aims to examine the subcellular partitioning of various metals considering their chemical affinity and essentiality at relatively low contamination levels. Class A (Y, Sr), class B (Cu, Cd, MeHg), and borderline (Fe, Mn) metal concentrations were measured in livers and subcellular fractions of yellow perch (n = 21) collected in Lake Saint-Pierre, QC, Canada. The results showed that all metals, apart from MeHg, were distributed among subcellular fractions according to their chemical affinity. More than 60% of Y, Sr, Fe, and Mn were found in the metal-sensitive fractions. Cd and Cu were largely associated with the metallothionein-like proteins and peptides (60% and 67% respectively) whereas MeHg was found mainly in the metal-sensitive fractions (86%). In addition, the difference between the subcellular distribution of Cu and other essential metals like Fe and Mn denotes that, although the essentiality of some metals is a determinant of their subcellular distribution, the chemical affinity of metals is also a key driver. The similarity of the subcellular partitioning results with previous studies on yellow perch and other fish species from higher contaminated areas supports the idea that metals are distributed in the cellular environment according to their chemical properties regardless of the bioaccumulation gradient.
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Affiliation(s)
- Kimberley Desjardins
- Groupe interuniversitaire en limnologie et en environnement aquatique (GRIL), Département de sciences biologiques, Complexe des sciences, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, Québec, H2V 0B3, Canada
| | - Mélissa Khadra
- Groupe interuniversitaire en limnologie et en environnement aquatique (GRIL), Département de sciences biologiques, Complexe des sciences, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, Québec, H2V 0B3, Canada
| | - Antoine Caron
- Groupe interuniversitaire en limnologie et en environnement aquatique (GRIL), Département de sciences biologiques, Complexe des sciences, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, Québec, H2V 0B3, Canada
| | - Dominic E Ponton
- Groupe interuniversitaire en limnologie et en environnement aquatique (GRIL), Département de sciences biologiques, Complexe des sciences, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, Québec, H2V 0B3, Canada
| | - Maikel Rosabal
- Groupe interuniversitaire en limnologie et en environnement aquatique (GRIL), Département des sciences biologiques, Université du Québec à Montréal, C.P., 8888, Succursale Centre-Ville, Montréal, Québec, H3C 3P8, Canada
| | - Marc Amyot
- Groupe interuniversitaire en limnologie et en environnement aquatique (GRIL), Département de sciences biologiques, Complexe des sciences, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, Québec, H2V 0B3, Canada.
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3
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Barker E, Shepherd J, Asencio IO. The Use of Cerium Compounds as Antimicrobials for Biomedical Applications. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27092678. [PMID: 35566026 PMCID: PMC9104093 DOI: 10.3390/molecules27092678] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 04/01/2022] [Accepted: 04/14/2022] [Indexed: 12/05/2022]
Abstract
Cerium and its derivatives have been used as remedies for wounds since the early 20th century. Cerium nitrate has attracted most attention in the treatment of deep burns, followed later by reports of its antimicrobial properties. Its ability to mimic and replace calcium is presumed to be a major mechanism of its beneficial action. However, despite some encouraging results, the overall data are somewhat confusing with seemingly the same compounds yielding opposing results. Despite this, cerium nitrate is currently used in wound treatment in combination with silver sulfadiazine as Flammacérium. Cerium oxide, especially in nanoparticle form (Nanoceria), has lately captured much interest due to its antibacterial properties mediated via oxidative stress, leading to an increase of published reports. The properties of Nanoceria depend on the synthesis method, their shape and size. Recently, the green synthesis route has gained a lot of interest as an alternative environmentally friendly method, resulting in production of effective antimicrobial and antifungal nanoparticles. Unfortunately, as is the case with antibiotics, emerging bacterial resistance against cerium-derived nanoparticles is a growing concern, especially in the case of bacterial biofilm. However, diverse strategies resulting from better understanding of the biology of cerium are promising. The aim of this paper is to present the progress to date in the use of cerium compounds as antimicrobials in clinical applications (in particular wound healing) and to provide an overview of the mechanisms of action of cerium at both the cellular and molecular level.
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4
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Neumaier F, Schneider T, Albanna W. Ca v2.3 channel function and Zn 2+-induced modulation: potential mechanisms and (patho)physiological relevance. Channels (Austin) 2020; 14:362-379. [PMID: 33079629 PMCID: PMC7583514 DOI: 10.1080/19336950.2020.1829842] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Voltage-gated calcium channels (VGCCs) are critical for Ca2+ influx into all types of excitable cells, but their exact function is still poorly understood. Recent reconstruction of homology models for all human VGCCs at atomic resolution provides the opportunity for a structure-based discussion of VGCC function and novel insights into the mechanisms underlying Ca2+ selective flux through these channels. In the present review, we use these data as a basis to examine the structure, function, and Zn2+-induced modulation of Cav2.3 VGCCs, which mediate native R-type currents and belong to the most enigmatic members of the family. Their unique sensitivity to Zn2+ and the existence of multiple mechanisms of Zn2+ action strongly argue for a role of these channels in the modulatory action of endogenous loosely bound Zn2+, pools of which have been detected in a number of neuronal, endocrine, and reproductive tissues. Following a description of the different mechanisms by which Zn2+ has been shown or is thought to alter the function of these channels, we discuss their potential (patho)physiological relevance, taking into account what is known about the magnitude and function of extracellular Zn2+ signals in different tissues. While still far from complete, the picture that emerges is one where Cav2.3 channel expression parallels the occurrence of loosely bound Zn2+ pools in different tissues and where these channels may serve to translate physiological Zn2+ signals into changes of electrical activity and/or intracellular Ca2+ levels.
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Affiliation(s)
- Felix Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5) , Jülich, Germany.,University of Cologne, Faculty of Medicine and University Hospital Cologne, Institute of Radiochemistry and Experimental Molecular Imaging , Cologne, Germany
| | - Toni Schneider
- Institute of Neurophysiology , Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Walid Albanna
- Department of Neurosurgery, RWTH Aachen University , Aachen, Germany
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5
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Zhang X, Xin P, Yoast RE, Emrich SM, Johnson MT, Pathak T, Benson JC, Azimi I, Gill DL, Monteith GR, Trebak M. Distinct pharmacological profiles of ORAI1, ORAI2, and ORAI3 channels. Cell Calcium 2020; 91:102281. [PMID: 32896813 DOI: 10.1016/j.ceca.2020.102281] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/25/2020] [Accepted: 08/25/2020] [Indexed: 12/18/2022]
Abstract
The ubiquitous Ca2+ release-activated Ca2+ (CRAC) channel is crucial to many physiological functions. Both gain and loss of CRAC function is linked to disease. While ORAI1 is a crucial subunit of CRAC channels, recent evidence suggests that ORAI2 and ORAI3 heteromerize with ORAI1 to form native CRAC channels. Furthermore, ORAI2 and ORAI3 can form CRAC channels independently of ORAI1, suggesting diverse native CRAC stoichiometries. Yet, most available CRAC modifiers are presumed to target ORAI1 with little knowledge of their effects on ORAI2/3 or heteromers of ORAIs. Here, we used ORAI1/2/3 triple-null cells to express individual ORAI1, ORAI2, ORAI3 or ORAI1/2/3 concatemers. We reveal that GSK-7975A and BTP2 essentially abrogate ORAI1 and ORAI2 activity while causing only a partial inhibition of ORAI3. Interestingly, Synta66 abrogated ORAI1 channel function, while potentiating ORAI2 with no effect on ORAI3. CRAC channel activities mediated by concatenated ORAI1-1, ORAI1-2 and ORAI1-3 dimers were inhibited by Synta66, while ORAI2-3 dimers were unaffected. The CRAC enhancer IA65 significantly potentiated ORAI1 and ORAI1-1 activity with marginal effects on other ORAIs. Further, we characterized the profiles of individual ORAI isoforms in the presence of Gd3+ (5μM), 2-APB (5 μM and 50 μM), as well as changes in intracellular and extracellular pH. Our data reveal unique pharmacological features of ORAI isoforms expressed in an ORAI-null background and provide new insights into ORAI isoform selectivity of widely used CRAC pharmacological compounds.
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Affiliation(s)
- Xuexin Zhang
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA.
| | - Ping Xin
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA
| | - Ryan E Yoast
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA
| | - Scott M Emrich
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA
| | - Martin T Johnson
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA
| | - Trayambak Pathak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA
| | - J Cory Benson
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA
| | - Iman Azimi
- School of Pharmacy and Pharmacology, College of Health and Medicine, University of Tasmania, Hobart 7001, Tasmania, Australia
| | - Donald L Gill
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA
| | - Gregory R Monteith
- School of Pharmacy, The University of Queensland, Brisbane 4072, Queensland, Australia
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA; Penn State Cancer Institute, The Pennsylvania State University College of Medicine, 500 University Dr. Hershey, PA, 17033 USA.
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6
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Americus B, Lotan T, Bartholomew JL, Atkinson SD. A comparison of the structure and function of nematocysts in free-living and parasitic cnidarians (Myxozoa). Int J Parasitol 2020; 50:763-769. [PMID: 32707121 DOI: 10.1016/j.ijpara.2020.04.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/23/2020] [Accepted: 04/28/2020] [Indexed: 11/30/2022]
Abstract
Myxozoans are obligate parasites that have complex life cycles requiring alternate vertebrate and invertebrate hosts, with transmission via microscopic waterborne spores. Unusually for parasites, they belong to the phylum Cnidaria, alongside thousands of free-living corals, sea anemones, jellyfish and hydrozoans. Their cnidarian affinity is affirmed by genetic relatedness and the presence of nematocysts, historically called "polar capsules" in myxozoan research. Free-living cnidarians utilise this cellular weaponry for defence, predation and adhesion, whereas myxozoans use it to anchor to their hosts as the first step in infection. Despite the ~650 million years of divergence between free-living cnidarians and myxozoans, their nematocysts retain many shared morphological and molecular characters. Both are intra-cellular capsules with a single opening, and contain a coiled, evertable tubule. They are composed of unique nematocyst proteins, nematogalectin and minicollagen, and both likely contain an internal matrix of metal cations covalently bound to the anionic polymer poly-gamma glutamate. The rapid dissociation of this matrix and the resulting increase in internal osmotic potential is the driving force behind tubule elongation during discharge. In this review, we compare the structure and function of nematocysts in Myxozoa and free-living Cnidaria, incorporating recent molecular characterizations. We propose that terminology for homologous myxozoan structures be synonymized with those from other Cnidaria, hence, "polar capsule" as a taxon-specific nematocyst morphotype and "polar filament" as "tubule." Despite taxonomic divergence, genome reduction and an evolution to parasitism, myxozoans maintain nematocysts that are structurally and functionally homologous to those of their free-living cnidarian relatives.
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Affiliation(s)
- Benjamin Americus
- Department of Microbiology, Oregon State University, Corvallis, OR, USA
| | - Tamar Lotan
- Department of Marine Biology, The Leon H.Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | | | - Stephen D Atkinson
- Department of Microbiology, Oregon State University, Corvallis, OR, USA.
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7
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Gaburjakova J, Almassy J, Gaburjakova M. Luminal addition of non-permeant Eu 3+ interferes with luminal Ca 2+ regulation of the cardiac ryanodine receptor. Bioelectrochemistry 2020; 132:107449. [PMID: 31918058 DOI: 10.1016/j.bioelechem.2019.107449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/17/2019] [Accepted: 12/17/2019] [Indexed: 10/25/2022]
Abstract
Dysregulation of the cardiac ryanodine receptor (RYR2) by luminal Ca2+ has been implicated in a life-threatening, stress-induced arrhythmogenic disease. The mechanism of luminal Ca2+-mediated RYR2 regulation is under debate, and it has been attributed to Ca2+ binding on the cytosolic face (the Ca2+ feedthrough mechanism) and/or the luminal face of the RYR2 channel (the true luminal mechanism). The molecular nature and location of the luminal Ca2+ site is unclear. At the single-channel level, we directly probed the RYR2 luminal face by Eu3+, considering the non-permeant nature of trivalent cations and their high binding affinities for Ca2+ sites. Without affecting essential determinants of the Ca2+ feedthrough mechanism, we found that luminal Eu3+ competitively antagonized the activation effect of luminal Ca2+ on RYR2 responsiveness to cytosolic caffeine, and no appreciable effect was observed for luminal Ba2+ (mimicking the absence of luminal Ca2+). Importantly, luminal Eu3+ caused no changes in RYR2 gating. Our results indicate that two distinct Ca2+ sites (available for luminal Ca2+ even when the channel is closed) are likely involved in the true luminal mechanism. One site facing the lumen regulates channel responsiveness to caffeine, while the other site, presumably positioned in the channel pore, governs the gating behavior.
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Affiliation(s)
- Jana Gaburjakova
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska Cesta 9, 840 05 Bratislava, Slovak Republic.
| | - Janos Almassy
- Department of Physiology, Faculty of Medicine, University of Debrecen, PO Box 400, Debrecen 4002, Hungary.
| | - Marta Gaburjakova
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska Cesta 9, 840 05 Bratislava, Slovak Republic.
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8
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Cardon PY, Triffault-Bouchet G, Caron A, Rosabal M, Fortin C, Amyot M. Toxicity and Subcellular Fractionation of Yttrium in Three Freshwater Organisms: Daphnia magna, Chironomus riparius, and Oncorhynchus mykiss. ACS OMEGA 2019; 4:13747-13755. [PMID: 31497692 PMCID: PMC6714508 DOI: 10.1021/acsomega.9b01238] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/31/2019] [Indexed: 05/21/2023]
Abstract
The demand for rare earth elements (REEs) has increased since the 1990s leading to the development of many mining projects worldwide. However, less is known about how organisms can handle these metals in natural aquatic systems. Through laboratory experiments, we assessed the chronic toxicity and subcellular fractionation of yttrium (Y), one of the four most abundant REEs, in three freshwater organisms commonly used in aquatic toxicology: Daphnia magna, Chironomus riparius, and Oncorhynchus mykiss. In bioassays using growth as an end point, C. riparius was the only organism showing toxicity at Y exposure concentrations close to environmental ones. The lowest observable effect concentrations (LOECs) of Y assessed for D. magna and O. mykiss were at least 100 times higher than the Y concentration in natural freshwater. A negative correlation between Y toxicity and water hardness was observed for D. magna. When exposed to their respective estimated LOECs, D. magna bioaccumulated 15-45 times more Y than the other two organisms exposed to their own LOECs. This former species sequestered up to 75% of Y in the NaOH-resistant fraction, a putative metal-detoxified subcellular fraction. To a lesser extent, C. riparius bioaccumulated 20-30% of Y in this detoxified fraction. In contrast, the Y subcellular distribution in O. mykiss liver did not highlight any notable detoxification strategy; Y was accumulated primarily in mitochondria (ca. 32%), a putative metal-sensitive fraction. This fraction was also the main sensitive fraction where Y accumulated in C. riparius and D. magna. Hence, the interaction of Y with mitochondria could explain its toxicity. In conclusion, there is a wide range of subcellular handling strategies for Y, with D. magna accumulating high quantities but sequestering most of it in detoxified fractions, whereas O. mykiss tending to accumulate less Y but in highly sensitive fractions.
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Affiliation(s)
- Pierre-Yves Cardon
- Département
de Sciences Biologiques, GRIL, Université
de Montréal (UdeM), Pavillon Marie-Victorin, 90 Avenue Vincent-d’Indy, Montréal, Québec H3C 3J7, Canada
| | - Gaëlle Triffault-Bouchet
- Division
de l’écotoxicologie et de l’évaluation
du risque, Centre d’expertise en
Analyse Environnementale du Québec (CEAEQ), 2700 rue Einstein, Québec, Québec G1P 3W8, Canada
| | - Antoine Caron
- Département
de Sciences Biologiques, GRIL, Université
de Montréal (UdeM), Pavillon Marie-Victorin, 90 Avenue Vincent-d’Indy, Montréal, Québec H3C 3J7, Canada
| | - Maikel Rosabal
- Département
des Sciences Biologiques, GRIL, Université
du Québec à Montréal (UQAM), 141 Avenue du président-Kennedy, Montréal, Québec H2X 1Y4, Canada
| | - Claude Fortin
- Centre
Eau Terre Environnement (INRS-ETE), Institut
National de la Recherche Scientifique, 490 rue de la Couronne, Québec, Québec G1K 9A9, Canada
| | - Marc Amyot
- Département
de Sciences Biologiques, GRIL, Université
de Montréal (UdeM), Pavillon Marie-Victorin, 90 Avenue Vincent-d’Indy, Montréal, Québec H3C 3J7, Canada
- E-mail: . Phone 1-514-343-7496 (M.A.)
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9
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Gualdani R, Guerrini A, Fantechi E, Tadini-Buoninsegni F, Moncelli MR, Sangregorio C. Superparamagnetic iron oxide nanoparticles (SPIONs) modulate hERG ion channel activity. Nanotoxicology 2019; 13:1197-1209. [PMID: 31437063 DOI: 10.1080/17435390.2019.1650969] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used in various biomedical applications, such as diagnostic agents in magnetic resonance imaging (MRI), for drug delivery vehicles and in hyperthermia treatment of tumors. Although the potential benefits of SPIONs are considerable, there is a distinct need to identify any potential cellular damage associated with their use. Since human ether à go-go-related gene (hERG) channel, a protein involved in the repolarization phase of cardiac action potential, is considered one of the main targets in the drug discovery process, we decided to evaluate the effects of SPIONs on hERG channel activity and to determine whether the oxidation state, the dimensions and the coating of nanoparticles (NPs) can influence the interaction with hERG channel. Using patch clamp recordings, we found that SPIONs inhibit hERG current and this effect depends on the coating of NPs. In particular, SPIONs with covalent coating aminopropylphosphonic acid (APPA) have a milder effect on hERG activity. We observed that the time-course of hERG channel modulation by SPIONs is biphasic, with a transient increase (∼20% of the amplitude) occurring within the first 1-3 min of perfusion of NPs, followed by a slower inhibition. Moreover, in the presence of SPIONs, deactivation kinetics accelerated and the activation and inactivation I-V curves were right-shifted, similarly to the effect described for the binding of other divalent metal ions (e.g. Cd2+ and Zn2+). Finally, our data show that a bigger size and the complete oxidation of SPIONs can significantly decrease hERG channel inhibition. Taken together, these results support the view that Fe2+ ions released from magnetite NPs may represent a cardiac risk factor, since they alter hERG gating and these alterations could compromise the cardiac action potential.
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Affiliation(s)
- Roberta Gualdani
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy.,Institute of Neuroscience, Laboratory of Cell Physiology, Université Catholique de Louvain , Brussels , Belgium
| | - Andrea Guerrini
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy
| | - Elvira Fantechi
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy
| | | | - Maria Rosa Moncelli
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy
| | - Claudio Sangregorio
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze , Sesto Fiorentino , Italy.,ICCOM-CNR and INSTM , Sesto Fiorentino , Italy
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10
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Wang D, Ragnarsson L, Lewis RJ. T-type Calcium Channels in Health and Disease. Curr Med Chem 2018; 27:3098-3122. [PMID: 30277145 DOI: 10.2174/0929867325666181001112821] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/28/2018] [Accepted: 08/30/2018] [Indexed: 12/12/2022]
Abstract
Low Voltage-Activated (LVA) T-type calcium channels are characterized by transient current and Low Threshold Spikes (LTS) that trigger neuronal firing and oscillatory behavior. Combined with their preferential localization in dendrites and their specific "window current", T-type calcium channels are considered to be key players in signal amplification and synaptic integration. Assisted by the emerging pharmacological tools, the structural determinants of channel gating and kinetics, as well as novel physiological and pathological functions of T-type calcium channels, are being uncovered. In this review, we provide an overview of structural determinants in T-type calcium channels, their involvement in disorders and diseases, the development of novel channel modulators, as well as Structure-Activity Relationship (SAR) studies that lead to rational drug design.
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Affiliation(s)
- Dan Wang
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane Qld 4072, Australia
| | - Lotten Ragnarsson
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane Qld 4072, Australia
| | - Richard J Lewis
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, the University of Queensland, Brisbane Qld 4072, Australia
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11
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Briner W. The Toxic Effect of Lanthanum on Planaria Is Mediated by a Variety of Ion Channels. TOXICS 2018; 6:toxics6020033. [PMID: 29912145 PMCID: PMC6027234 DOI: 10.3390/toxics6020033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/11/2018] [Accepted: 06/13/2018] [Indexed: 11/16/2022]
Abstract
The effect of toxic concentrations of La3+ on the Ca, K, Na, Mg, and Cl channels of planaria was investigated through the use of various agonists and antagonists to those channels. It was demonstrated that La exerts its toxic effects through L-type, but not T-type, Ca channels. La also demonstrated activity at Na, K, Mg, and Cl channels, but, these effects were most likely mediated by other effects of La on Ca activity. However, these interactions appear to be very complex and confounded by oxidative stresses. The study also introduces a planaria stress scale which allows the effects of toxic substances to be examined on a continuum.
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Affiliation(s)
- Wayne Briner
- College of Health Human Service and Sciences, Ashford University, San Diego, CA 92123, USA.
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12
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Gioia DA, Xu M, Wayman WN, Woodward JJ. Effects of drugs of abuse on channelrhodopsin-2 function. Neuropharmacology 2018; 135:316-327. [PMID: 29580953 DOI: 10.1016/j.neuropharm.2018.03.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 01/16/2023]
Abstract
Channelrhodopsins are light activated ion channels used extensively over the past decade to probe the function of genetically defined neuronal populations and distinct neural circuits with high temporal and spatial precision. The widely used Channelrhodopsin-2 variant (ChR2) is an excitatory opsin that undergoes conformational changes in response to blue light, allowing non-selective passage of protons and cations across the plasma membrane thus leading to depolarization. In the addiction neuroscience field, opsins such as ChR2 provide a means to disambiguate the overlapping circuitry involved in mediating the reinforcing and aversive effects of drugs of abuse as well as to determine the plasticity that can occur in these circuits during the development of dependence. Although ChR2 has been widely used in animal models of drug and alcohol self-administration, direct effects of drugs of abuse on ChR2 function may confound its use and lead to misinterpretation of data. As a variety of neuronal ion channels are primary targets of various drugs of abuse, it is critical to determine whether ChR2-mediated currents are modulated by these drugs. In this study, we performed whole-cell electrophysiological recordings in HEK293 cells expressing the commonly used ChR2(H134R) variant and examined the effects of various drugs of abuse and other commonly used agents on light-induced currents. We found no differences in ChR2-mediated currents in the presence of 30 μM nicotine, 30 μM cocaine, 100 μM methamphetamine or 3 mM toluene. Similarly, ChR2 currents were insensitive to 30 mM ethanol but higher concentrations (100-300 mM) produced significant effects on the desensitization and amplitude of light-evoked currents. Tetrahydrocannabinol (1-10 μM) and morphine (30-100 μM) significantly inhibited ChR2 currents while the cannabinoid receptor antagonist AM-251 had no effect. The sodium channel blocker tetrodotoxin (5 μM) and the generic channel blocker/contrast agent gadolinium chloride (10 mM) also reduced ChR2 currents while the divalent ion magnesium (10 mM) had no effect. Together, the results from this study highlight the importance of conducting appropriate control experiments when testing new compounds in combination with optogenetic approaches.
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Affiliation(s)
- Dominic A Gioia
- Medical University of South Carolina, Institute of Psychiatry, 67 President St, Charleston, SC, 29425, United States.
| | - Minfu Xu
- Medical University of South Carolina, Institute of Psychiatry, 67 President St, Charleston, SC, 29425, United States.
| | - Wesley N Wayman
- Medical University of South Carolina, Institute of Psychiatry, 67 President St, Charleston, SC, 29425, United States.
| | - John J Woodward
- Medical University of South Carolina, Institute of Psychiatry, 67 President St, Charleston, SC, 29425, United States.
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Mishra A, Punia JK, Bladen C, Zamponi GW, Goel RK. Anticonvulsant mechanisms of piperine, a piperidine alkaloid. Channels (Austin) 2016; 9:317-23. [PMID: 26542628 DOI: 10.1080/19336950.2015.1092836] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Piperine, a natural compound isolated from the fruits of Piper, is known to modulate several neurotransmitter systems such as serotonin, norepinephrine, and GABA, all of which have been linked to the development of convulsions. Fruits of Piper species have been suggested as means for managing seizure disorders. The present study was designed to elucidate the anticonvulsant effect of piperine and its mechanisms of action using in-silico, in-vivo and in-vitro techniques.PASS software was used to determine its possible activity and mechanisms. Furthermore the latency for development of convulsions and mortality rate was recorded in different experimental mouse models of epilepsy (pentylenetetrazole, maximal electroshock, NMDA, picrotoxin, bicuculline, BAYK-8644, strychnine-induced convulsions) after administration of various doses of piperine (5, 10 and 20 mg/kg, i.p.). Finally, the effect of piperine on Na(+) and Ca(2+) channels were evaluated using the whole cell patch clamp techniqueOur results revealed that piperine decreased mortality in the MES-induced seizure model. Moreover, piperine (10 mg/kg) delayed the onset of tonic clonic convulsions in the pentylenetetrazole test and reduced associated mortality. Furthermore, an anticonvulsant dose of piperine also delayed the onset of tonic clonic seizures in strychnine, picrotoxin and BAY K-8644. Complete protection against mortality was observed in BAYK-8644 induced convulsions. Finally, whole cell patch clamp analysis suggested an inhibitory effect of piperine on Na(+) channels. Together, our data suggest Na(+) channel antagonist activity as a contributor to the complex anticonvulsant mechanisms of piperine.
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Affiliation(s)
- Awanish Mishra
- a Department of Pharmaceutical Sciences and Drug Research ; Punjabi University ; Patiala , Punjab , India
| | - Jasmine Kaur Punia
- a Department of Pharmaceutical Sciences and Drug Research ; Punjabi University ; Patiala , Punjab , India
| | - Chris Bladen
- b Department of Physiology & Pharmacology ; Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary ; Calgary , Alberta , Canada
| | - Gerald W Zamponi
- b Department of Physiology & Pharmacology ; Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary ; Calgary , Alberta , Canada
| | - Rajesh Kumar Goel
- a Department of Pharmaceutical Sciences and Drug Research ; Punjabi University ; Patiala , Punjab , India
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Zamponi GW, Striessnig J, Koschak A, Dolphin AC. The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential. Pharmacol Rev 2015; 67:821-70. [PMID: 26362469 PMCID: PMC4630564 DOI: 10.1124/pr.114.009654] [Citation(s) in RCA: 684] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.
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Affiliation(s)
- Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Joerg Striessnig
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Alexandra Koschak
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Annette C Dolphin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
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15
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Jiang C, Shang J, Li Z, Qin A, Ouyang Z, Qu X, Li H, Tian B, Wang W, Wu C, Wang J, Dai M. Lanthanum Chloride Attenuates Osteoclast Formation and Function Via the Downregulation of Rankl-Induced Nf-κb and Nfatc1 Activities. J Cell Physiol 2015; 231:142-51. [PMID: 26060084 DOI: 10.1002/jcp.25065] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 06/01/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Chuan Jiang
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital; Shanghai JiaoTong University School of Medicine; Shanghai China
| | - Jiangyinzi Shang
- Department of Orthopaedics; The First Affiliated Hospital; Nanchang University; Nanchang Jiangxi Province China
| | - Zhe Li
- Department of Orthopaedics; The First Affiliated Hospital; Nanchang University; Nanchang Jiangxi Province China
| | - An Qin
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital; Shanghai JiaoTong University School of Medicine; Shanghai China
| | - Zhengxiao Ouyang
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital; Shanghai JiaoTong University School of Medicine; Shanghai China
| | - Xinhua Qu
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital; Shanghai JiaoTong University School of Medicine; Shanghai China
| | - Haowei Li
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital; Shanghai JiaoTong University School of Medicine; Shanghai China
| | - Bo Tian
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital; Shanghai JiaoTong University School of Medicine; Shanghai China
| | - Wengang Wang
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital; Shanghai JiaoTong University School of Medicine; Shanghai China
| | - Chuanlong Wu
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital; Shanghai JiaoTong University School of Medicine; Shanghai China
| | - Jinwu Wang
- Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital; Shanghai JiaoTong University School of Medicine; Shanghai China
| | - Min Dai
- Department of Orthopaedics; The First Affiliated Hospital; Nanchang University; Nanchang Jiangxi Province China
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Vrecl M, Babnik M, Sepčić K, Žužek MC, Maček P, Diacci U, Frangež R. Effect of the ostreolysin A/pleurotolysin B pore-forming complex on intracellular Ca2+ activity in the vascular smooth muscle cell line A10. Toxicol In Vitro 2015; 29:2015-21. [PMID: 26320834 DOI: 10.1016/j.tiv.2015.08.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 08/14/2015] [Accepted: 08/26/2015] [Indexed: 02/01/2023]
Abstract
Ostreolysin A/pleurotolysin B (OlyA/PlyB) is a binary pore-forming protein complex that produces a rapid cardiorespiratory arrest. Increased tonus of the coronary vascular wall produced by OlyA/PlyB may lead to ischemia, arrhythmias, the hypoxic injury of cardiomyocytes and cardiotoxicity. We evaluated the effects of OlyA/PlyB in cultured vascular smooth muscle A10 cells. Fluorometric measurements using the Ca(2+) indicator Fluo-4 AM and Fura-2 AM revealed that nanomolar concentrations of OlyA/PlyB increased the intracellular Ca(2+) activity [Ca(2+)]i in A10 cells. This effect was absent in a Ca(2+)-free medium, indicating that OlyA/PlyB-induced [Ca(2+)]i increase was dependent on Ca(2+) influx into cells. The increase in [Ca(2+)]i by OlyA/PlyB was partially prevented by: i) the calcium channel blockers verapamil and La(3+), ii) the inhibitor of the sodium-calcium exchanger (NCX) benzamil, and iii) the iso-osmotic replacement of NaCl by sucrose. The pre-treatment of cells with the Ca(2+)-ATPase inhibitor thapsigargin reduced the [Ca(2+)]i increase evoked by OlyA/PlyB, whereas the plasma membrane depolarization with high K(+) in the medium did not prevent OlyA/PlyB-induced [Ca(2+)]i. In summary, our data could suggest that the OlyA/PlyB-induced increase in [Ca(2+)]i is due to an influx of Ca(2+) through a variety of co-existing plasma membrane Ca(2+)-permeable channels, Ca(2+) entry through non-selective ion permeable pores formed de novo by OlyA/PlyB in the plasma membrane and calcium-induced intracellular Ca(2+) release, altogether leading to disturbed Ca(2+) homeostasis in A10 cells.
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Affiliation(s)
- Milka Vrecl
- Veterinary Faculty, Institute of Anatomy, Histology and Embryology, Gerbičeva 60, SI-1000 Ljubljana, Slovenia
| | - Monika Babnik
- Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia
| | - Kristina Sepčić
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Monika C Žužek
- Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia
| | - Peter Maček
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Uroš Diacci
- Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia
| | - Robert Frangež
- Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, 1000 Ljubljana, Slovenia.
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Abstract
During his long and illustrious career that now spans over 50 years David Triggle has had a major impact on biomedical science that can be linked to his research spanning the disciplines of chemistry and biology. Capitalizing on his undergraduate and postgraduate education in chemistry David's early research explored the pharmacology of adreno- and muscarinic receptors ultimately leading to studies of the cellular signaling processes that mediated the effects of receptor activation particularly with respect to calcium homeostasis. David's contributions to the identification and development of calcium channel antagonists resulted in benefits beyond the impact of such drugs in the treatment of diseases of the cardiovascular system. During David's 50+ year career many technological changes have occurred that have affected how research is conducted, funded and published and how its impact evaluated. Not all of these technological advances are necessarily positive and it is valuable to reflect on the long lasting impact of David's accomplishments with reference to such changes.
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Affiliation(s)
- Chris R Triggle
- Departments of Medical Education and Pharmacology, Weill Cornell Medical College in Qatar, Qatar Foundation, Education City, P.O. Box 24144, Doha, Qatar.
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18
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Voltage-gated calcium channels: Determinants of channel function and modulation by inorganic cations. Prog Neurobiol 2015; 129:1-36. [PMID: 25817891 DOI: 10.1016/j.pneurobio.2014.12.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 12/15/2014] [Accepted: 12/27/2014] [Indexed: 11/20/2022]
Abstract
Voltage-gated calcium channels (VGCCs) represent a key link between electrical signals and non-electrical processes, such as contraction, secretion and transcription. Evolved to achieve high rates of Ca(2+)-selective flux, they possess an elaborate mechanism for selection of Ca(2+) over foreign ions. It has been convincingly linked to competitive binding in the pore, but the fundamental question of how this is reconcilable with high rates of Ca(2+) transfer remains unanswered. By virtue of their similarity to Ca(2+), polyvalent cations can interfere with the function of VGCCs and have proven instrumental in probing the mechanisms underlying selective permeation. Recent emergence of crystallographic data on a set of Ca(2+)-selective model channels provides a structural framework for permeation in VGCCs, and warrants a reconsideration of their diverse modulation by polyvalent cations, which can be roughly separated into three general mechanisms: (I) long-range interactions with charged regions on the surface, affecting the local potential sensed by the channel or influencing voltage-sensor movement by repulsive forces (electrostatic effects), (II) short-range interactions with sites in the ion-conducting pathway, leading to physical obstruction of the channel (pore block), and in some cases (III) short-range interactions with extracellular binding sites, leading to non-electrostatic modifications of channel gating (allosteric effects). These effects, together with the underlying molecular modifications, provide valuable insights into the function of VGCCs, and have important physiological and pathophysiological implications. Allosteric suppression of some of the pore-forming Cavα1-subunits (Cav2.3, Cav3.2) by Zn(2+) and Cu(2+) may play a major role for the regulation of excitability by endogenous transition metal ions. The fact that these ions can often traverse VGCCs can contribute to the detrimental intracellular accumulation of metal ions following excessive release of endogenous Cu(2+) and Zn(2+) or exposure to non-physiological toxic metal ions.
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19
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Treinys R, Kaselis A, Jover E, Bagnard D, Šatkauskas S. R-type calcium channels are crucial for semaphorin 3A-induced DRG axon growth cone collapse. PLoS One 2014; 9:e102357. [PMID: 25032951 PMCID: PMC4102519 DOI: 10.1371/journal.pone.0102357] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 06/18/2014] [Indexed: 12/20/2022] Open
Abstract
Semaphorin 3A (Sema3A) is a secreted protein involved in axon path-finding during nervous system development. Calcium signaling plays an important role during axonal growth in response to different guidance cues; however it remains unclear whether this is also the case for Sema3A. In this study we used intracellular calcium imaging to figure out whether Sema3A-induced growth cone collapse is a Ca2+ dependent process. Intracellular Ca2+ imaging results using Fura-2 AM showed Ca2+ increase in E15 mice dorsal root ganglia neurons upon Sema3A treatment. Consequently we analyzed Sema3A effect on growth cones after blocking or modifying intracellular and extracellular Ca2+ channels that are expressed in E15 mouse embryos. Our results demonstrate that Sema3A increased growth cone collapse rate is blocked by the non-selective R- and T- type Ca2+ channel blocker NiCl2 and by the selective R-type Ca2+ channel blocker SNX482. These Ca2+ channel blockers consistently decreased the Sema3A-induced intracellular Ca2+ concentration elevation. Overall, our results demonstrate that Sema3A-induced growth cone collapses are intimately related with increase in intracellular calcium concentration mediated by R-type calcium channels.
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Affiliation(s)
- Rimantas Treinys
- Biophysical Research Group, Biology department, Vytautas Magnus University, Kaunas, Lithuania
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Andrius Kaselis
- Biophysical Research Group, Biology department, Vytautas Magnus University, Kaunas, Lithuania
| | - Emmanuel Jover
- INCI – UPR-CNRS 3212, Neurotransmission et sécrétion neuroendocrine, Strasbourg, France
| | - Dominique Bagnard
- INSERM U1109, MN3t lab, Labex Medalis, University of Strasbourg, Strasbourg, France
| | - Saulius Šatkauskas
- Biophysical Research Group, Biology department, Vytautas Magnus University, Kaunas, Lithuania
- * E-mail:
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Fortunato MJ, Ball CE, Hollinger K, Patel NB, Modi JN, Rajasekaran V, Nonneman DJ, Ross JW, Kennedy EJ, Selsby JT, Beedle AM. Development of rabbit monoclonal antibodies for detection of alpha-dystroglycan in normal and dystrophic tissue. PLoS One 2014; 9:e97567. [PMID: 24824861 PMCID: PMC4019581 DOI: 10.1371/journal.pone.0097567] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 04/21/2014] [Indexed: 12/22/2022] Open
Abstract
Alpha-dystroglycan requires a rare O-mannose glycan modification to form its binding epitope for extracellular matrix proteins such as laminin. This functional glycan is disrupted in a cohort of muscular dystrophies, the secondary dystroglycanopathies, and is abnormal in some metastatic cancers. The most commonly used reagent for detection of alpha-dystroglycan is mouse monoclonal antibody IIH6, but it requires the functional O-mannose structure for recognition. Therefore, the ability to detect alpha-dystroglycan protein in disease states where it lacks the full O-mannose glycan has been limited. To overcome this hurdle, rabbit monoclonal antibodies against the alpha-dystroglycan C-terminus were generated. The new antibodies, named 5–2, 29–5, and 45–3, detect alpha-dystroglycan from mouse, rat and pig skeletal muscle by Western blot and immunofluorescence. In a mouse model of fukutin-deficient dystroglycanopathy, all antibodies detected low molecular weight alpha-dystroglycan in disease samples demonstrating a loss of functional glycosylation. Alternately, in a porcine model of Becker muscular dystrophy, relative abundance of alpha-dystroglycan was decreased, consistent with a reduction in expression of the dystrophin-glycoprotein complex in affected muscle. Therefore, these new rabbit monoclonal antibodies are suitable reagents for alpha-dystroglycan core protein detection and will enhance dystroglycan-related studies.
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Affiliation(s)
- Marisa J. Fortunato
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Charlotte E. Ball
- Center for Undergraduate Research, University of Georgia, Athens, Georgia, United States of America
| | - Katrin Hollinger
- Department of Animal Science, Iowa State University, Ames, Iowa, United States of America
| | - Niraj B. Patel
- Center for Undergraduate Research, University of Georgia, Athens, Georgia, United States of America
| | - Jill N. Modi
- Center for Undergraduate Research, University of Georgia, Athens, Georgia, United States of America
| | - Vedika Rajasekaran
- Center for Undergraduate Research, University of Georgia, Athens, Georgia, United States of America
| | - Dan J. Nonneman
- United States Department of Agriculture Agricultural Research Service, United States Meat Animal Research Center, Clay Center, Nebraska, United States of America
| | - Jason W. Ross
- Department of Animal Science, Iowa State University, Ames, Iowa, United States of America
| | - Eileen J. Kennedy
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Joshua T. Selsby
- Department of Animal Science, Iowa State University, Ames, Iowa, United States of America
| | - Aaron M. Beedle
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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21
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Bladen C, Hamid J, Souza IA, Zamponi GW. Block of T-type calcium channels by protoxins I and II. Mol Brain 2014; 7:36. [PMID: 24886690 PMCID: PMC4030284 DOI: 10.1186/1756-6606-7-36] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 05/05/2014] [Indexed: 01/08/2023] Open
Abstract
Background Low-voltage-activated (T-type) calcium channels play a crucial role in a number of physiological processes, including neuronal and cardiac pacemaker activity and nociception. Therefore, finding specific modulators and/or blockers of T-type channels has become an important field of drug discovery. One characteristic of T-type calcium channels is that they share several structural similarities with voltage-gated sodium channels (VGSCs). We therefore hypothesized that binding sites for certain sodium channel blocking peptide toxins may be present in T-type calcium channels. Findings The sodium channel blocker ProTx I tonically blocked native and transiently expressed T-type channels in the sub- to low micro molar range with at least a ten-fold selectivity for the T-type calcium channel hCav3.1 over hCav3.3, and more than one hundred fold selectivity over hCav3.2. Using chimeras of hCav3.1 and hCav3.3, we determined that the domain IV region of hCav3.1 is a major determinant of toxin affinity, with a minor contribution from domain II. Further analysis revealed several residues in a highly conserved region between T-type and sodium channels that may correspond to toxin binding sites. Mutagenesis of several of these residues on an individual basis, however, did not alter the blocking effects of the toxin. ProTx II on the other hand preferentially blocked hCav3.2 and significantly shifted the steady state inactivation of this channel. Conclusions ProTx I blocks hCav3.1 both selectively and with high affinity. Domain IV appears to play a major role in this selectivity with some contribution from domain II. Given the structural similarities between sodium and T-type calcium channels and the apparent conservation in toxin binding sites, these data could provide insights into the development and synthesis of novel T-type channel antagonists.
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Affiliation(s)
| | | | | | - Gerald W Zamponi
- Department of Physiology & Pharmacology, Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive, Calgary, NW, Canada.
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Ebihara L, Korzyukov Y, Kothari S, Tong JJ. Cx46 hemichannels contribute to the sodium leak conductance in lens fiber cells. Am J Physiol Cell Physiol 2014; 306:C506-13. [PMID: 24380846 PMCID: PMC4042622 DOI: 10.1152/ajpcell.00353.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 12/24/2013] [Indexed: 11/22/2022]
Abstract
The lens is proposed to have an internal microcirculation system consisting of continuously circulating ionic fluxes that play an essential role in maintaining lens transparency. One of the key components of this system is the sodium leak conductance. Here we investigate the contribution of Cx46 hemichannels to the basal membrane permeability of peripheral fiber cells isolated from transgenic mouse lenses lacking Cx50 or both Cx50 and Cx46 (dKO) using the whole cell patch-clamp technique. Our results show that Cx46 hemichannels were largely closed at a resting voltage of -60 mV in the presence of millimolar divalent cation concentrations. However, even though the vast majority of these channels were closed at -60 mV, a small, persistent, inward current could still be detected. This current could be mostly blocked by exposure to 1 mM La(3+) and was not observed in fiber cells isolated from dKO mouse lenses suggesting that it was due to Cx46 hemichannels. In addition, Cx50(-/-) fiber cells showed increased open channel noise and a depolarized resting potential compared with dKO fiber cells. Exposure of Cx50(-/-) fiber cells to La(3+) hyperpolarized the resting potential to -58 mV, which is similar to the value of resting potential measured in dKO fiber and significantly reduced the open channel noise. In conclusion, these results suggest that Cx46 hemichannels may contribute to the sodium leak conductance in lens fiber cells.
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Affiliation(s)
- Lisa Ebihara
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois
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Models of calcium permeation through T-type channels. Pflugers Arch 2014; 466:635-44. [DOI: 10.1007/s00424-013-1437-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 12/27/2013] [Accepted: 12/28/2013] [Indexed: 12/19/2022]
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24
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Bladen C, Gündüz MG, Şimşek R, Şafak C, Zamponi GW. Synthesis and Evaluation of 1,4-Dihydropyridine Derivatives with Calcium Channel Blocking Activity. Pflugers Arch 2013; 466:1355-63. [DOI: 10.1007/s00424-013-1376-z] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 10/01/2013] [Accepted: 10/01/2013] [Indexed: 01/29/2023]
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25
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Morgan PJ, Hübner R, Rolfs A, Frech MJ. Spontaneous Calcium Transients in Human Neural Progenitor Cells Mediated by Transient Receptor Potential Channels. Stem Cells Dev 2013; 22:2477-86. [DOI: 10.1089/scd.2013.0061] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Peter J. Morgan
- University of Rostock, Albrecht-Kossel-Institute for Neuroregeneration, Rostock, Germany
| | - Rayk Hübner
- University of Rostock, Albrecht-Kossel-Institute for Neuroregeneration, Rostock, Germany
| | - Arndt Rolfs
- University of Rostock, Albrecht-Kossel-Institute for Neuroregeneration, Rostock, Germany
| | - Moritz J. Frech
- University of Rostock, Albrecht-Kossel-Institute for Neuroregeneration, Rostock, Germany
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Citta A, Folda A, Scutari G, Cesaro L, Bindoli A, Rigobello MP. Inhibition of thioredoxin reductase by lanthanum chloride. J Inorg Biochem 2012; 117:18-24. [DOI: 10.1016/j.jinorgbio.2012.08.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 08/22/2012] [Accepted: 08/24/2012] [Indexed: 11/30/2022]
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Lopin KV, Gray IP, Obejero-Paz CA, Thévenod F, Jones SW. Fe²⁺ block and permeation of CaV3.1 (α1G) T-type calcium channels: candidate mechanism for non-transferrin-mediated Fe²⁺ influx. Mol Pharmacol 2012; 82:1194-204. [PMID: 22973060 DOI: 10.1124/mol.112.080184] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Iron is a biologically essential metal, but excess iron can cause damage to the cardiovascular and nervous systems. We examined the effects of extracellular Fe²⁺ on permeation and gating of Ca(V)3.1 channels stably transfected in HEK293 cells, by using whole-cell recording. Precautions were taken to maintain iron in the Fe²⁺ state (e.g., use of extracellular ascorbate). With the use of instantaneous I-V currents (measured after strong depolarization) to isolate the effects on permeation, extracellular Fe²⁺ rapidly blocked currents with 2 mM extracellular Ca²⁺ in a voltage-dependent manner, as described by a Woodhull model with K(D) = 2.5 mM at 0 mV and apparent electrical distance δ = 0.17. Extracellular Fe²⁺ also shifted activation to more-depolarized voltages (by ∼10 mV with 1.8 mM extracellular Fe²⁺) somewhat more strongly than did extracellular Ca²⁺ or Mg²⁺, which is consistent with a Gouy-Chapman-Stern model with surface charge density σ = 1 e(-)/98 Ų and K(Fe) = 4.5 M⁻¹ for extracellular Fe²⁺. In the absence of extracellular Ca²⁺ (and with extracellular Na⁺ replaced by TEA), Fe²⁺ carried detectable, whole-cell, inward currents at millimolar concentrations (73 ± 7 pA at -60 mV with 10 mM extracellular Fe²⁺). With a two-site/three-barrier Eyring model for permeation of Ca(V)3.1 channels, we estimated a transport rate for Fe²⁺ of ∼20 ions/s for each open channel at -60 mV and pH 7.2, with 1 μM extracellular Fe²⁺ (with 2 mM extracellular Ca²⁺). Because Ca(V)3.1 channels exhibit a significant "window current" at that voltage (open probability, ∼1%), Ca(V)3.1 channels represent a likely pathway for Fe²⁺ entry into cells with clinically relevant concentrations of extracellular Fe²⁺.
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Affiliation(s)
- Kyle V Lopin
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA
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Bladen C, Zamponi GW. Common Mechanisms of Drug Interactions with Sodium and T-Type Calcium Channels. Mol Pharmacol 2012; 82:481-7. [DOI: 10.1124/mol.112.079715] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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Lembrechts R, Brouns I, Schnorbusch K, Pintelon I, Timmermans JP, Adriaensen D. Neuroepithelial bodies as mechanotransducers in the intrapulmonary airway epithelium: involvement of TRPC5. Am J Respir Cell Mol Biol 2012; 47:315-23. [PMID: 22461428 DOI: 10.1165/rcmb.2012-0068oc] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In rodent lungs, a major part of the myelinated vagal airway afferents selectively contacts pulmonary neuroepithelial bodies (NEBs). Because most myelinated vagal airway afferents concern physiologically characterized mechanoreceptors, the present study aimed at unraveling the potential involvement of NEB cells in transducing mechanosensory information from the airways to the central nervous system. Physiological studies were performed using confocal Ca(2+) imaging of airway epithelium in murine lung slices. Mechanical stimulation by short-term application of a mild hypoosmotic solution (230 mosmol) resulted in a selective, fast, reversible, and reproducible Ca(2+) rise in NEB cells. Other airway epithelial cells could only be activated using more severe hypoosmotic stimuli (< 200 mosmol). NEB cells selectively expressed the Ca(2+)-permeable osmo- and mechanosensitive transient receptor potential canonical channel 5 (TRPC5) in their apical membranes, whereas immunoreactivity for TRP vanilloid-4 and TRP melastatin-3 was abundant in virtually all other airway epithelial cells. Hypoosmotic activation of NEB cells was prevented by GsMTx-4, an inhibitor of mechanosensitive ion channels, and by SKF96365, an inhibitor of TRPC channels. Short application of gadolinium, reported to activate TRPC5 channels, evoked a transient Ca(2+) rise in NEB cells. Osmomechanical activation of NEB cells gave rise to a typical delayed activation of Clara-like cells due to the release of ATP from NEB cells. Because ATP may activate the NEB-associated P2X(2/3) ATP receptor expressing myelinated vagal afferents, the current observations strongly suggest that pulmonary NEB cells are fully equipped to initiate mechanosensory signal transduction to the central nervous system via a purinergic signaling pathway.
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Affiliation(s)
- Robrecht Lembrechts
- Laboratory of Cell Biology and Histology, Department of Veterinary Sciences, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium
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Zhang Z, Wang J, Li J, Xu S. Telomerase-mediated apoptosis of chicken lymphoblastoid tumor cell line by lanthanum chloride. Biol Trace Elem Res 2011; 144:657-67. [PMID: 21448564 DOI: 10.1007/s12011-011-9027-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 03/08/2011] [Indexed: 11/25/2022]
Abstract
To investigate the biological effects of lanthanum on chicken lymphoid tumors, cultures of the MDCC-MSB1 chicken lymphoblastoid cell line were treated with 2.5 mM lanthanum chloride for 2 days at 12-h intervals. The apoptotic cells were detected using the TdT-mediated dUTP nick end labeling assay and flow cytometer analysis. The telomerase activity and the chTERT mRNA expression levels of the MDCC-MSB1 cells were examined. The results showed that MDCC-MSB1 cell apoptosis occurred after incubation for 12 to 48 h induced by 2.5 mM LaCl(3). Consistent with the apoptosis results, telomerase activities in LaCl(3)-treated cells significantly decreased (P < 0.05) compared with 0 h group. Furthermore, the transcription of chTERT gene in MDCC-MSB1 cell was significantly inhibited in LaCl(3) treatment group (P < 0.05). These results suggest that the decrease of the chTERT transcription and telomerase activity play an important role in the La-induced apoptosis in chicken lymphoid tumor.
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Affiliation(s)
- Ziwei Zhang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, People's Republic of China.
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You H, Gadotti VM, Petrov RR, Zamponi GW, Diaz P. Functional characterization and analgesic effects of mixed cannabinoid receptor/T-type channel ligands. Mol Pain 2011; 7:89. [PMID: 22093952 PMCID: PMC3250956 DOI: 10.1186/1744-8069-7-89] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 11/17/2011] [Indexed: 02/06/2023] Open
Abstract
Background Both T-type calcium channels and cannabinoid receptors modulate signalling in the primary afferent pain pathway. Here, we investigate the analgesics activities of a series of novel cannabinoid receptor ligands with T-type calcium channel blocking activity. Results Novel compounds were characterized in radioligand binding assays and in vitro functional assays at human and rat CB1 and CB2 receptors. The inhibitory effects of these compounds on transient expressed human T-type calcium channels were examined in tsA-201 cells using standard whole-cell voltage clamp techniques, and their analgesic effects in response to various administration routes (intrathecally, intraplantarly, intraperitoneally) assessed in the formalin model. A series of compounds were synthesized and evaluated for channel and receptor activity. Compound NMP-7 acted as non-selective CB1/CB2 agonist while NMP4 was found to be a CB1 partial agonist and CB2 inverse agonist. Furthermore, NMP-144 behaved as a selective CB2 inverse agonist. All of these three compounds completely inhibited peak Cav3.2 currents with IC50 values in the low micromolar range. All compounds mediated analgesic effects in the formalin model, but depending on the route of administration, could differentially affect phase 1 and phase 2 of the formalin response. Conclusions Our results reveal that a set of novel cannabinioid receptor ligands potently inhibit T-type calcium channels and show analgesic effects in vivo. Our findings suggest possible novel means of mediating pain relief through mixed T-type/cannabinoid receptor ligands.
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Affiliation(s)
- Haitao You
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, Canada
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Malasics A, Boda D, Valiskó M, Henderson D, Gillespie D. Simulations of calcium channel block by trivalent cations: Gd(3+) competes with permeant ions for the selectivity filter. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:2013-21. [PMID: 20696128 DOI: 10.1016/j.bbamem.2010.08.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 07/29/2010] [Accepted: 08/02/2010] [Indexed: 10/19/2022]
Abstract
Current through L-type calcium channels (Ca(V)1.2 or dihydropyridine receptor) can be blocked by micromolar concentrations of trivalent cations like the lanthanide gadolinium (Gd(3+)). It has been proposed that trivalent block is due to ions competing for a binding site in both the open and closed configuration, but possibly with different trivalent affinities. Here, we corroborate this general view of trivalent block by computing conductance of a model L-type calcium channel. The model qualitatively reproduces the Gd(3+) concentration dependence and the effect that substantially more Gd(3+) is required to produce similar block in the presence of Sr(2+) (compared to Ba(2+)) and even more in the presence of Ca(2+). Trivalent block is explained in this model by cations binding in the selectivity filter with the charge/space competition mechanism. This is the same mechanism that in the model channel governs other selectivity properties. Specifically, selectivity is determined by the combination of ions that most effectively screen the negative glutamates of the protein while finding space in the midst of the closely packed carboxylate groups of the glutamate residues.
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Affiliation(s)
- Attila Malasics
- Department of Physical Chemistry, University of Pannonia, Veszprém, Hungary
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Charles SM, Zhang L, Cipolla MJ, Buchholz JN, Pearce WJ. Roles of cytosolic Ca2+ concentration and myofilament Ca2+ sensitization in age-dependent cerebrovascular myogenic tone. Am J Physiol Heart Circ Physiol 2010; 299:H1034-44. [PMID: 20639216 DOI: 10.1152/ajpheart.00214.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In light of evidence that immature arteries contain a higher proportion of noncontractile smooth muscle cells than found in fully differentiated mature arteries, the present study explored the hypothesis that age-related differences in the smooth muscle phenotype contribute to age-related differences in contractility. Because Ca(2+) handling differs markedly between contractile and noncontractile smooth muscle, the present study specifically tested the hypothesis that the relative contributions of Ca(2+) influx and myofilament sensitization to myogenic tone are upregulated, whereas Ca(2+) release is downregulated, in immature [14 days postnatal (P14)] compared with mature (6 mo old) rat middle cerebral arteries (MCAs). Myofilament Ca(2+) sensitivity measured in β-escin-permeabilized arteries increased with pressure in P14 but not adult MCAs. Cyclopiazonic acid (an inhibitor of Ca(2+) release from the sarcoplasmic reticulum) increased diameter and reduced Ca(2+) in adult MCAs but increased diameter with no apparent change in Ca(2+) in P14 MCAs. La(3+) (Ca(2+) influx inhibitor) increased diameter and decreased Ca(2+) in adult MCAs, but in P14 MCAs, La(3+) increased diameter with no apparent change in Ca(2+). After treatment with both La(3+) and CPA, diameters were passive in both adult and P14 MCAs, but Ca(2+) was decreased only in adult MCAs. To quantify the fraction of smooth muscle cells in the fully differentiated contractile phenotype, extents of colocalization between smooth muscle α-actin and SM2 myosin heavy chain were determined and found to be at least twofold greater in adult than pup MCAs. These data suggest that compared with adult MCAs, pup MCAs contain a greater proportion of noncontractile smooth muscle and, as a consequence, rely more on myofilament Ca(2+) sensitization and Ca(2+) influx to maintain myogenic reactivity. The inability of La(3+) to reduce cytosolic Ca(2+) in the pup MCA appears due to La(3+)-insensitive noncontractile smooth muscle cells, which contribute to the spatially averaged measurements of Ca(2+) but not contraction.
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Affiliation(s)
- Shelton M Charles
- Center for Perinatal Biology, Division of Physiology, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
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Osterstock G, Escobar P, Mitutsova V, Gouty-Colomer LA, Fontanaud P, Molino F, Fehrentz JA, Carmignac D, Martinez J, Guerineau NC, Robinson ICAF, Mollard P, Méry PF. Ghrelin stimulation of growth hormone-releasing hormone neurons is direct in the arcuate nucleus. PLoS One 2010; 5:e9159. [PMID: 20161791 PMCID: PMC2820089 DOI: 10.1371/journal.pone.0009159] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Accepted: 01/08/2010] [Indexed: 11/26/2022] Open
Abstract
Background Ghrelin targets the arcuate nucleus, from where growth hormone releasing hormone (GHRH) neurones trigger GH secretion. This hypothalamic nucleus also contains neuropeptide Y (NPY) neurons which play a master role in the effect of ghrelin on feeding. Interestingly, connections between NPY and GHRH neurons have been reported, leading to the hypothesis that the GH axis and the feeding circuits might be co-regulated by ghrelin. Principal Findings Here, we show that ghrelin stimulates the firing rate of identified GHRH neurons, in transgenic GHRH-GFP mice. This stimulation is prevented by growth hormone secretagogue receptor-1 antagonism as well as by U-73122, a phospholipase C inhibitor and by calcium channels blockers. The effect of ghrelin does not require synaptic transmission, as it is not antagonized by γ-aminobutyric acid, glutamate and NPY receptor antagonists. In addition, this hypothalamic effect of ghrelin is independent of somatostatin, the inhibitor of the GH axis, since it is also found in somatostatin knockout mice. Indeed, ghrelin does not modify synaptic currents of GHRH neurons. However, ghrelin exerts a strong and direct depolarizing effect on GHRH neurons, which supports their increased firing rate. Conclusion Thus, GHRH neurons are a specific target for ghrelin within the brain, and not activated secondary to altered activity in feeding circuits. These results support the view that ghrelin related therapeutic approaches could be directed separately towards GH deficiency or feeding disorders.
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Affiliation(s)
- Guillaume Osterstock
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Pauline Escobar
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Violeta Mitutsova
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Laurie-Anne Gouty-Colomer
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Pierre Fontanaud
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - François Molino
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Jean-Alain Fehrentz
- Université Montpellier 1, 2, Montpellier, France
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron, Montpellier, France
| | - Danielle Carmignac
- Division of Molecular Neuroendocrinology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom
| | - Jean Martinez
- Université Montpellier 1, 2, Montpellier, France
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron, Montpellier, France
| | - Nathalie C. Guerineau
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Iain C. A. F. Robinson
- Division of Molecular Neuroendocrinology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom
| | - Patrice Mollard
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Pierre-François Méry
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
- * E-mail:
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Tadross MR, Ben Johny M, Yue DT. Molecular endpoints of Ca2+/calmodulin- and voltage-dependent inactivation of Ca(v)1.3 channels. ACTA ACUST UNITED AC 2010; 135:197-215. [PMID: 20142517 PMCID: PMC2828906 DOI: 10.1085/jgp.200910308] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Ca2+/calmodulin- and voltage-dependent inactivation (CDI and VDI) comprise vital prototypes of Ca2+ channel modulation, rich with biological consequences. Although the events initiating CDI and VDI are known, their downstream mechanisms have eluded consensus. Competing proposals include hinged-lid occlusion of channels, selectivity filter collapse, and allosteric inhibition of the activation gate. Here, novel theory predicts that perturbations of channel activation should alter inactivation in distinctive ways, depending on which hypothesis holds true. Thus, we systematically mutate the activation gate, formed by all S6 segments within CaV1.3. These channels feature robust baseline CDI, and the resulting mutant library exhibits significant diversity of activation, CDI, and VDI. For CDI, a clear and previously unreported pattern emerges: activation-enhancing mutations proportionately weaken inactivation. This outcome substantiates an allosteric CDI mechanism. For VDI, the data implicate a “hinged lid–shield” mechanism, similar to a hinged-lid process, with a previously unrecognized feature. Namely, we detect a “shield” in CaV1.3 channels that is specialized to repel lid closure. These findings reveal long-sought downstream mechanisms of inactivation and may furnish a framework for the understanding of Ca2+ channelopathies involving S6 mutations.
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Affiliation(s)
- Michael R Tadross
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Acid-evoked Ca2+ signalling in rat sensory neurones: effects of anoxia and aglycaemia. Pflugers Arch 2010; 459:159-81. [PMID: 19806360 PMCID: PMC2765625 DOI: 10.1007/s00424-009-0715-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 07/30/2009] [Accepted: 08/14/2009] [Indexed: 12/11/2022]
Abstract
Ischaemia excites sensory neurones (generating pain) and promotes calcitonin gene-related peptide release from nerve endings. Acidosis is thought to play a key role in mediating excitation via the activation of proton-sensitive cation channels. In this study, we investigated the effects of acidosis upon Ca2+ signalling in sensory neurones from rat dorsal root ganglia. Both hypercapnic (pHo 6.8) and metabolic–hypercapnic (pHo 6.2) acidosis caused a biphasic increase in cytosolic calcium concentration ([Ca2+]i). This comprised a brief Ca2+ transient (half-time approximately 30 s) caused by Ca2+ influx followed by a sustained rise in [Ca2+]i due to Ca2+ release from caffeine and cyclopiazonic acid-sensitive internal stores. Acid-evoked Ca2+ influx was unaffected by voltage-gated Ca2+-channel inhibition with nickel and acid sensing ion channel (ASIC) inhibition with amiloride but was blocked by inhibition of transient receptor potential vanilloid receptors (TRPV1) with (E)-3-(4-t-butylphenyl)-N-(2,3-dihydrobenzo[b][1,4] dioxin-6-yl)acrylamide (AMG 9810; 1 μM) and N-(4-tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl) tetrahydropryazine-1(2H)-carbox-amide (BCTC; 1 μM). Combining acidosis with anoxia and aglycaemia increased the amplitude of both phases of Ca2+ elevation and prolonged the Ca2+ transient. The Ca2+ transient evoked by combined acidosis, aglycaemia and anoxia was also substantially blocked by AMG 9810 and BCTC and, to a lesser extent, by amiloride. In summary, the principle mechanisms mediating increase in [Ca2+]i in response to acidosis are a brief Ca2+ influx through TRPV1 followed by sustained Ca2+ release from internal stores. These effects are potentiated by anoxia and aglycaemia, conditions also prevalent in ischaemia. The effects of anoxia and aglycaemia are suggested to be largely due to the inhibition of Ca2+-clearance mechanisms and possible increase in the role of ASICs.
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Evans RM, You H, Hameed S, Altier C, Mezghrani A, Bourinet E, Zamponi GW. Heterodimerization of ORL1 and opioid receptors and its consequences for N-type calcium channel regulation. J Biol Chem 2010; 285:1032-40. [PMID: 19887453 PMCID: PMC2801230 DOI: 10.1074/jbc.m109.040634] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 10/22/2009] [Indexed: 01/15/2023] Open
Abstract
We have investigated the heterodimerization of ORL1 receptors and classical members of the opioid receptor family. All three classes of opioid receptors could be co-immunoprecipitated with ORL1 receptors from both transfected tsA-201 cell lysate and rat dorsal root ganglia lysate, suggesting that these receptors can form heterodimers. Consistent with this hypothesis, in cells expressing either one of the opioid receptors together with ORL1, prolonged ORL1 receptor activation via nociceptin application resulted in internalization of the opioid receptors. Conversely, mu-, delta-, and kappa-opioid receptor activation with the appropriate ligands triggered the internalization of ORL1. The mu-opioid receptor/ORL1 receptor heterodimers were shown to associate with N-type calcium channels, with activation of mu-opioid receptors triggering N-type channel internalization, but only in the presence of ORL1. Furthermore, the formation of opioid receptor/ORL1 receptor heterodimers attenuated the ORL1 receptor-mediated inhibition of N-type channels, in part because of constitutive opioid receptor activity. Collectively, our data support the existence of heterodimers between ORL1 and classical opioid receptors, with profound implications for effectors such as N-type calcium channels.
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Affiliation(s)
- Rhian M. Evans
- From the Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary T2N 4N1, Canada and
| | - Haitao You
- From the Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary T2N 4N1, Canada and
| | - Shahid Hameed
- From the Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary T2N 4N1, Canada and
| | - Christophe Altier
- From the Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary T2N 4N1, Canada and
| | | | - Emmanuel Bourinet
- the Institut de Génomique Fonctionnelle, CNRS, 34094 Montpellier, France
| | - Gerald W. Zamponi
- From the Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary T2N 4N1, Canada and
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You H, Altier C, Zamponi GW. CCR2 Receptor Ligands Inhibit Cav3.2 T-Type Calcium Channels. Mol Pharmacol 2009; 77:211-7. [DOI: 10.1124/mol.109.059022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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Transient receptor potential canonical 5 channels activate Ca2+/calmodulin kinase Igamma to promote axon formation in hippocampal neurons. J Neurosci 2009; 29:9794-808. [PMID: 19657032 DOI: 10.1523/jneurosci.1544-09.2009] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Functionality of neurons is dependent on their compartmentalized polarization of dendrites and an axon. The rapid and selective outgrowth of one neurite, relative to the others, to form the axon is critical in initiating neuronal polarity. Axonogenesis is regulated in part by an optimal intracellular calcium concentration. Our investigation of Ca(2+)-signaling pathways involved in axon formation using cultured hippocampal neurons demonstrates a role for Ca(2+)/calmodulin kinase kinase (CaMKK) and its downstream target Ca(2+)/calmodulin kinase I (CaMKI). Expression of constitutively active CaMKI induced formation of multiple axons, whereas blocking CaMKK or CaMKI activity with pharmacological, dominant-negative, or short hairpin RNA (shRNA) methods significantly inhibited axon formation. CaMKK signals via the gamma-isoform of CaMKI as shRNA to CaMKIgamma, but not the other CaMKI isoforms, inhibited axon formation. Furthermore, overexpression of wild-type CaMKIgamma, but not a mutant incapable of membrane association, accelerated the rate of axon formation. Pharmacological or small interfering RNA inhibition of transient receptor potential canonical 5 (TRPC5) channels, which are present in developing axonal growth cones, suppressed CaMKK-mediated activation of CaMKIgamma as well as axon formation. We demonstrate using biochemical fractionation and immunocytochemistry that CaMKIgamma and TRPC5 colocalize to lipid rafts. These results are consistent with a model in which highly localized calcium influx through the TRPC5 channels activates CaMKK and CaMKIgamma, which subsequently promote axon formation.
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Jakubek LM, Marangoudakis S, Raingo J, Liu X, Lipscombe D, Hurt RH. The inhibition of neuronal calcium ion channels by trace levels of yttrium released from carbon nanotubes. Biomaterials 2009; 30:6351-7. [PMID: 19698989 DOI: 10.1016/j.biomaterials.2009.08.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 08/05/2009] [Indexed: 11/28/2022]
Abstract
Carbon nanotubes (CNTs) are used with increasing frequency in neuroengineering applications. CNT scaffolds are used to transmit electrical stimulation to cultured neurons and to control outgrowth and branching patterns of neurites. CNTs have been reported to disrupt normal neuronal function including alterations in endocytotic capability and inhibition of ion channels. Calcium ion channels regulate numerous neuronal and cellular functions including endo and exocytosis, neurite outgrowth, and gene expression. Strong CNT interactions with neuronal calcium ion channels would have profound biological implications. Here we show that physiological solutions containing CNTs inhibit neuronal voltage-gated calcium ion channels in a dose-dependent and CNT sample-dependent manner with IC50 as low as 1.2 microg/ml. Importantly, we demonstrate that the inhibitory activity does not involve tubular graphene as previously reported, but rather very low concentrations of soluble yttrium released from the nanotube growth catalyst. Cationic yttrium potently inhibits calcium ion channel function with an inhibitory efficacy, IC50, of 0.07 ppm w/w. Because of this potency, unpurified and even some reportedly "purified" CNT samples contain sufficient bioavailable yttrium to inhibit channel function. Our results have important implications for emerging nano-neurotechnology and highlight the critical role that trace components can play in the biological response to complex nanomaterials.
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Affiliation(s)
- Lorin M Jakubek
- Division of Engineering, Brown University, Providence, RI 02912, USA
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Su X, Zheng X, Ni J. Lanthanum citrate induces anoikis of Hela cells. Cancer Lett 2009; 285:200-9. [PMID: 19679391 DOI: 10.1016/j.canlet.2009.05.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 05/18/2009] [Accepted: 05/18/2009] [Indexed: 02/08/2023]
Abstract
Some reports show that lanthanum, a rare earth element, induces apoptosis in certain cancer cells. In the present paper, we report the first observation of anoikis induced by lanthanum citrate (LaCit) in Hela cells at a concentration of 0.001-0.1 mmol/L after 48h-treatment. Before cell treatment, Hela cells were subjected to anoikis-resistant selection to remove anoikis-sensitive cells and ensure specificity of LaCit-induced anoikis. Anoikis was determined by Annexin/PI, AO/EB staining, cleavage of PARP and soft-agar colony forming assay. Further, findings of decreased mitochondrial membrane potential, the cleavage of caspase-9 and a dose-dependent increase expression of Bax were detected, suggesting that the intrinsic caspase pathway was involved in the anoikis induced by LaCit. In addition, activation of caspase-8 occurred later than that of caspase-9. LaCit also caused reorganization of actin cytoskeleton, and was accompanied by an increase in co-localization of F-actin with mitochondria, implying that both actin cytoskeleton and mitochondria may play important roles in LaCit -induced anoikis.
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Affiliation(s)
- Xiange Su
- College of Life Science, Shenzhen University, Shenzhen 518060, PR China.
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Mont MR, Carlson CG, Geisbuhler TP. Resting Ca2+ influx does not contribute to anoxia-induced cell death in adult rat cardiac myocytes. Can J Physiol Pharmacol 2009; 87:360-70. [PMID: 19448734 DOI: 10.1139/y09-020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calcium has been proposed as a primary influence on cell death during ischemic episodes in myocardial cells. One component of calcium entry into a cell is resting calcium influx. This basal movement of calcium is blocked by 100 micromol/L gadolinium chloride (GdCl3) in cardiac myocytes. Therefore, GdCl3 should be cardioprotective under anoxic conditions. To test this, cardiac myocytes isolated from adult male rats were subjected to anoxia (100% N2) in the presence or absence of 100 micromol/L GdCl3 in one of 2 ways. In the first method, cells were suspended in media and rendered anoxic for 0, 30, and 60 min, after which cell morphology and viability were scored. After 60 min of anoxia, rod-shaped cells accounted for 46% +/- 4% of total cells (viability 81%); 10 min of reoxygenation markedly reduced rod-shaped cells to 27% (viability 72%). GdCl3 in the medium did not protect the cells (anoxic rods 49%, reoxygenated rods 30%, viability 77%). In the second method, cells were attached to a laminin substrate, rendered anoxic, and then videotaped for up to 6 h. In this system, cells maintained their shape for some time after the onset of anoxia, and then began to 'die' (i.e., to take on either a rigor form or hypercontracted form) at a measurable rate. Time to onset of 'death' (t0), time to 50% and 100% 'death' (t50 and t100), and rate of 'death' were used to measure anoxic damage. Without GdCl3, cells on average began to die 115 +/- 32 min after the onset of anoxia (t0); they died at an average rate of 0.046 cells/min. t50 was achieved in 149 +/- 42 min, t100 in 183 +/- 54 min. Addition of 100 micromol/L GdCl3 did not affect any of these parameters. We concluded that GdCl3 was not cardioprotective for anoxic myocytes and that cell damage generated by anoxia could not be attributed to resting calcium influx.
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Affiliation(s)
- Meghan R Mont
- Department of Physiology, A.T. Still University of Health Sciences, 800 West Jefferson Street, Kirksville College of Osteopathic Medicine, Kirksville, MO 63501, USA
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Kobayashi Y, Ikka T, Kimura K, Yasuda O, Koyama H. Characterisation of lanthanum toxicity for root growth of Arabidopsis thaliana from the aspect of natural genetic variation. FUNCTIONAL PLANT BIOLOGY : FPB 2007; 34:984-994. [PMID: 32689426 DOI: 10.1071/fp07133] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Accepted: 08/07/2007] [Indexed: 06/11/2023]
Abstract
The mechanism of lanthanum (La3+) toxicity on root growth of Arabidopsis was studied by physiological and genetic approaches using Landsberg erecta (Ler) × Columbia (Col) recombinant inbred lines (RILs) and other natural accessions. Quantitative trait locus (QTL) analyses revealed regulation of La3+ tolerance of the Ler × Col RILs by multiple genetic factors consisted of three significant QTLs and seven epistatic interacting loci pairs. The La content in the root tip was not correlated with La3+ tolerance in the RILs, indicating that the observed La3+ rhizotoxicity was not related to direct toxicity of La3+ in the symplast. The La3+ tolerance of root growth in the RILs was not correlated with Al3+ and Cu2+ tolerances, but was correlated with tolerances for other rare earth elements, including Gd3+, a known Ca2+ channel antagonist, and verapamil, a Ca2+ channel blocker. The genetic architecture of verapamil tolerance in root growth, which was identified by QTL analysis, was closely related to that of La3+ tolerance. La3+ tolerance and verapamil tolerance or Gd3+ tolerance in natural accessions of Arabidopsis also showed a positive correlation. These results indicate that the major La3+ toxicity on the root growth of Arabidopsis may involve its action as a Ca2+ channel antagonist.
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Affiliation(s)
- Yuriko Kobayashi
- Laboratory of Plant Cell Technology, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Takashi Ikka
- Laboratory of Plant Cell Technology, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Kazuhiko Kimura
- School of Food, Agricultural and Environmental Sciences, Miyagi University, 2-2-1 Hatatate, Taihaku-ku, Sendai 982-0215, Japan
| | - Orito Yasuda
- Laboratory of Plant Cell Technology, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Hiroyuki Koyama
- Laboratory of Plant Cell Technology, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
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Xie A, Aihara Y, Bouryi VA, Nikitina E, Jahromi BS, Zhang ZD, Takahashi M, Macdonald RL. Novel mechanism of endothelin-1-induced vasospasm after subarachnoid hemorrhage. J Cereb Blood Flow Metab 2007; 27:1692-701. [PMID: 17392694 DOI: 10.1038/sj.jcbfm.9600471] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cerebral vasospasm is a major cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (SAH). It is a sustained constriction of the cerebral arteries that can be reduced by endothelin (ET) receptor antagonists. Voltage-gated Ca(2+) channel antagonists such as nimodipine are relatively less effective. Endothelin-1 is not increased enough after SAH to directly cause the constriction, so we sought alternate mechanisms by which ET-1 might mediate vasospasm. Vasospasm was created in dogs, and the smooth muscle cells were studied molecularly, electrophysiologically, and by isometric tension. During vasospasm, ET-1, 10 nmol/L, induced a nonselective cation current carried by Ca(2+) in 64% of cells compared with in only 7% of control cells. Nimodipine and 2-aminoethoxydiphenylborate (a specific antagonist of store-operated channels) had no effect, whereas SKF96365 (a nonspecific antagonist of nonselective cation channels) decreased this current in vasospastic smooth muscle cells. Transient receptor potential (TRP) proteins may mediate entry of Ca(2+) through nonselective cationic pathways. We tested their role by incubating smooth muscle cells with anti-TRPC1 or TRPC4, both of which blocked ET-1-induced currents in SAH cells. Anti-TRPC5 had no effect. Anti-TRPC1 also inhibited ET-1 contraction of SAH arteries in vitro. Quantitative polymerase chain reaction and Western blotting of seven TRPC isoforms found increased expression of TRPC4 and a novel splice variant of TRPC1 and increased protein expression of TRPC4 and TRPC1. Taken together, the results support a novel mechanism whereby ET-1 significantly increases Ca(2+) influx mediated by TRPC1 and TRPC4 or their heteromers in smooth muscle cells, which promotes development of vasospasm after SAH.
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Affiliation(s)
- An Xie
- Section of Neurosurgery, Department of Surgery, University of Chicago Medical Center and Pritzker School of Medicine, Chicago, Illinois, USA
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Babich O, Matveev V, Harris AL, Shirokov R. Ca2+-dependent inactivation of CaV1.2 channels prevents Gd3+ block: does Ca2+ block the pore of inactivated channels? ACTA ACUST UNITED AC 2007; 129:477-83. [PMID: 17535960 PMCID: PMC2151623 DOI: 10.1085/jgp.200709734] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Lanthanide gadolinium (Gd(3+)) blocks Ca(V)1.2 channels at the selectivity filter. Here we investigated whether Gd(3+) block interferes with Ca(2+)-dependent inactivation, which requires Ca(2+) entry through the same site. Using brief pulses to 200 mV that relieve Gd(3+) block but not inactivation, we monitored how the proportions of open and open-blocked channels change during inactivation. We found that blocked channels inactivate much less. This is expected for Gd(3+) block of the Ca(2+) influx that enhances inactivation. However, we also found that the extent of Gd(3+) block did not change when inactivation was reduced by abolition of Ca(2+)/calmodulin interaction, showing that Gd(3+) does not block the inactivated channel. Thus, Gd(3+) block and inactivation are mutually exclusive, suggesting action at a common site. These observations suggest that inactivation causes a change at the selectivity filter that either hides the Gd(3+) site or reduces its affinity, or that Ca(2+) occupies the binding site at the selectivity filter in inactivated channels. The latter possibility is supported by previous findings that the EEQE mutation of the selectivity EEEE locus is void of Ca(2+)-dependent inactivation (Zong Z.Q., J.Y. Zhou, and T. Tanabe. 1994. Biochem. Biophys. Res. Commun. 201:1117-11123), and that Ca(2+)-inactivated channels conduct Na(+) when Ca(2+) is removed from the extracellular medium (Babich O., D. Isaev, and R. Shirokov. 2005. J. Physiol. 565:709-717). Based on these results, we propose that inactivation increases affinity of the selectivity filter for Ca(2+) so that Ca(2+) ion blocks the pore. A minimal model, in which the inactivation "gate" is an increase in affinity of the selectivity filter for permeating ions, successfully simulates the characteristic U-shaped voltage dependence of inactivation in Ca(2+).
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Affiliation(s)
- Olga Babich
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA
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Babich O, Reeves J, Shirokov R. Block of CaV1.2 channels by Gd3+ reveals preopening transitions in the selectivity filter. ACTA ACUST UNITED AC 2007; 129:461-75. [PMID: 17535959 PMCID: PMC2151628 DOI: 10.1085/jgp.200709733] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Using the lanthanide gadolinium (Gd3+) as a Ca2+ replacing probe, we investigated the voltage dependence of pore blockage of CaV1.2 channels. Gd+3 reduces peak currents (tonic block) and accelerates decay of ionic current during depolarization (use-dependent block). Because diffusion of Gd3+ at concentrations used (<1 μM) is much slower than activation of the channel, the tonic effect is likely to be due to the blockage that occurred in closed channels before depolarization. We found that the dose–response curves for the two blocking effects of Gd3+ shifted in parallel for Ba2+, Sr2+, and Ca2+ currents through the wild-type channel, and for Ca2+ currents through the selectivity filter mutation EEQE that lowers the blocking potency of Gd3+. The correlation indicates that Gd3+ binding to the same site causes both tonic and use-dependent blocking effects. The apparent on-rate for the tonic block increases with the prepulse voltage in the range −60 to −45 mV, where significant gating current but no ionic current occurs. When plotted together against voltage, the on-rates of tonic block (−100 to −45 mV) and of use-dependent block (−40 to 40 mV) fall on a single sigmoid that parallels the voltage dependence of the gating charge. The on-rate of tonic block by Gd3+ decreases with concentration of Ba2+, indicating that the apparent affinity of the site to permeant ions is about 1 mM in closed channels. Therefore, we propose that at submicromolar concentrations, Gd3+ binds at the entry to the selectivity locus and that the affinity of the site for permeant ions decreases during preopening transitions of the channel.
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Affiliation(s)
- Olga Babich
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA
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Abstract
Despite their presence in many tissues and their potential implication in various disease states, low-voltage activated T-type calcium channels (T-channels) have only recently become targets of interest. Unfortunately, the lack of selective T-channel blockers has hampered further characterisation of these channels. The recent availability of cloned T-channels, the Ca(V)3 proteins, facilitates identification of novel T-channel blockers. Also, studies performed in knockout animals have fostered novel interest. Selective inhibition of T-channels may have clinical importance in cardiovascular diseases, some forms of epilepsy, sleep disorders, pain and possibly cancer. This review focuses on novel research approaches to discover potent and selective T-channel modulators. These molecules may be potential drugs for treating human diseases, as well as important tools to decipher the physiological role of these channels.
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Affiliation(s)
- Philippe Lory
- Institut de Génomique Fonctionnelle, Département de Physiologie, CNRS UMR 5203, INSERM U661, IFR3, Universités de Montpellier I and II, Montpellier cedex 05, France.
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Sun HS, Hui K, Lee DWK, Feng ZP. Zn2+ sensitivity of high- and low-voltage activated calcium channels. Biophys J 2007; 93:1175-83. [PMID: 17526568 PMCID: PMC1929049 DOI: 10.1529/biophysj.106.103333] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The essential cation zinc (Zn2+) blocks voltage-dependent calcium channels in several cell types, which exhibit different sensitivities to Zn2+. The specificity of the Zn2+ effect on voltage-dependent calcium channel subtypes has not been systematically investigated. In this study, we used a transient protein expression system to determine the Zn2+ effect on low- and high-voltage activated channels. We found that in Ba2+, the IC50 value of Zn2+ was alpha1-subunit-dependent with lowest value for CaV1.2, and highest for CaV3.1; the sensitivity of the channels to Zn2+ was approximately ranked as CaV1.2>CaV3.2>CaV2.3>CaV2.2=CaV 2.1>or=CaV3.3=CaV3.1. Although the CaV2.2 and CaV3.1 channels had similar IC50 for Zn2+ in Ba2+, the CaV2.2, but not CaV3.1 channels, had approximately 10-fold higher IC50 to Zn2+ in Ca2+. The reduced sensitivity of CaV2.2 channels to Zn2+ in Ca2+ was partially reversed by disrupting a putative EF-hand motif located external to the selectivity filter EEEE locus. Thus, our findings support the notion that the Zn2+ block, mediated by multiple mechanisms, may depend on conformational changes surrounding the alpha1 pore regions. These findings provide fundamental insights into the mechanism underlying the inhibitory effect of zinc on various Ca2+ channel subtypes.
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Affiliation(s)
- Hong-Shuo Sun
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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Doering CJ, McRory JE. Effects of extracellular pH on neuronal calcium channel activation. Neuroscience 2007; 146:1032-43. [PMID: 17434266 DOI: 10.1016/j.neuroscience.2007.02.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Revised: 02/23/2007] [Accepted: 02/28/2007] [Indexed: 11/16/2022]
Abstract
Previous studies have shown that extracellular pH (pHo) alters gating and permeation properties of cardiac L- and T-type channels. However, a comprehensive study investigating the effects of pHo on all other voltage-gated calcium channels is lacking. Here, we report the effects of pHo on activation parameters slope factor (S), half-activation potential (Va), reversal potential (Erev), and maximum slope conductance (Gmax) of the nine known neuronal voltage-gated calcium channels transiently expressed in tsA-201 cells. In all cases, acidification of the extracellular bathing solution results in a depolarizing shift in the activation curve and reduction in peak current amplitudes. Relative to a physiological pHo of 7.25, statistically significant depolarizing shifts in Va were observed for all channels at pHo 7.00 except Cav1.3 and 3.2, which showed significant shifts at pHo 6.75 and below. All channels displayed significant reductions in Gmax relative to pHo 7.25 at pHo 7.00 except Cav1.2, 2.1, and 3.1 which required acidification to pHo 6.75. Upon acidification Cav3 channels displayed the largest changes in Vas and exhibited the largest reduction in Gmax compared with other channel subtypes. Taken together, these results suggest that significant modulation of calcium channel currents can occur with changes in pHo. Acidification of the external solution did not produce significant shifts in observed Erevs or blockade of outward currents for any of the nine channel subtypes. Finally, we tested a simple Woodhull-type model of current block by assuming blockade of the pore by a single proton. In all cases, the amount of blockade observed could not be explained in these simple terms, suggesting that proton modulation is more complicated, involving more than one site or gating modification as has been previously described for cardiac L- and T-type channels.
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Affiliation(s)
- C J Doering
- Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4N1
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Hamid J, Peloquin JB, Monteil A, Zamponi GW. Determinants of the differential gating properties of Cav3.1 and Cav3.3 T-type channels: a role of domain IV? Neuroscience 2006; 143:717-28. [PMID: 16996222 DOI: 10.1016/j.neuroscience.2006.08.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 08/11/2006] [Accepted: 08/15/2006] [Indexed: 11/24/2022]
Abstract
We have investigated the channel structural determinants that underlie the difference in gating properties of Cav3.1 and Cav3.3 T-type channels, by creating a series of chimeric channel constructs in which the major transmembrane domains were swapped. The chimeras were then expressed in tsA-201 cells and subjected to whole cell patch clamp analysis. Our data reveal that domains I and IV are major determinants of the half-activation potential. Substitution of domain IV was the most important determinant of activation time constant and time constant for recovery from inactivation, with domains I and II mediating a smaller role. In contrast, the carboxy terminal region did not appear to be involved. Determinants of the time constant for inactivation could not be localized to a specific transmembrane domain, but the concomitant substitution of domains I+IV was able to partially confer the inactivation kinetics among the two wild type channels. Our data indicate that the domain IV region mediates an important role in T-type channel activation, whereas multiple channel structural determinants appear to control T-type channel inactivation.
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Affiliation(s)
- J Hamid
- Hotchkiss Brain Institute and Department of Physiology and Biophysics, University of Calgary, 3330 Hospital Drive Northwest, Calgary, Canada T2N 4N1
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