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Capel RA, Bose SJ, Collins TP, Rajasundaram S, Ayagama T, Zaccolo M, Burton RAB, Terrar DA. IP 3-mediated Ca 2+ release regulates atrial Ca 2+ transients and pacemaker function by stimulation of adenylyl cyclases. Am J Physiol Heart Circ Physiol 2020; 320:H95-H107. [PMID: 33064562 PMCID: PMC7864251 DOI: 10.1152/ajpheart.00380.2020] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Inositol trisphosphate (IP3) is a Ca2+-mobilizing second messenger shown to modulate atrial muscle contraction and is thought to contribute to atrial fibrillation. Cellular pathways underlying IP3 actions in cardiac tissue remain poorly understood, and the work presented here addresses the question whether IP3-mediated Ca2+ release from the sarcoplasmic reticulum is linked to adenylyl cyclase activity including Ca2+-stimulated adenylyl cyclases (AC1 and AC8) that are selectively expressed in atria and sinoatrial node (SAN). Immunocytochemistry in guinea pig atrial myocytes identified colocalization of type 2 IP3 receptors with AC8, while AC1 was located in close vicinity. Intracellular photorelease of IP3 by UV light significantly enhanced the amplitude of the Ca2+ transient (CaT) evoked by electrical stimulation of atrial myocytes (31 ± 6% increase 60 s after photorelease, n = 16). The increase in CaT amplitude was abolished by inhibitors of adenylyl cyclases (MDL-12,330) or protein kinase A (H89), showing that cAMP signaling is required for this effect of photoreleased IP3. In mouse, spontaneously beating right atrial preparations, phenylephrine, an α-adrenoceptor agonist with effects that depend on IP3-mediated Ca2+ release, increased the maximum beating rate by 14.7 ± 0.5%, n = 10. This effect was substantially reduced by 2.5 µmol/L 2-aminoethyl diphenylborinate and abolished by a low dose of MDL-12,330, observations which are again consistent with a functional interaction between IP3 and cAMP signaling involving Ca2+ stimulation of adenylyl cyclases in the SAN pacemaker. Understanding the interaction between IP3 receptor pathways and Ca2+-stimulated adenylyl cyclases provides important insights concerning acute mechanisms for initiation of atrial arrhythmias. NEW & NOTEWORTHY This study provides evidence supporting the proposal that IP3 signaling in cardiac atria and sinoatrial node involves stimulation of Ca2+-activated adenylyl cyclases (AC1 and AC8) by IP3-evoked Ca2+ release from junctional sarcoplasmic reticulum. AC8 and IP3 receptors are shown to be located close together, while AC1 is nearby. Greater understanding of these novel aspects of the IP3 signal transduction mechanism is important for future study in atrial physiology and pathophysiology, particularly atrial fibrillation.
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Affiliation(s)
- Rebecca A Capel
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Samuel J Bose
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Thomas P Collins
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Skanda Rajasundaram
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Thamali Ayagama
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Rebecca-Ann Beatrice Burton
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Derek A Terrar
- Department of Pharmacology, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
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2
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Kaiser E, Tian Q, Wagner M, Barth M, Xian W, Schröder L, Ruppenthal S, Kaestner L, Boehm U, Wartenberg P, Lu H, McMillin SM, Bone DBJ, Wess J, Lipp P. DREADD technology reveals major impact of Gq signalling on cardiac electrophysiology. Cardiovasc Res 2020; 115:1052-1066. [PMID: 30321287 DOI: 10.1093/cvr/cvy251] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 06/02/2018] [Accepted: 10/11/2018] [Indexed: 02/04/2023] Open
Abstract
AIMS Signalling via Gq-coupled receptors is of profound importance in many cardiac diseases such as hypertrophy and arrhythmia. Nevertheless, owing to their widespread expression and the inability to selectively stimulate such receptors in vivo, their relevance for cardiac function is not well understood. We here use DREADD technology to understand the role of Gq-coupled signalling in vivo in cardiac function. METHODS AND RESULTS We generated a novel transgenic mouse line that expresses a Gq-coupled DREADD (Dq) in striated muscle under the control of the muscle creatine kinase promotor. In vivo injection of the DREADD agonist clozapine-N-oxide (CNO) resulted in a dose-dependent, rapid mortality of the animals. In vivo electrocardiogram data revealed severe cardiac arrhythmias including lack of P waves, atrioventricular block, and ventricular tachycardia. Following Dq activation, electrophysiological malfunction of the heart could be recapitulated in the isolated heart ex vivo. Individual ventricular and atrial myocytes displayed a positive inotropic response and arrhythmogenic events in the absence of altered action potentials. Ventricular tissue sections revealed a strong co-localization of Dq with the principal cardiac connexin CX43. Western blot analysis with phosphor-specific antibodies revealed strong phosphorylation of a PKC-dependent CX43 phosphorylation site following CNO application in vivo. CONCLUSION Activation of Gq-coupled signalling has a major impact on impulse generation, impulse propagation, and coordinated impulse delivery in the heart. Thus, Gq-coupled signalling does not only modulate the myocytes' Ca2+ handling but also directly alters the heart's electrophysiological properties such as intercellular communication. This study greatly advances our understanding of the plethora of modulatory influences of Gq signalling on the heart in vivo.
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Affiliation(s)
- Elisabeth Kaiser
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology; Medical Faculty, Saarland University, Homburg, Germany
| | - Qinghai Tian
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology; Medical Faculty, Saarland University, Homburg, Germany
| | - Michael Wagner
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology; Medical Faculty, Saarland University, Homburg, Germany
| | - Monika Barth
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology; Medical Faculty, Saarland University, Homburg, Germany
| | - Wenying Xian
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology; Medical Faculty, Saarland University, Homburg, Germany
| | - Laura Schröder
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology; Medical Faculty, Saarland University, Homburg, Germany
| | - Sandra Ruppenthal
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology; Medical Faculty, Saarland University, Homburg, Germany
| | - Lars Kaestner
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology; Medical Faculty, Saarland University, Homburg, Germany
| | - Ulrich Boehm
- Center for Molecular Signaling (PZMS), Institute for Experimental and Clinical Pharmacology and Toxicology, Medical Faculty, Saarland University, Homburg, Germany
| | - Philipp Wartenberg
- Center for Molecular Signaling (PZMS), Institute for Experimental and Clinical Pharmacology and Toxicology, Medical Faculty, Saarland University, Homburg, Germany
| | - Huiyan Lu
- Mouse Transgenic Core Facility, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Sara M McMillin
- Molecular Signaling Section, Lab. of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Derek B J Bone
- Molecular Signaling Section, Lab. of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Jürgen Wess
- Molecular Signaling Section, Lab. of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Peter Lipp
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology; Medical Faculty, Saarland University, Homburg, Germany
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3
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Deisl C, Fine M, Moe OW, Hilgemann DW. Hypertrophy of human embryonic stem cell-derived cardiomyocytes supported by positive feedback between Ca 2+ and diacylglycerol signals. Pflugers Arch 2019; 471:1143-1157. [PMID: 31250095 PMCID: PMC6614165 DOI: 10.1007/s00424-019-02293-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/04/2019] [Accepted: 06/11/2019] [Indexed: 12/19/2022]
Abstract
Human embryonic stem cell-derived cardiomyocytes develop pronounced hypertrophy in response to angiotensin-2, endothelin-1, and a selected mix of three fatty acids. All three of these responses are accompanied by increases in both basal cytoplasmic Ca2+ and diacylglycerol, quantified with the Ca2+ sensor Fluo-4 and a FRET-based diacylglycerol sensor expressed in these cardiomyocytes. The heart glycoside, ouabain (30 nM), and a recently developed inhibitor of diacylglycerol lipases, DO34 (1 μM), cause similar hypertrophy responses, and both responses are accompanied by equivalent increases of basal Ca2+ and diacylglycerol. These results together suggest that basal Ca2+ and diacylglycerol form a positive feedback signaling loop that promotes execution of cardiac growth programs in these human myocytes. Given that basal Ca2+ in myocytes depends strongly on the Na+ gradient, we also tested whether nanomolar ouabain concentrations might stimulate Na+/K+ pumps, as described by others, and thereby prevent hypertrophy. However, stimulatory effects of nanomolar ouabain (1.5 nM) were not verified on Na+/K+ pump currents in stem cell-derived myocytes, nor did nanomolar ouabain block hypertrophy induced by endothelin-1. Thus, low-dose ouabain is not a "protective" intervention under the conditions of these experiments in this human myocyte model. To summarize, the major aim of this study has been to characterize the progression of hypertrophy in human embryonic stem cell-derived cardiac myocytes in dependence on diacylglycerol and Na+ gradient changes, developing a case that positive feedback coupling between these mechanisms plays an important role in the initiation of hypertrophy programs.
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Affiliation(s)
- Christine Deisl
- Departments of Physiology and Internal Medicine, Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75235, USA.
| | - Michael Fine
- Departments of Physiology and Internal Medicine, Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75235, USA
| | - Orson W Moe
- Departments of Physiology and Internal Medicine, Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75235, USA
| | - Donald W Hilgemann
- Departments of Physiology and Internal Medicine, Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75235, USA.
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4
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Zhang YH, Han J. A new stone for a new path, from "physiology to the bedside". Pflugers Arch 2019; 471:1043-1044. [PMID: 31270620 DOI: 10.1007/s00424-019-02296-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 06/24/2019] [Accepted: 06/28/2019] [Indexed: 10/26/2022]
Affiliation(s)
- Yin Hua Zhang
- Department of Physiology & Biomedical Sciences, Ischemic/hypoxic disease institute, College of Medicine, Seoul National University, 103 Dae Hak Ro, Chong No Gu, Seoul, 03080, South Korea. .,Yanbian University Hospital, Yanji, Jilin Province, China. .,Cardiovascular Institute, Manchester University, Manchester, UK.
| | - Jin Han
- Department of Physiology & Cardiovascular and Metabolic Disease Center, College of Medicine, Inje University, Busan, South Korea
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5
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Mayourian J, Ceholski DK, Gonzalez DM, Cashman TJ, Sahoo S, Hajjar RJ, Costa KD. Physiologic, Pathologic, and Therapeutic Paracrine Modulation of Cardiac Excitation-Contraction Coupling. Circ Res 2019; 122:167-183. [PMID: 29301848 DOI: 10.1161/circresaha.117.311589] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cardiac excitation-contraction coupling (ECC) is the orchestrated process of initial myocyte electrical excitation, which leads to calcium entry, intracellular trafficking, and subsequent sarcomere shortening and myofibrillar contraction. Neurohumoral β-adrenergic signaling is a well-established mediator of ECC; other signaling mechanisms, such as paracrine signaling, have also demonstrated significant impact on ECC but are less well understood. For example, resident heart endothelial cells are well-known physiological paracrine modulators of cardiac myocyte ECC mainly via NO and endothelin-1. Moreover, recent studies have demonstrated other resident noncardiomyocyte heart cells (eg, physiological fibroblasts and pathological myofibroblasts), and even experimental cardiotherapeutic cells (eg, mesenchymal stem cells) are also capable of altering cardiomyocyte ECC through paracrine mechanisms. In this review, we first focus on the paracrine-mediated effects of resident and therapeutic noncardiomyocytes on cardiomyocyte hypertrophy, electrophysiology, and calcium handling, each of which can modulate ECC, and then discuss the current knowledge about key paracrine factors and their underlying mechanisms of action. Next, we provide a case example demonstrating the promise of tissue-engineering approaches to study paracrine effects on tissue-level contractility. More specifically, we present new functional and molecular data on the effects of human adult cardiac fibroblast conditioned media on human engineered cardiac tissue contractility and ion channel gene expression that generally agrees with previous murine studies but also suggests possible species-specific differences. By contrast, paracrine secretions by human dermal fibroblasts had no discernible effect on human engineered cardiac tissue contractile function and gene expression. Finally, we discuss systems biology approaches to help identify key stem cell paracrine mediators of ECC and their associated mechanistic pathways. Such integration of tissue-engineering and systems biology methods shows promise to reveal novel insights into paracrine mediators of ECC and their underlying mechanisms of action, ultimately leading to improved cell-based therapies for patients with heart disease.
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Affiliation(s)
- Joshua Mayourian
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Delaine K Ceholski
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - David M Gonzalez
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Timothy J Cashman
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Susmita Sahoo
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Roger J Hajjar
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Kevin D Costa
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY.
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6
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Light-triggered release of photocaged therapeutics - Where are we now? J Control Release 2019; 298:154-176. [PMID: 30742854 DOI: 10.1016/j.jconrel.2019.02.006] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 01/02/2023]
Abstract
The current available therapeutics face several challenges such as the development of ideal drug delivery systems towards the goal of personalized treatments for patients benefit. The application of light as an exogenous activation mechanism has shown promising outcomes, owning to the spatiotemporal confinement of the treatment in the vicinity of the diseased tissue, which offers many intriguing possibilities. Engineering therapeutics with light responsive moieties have been explored to enhance the bioavailability, and drug efficacy either in vitro or in vivo. The tailor-made character turns the so-called photocaged compounds highly desirable to reduce the side effects of drugs and, therefore, have received wide research attention. Herein, we seek to highlight the potential of photocaged compounds to obtain a clear understanding of the mechanisms behind its use in therapeutic delivery. A deep overview on the progress achieved in the design, fabrication as well as current and possible future applications in therapeutics of photocaged compounds is provided, so that novel formulations for biomedical field can be designed.
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7
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Smyrnias I, Goodwin N, Wachten D, Skogestad J, Aronsen JM, Robinson EL, Demydenko K, Segonds-Pichon A, Oxley D, Sadayappan S, Sipido K, Bootman MD, Roderick HL. Contractile responses to endothelin-1 are regulated by PKC phosphorylation of cardiac myosin binding protein-C in rat ventricular myocytes. J Mol Cell Cardiol 2018; 117:1-18. [DOI: 10.1016/j.yjmcc.2018.02.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/02/2018] [Accepted: 02/16/2018] [Indexed: 01/07/2023]
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8
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Enhancement of contraction and L-type Ca2+ current by murrayafoline-A via protein kinase C in rat ventricular myocytes. Eur J Pharmacol 2016; 784:33-41. [DOI: 10.1016/j.ejphar.2016.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 04/30/2016] [Accepted: 05/04/2016] [Indexed: 11/17/2022]
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9
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Liu F, Weng SJ, Yang XL, Zhong YM. Orexin-A potentiates L-type calcium/barium currents in rat retinal ganglion cells. Neuroscience 2015; 305:225-37. [PMID: 26259903 DOI: 10.1016/j.neuroscience.2015.08.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/27/2015] [Accepted: 08/04/2015] [Indexed: 01/07/2023]
Abstract
Two neuropeptides, orexin-A and orexin-B (also called hypocretin-1 and -2), have been implicated in sleep/wake regulation, feeding behaviors via the activation of two subtypes of G-protein-coupled receptors: orexin 1 and orexin 2 receptors (OX1R and OX2R). While the expression of orexins and orexin receptors is immunohistochemically revealed in retinal neurons, the function of these peptides in the retina is largely unknown. Using whole-cell patch-clamp recordings in rat retinal slices, we demonstrated that orexin-A increased L-type-like barium currents (IBa,L) in ganglion cells (GCs), and the effect was blocked by the selective OX1R antagonist SB334867, but not by the OX2R antagonist TCS OX2 29. The orexin-A effect was abolished by intracellular dialysis of GDP-β-S/GPAnt-2A, a Gq protein inhibitor, suggesting the mediation of Gq. Additionally, during internal dialysis of the phosphatidylinositol (PI)-phospholipase C (PLC) inhibitor U73122, orexin-A did not change the IBa,L of GCs, whereas the orexin-A effect persisted in the presence of the phosphatidylcholine (PC)-PLC inhibitor D609. The orexin-A-induced potentiation was not seen with internal infusion of Ca(2+)-free solution or when inositol 1,4,5-trisphosphate (IP3)-sensitive Ca(2+) release from intracellular stores was blocked by heparin/xestospongins-C. Moreover, the orexin-A effect was mimicked by the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate, but was eliminated when PKC was inhibited by bisindolylmaleimide IV (Bis-IV)/Gö6976. Neither adenosine 3',5'-cyclic monophosphate (cAMP)-protein kinase A (PKA) nor guanosine 3',5'-cyclic monophosphate (cGMP)-protein kinase G (PKG) signaling pathway was likely involved, as orexin-A persisted to potentiate the IBa,L of GCs no matter these two pathways were activated or inhibited. These results suggest that, by activating OX1R, orexin-A potentiates the IBa,L of rat GCs through a distinct Gq/PI-PLC/IP3/Ca(2+)/PKC signaling pathway.
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Affiliation(s)
- F Liu
- Institute of Neurobiology, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - S-J Weng
- Institute of Neurobiology, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - X-L Yang
- Institute of Neurobiology, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Y-M Zhong
- Institute of Neurobiology, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
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10
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Höglinger D, Nadler A, Schultz C. Caged lipids as tools for investigating cellular signaling. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:1085-96. [PMID: 24713581 DOI: 10.1016/j.bbalip.2014.03.012] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/27/2014] [Accepted: 03/27/2014] [Indexed: 12/21/2022]
Abstract
Lipid derivatives that can be activated by light, often referred to as 'caged' lipids, are useful tools to manipulate intact cells non-invasively. Here we focus on experimental approaches that have made use of caged lipids. Apart from summarizing the recent advances and available tools in the field, we strive to highlight the experimental challenges that arise from lipid-specific biophysical properties and the abundance of an enormous diversity of distinct molecular lipid species in cells. This article is part of a Special Issue entitled Tools to study lipid functions.
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Affiliation(s)
- Doris Höglinger
- European Molecular Biology Laboratory (EMBL), Cell Biology & Biophysics Unit, Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - André Nadler
- European Molecular Biology Laboratory (EMBL), Cell Biology & Biophysics Unit, Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Cell Biology & Biophysics Unit, Meyerhofstr. 1, 69117 Heidelberg, Germany.
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11
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Zhao Y, Zhou W, Xue L, Zhang W, Zhan Q. Nicotine activates YAP1 through nAChRs mediated signaling in esophageal squamous cell cancer (ESCC). PLoS One 2014; 9:e90836. [PMID: 24621512 PMCID: PMC3951250 DOI: 10.1371/journal.pone.0090836] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 02/06/2014] [Indexed: 01/03/2023] Open
Abstract
Cigarette smoking is an established risk factor for esophageal cancers. Yes-associated protein 1 (YAP1), the key transcription factor of the mammalian Hippo pathway, has been reported to be an oncogenic factor for many cancers. In this study, we find nicotine administration can induce nuclear translocation and activation of YAP1 in ESCC. Consistently, we observed nuclear translocation and activation of YAP1 by knockdown of CHRNA3, which is a negative regulator of nicotine signaling in bronchial and esophageal cancer cells. Nicotine administration or CHRNA3 depletion substantially increased proliferation and migration in esophageal cancer cells. Interestingly, we find that YAP1 physically interacts with nAChRs, and nAChRs-signaling dissociates YAP1 from its negative regulatory complex composed with α-catenin, β-catenin and 14-3-3 in the cytoplasm, leading to upregulation and nuclear translocation of YAP1. This process likely requires PKC activation, as PKC specific inhibitor Enzastaurin can block nicotine induced YAP1 activation. In addition, we find nicotine signaling also inhibits the interaction of YAP1 with P63, which contributes to the inhibitory effect of nicotine on apoptosis. Using immunohistochemistry analysis we observed upregulation of YAP1 in a significant portion of esophageal cancer samples. Consistently, we have found a significant association between YAP1 upregulation and cigarette smoking in the clinical esophageal cancer samples. Together, these findings suggest that the nicotine activated nAChRs signaling pathway which further activates YAP1 plays an important role in the development of esophageal cancer, and this mechanism may be of a general significance for the carcinogenesis of smoking related cancers.
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Affiliation(s)
- Yue Zhao
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Wei Zhou
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Liyan Xue
- Department of Pathology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Weimin Zhang
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Qimin Zhan
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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12
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Hohendanner F, McCulloch AD, Blatter LA, Michailova AP. Calcium and IP3 dynamics in cardiac myocytes: experimental and computational perspectives and approaches. Front Pharmacol 2014; 5:35. [PMID: 24639654 PMCID: PMC3944219 DOI: 10.3389/fphar.2014.00035] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 02/18/2014] [Indexed: 11/22/2022] Open
Abstract
Calcium plays a crucial role in excitation-contraction coupling (ECC), but it is also a pivotal second messenger activating Ca2+-dependent transcription factors in a process termed excitation-transcription coupling (ETC). Evidence accumulated over the past decade indicates a pivotal role of inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca2+ release in the regulation of cytosolic and nuclear Ca2+ signals. IP3 is generated by stimulation of plasma membrane receptors that couple to phospholipase C (PLC), liberating IP3 from phosphatidylinositol 4,5-bisphosphate (PIP2). An intriguing aspect of IP3 signaling is the presence of the entire PIP2-PLC-IP3 signaling cascade as well as the presence of IP3Rs at the inner and outer membranes of the nuclear envelope (NE) which functions as a Ca2+ store. The observation that the nucleus is surrounded by its own putative Ca2+ store raises the possibility that nuclear IP3-dependent Ca2+ release plays a critical role in ETC. This provides a potential mechanism of regulation that acts locally and autonomously from the global cytosolic Ca2+ signal underlying ECC. Moreover, there is evidence that: (i) the sarcoplasmic reticulum (SR) and NE are a single contiguous Ca2+ store; (ii) the nuclear pore complex is the major gateway for Ca2+ and macromolecules to pass between the cytosol and the nucleoplasm; (iii) the inner membrane of the NE hosts key Ca2+ handling proteins including the Na+/Ca2+ exchanger (NCX)/GM1 complex, ryanodine receptors (RyRs), nicotinic acid adenine dinucleotide phosphate receptors (NAADPRs), Na+/K+ ATPase, and Na+/H+ exchanger. Thus, it appears that the nucleus represents a Ca2+ signaling domain equipped with its own ion channels and transporters that allow for complex local Ca2+ signals. Many experimental and modeling approaches have been used for the study of intracellular Ca2+ signaling but the key to the understanding of the dual role of Ca2+ mediating ECC and ECT lays in quantitative differences of local [Ca2+] in the nuclear and cytosolic compartment. In this review, we discuss the state of knowledge regarding the origin and the physiological implications of nuclear Ca2+ transients in different cardiac cell types (adult atrial and ventricular myocytes) as well as experimental and mathematical approaches to study Ca2+ and IP3 signaling in the cytosol and nucleus. In particular, we focus on the concept that highly localized Ca2+ signals are required to translocate and activate Ca2+-dependent transcription factors (e.g., nuclear factor of activated T-cells, NFAT; histone deacetylase, HDAC) through phosphorylation/dephosphorylation processes.
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Affiliation(s)
- Felix Hohendanner
- Department of Molecular Biophysics and Physiology, Rush University Medical Center Chicago, IL, USA
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego La Jolla, CA, USA
| | - Lothar A Blatter
- Department of Molecular Biophysics and Physiology, Rush University Medical Center Chicago, IL, USA
| | - Anushka P Michailova
- Department of Bioengineering, University of California San Diego La Jolla, CA, USA
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13
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Fanchaouy M, Cubano L, Maldonado H, Bychkov R. PKC independent inhibition of voltage gated calcium channels by volatile anesthetics in freshly isolated vascular myocytes from the aorta. Cell Calcium 2013; 54:257-65. [PMID: 23948226 DOI: 10.1016/j.ceca.2013.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 07/12/2013] [Accepted: 07/18/2013] [Indexed: 11/16/2022]
Abstract
In this study we used barium currents through voltage gated L-type calcium channels (recorded in freshly isolated cells with a conventional patch-clamp technique) to elucidate the cellular action mechanism for volatile anesthetics. It was found that halothane and isoflurane inhibited (dose-dependently and voltage independently) Ba2+ currents through voltage gated Ca2+ channels. Half maximal inhibitions occurred at 0.64 ± 0.07 mM and 0.86 ± 0.1 mM. The Hill slope value was 2 for both volatile anesthetics, suggesting the presence of more than one interaction site. Current inhibition by volatile anesthetics was prominent over the whole voltage range without changes in the peak of the current voltage relationship. Intracellular infusion of the GDPβS (100 μM) together with staurosporine (200 nM) did not prevent the inhibitory effect of volatile anesthetics. Unlike pharmacological Ca2+ channel blockers, volatile anesthetics blocked Ca2+ channel currents at resting membrane potentials. In other words, halothane and isoflurane induced an 'initial block'. After the first 4-7 control pulses, the cells were left unstimulated and anesthetics were applied. The first depolarization after the pause evoked a Ca2+ channel current whose amplitude was reduced to 41 ± 3.4% and to 57 ± 4.2% of control values. In an analysis of the steady-state inactivation curve for voltage dependence, volatile anesthetics induced a negative shift of the 50% inactivation of the calcium channels. By contrast, the steepness factor characterizing the voltage sensitivity of the channels was unaffected. Unitary L-type Ca2+ channels blockade occurred under cell-attached configuration, suggesting a possible action of volatile anesthetics from within the intracellular space or from the part of the channel inside the lipid bilayer.
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14
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Drawnel FM, Archer CR, Roderick HL. The role of the paracrine/autocrine mediator endothelin-1 in regulation of cardiac contractility and growth. Br J Pharmacol 2013; 168:296-317. [PMID: 22946456 DOI: 10.1111/j.1476-5381.2012.02195.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 08/23/2012] [Accepted: 08/28/2012] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Endothelin-1 (ET-1) is a critical autocrine and paracrine regulator of cardiac physiology and pathology. Produced locally within the myocardium in response to diverse mechanical and neurohormonal stimuli, ET-1 acutely modulates cardiac contractility. During pathological cardiovascular conditions such as ischaemia, left ventricular hypertrophy and heart failure, myocyte expression and activity of the entire ET-1 system is enhanced, allowing the peptide to both initiate and maintain maladaptive cellular responses. Both the acute and chronic effects of ET-1 are dependent on the activation of intracellular signalling pathways, regulated by the inositol-trisphosphate and diacylglycerol produced upon activation of the ET(A) receptor. Subsequent stimulation of protein kinases C and D, calmodulin-dependent kinase II, calcineurin and MAPKs modifies the systolic calcium transient, myofibril function and the activity of transcription factors that coordinate cellular remodelling. The precise nature of the cellular response to ET-1 is governed by the timing, localization and context of such signals, allowing the peptide to regulate both cardiomyocyte physiology and instigate disease. LINKED ARTICLES This article is part of a themed section on Endothelin. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.168.issue-1.
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Affiliation(s)
- Faye M Drawnel
- Babraham Research Campus, Babraham Institute, Cambridge, UK
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15
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Yu L, Li M, She T, Shi C, Meng W, Wang B, Cheng M. Endothelin-1 stimulates the expression of L-type Ca2+ channels in neonatal rat cardiomyocytes via the extracellular signal-regulated kinase 1/2 pathway. J Membr Biol 2013; 246:343-53. [PMID: 23546014 DOI: 10.1007/s00232-013-9538-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Accepted: 03/16/2013] [Indexed: 01/07/2023]
Abstract
The cardiac L-type Ca(2+) channel current (I(Ca,L)) plays an important role in controlling both cardiac excitability and excitation-contraction coupling and is involved in the electrical remodeling during postnatal heart development and cardiac hypertrophy. However, the possible role of endothelin-1 (ET-1) in the electrical remodeling of postnatal and diseased hearts remains unclear. Therefore, the present study was designed to investigate the transcriptional regulation of I(Ca,L) mediated by ET-1 in neonatal rat ventricular myocytes using the whole-cell patch-clamp technique, quantitative RT-PCR and Western blotting. Furthermore, we determined whether the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway is involved. ET-1 increased I(Ca,L) density without altering its voltage dependence of activation and inactivation. In line with the absence of functional changes, ET-1 increased L-type Ca(2+) channel pore-forming α1C-subunit mRNA and protein levels without affecting the mRNA expression of auxiliary β- and α2/δ-subunits. Furthermore, an actinomycin D chase experiment revealed that ET-1 did not alter α1C-subunit mRNA stability. These effects of ET-1 were inhibited by the ETA receptor antagonist BQ-123 but not the ETB receptor antagonist BQ-788. Moreover, the effects of ET-1 on I(Ca,L) and α1C-subunit expression were abolished by the ERK1/2 inhibitor (PD98059) but not by the p38 MAPK inhibitor (SB203580) or the c-Jun N-terminal kinase inhibitor (SP600125). These findings indicate that ET-1 increased the transcription of L-type Ca(2+) channel in cardiomyocytes via activation of ERK1/2 through the ETA receptor, which may contribute to the electrical remodeling of heart during postnatal development and cardiac hypertrophy.
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Affiliation(s)
- Liangzhu Yu
- Hubei Province Key Laboratory on Cardiovascular, Cerebrovascular, and Metabolic Disorders, Hubei University of Science and Technology, Xianning, Peoples Republic of China.
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16
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Horn T, Ullrich ND, Egger M. 'Eventless' InsP3-dependent SR-Ca2+ release affecting atrial Ca2+ sparks. J Physiol 2013; 591:2103-11. [PMID: 23381902 DOI: 10.1113/jphysiol.2012.247288] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Augmented inositol 1,4,5-trisphosphate receptor (InsP3R) function has been linked to a variety of cardiac pathologies, including cardiac arrhythmia. The contribution of inositol 1,4,5-trisphosphate-induced Ca(2+) release (IP3ICR) in excitation-contraction coupling (ECC) under physiological conditions, as well as under cellular remodelling, remains controversial. Here we test the hypothesis that local IP3ICR directly affects ryanodine receptor (RyR) function and subsequent Ca(2+)-induced Ca(2+) release in atrial myocytes. IP3ICR was evoked by UV-flash photolysis of caged InsP3 under whole-cell configuration of the voltage-clamp technique in atrial myocytes isolated from C57/BL6 mice. Photolytic release of InsP3 was accompanied by a significant increase in the Ca(2+) release event frequency (4.14 ± 0.72 vs. 6.20 ± 0.76 events (100 μm)(-1) s(-1)). These individual photolytically triggered Ca(2+) release events were identified as Ca(2+) sparks, which originated from RyR openings. This was verified by Ca(2+) spark analysis and pharmacological separation between RyR and InsP3R-dependent sarcoplasmic reticulum (SR)-Ca(2+) release (2-aminoethoxydiphenyl borate, xestospongin C, tetracaine). Significant SR-Ca(2+) flux but eventless SR-Ca(2+) release through InsP3R were characterized using SR-Ca(2+) leak/SR-Ca(2+) load measurements. These results strongly support the idea that IP3ICR can effectively modulate RyR openings and Ca(2+) spark probability. We conclude that eventless and highly efficient InsP3-dependent SR-Ca(2+) flux is the main mechanism of functional cross-talk between InsP3Rs and RyRs, which may be an important factor in the modulation of ECC sensitivity.
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Affiliation(s)
- Tamara Horn
- Department of Physiology, University of Bern, Bühlplatz 5, CH-3012 Bern, Switzerland
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17
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Doyle C, Sergeant GP, Hollywood MA, McHale NG, Thornbury KD. Effects of Phenylephrine on Spontaneous Activity and L‐Type Ca2+ Current in Isolated Corpus Cavernosum Myocytes. J Sex Med 2012; 9:2795-805. [DOI: 10.1111/j.1743-6109.2012.02847.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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Undem C, Rios EJ, Maylor J, Shimoda LA. Endothelin-1 augments Na⁺/H⁺ exchange activity in murine pulmonary arterial smooth muscle cells via Rho kinase. PLoS One 2012; 7:e46303. [PMID: 23029469 PMCID: PMC3460862 DOI: 10.1371/journal.pone.0046303] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 08/29/2012] [Indexed: 12/20/2022] Open
Abstract
Excessive production of endothelin-1 (ET-1), a potent vasoconstrictor, occurs with several forms of pulmonary hypertension. In addition to modulating vasomotor tone, ET-1 can potentiate pulmonary arterial smooth muscle cell (PASMC) growth and migration, both of which contribute to the vascular remodeling that occurs during the development of pulmonary hypertension. It is well established that changes in cell proliferation and migration in PASMCs are associated with alkalinization of intracellular pH (pHi), typically due to activation of Na+/H+ exchange (NHE). In the systemic vasculature, ET-1 increases pHi, Na+/H+ exchange activity and stimulates cell growth via a mechanism dependent on protein kinase C (PKC). These results, coupled with data describing elevated levels of ET-1 in hypertensive animals/humans, suggest that ET-1 may play an important role in modulating pHi and smooth muscle growth in the lung; however, the effect of ET-1 on basal pHi and NHE activity has yet to be examined in PASMCs. Thus, we used fluorescent microscopy in transiently (3–5 days) cultured rat PASMCs and the pH-sensitive dye, BCECF-AM, to measure changes in basal pHi and NHE activity induced by increasing concentrations of ET-1 (10−10 to 10−8 M). We found that application of exogenous ET-1 increased pHi and NHE activity in PASMCs and that the ET-1-induced augmentation of NHE was prevented in PASMCs pretreated with an inhibitor of Rho kinase, but not inhibitors of PKC. Moreover, direct activation of PKC had no effect on pHi or NHE activity in PASMCs. Our results indicate that ET-1 can modulate pH homeostasis in PASMCs via a signaling pathway that includes Rho kinase and that, in contrast to systemic vascular smooth muscle, activation of PKC does not appear to be an important regulator of PASMC pHi.
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MESH Headings
- Animals
- Cells, Cultured
- Dose-Response Relationship, Drug
- Endothelin-1/pharmacology
- Enzyme Activation/drug effects
- Fluoresceins
- Fluorescent Dyes
- Hydrogen-Ion Concentration
- Male
- Mice
- Mice, Inbred C57BL
- Microscopy, Fluorescence
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/enzymology
- Protein Kinase C/metabolism
- Protein Kinase Inhibitors/pharmacology
- Pulmonary Artery/cytology
- Pulmonary Artery/drug effects
- Pulmonary Artery/enzymology
- Signal Transduction/drug effects
- Sodium-Potassium-Exchanging ATPase/antagonists & inhibitors
- Sodium-Potassium-Exchanging ATPase/metabolism
- rho-Associated Kinases/antagonists & inhibitors
- rho-Associated Kinases/metabolism
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Affiliation(s)
- Clark Undem
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Eon J. Rios
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Julie Maylor
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Larissa A. Shimoda
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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19
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Kang M, Chung KY. PKC-ε mediates multiple endothelin-1 actions on systolic Ca2+ and contractility in ventricular myocytes. Biochem Biophys Res Commun 2012; 423:600-5. [PMID: 22699119 DOI: 10.1016/j.bbrc.2012.06.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 06/06/2012] [Indexed: 11/26/2022]
Abstract
Endothelin-1 (ET-1) induces positive inotropy (enhanced contractility) in cardiac muscle, but establishing underlying cellular mechanisms has been controversial in part because of a growing number of signaling pathways and end effectors targeted by ET-1. Here we present evidence that ET-1 induces positive inotropism in ventricular tissue by increasing both systolic Ca2+ and myofilament Ca2+ sensitivity. To examine the roles of PKC-δ and PKC-ε in these acute responses to ET-1, kinase inactive dominant negative PKC (dn-PKC) constructs were expressed in adult rat ventricular myocytes. Yellow fluorescent protein (YFP) was fused to dn-PKC constructs to visualize expression and localization of dn-PKC in living myocytes. Due to an alanine to glutamate mutation in the pseudosubstrate site, dn-PKCs constitutively translocated to anchoring sites and were unaffected by agonist or phorbol ester treatment. Dn-PKC-δ-YFP mainly distributed at Z-lines and at intercalated disks in adult myocytes, whereas dn-PKC-ε-YFP stained the surface sarcolemma, T-tubules/Z-lines and perinuclear region. Myocytes expressing dn-PKC-δ-YFP showed normal systolic Ca2+ and contractile responses to ET-1. In contrast, the entire ensemble of ET-1 responses was blocked in myocytes expressing dn-PKC-ε-YFP including increased Ca2+ transients, enhanced myofilament Ca2+ sensitivity, and positive inotropy. This report provides direct evidence that PKC-ε is activated early and robustly following ET-1 stimulation and thus mediates multiple intracellular changes underlying the acute actions of ET-1 on myocardium.
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Affiliation(s)
- Misuk Kang
- Molecular and Cellular Pharmacology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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20
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Jain A, Olovsson M, Burton GJ, Yung HW. Endothelin-1 induces endoplasmic reticulum stress by activating the PLC-IP(3) pathway: implications for placental pathophysiology in preeclampsia. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:2309-20. [PMID: 22503784 DOI: 10.1016/j.ajpath.2012.03.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 02/23/2012] [Accepted: 03/01/2012] [Indexed: 02/04/2023]
Abstract
Recent evidence implicates placental endoplasmic reticulum (ER) stress in the pathophysiological characteristics of preeclampsia. Herein, we investigate whether endothelin (ET)-1, which induces Ca(2+) release from the ER, can induce placental ER stress. Loss of ER Ca(2+) homeostasis impairs post-translational modification of proteins, triggering ER stress-response pathways. IHC confirmed the presence of both ET-1 and its receptors in the syncytiotrophoblast. Protein levels and immunoreactivity of ET-1 and the endothelin B receptor (ETBR) were increased in preeclamptic samples compared with normotensive controls. JEG-3 and BeWo choriocarcinoma cells treated with ET-1 displayed an increase in ER stress markers. ET-1 induced phospho-activation of the ETBR. Treating cells with BQ788, an ETBR antagonist, or small-interfering RNA knockdown of the receptor inhibited induction of ER stress. ET-1 also stimulated p-phospholipase C (PLC)γ1 levels. By using inhibitors of PLC activation, U73122, and the inositol 1,4,5-triphosphate (IP(3)) receptor, xestospongin-C, we demonstrated that ET-1 induces ER stress via the PLC-IP(3) pathway. Furthermore, ET-1 levels increased in the syncytiotrophoblast of explants from normal placentas after hypoxia-reoxygenation in vitro. Conditioned medium from hypoxia-reoxygenation explants also contained higher ET-1 levels, which induced ER stress in JEG-3 cells that was abolished by an ET-1-neutralizing antibody. Collectively, the data show that ET-1 induced ER stress in trophoblasts via the ETBR and initiation of signaling through the PLC-IP(3) pathway, with the potential for autocrine stimulation.
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Affiliation(s)
- Arjun Jain
- Center for Trophoblast Research, Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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21
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Luke T, Maylor J, Undem C, Sylvester JT, Shimoda LA. Kinase-dependent activation of voltage-gated Ca2+ channels by ET-1 in pulmonary arterial myocytes during chronic hypoxia. Am J Physiol Lung Cell Mol Physiol 2012; 302:L1128-39. [PMID: 22387294 DOI: 10.1152/ajplung.00396.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exposure to chronic hypoxia (CH) causes pulmonary hypertension. The vasoconstrictor endothelin-1 (ET-1) is thought to play a role in the development of hypoxic pulmonary hypertension. In pulmonary arterial smooth muscle cells (PASMCs) from chronically hypoxic rats, ET-1 signaling is altered, with the ET-1-induced change in intracellular calcium concentration (Δ[Ca(2+)](i)) occurring through activation of voltage-dependent Ca(2+) channels (VDCC) even though ET-1-induced depolarization via inhibition of K(+) channels is lost. The mechanism underlying this response is unclear. We hypothesized that activation of VDCCs by ET-1 following CH might be mediated by protein kinase C (PKC) and/or Rho kinase, both of which have been shown to phosphorylate and activate VDCCs. To test this hypothesis, we examined the effects of PKC and Rho kinase inhibitors on the ET-1-induced Δ[Ca(2+)](i) in PASMCs from rats exposed to CH (10% O(2), 3 wk) using the Ca(2+)-sensitive dye fura 2-AM and fluorescent microscopy techniques. We found that staurosporine and GF109203X, inhibitors of PKC, and Y-27632 and HA 1077, Rho kinase inhibitors, reduced the ET-1-induced Δ[Ca(2+)](i) by >70%. Inhibition of tyrosine kinases (TKs) with genistein or tyrphostin A23, or combined inhibition of PKC, TKs, and Rho kinase, reduced the Δ[Ca(2+)](i) to a similar extent as inhibition of either PKC or Rho kinase alone. The ability of PKC or Rho kinase to activate VDCCs in our cells was verified using phorbol 12-myristate 13-acetate and GTP-γ-S. These results suggest that following CH, the ET-1-induced Δ[Ca(2+)](i) in PASMCs occurs via Ca(2+) influx through VDCCs mediated primarily by PKC, TKs, and Rho kinase.
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Affiliation(s)
- Trevor Luke
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA
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22
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Ferreira JCB, Mochly-Rosen D, Boutjdir M. Regulation of cardiac excitability by protein kinase C isozymes. Front Biosci (Schol Ed) 2012; 4:532-546. [PMID: 22202075 PMCID: PMC3527095 DOI: 10.2741/s283] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Cardiac excitability and electrical activity are determined by the sum of individual ion channels, gap junctions and exchanger activities. Electrophysiological remodeling during heart disease involves changes in membrane properties of cardiomyocytes and is related to higher prevalence of arrhythmia-associated morbidity and mortality. Pharmacological and genetic manipulation of cardiac cells as well as animal models of cardiovascular diseases are used to identity changes in electrophysiological properties and the molecular mechanisms associated with the disease. Protein kinase C (PKC) and several other kinases play a pivotal role in cardiac electrophysiological remodeling. Therefore, identifying specific therapies that regulate these kinases is the main focus of current research. PKC, a family of serine/threonine kinases, has been implicated as potential signaling nodes associated with biochemical and biophysical stress in cardiovascular diseases. In this review, we describe the role of PKC isozymes that are involved in cardiac excitability and discuss both genetic and pharmacological tools that were used, their attributes and limitations. Selective and effective pharmacological interventions to normalize cardiac electrical activities and correct cardiac arrhythmias will be of great clinical benefit.
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Affiliation(s)
- Julio Cesar Batista Ferreira
- Stanford University, School of Medicine, Stanford CA
- School of Physical Education and Sport, University of Sao Paulo, SP, Brazil
| | | | - Mohamed Boutjdir
- VA New York Harbor Healthcare System, State University of New York Downstate Medical Center and New York University School of Medicine, NY, NY
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23
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Ferreira JCB, Mochly-Rosen D, Boutjdir M. Regulation of cardiac excitability by protein kinase C isozymes. Front Biosci (Schol Ed) 2012. [PMID: 22202075 DOI: 10.2741/283] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cardiac excitability and electrical activity are determined by the sum of individual ion channels, gap junctions and exchanger activities. Electrophysiological remodeling during heart disease involves changes in membrane properties of cardiomyocytes and is related to higher prevalence of arrhythmia-associated morbidity and mortality. Pharmacological and genetic manipulation of cardiac cells as well as animal models of cardiovascular diseases are used to identity changes in electrophysiological properties and the molecular mechanisms associated with the disease. Protein kinase C (PKC) and several other kinases play a pivotal role in cardiac electrophysiological remodeling. Therefore, identifying specific therapies that regulate these kinases is the main focus of current research. PKC, a family of serine/threonine kinases, has been implicated as potential signaling nodes associated with biochemical and biophysical stress in cardiovascular diseases. In this review, we describe the role of PKC isozymes that are involved in cardiac excitability and discuss both genetic and pharmacological tools that were used, their attributes and limitations. Selective and effective pharmacological interventions to normalize cardiac electrical activities and correct cardiac arrhythmias will be of great clinical benefit.
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24
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Komukai K, O-Uchi J, Morimoto S, Kawai M, Hongo K, Yoshimura M, Kurihara S. Role of Ca(2+)/calmodulin-dependent protein kinase II in the regulation of the cardiac L-type Ca(2+) current during endothelin-1 stimulation. Am J Physiol Heart Circ Physiol 2010; 298:H1902-7. [PMID: 20304814 DOI: 10.1152/ajpheart.01141.2009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endothelin-1 (ET-1) shows a positive inotropic effect on cardiac muscle. Although the L-type Ca(2+) current (I(Ca)) is one of the important determinants of cardiac excitation-contraction coupling, the effect of ET-1 on the I(Ca) is not always clear. The controversial results appear to be due to different patch-clamp methods. The present study measured the effect of ET-1 on the I(Ca) of rat ventricular myocytes using the perforated patch-clamp technique. The holding potential was set to -40 mV, and depolarization was applied every 10 s. ET-1 (10 nM) increased the I(Ca) in a monophasic manner. The current reached a steady state 15 min after the application of ET-1, when the measurement was done. Endothelin receptor subtype expression was also investigated using Western immunoblotting. ET(A)-receptor protein was expressed, but ET(B)-receptor protein was not expressed, in the cell membranes of rat ventricular myocytes. The effect of ET-1 on the I(Ca) was inhibited by a selective ET(A)-receptor antagonist, BQ-123, but not by a selective ET(B)-receptor antagonist, BQ-788. The effect was inhibited by protein kinase C (PKC) inhibitor chelerythrine and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) inhibitor KN-93, but not by its inactive analog KN-92. The effect of ET-1 was also blocked by another CaMKII inhibitor, autocamtide-2-related inhibitory peptide. These results suggest that ET-1 increases the I(Ca) via the ET(A)-receptor-PKC-CaMKII pathway.
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Affiliation(s)
- Kimiaki Komukai
- Division of Cardiology, The Jikei Univ. School of Medicine, 3-25-8 Nishi-Shimbashi, Minato-ku, Tokyo, 105-8461 Japan.
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25
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Thorin E, Clozel M. The cardiovascular physiology and pharmacology of endothelin-1. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2010; 60:1-26. [PMID: 21081213 PMCID: PMC3693982 DOI: 10.1016/b978-0-12-385061-4.00001-5] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
One year after the discovery in 1980 that the endothelium was obligatory for acetylcholine to relax isolated arteries, it was clearly shown that the endothelium could also promote contraction. In 1988, Dr Yanagisawa's group identified endothelin-1 (ET-1) as the first endothelium-derived contracting factor. The circulating levels of this short (21 amino acids) peptide were quickly determined in humans and it was reported that in most cardiovascular diseases, circulating levels of ET-1 were increased and ET-1 was then recognized as a likely mediator of pathological vasoconstriction in human. The discovery of two receptor subtypes in 1990, ET(A) and ET(B), permitted optimization of bosentan, which entered clinical development in 1993, and was offered to patients with pulmonary arterial hypertension in 2001. In this report, we discuss the physiological and pathophysiological role of endothelium-derived ET-1, the pharmacology of its two receptors, focusing on the regulation of the vascular tone and as much as possible in humans. The coronary bed will be used as a running example, but references to the pulmonary, cerebral, and renal circulation will also be made. Many of the cardiovascular complications associated with aging and cardiovascular risk factors are initially attributable, at least in part, to endothelial dysfunction, particularly dysregulation of the vascular function associated with an imbalance in the close interdependence of NO and ET-1, in which the implication of the ET(B) receptor may be central.
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Affiliation(s)
- Eric Thorin
- Department of Surgery, Montreal Heart Institute, Research Center, Université de Montréal, Montreal, Quebec, Canada
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26
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Yang L, Doshi D, Morrow J, Katchman A, Chen X, Marx SO. Protein kinase C isoforms differentially phosphorylate Ca(v)1.2 alpha(1c). Biochemistry 2009; 48:6674-83. [PMID: 19527072 DOI: 10.1021/bi900322a] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The regulation of Ca(2+) influx through the phosphorylation of the L-type Ca(2+) channel, Ca(v)1.2, is important for the modulation of excitation-contraction (E-C) coupling in the heart. Ca(v)1.2 is thought to be the target of multiple kinases that mediate the signals of both the renin-angiotensin and sympathetic nervous systems. Detailed biochemical information regarding the protein phosphorylation reactions involved in the regulation of Ca(v)1.2 is limited. The protein kinase C (PKC) family of kinases can modulate cardiac contractility in a complex manner, such that contractility is either enhanced or depressed and relaxation is either accelerated or slowed. We have previously reported that Ser(1928) in the C-terminus of alpha(1c) was a target for PKCalpha, -zeta, and -epsilon phosphorylation. Here, we report the identification of seven PKC phosphorylation sites within the alpha(1c) subunit. Using phospho-epitope specific antibodies to Ser(1674) and Ser(1928), we demonstrate that both sites within the C-terminus are phosphorylated in HEK cells in response to PMA. Phosphorylation was inhibited with a PKC inhibitor, bisindolylmaleimide. In Langendorff-perfused rat hearts, both Ser(1674) and Ser(1928) were phosphorylated in response to PMA. Phosphorylation of Ser(1674), but not Ser(1928), is PKC isoform specific, as only PKCalpha, -betaI, -betaII, -gamma, -delta, and -theta, but not PKCepsilon, -zeta, and -eta, were able to phosphorylate this site. Our results identify a molecular mechanism by which PKC isoforms can have different effects on channel activity by phosphorylating different residues.
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Affiliation(s)
- Lin Yang
- Division of Cardiology, Department of Medicine, College of Physicians and Surgeons,Columbia University, New York, New York 10032, USA
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27
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Dai S, Hall DD, Hell JW. Supramolecular assemblies and localized regulation of voltage-gated ion channels. Physiol Rev 2009; 89:411-52. [PMID: 19342611 DOI: 10.1152/physrev.00029.2007] [Citation(s) in RCA: 264] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
This review addresses the localized regulation of voltage-gated ion channels by phosphorylation. Comprehensive data on channel regulation by associated protein kinases, phosphatases, and related regulatory proteins are mainly available for voltage-gated Ca2+ channels, which form the main focus of this review. Other voltage-gated ion channels and especially Kv7.1-3 (KCNQ1-3), the large- and small-conductance Ca2+-activated K+ channels BK and SK2, and the inward-rectifying K+ channels Kir3 have also been studied to quite some extent and will be included. Regulation of the L-type Ca2+ channel Cav1.2 by PKA has been studied most thoroughly as it underlies the cardiac fight-or-flight response. A prototypical Cav1.2 signaling complex containing the beta2 adrenergic receptor, the heterotrimeric G protein Gs, adenylyl cyclase, and PKA has been identified that supports highly localized via cAMP. The type 2 ryanodine receptor as well as AMPA- and NMDA-type glutamate receptors are in close proximity to Cav1.2 in cardiomyocytes and neurons, respectively, yet independently anchor PKA, CaMKII, and the serine/threonine phosphatases PP1, PP2A, and PP2B, as is discussed in detail. Descriptions of the structural and functional aspects of the interactions of PKA, PKC, CaMKII, Src, and various phosphatases with Cav1.2 will include comparisons with analogous interactions with other channels such as the ryanodine receptor or ionotropic glutamate receptors. Regulation of Na+ and K+ channel phosphorylation complexes will be discussed in separate papers. This review is thus intended for readers interested in ion channel regulation or in localization of kinases, phosphatases, and their upstream regulators.
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Affiliation(s)
- Shuiping Dai
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242-1109, USA
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Left ventricular unloading before reperfusion reduces endothelin-1 release and calcium overload in porcine myocardial infarction. J Thorac Cardiovasc Surg 2008; 136:343-51. [DOI: 10.1016/j.jtcvs.2008.01.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 01/04/2008] [Accepted: 01/29/2008] [Indexed: 11/22/2022]
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Zeng Q, Zhou Q, Yao F, O'Rourke ST, Sun C. Endothelin-1 regulates cardiac L-type calcium channels via NAD(P)H oxidase-derived superoxide. J Pharmacol Exp Ther 2008; 326:732-8. [PMID: 18539650 DOI: 10.1124/jpet.108.140301] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
It has been shown that reactive oxygen species (ROS) are involved in the intracellular signaling response to G-protein coupled receptor stimuli in vascular smooth muscle cells and in neurons. In the present study, we tested the hypothesis that NAD(P)H oxidase-derived ROS are involved endothelin-1 (ET-1)-induced L-type calcium channel activation in isolated cardiac myocytes. ET-1 (10 nM) induced a 2-fold increase in L-type calcium channel open-state probability (NPo). This effect of ET-1 was abolished by the ET(A) receptor antagonist cyclo(D-Trp-D-Asp-Pro-D-Val-Leu) [BQ-123 (1 microM)] but was not altered in the presence of an ET(B) receptor antagonist N-cis-2,6-dimethylpiperidinocarbonyl-b-tBu-Ala-D-Trp(1-methoxycarbonyl)-D-Nle-OH [BQ-788 (1 microM)]. Pretreatment of cells with the ROS scavenger tempol (100 microM), polyethylene glycol-superoxide dismutase (SOD, 25 U/ml), or the NAD(P)H-oxidase inhibitor gp91ds-tat ([H]RKKRRQRRR-CSTRIRRQL[NH(3)]) (5 microM) significantly attenuated ET-1-induced increases in calcium channel NPo. Tempol, SOD, and gp91ds-tat alone had no effect on basal calcium channel activity. In addition, ET-1 significantly increased NAD(P)H oxidase activity and elevated intracellular superoxide levels in cultured cardiac myocytes. The superoxide generator, xanthine-xanthine oxidase (10 mM, 20 mU/ml), also increased calcium channel NPo in cardiac myocytes, mimicking the effect of ET-1. These observations provide the first evidence that ET-1 induces the activation of L-type Ca(2+) channels via stimulation of NAD(P)H-derived superoxide production in cardiac myocytes.
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Affiliation(s)
- Qinghua Zeng
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58105, USA
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Nishimaru K, Arimoto T, Takeishi Y, Kubota I, Ishii K, Endoh M. Overexpression of diacylglycerol kinase zeta inhibits endothelin-1-induced decreases in Ca2+ transients and cell shortening in mouse ventricular myocytes. J Mol Cell Cardiol 2008; 44:520-6. [PMID: 18275971 DOI: 10.1016/j.yjmcc.2007.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 12/13/2007] [Accepted: 12/14/2007] [Indexed: 10/22/2022]
Abstract
Endothelin-1 (ET-1) is released in various cardiovascular disorders including congestive heart failure, and may modulate significantly the disease process by its potent action on vascular and cardiac muscle cell function and gene regulation. In adult mouse ventricular cardiomyocytes loaded with indo-1, ET-1 induced a sustained negative inotropic effect (NIE) in association with decreases in Ca(2+) transients. The ET-1-induced effects on Ca(2+) transients and cell shortening were abolished in diacylglycerol (DAG) kinase zeta-overexpressing mouse ventricular myocytes. A nonselective protein kinase C (PKC) inhibitor, GF109203X, inhibited the ET-1-induced decreases in Ca(2+) transients and cell shortening in concentration-dependent manners, whereas a selective Ca(2+)-dependent PKC inhibitor, Gö6976, did not affect the ET-1-induced effects. A phospholipase Cbeta inhibitor, U73122, and an inhibitor of phospholipase D, C(2)-ceramide, partially, but significantly, attenuated the ET-1-induced effects. Derivatives of the respective inhibitors with no specific effects, U73343 and dihydro-C(2)-ceramide, did not affect the ET-1-induced effects. Taken together, these results indicate that activation of a Ca(2+)-independent PKC isozyme by 1,2-DAG, which is generated by phospholipase Cbeta and phospholipase D activation and inactivated by phosphorylation via DAG kinase, is responsible for the ET-1-induced decreases in Ca(2+) transients and cell shortening in mouse ventricular cardiomyocytes.
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Affiliation(s)
- Kazuhide Nishimaru
- Department of Cardiovascular Pharmacology, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata, 990-9585 Japan
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31
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Domeier TL, Zima AV, Maxwell JT, Huke S, Mignery GA, Blatter LA. IP3 receptor-dependent Ca2+ release modulates excitation-contraction coupling in rabbit ventricular myocytes. Am J Physiol Heart Circ Physiol 2007; 294:H596-604. [PMID: 18055509 DOI: 10.1152/ajpheart.01155.2007] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R)-dependent Ca(2+) signaling exerts positive inotropic, but also arrhythmogenic, effects on excitation-contraction coupling (ECC) in the atrial myocardium. The role of IP(3)R-dependent sarcoplasmic reticulum (SR) Ca(2+) release in ECC in the ventricular myocardium remains controversial. Here we investigated the role of this signaling pathway during ECC in isolated rabbit ventricular myocytes. Immunoblotting of proteins from ventricular myocytes showed expression of both type 2 and type 3 IP(3)R at levels approximately 3.5-fold less than in atrial myocytes. In permeabilized myocytes, direct application of IP(3) (10 microM) produced a transient 21% increase in the frequency of Ca(2+) sparks (P < 0.05). This increase was accompanied by a 13% decrease in spark amplitude (P < 0.05) and a 7% decrease in SR Ca(2+) load (P < 0.05) and was inhibited by IP(3)R antagonists 2-aminoethoxydiphenylborate (2-APB; 20 microM) and heparin (0.5 mg/ml). In intact myocytes endothelin-1 (100 nM) was used to stimulate IP(3) production and caused a 38% (P < 0.05) increase in the amplitude of action potential-induced (0.5 Hz, field stimulation) Ca(2+) transients. This effect was abolished by the IP(3)R antagonist 2-APB (2 microM) or by using adenoviral expression of an IP(3) affinity trap that buffers cellular IP(3). Together, these data suggest that in rabbit ventricular myocytes IP(3)R-dependent Ca(2+) release has positive inotropic effects on ECC by facilitating Ca(2+) release through ryanodine receptor clusters.
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Affiliation(s)
- Timothy L Domeier
- Department of Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
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James AF. Negative inotropic effects of endothelin-1 in mouse cardiomyocytes: evidence of a role for Na+-Ca2+ exchange. Br J Pharmacol 2007; 152:417-9. [PMID: 17721550 PMCID: PMC2050820 DOI: 10.1038/sj.bjp.0707438] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Endothelin-1 (ET-1) is a peptide hormone produced within the myocardium which may modulate myocardial contractility in a paracrine-autocrine fashion. In the majority of species, ET-1 has a direct positive inotropic effect on the myocardium that involves both increased myofilament Ca(2+) sensitivity and increased Ca(2+) transients. Ca(2+) entry through reverse-mode Na(+)-Ca(2+) exchange, involving both indirect effects via elevation of intracellular [Na(+)] and direct activation of the Na(+)-Ca(2+) exchanger, have been suggested to contribute to the increase in Ca(2+) transients. Conversely, mouse cardiomyocytes show an exclusively negative inotropic response to ET-1. Here, Nishimaru and colleagues present novel evidence that the negative inotropic effect of ET-1 in mouse cardiomyocytes involves both a reduction in myofilament Ca(2+) sensitivity and increased Ca(2+) extrusion, via Na(+)-Ca(2+) exchange. Data obtained using the selective Na(+)-Ca(2+) exchange blocker, SEA0400, suggest that a re-assessment of the role of the exchanger in Ca(2+)-handling by mouse cardiomyocytes may be necessary.
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Affiliation(s)
- A F James
- Department of Physiology and Pharmacology and Bristol Heart Institute Cardiovascular Research Laboratories, School of Medical Sciences, University of Bristol, University Walk, Bristol, UK.
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Kang M, Chung KY, Walker JW. G-protein coupled receptor signaling in myocardium: not for the faint of heart. Physiology (Bethesda) 2007; 22:174-84. [PMID: 17557938 DOI: 10.1152/physiol.00051.2006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Catecholamines, endothelin-1 and angiotensin II are among a diverse group of diffusible extracellular signals that regulate pump function of the heart by binding to G-protein coupled receptors (GPCR). When the body demands a temporary boost of power output or if temporary budgeting of resources is required, these signals can adjust heart rate and contractile strength to maintain continuous perfusion of all vascular beds with nutrient- and oxygen-rich blood. Given adequate time in the face of prolonged challenges, activation of GPCRs can also promote "remodeling of the heart" by increasing cell size, organ size, and chamber dimensions, or by varying tissue composition and altering the expression of protein isoforms controlling excitability and contractility. A common feature of heart disease is the state of chronic activation of GPCR signaling systems. Paradoxically, whereas acute activation is beneficial, chronic activation often contributes to further deterioration of cardiac performance. A better understanding of how chronic GPCR activation contributes to the development of heart disease is needed so that it can be translated into better prevention and therapeutic strategies in the clinic.
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Affiliation(s)
- Misuk Kang
- Department of Physiology, University of Wisconsin School of Medicine, Madison, Wisconsin, USA
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Park WS, Kang SH, Son YK, Kim N, Ko JH, Kim HK, Ko EA, Kim CD, Han J. The mitochondrial Ca2+-activated K+ channel activator, NS 1619 inhibits L-type Ca2+ channels in rat ventricular myocytes. Biochem Biophys Res Commun 2007; 362:31-36. [PMID: 17698036 DOI: 10.1016/j.bbrc.2007.07.057] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Accepted: 07/13/2007] [Indexed: 11/22/2022]
Abstract
We examined the effects of the mitochondrial Ca(2+)-activated K(+) (mitoBK(Ca)) channel activator NS 1619 on L-type Ca(2+) channels in rat ventricular myocytes. NS 1619 inhibited the Ca(2+) current in a dose-dependent manner. NS 1619 shifted the activation curve to more positive potentials, but did not have a significant effect on the inactivation curve. Pretreatment with inhibitors of membrane BK(Ca) channel, mitoBK(Ca) channel, protein kinase C, protein kinase A, and protein kinase G had little effect on the Ca(2+) current and did not alter the inhibitory effect of NS 1619 significantly. The application of additional NS 1619 in the presence of isoproterenol, a selective beta-adrenoreceptor agonist, reduced the Ca(2+) current to approximately the same level as a single application of NS 1619. In conclusion, our results suggest that NS 1619 inhibits the Ca(2+) current independent of the mitoBK(Ca) channel and protein kinases. Since NS 1619 is widely used to study mitoBK(Ca) channel function, it is essential to verify these unexpected effects of NS 1619 before experimental data can be interpreted accurately.
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Affiliation(s)
- Won Sun Park
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondrial Research Group, Department of Physiology and Biophysics, College of Medicine, Biohealth Products Research Center, Cardiovascular and Metabolic Disease Center, Inje University, 633-165 Gaegeum-Dong, Busanjin-Gu, Busan 613-735, Republic of Korea
| | - Sung Hyun Kang
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondrial Research Group, Department of Physiology and Biophysics, College of Medicine, Biohealth Products Research Center, Cardiovascular and Metabolic Disease Center, Inje University, 633-165 Gaegeum-Dong, Busanjin-Gu, Busan 613-735, Republic of Korea
| | - Youn Kyoung Son
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondrial Research Group, Department of Physiology and Biophysics, College of Medicine, Biohealth Products Research Center, Cardiovascular and Metabolic Disease Center, Inje University, 633-165 Gaegeum-Dong, Busanjin-Gu, Busan 613-735, Republic of Korea
| | - Nari Kim
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondrial Research Group, Department of Physiology and Biophysics, College of Medicine, Biohealth Products Research Center, Cardiovascular and Metabolic Disease Center, Inje University, 633-165 Gaegeum-Dong, Busanjin-Gu, Busan 613-735, Republic of Korea
| | - Jae-Hong Ko
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondrial Research Group, Department of Physiology and Biophysics, College of Medicine, Biohealth Products Research Center, Cardiovascular and Metabolic Disease Center, Inje University, 633-165 Gaegeum-Dong, Busanjin-Gu, Busan 613-735, Republic of Korea
| | - Hyoung Kyu Kim
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondrial Research Group, Department of Physiology and Biophysics, College of Medicine, Biohealth Products Research Center, Cardiovascular and Metabolic Disease Center, Inje University, 633-165 Gaegeum-Dong, Busanjin-Gu, Busan 613-735, Republic of Korea
| | - Eun A Ko
- Department of Pharmacology, College of Medicine and Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Busan, Republic of Korea
| | - Chi Dae Kim
- Department of Pharmacology, College of Medicine and Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Busan, Republic of Korea
| | - Jin Han
- National Research Laboratory for Mitochondrial Signaling, FIRST Mitochondrial Research Group, Department of Physiology and Biophysics, College of Medicine, Biohealth Products Research Center, Cardiovascular and Metabolic Disease Center, Inje University, 633-165 Gaegeum-Dong, Busanjin-Gu, Busan 613-735, Republic of Korea.
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Nishimaru K, Miura Y, Endoh M. Mechanisms of endothelin-1-induced decrease in contractility in adult mouse ventricular myocytes. Br J Pharmacol 2007; 152:456-63. [PMID: 17641672 PMCID: PMC2050817 DOI: 10.1038/sj.bjp.0707392] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND AND PURPOSE The potent vasoconstrictor polypeptide endothelin-1 (ET-1) plays an important pathophysiological role in progression of cardiovascular diseases and elicits prominent effects on myocardial contractility. Although ET-1 produces a positive inotropy in cardiac muscle of most mammalian species, it induces a sustained negative inotropy in mice. This study was performed to gain an insight into the cellular mechanisms underlying the negative inotropy in adult mouse ventricular myocytes. EXPERIMENTAL APPROACH Cell shortening and Ca(2+) transients were simultaneously recorded from isolated mouse ventricular myocytes loaded with the Ca(2+)-sensitive fluorescent dye indo-1. KEY RESULTS ET-1 decreased cell shortening in a concentration-dependent manner (pD(2) value of 10.1). The ET-1-induced decrease in cell shortening was associated with a decrease in Ca(2+) transients. In addition, the Ca(2+) transient/cell-shortening relationship was shifted to the right by ET-1, indicating decreased myofilament Ca(2+) sensitivity. The instantaneous relationship of the rising phase of the Ca(2+) transient and cell shortening was shifted to the right by ET-1. Decreased Ca(2+) transients and cell shortening induced by ET-1 were markedly attenuated by the specific Na(+)/Ca(2+) exchange inhibitor SEA0400. CONCLUSIONS AND IMPLICATIONS ET-1-induced negative inotropy in mouse ventricular myocytes was mediated by decreased Ca(2+) transients and myofilament Ca(2+) sensitivity. These data are entirely consistent with the involvement of increased Ca(2+) extrusion via the Na(+)/Ca(2+) exchanger in the ET-1-mediated decrease in Ca(2+) transients. Decreased Ca(2+) sensitivity may be due to retardation of cell shortening in response to a rise in Ca(2+) transients.
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Affiliation(s)
- K Nishimaru
- Department of Cardiovascular Pharmacology, Yamagata University School of Medicine Yamagata, Japan
| | - Y Miura
- Department of Cardiovascular Pharmacology, Yamagata University School of Medicine Yamagata, Japan
| | - M Endoh
- Department of Cardiovascular Pharmacology, Yamagata University School of Medicine Yamagata, Japan
- Author for correspondence:
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Wong AOL, Chuk MCY, Chan HC, Lee EKY. Mechanisms for gonadotropin-releasing hormone potentiation of growth hormone rebound following norepinephrine inhibition in goldfish pituitary cells. Am J Physiol Endocrinol Metab 2007; 292:E203-14. [PMID: 16940469 DOI: 10.1152/ajpendo.00337.2006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the goldfish, norepinephrine (NE) inhibits growth hormone (GH) secretion through activation of pituitary alpha(2)-adrenergic receptors. Interestingly, a GH rebound is observed after NE withdrawal, which can be markedly enhanced by prior exposure to gonadotropin-releasing hormone (GnRH). Here we examined the mechanisms responsible for GnRH potentiation of this "postinhibition" GH rebound. In goldfish pituitary cells, alpha(2)-adrenergic stimulation suppressed both basal and GnRH-induced GH mRNA expression, suggesting that a rise in GH synthesis induced by GnRH did not contribute to its potentiating effect. Using a column perifusion approach, GnRH given during NE treatment consistently enhanced the GH rebound following NE withdrawal. This potentiating effect was mimicked by activation of PKC and adenylate cyclase (AC) but not by induction of Ca(2+) entry through voltage-sensitive Ca(2+) channels (VSCC). Furthermore, GnRH-potentiated GH rebound could be alleviated by inactivation of PKC, removal of extracellular Ca(2+), blockade of VSCC, and inhibition of Ca(2+)/calmodulin (CaM)-dependent protein kinase II (CaMKII). Inactivation of AC and PKA, however, was not effective in this regard. These results, as a whole, suggest that GnRH potentiation of GH rebound following NE inhibition is mediated by PKC coupled to Ca(2+) entry through VSCC and subsequent activation of CaMKII. Apparently, the Ca(2+)-dependent cascades are involved in GH secretion during the rebound phase but are not essential for the initiation of GnRH potentiation. Since GnRH has been previously shown to have no effects on cAMP synthesis in goldfish pituitary cells, the involvement of cAMP-dependent mechanisms in GnRH potentiation is rather unlikely.
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Affiliation(s)
- Anderson O L Wong
- Dept. of Zoology, Univ. of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
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Proven A, Roderick HL, Conway SJ, Berridge MJ, Horton JK, Capper SJ, Bootman MD. Inositol 1,4,5-trisphosphate supports the arrhythmogenic action of endothelin-1 on ventricular cardiac myocytes. J Cell Sci 2006; 119:3363-75. [PMID: 16882691 DOI: 10.1242/jcs.03073] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although ventricular cardiomyocytes express inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] receptors, it is unclear how these Ca2+ channels contribute to the effects of Gq-coupled agonists. Endothelin-1 augmented the amplitude of pacing-evoked Ca2+ signals (positive inotropy), and caused an increasing frequency of spontaneous diastolic Ca2+-release transients. Both effects of endothelin-1 were blocked by an antagonist of phospholipase C, suggesting that Ins(1,4,5)P3 and/or diacylglycerol production was necessary. The endothelin-1-mediated spontaneous Ca2+ transients were abolished by application of 2-aminoethoxydiphenyl borate (2-APB), an antagonist of Ins(1,4,5)P3 receptors. Incubation of electrically-paced ventricular myocytes with a membrane-permeant Ins(1,4,5)P3 ester provoked the occurrence of spontaneous diastolic Ca2+ transients with the same characteristics and sensitivity to 2-APB as the events stimulated by endothelin-1. In addition to evoking spontaneous Ca2+ transients, stimulation of ventricular myocytes with the Ins(1,4,5)P3 ester caused a positive inotropic effect. The effects of endothelin-1 were compared with two other stimuli, isoproterenol and digoxin, which are known to induce inotropy and spontaneous Ca2+ transients by overloading intracellular Ca2+ stores. The events evoked by isoproterenol and digoxin were dissimilar from those triggered by endothelin-1 in several ways. We propose that Ins(1,4,5)P3 receptors support the development of both inotropy and spontaneous pro-arrhythmic Ca2+ signals in ventricular myocytes stimulated with a Gq-coupled agonist.
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MESH Headings
- Animals
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/metabolism
- Boron Compounds/pharmacology
- Calcium/metabolism
- Calcium Channels/metabolism
- Calcium Signaling
- Digoxin/pharmacology
- Endothelin-1/pharmacology
- Heart Ventricles/drug effects
- Heart Ventricles/metabolism
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate Receptors
- Isoproterenol/pharmacology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Rats
- Rats, Wistar
- Receptors, Cytoplasmic and Nuclear/metabolism
- Type C Phospholipases/pharmacology
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Affiliation(s)
- Andrew Proven
- Calcium Group, Laboratory of Molecular Signalling, Babraham Institute, Babraham, Cambridge, CB2 4AT, UK
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Ko EA, Park WS, Ko JH, Han J, Kim N, Earm YE. Endothelin-1 increases intracellular Ca(2+) in rabbit pulmonary artery smooth muscle cells through phospholipase C. Am J Physiol Heart Circ Physiol 2005; 289:H1551-9. [PMID: 16162868 DOI: 10.1152/ajpheart.00131.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In freshly isolated rabbit pulmonary artery smooth muscle cells, endothelin (ET)-1 induced a transient increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) followed by a return to the initial [Ca(2+)](i). This response was not abolished by the voltage-dependent Ca(2+) channel blocker nicardipine or removal of Ca(2+) from the bath solution but was inhibited by ryanodine and thapsigargin. This finding suggested that the increase in [Ca(2+)](i) induced by ET-1 was attributable to release of Ca(2+) from ryanodine- and inositol 1,4,5-trisphosphate-sensitive intracellular Ca(2+) stores. The transient increase in [Ca(2+)](i) induced by ET-1 was also inhibited by pretreatment with antagonists of ET type A and B (ET(A) and ET(B)) receptors (BQ-123 and BQ-788, respectively). Furthermore, the ET(B) receptor agonist IRL-1620 induced an increase in [Ca(2+)](i) that was followed by a sustained increase in [Ca(2+)](i); the sustained increase in [Ca(2+)](i) was blocked by nicardipine. Using the nystatin-perforated patch-clamp technique, we found that IRL-1620 caused an increase in Ca(2+) current that was inhibited by addition of ET-1. ET-1 did not inhibit Ca(2+) current when cells were pretreated with BQ-123. These results suggested that when both receptor types are activated, the opposing responses lead to abolition of the sustained [Ca(2+)](i) increases induced by ET(B) receptor activation. Western blot analysis confirmed expression of ET(A) and ET(B) receptors. Finally, U-73122 inhibited the ET-1-induced [Ca(2+)](i) increase, indicating that phospholipase C was involved in modulation of the ET-1-induced [Ca(2+)](i) increase in rabbit pulmonary artery smooth muscle cells.
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Affiliation(s)
- Eun A Ko
- Department of Physiology and National Research Laboratory for Cellular Signalling, Seoul National University College of Medicine, Seoul, Korea
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Westfall MV, Lee AM, Robinson DA. Differential contribution of troponin I phosphorylation sites to the endothelin-modulated contractile response. J Biol Chem 2005; 280:41324-31. [PMID: 16236710 DOI: 10.1074/jbc.m506043200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cardiac troponin I is a phosphorylation target for endothelin-activated protein kinase C. Earlier work in cardiac myocytes expressing nonphosphorylatable slow skeletal troponin I provided evidence that protein kinase C-mediated cardiac troponin I phosphorylation accelerates relaxation. However, replacement with the slow skeletal isoform also alters the myofilament pH response and the Ca2+ transient, which could influence endothelin-mediated relaxation. Here, differences in the Ca2+ transient could not explain the divergent relaxation response to endothelin in myocytes expressing cardiac versus slow skeletal troponin I nor could activation of Na+/H+ exchange. Three separate clusters within cardiac troponin I are phosphorylated by protein kinase C, and we set out to determine the contribution of the Thr144 and Ser23/Ser24 clusters to the endothelin-mediated contractile response. Myocyte replacement with a cardiac troponin I containing a Thr144 substituted with the Pro residue found in slow skeletal troponin I resulted in prolonged relaxation in response to acute endothelin compared with control myocytes. Ser23/Ser24 also is a target for protein kinase C phosphorylation of purified cardiac troponin I, and although this cluster was not acutely phosphorylated in intact myocytes, significant phosphorylation developed within 1 h after adding endothelin. Replacement of Ser23/Ser24 with Ala indicated that this cluster contributes significantly to relaxation during more prolonged endothelin stimulation. Overall, results with these mutants provide evidence that Thr144 plays an important role in the acute acceleration of relaxation, whereas Ser23/Ser24 contributes to relaxation during more prolonged activation of protein kinase C by endothelin.
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Affiliation(s)
- Margaret V Westfall
- Department of Surgery, University of Michigan, Ann Arbor, Michigan 48109, USA.
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40
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Sosa R, Gleason E. Activation of mGluR5 modulates Ca2+ currents in retinal amacrine cells from the chick. Vis Neurosci 2005; 21:807-16. [PMID: 15733336 DOI: 10.1017/s0952523804216017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Indexed: 11/07/2022]
Abstract
In the inner plexiform layer, amacrine cells receive glutamatergic input from bipolar cells. Glutamate can depolarize amacrine cells by activation of ionotropic glutamate receptors or mediate potentially more diverse changes via activation of G protein-coupled metabotropic glutamate receptors (mGluR5). Here, we asked whether selective activation of metabotropic glutamate receptor 5 is linked to modulation of the voltage-gated Ca2+ channels expressed by cultured GABAergic amacrine cells. To address this, we performed whole-cell voltage clamp experiments, primarily in the perforated-patch configuration. We found that agonists selective for mGluR5, including (RS)-2-chloro-5-hydroxyphenylglycine (CHPG), enhanced the amplitude of the voltage-dependent Ca2+ current. The voltage-dependent Ca2+ current and CHPG-dependent current enhancement were blocked by nifedipine, indicating that L-type Ca2+ channels, specifically, were being modulated. We have previously shown that activation of mGluR5 produces Ca2+ elevations in cultured amacrine cells (Sosa et al., 2002). Loading the cells with 5 mM BAPTA inhibited the mGluR5-dependent enhancement, suggesting that the cytosolic Ca2+ elevations are required for modulation of the current. Although activation of mGluR5 is typically linked to activation of protein kinase C, we found that direct activation of this kinase leads to inhibition of the Ca2+ current, indicating that stimulation of this enzyme is not responsible for the mGluR5-dependent enhancement. Interestingly, direct stimulation of protein kinase A produced an enhancement of the Ca2+ current similar to that observed with activation of mGluR5. Thus, activation of mGluR5 may modulate the L-type voltage-gated Ca2+ current in these GABAergic amacrine cells via activation of protein kinase A, possibly via direct activation of a Ca2(+)-dependent adenylate cyclase.
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Affiliation(s)
- Romina Sosa
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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41
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Ko JH, Park WS, Earm YE. The protein kinase inhibitor, staurosporine, inhibits L-type Ca2+ current in rabbit atrial myocytes. Biochem Biophys Res Commun 2005; 329:531-7. [PMID: 15737619 DOI: 10.1016/j.bbrc.2005.01.156] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Indexed: 11/22/2022]
Abstract
A whole-cell patch recording was used to determine the effects of staurosporine (ST), a potent protein kinase C (PKC) inhibitor, on L-type Ca(2+) channel (LTCC) activity in rabbit atrial myocytes. Bath application of ST (300 nM) caused a significant reduction in peak I-V relationship of LTCC (from -16.8+/-2.55 to -3.74+/-1.22pApF(-1) at 0 mV). The level of L-type Ca(2+) current (I(Ca,L)) inhibition produced by ST was independent of the voltage at which the effect was measured. ST inhibited the I(Ca,L) in a dose-dependent manner with a K(d) value of 61.98+/-6.802 nM. ST shifted the activation curve to more positive potentials, but did not have any significant effect on the voltage dependence of the inactivation curve. Other PKC inhibitors, GF 109203X (1 microM) and chelerythrine (3 microM), and PKA inhibitor, PKA-IP (5 microM), did not show any inhibitory effect on I(Ca,L). Additional application of ST in the presence of isoproterenol (1 microM), a selective beta-adrenoreceptor agonist, reduced peak I(Ca,L) (78.2%) approximately to the same level with single application of ST (77.8%). In conclusion, our results indicate that ST directly blocks the LTCC in a PKC or PKA-independent manner on LTCC and it should be taken into consideration when ST is used in functional studies of ion channel modulation by protein phosphorylation.
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Affiliation(s)
- Jae Hong Ko
- Department of Physiology and National Research Laboratory for Cellular Signaling, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea
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42
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Guinamard R, Chatelier A, Lenfant J, Bois P. Activation of the Ca(2+)-activated nonselective cation channel by diacylglycerol analogues in rat cardiomyocytes. J Cardiovasc Electrophysiol 2004; 15:342-8. [PMID: 15030426 DOI: 10.1046/j.1540-8167.2004.03477.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Cardiac hypertrophy is associated with changes in electrophysiologic properties due to ionic channel modifications and increases in protein kinase C (PKC) activity and diacylglycerol (DAG) content. These changes may contribute to an increased propensity for arrhythmia. Similar electrophysiologic modifications have been reported in adult rat cardiomyocytes undergoing dedifferentiation in primary culture. METHODS AND RESULTS Single-channel measurements on such cells identified the appearance of a Ca(2+)-activated nonselective cation channel (NSC(Ca)) during the dedifferentiation process. The current study investigated the sensitivity of this channel to PKC and DAG analogues. In the cell-attached configuration, channel conductance was 20.2 pS under physiologic conditions. Perfusion with the DAG analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG, 0.1 mM) or the PKC activator phorbol 12-myristate 13-acetate (PMA, 0.5 microM) increased the channel normalized open probability (nPo), whereas in the presence of the PKC inhibitor calphostin C (1 microM), only OAG retained this effect. In the inside-out configuration, perfusion of both DAG analogues OAG (0.1 mM) and 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG, 10 microM) on the inside of the membrane increased nPo. These results indicate that DAG regulates the NSC(Ca) channel via both the PKC pathway and by a direct interaction. CONCLUSION DAG content, PKC activity, and channel expression increased during hypertrophy. This indicates that the NSC(Ca) channel exhibits high activity in this condition and, therefore, is a candidate for the genesis of arrhythmias in ventricular cardiomyocytes. In addition, regulation of the channel by DAG and PKC contributes to current understanding of the physiologic role of this channel, which shares properties with the cloned TRPM4b channel.
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Affiliation(s)
- Romain Guinamard
- Laboratoire des Biomembranes et Signalisation Cellulaire, CNRS UMR 6558, Université de Poitiers, Poitiers, France.
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43
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Souroujon MC, Yao L, Chen H, Endemann G, Khaner H, Geeraert V, Schechtman D, Gordon AS, Diamond I, Mochly-Rosen D. State-specific monoclonal antibodies identify an intermediate state in epsilon protein kinase C activation. J Biol Chem 2004; 279:17617-24. [PMID: 14761958 DOI: 10.1074/jbc.m400962200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Evaluation of the activation state of protein kinase C (PKC) isozymes relies on analysis of subcellular translocation. A monoclonal antibody, 14E6, specific for the activated conformation of epsilonPKC, was raised using the first variable (V1) domain of epsilonPKC as the immunogen. 14E6 binding is specific for epsilonPKC and is greatly increased in the presence of PKC activators. Immunofluorescence staining by 14E6 of neonatal rat primary cardiac myocytes and the NG108-15 neuroblastoma glioma cell line, NG108-15/D2, increases rapidly following cell activation and is localized to new subcellular sites. However, staining of translocated epsilonPKC with 14E6 is transient, and the epitope disappears 30 min after activation of NG-108/15 cells by a D2 receptor agonist. In contrast, subcellular localization associated with activation, as determined by commercially available polyclonal antibodies, persists for at least 30 min. In vitro, epsilonRACK, the receptor for activated epsilonPKC, inhibits 14E6 binding to epsilonPKC, suggesting that the 14E6 epitope is lost or hidden when active epsilonPKC binds to its RACK. Therefore, the 14E6 antibody appears to identify a transient state of activated but non-anchored epsilonPKC. Moreover, binding of 14E6 to epsilonPKC only after activation suggests that lipid-dependent conformational changes associated with epsilonPKC activation precede binding of the activated isozyme to its specific RACK, epsilonRACK. Further, monoclonal antibody 14E6 should be a powerful tool to study the pathways that control rapid translocation of epsilonPKC from cytosolic to membrane localization on activation.
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Affiliation(s)
- Miriam C Souroujon
- Department of Molecular Pharmacology, Stanford University School of Medicine, Stanford, California 94305, USA
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duBell WH, Rogers TB. Protein phosphatase 1 and an opposing protein kinase regulate steady-state L-type Ca2+ current in mouse cardiac myocytes. J Physiol 2004; 556:79-93. [PMID: 14742732 PMCID: PMC1664898 DOI: 10.1113/jphysiol.2003.059329] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Studies have suggested that integration of kinase and phosphatase activities maintains the steady-state L-type Ca(2+) current in ventricular myocytes, a balance disrupted in failing hearts. As we have recently reported that the PP1/PP2A inhibitor calyculin A evokes pronounced increases in L-type I(Ca), the goal of this study was to identify the counteracting kinase and phosphatase that determine 'basal'I(Ca) in isolated mouse ventricular myocytes. Whole-cell voltage-clamp studies, with filling solutions containing 10 mm EGTA, revealed that calyculin A (100 nm) increased I(Ca) at test potentials between -42 and +49 mV (44% at 0 mV) from a holding potential of -80 mV. It also shifted the V(0.5) (membrane potential at half-maximal) of both activation (from -17 to -25 mV) and steady-state inactivation (from -32 to -37 mV) in the hyperpolarizing direction. The broad-spectrum protein kinase inhibitor, staurosporine (300 nm), was without effect on I(Ca) when added after calyculin A. However, by itself, staurosporine decreased I(Ca) throughout the voltage range examined (50% at 0 mV) and blocked the response to calyculin A, indicating that the phosphatase inhibitor's effects depend upon an opposing kinase activity. The PKA inhibitors Rp-cAMPs (100 microm in the pipette) and H89 (1 microm) failed to reduce basal I(Ca) or to block the calyculin A-evoked increase in I(Ca). Likewise, calyculin A was still active with 10 mm intracellular BAPTA or when Ba(2+) was used as the charge carrier. These data eliminate roles for protein kinase A (PKA) and calmodulin-dependent protein kinase II (CaMKII) as counteracting kinases. However, the protein kinase C (PKC) inhibitors Ro 31-8220 (1 microm) and Gö 6976 (200 nm) decreased steady-state I(Ca) and blunted the effect of calyculin A. PP2A is not involved in this regulation as intracellular applications of 10-100 nm okadaic acid or 500 nm fostriecin failed to increase I(Ca). However, PP1 is important, as dialysis with 2 microm okadaic acid or 500 nm inhibitor-2 mimicked the increases in I(Ca) seen with calyculin A. These in situ studies identify constitutive activity of PP1 and the counteracting activity of certain isoforms of PKC, in pathways distinct from receptor-mediated signalling cascades, as regulatory components that determine the steady-state level of cardiac L-type I(Ca).
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Affiliation(s)
- William H duBell
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Robu VG, Pfeiffer ES, Robia SL, Balijepalli RC, Pi Y, Kamp TJ, Walker JW. Localization of functional endothelin receptor signaling complexes in cardiac transverse tubules. J Biol Chem 2003; 278:48154-61. [PMID: 12972433 DOI: 10.1074/jbc.m304396200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endothelin-1 (ET-1) is an autocrine factor in the mammalian heart important in enhancing cardiac performance, protecting against myocardial ischemia, and initiating the development of cardiac hypertrophy. The ETA receptor is a seven-transmembrane G-protein-coupled receptor whose precise subcellular localization in cardiac muscle is unknown. Here we used fluorescein ET-1 and 125I-ET-1 to provide evidence for ET-1 receptors in cardiac transverse tubules (T-tubules). Moreover, the ETA receptor and downstream effector phospholipase C-beta 1 were co-localized within T-tubules using standard immunofluorescence techniques, and protein kinase C (PKC)-epsilon-enhanced green fluorescent protein bound reversibly to T-tubules upon activation. Localized photorelease of diacylglycerol further suggested compartmentation of PKC signaling, with release at the myocyte "surface" mimicking the negative inotropic effects of bath-applied PKC activators and "deep" release mimicking the positive inotropic effect of ET-1. The functional significance of T-tubular ET-1 receptors was further tested by rendering the T-tubule lumen inaccessible to bath-applied ET-1. Such "detubulated" cardiac myocytes showed no positive inotropic response to 20 nM ET-1, despite retaining both a nearly normal twitch response to field stimulation and a robust positive inotropic response to 20 nm isoproterenol. We propose that ET-1 enhances myocyte contractility by activating ETA receptor-phospholipase C-beta 1-PKC-epsilon signaling complexes preferentially localized in cardiac T-tubules. Compartmentation of ET-1 signaling complexes may explain the discordant effects of ET-1 versus bath applied PKC activators and may contribute to both the specificity and diversity of the cardiac actions of ET-1.
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Affiliation(s)
- Valentin G Robu
- Department of Physiology, University of Wisconsin, Madison, Wisconsin 53706, USA
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Pi Y, Zhang D, Kemnitz KR, Wang H, Walker JW. Protein kinase C and A sites on troponin I regulate myofilament Ca2+ sensitivity and ATPase activity in the mouse myocardium. J Physiol 2003; 552:845-57. [PMID: 12923217 PMCID: PMC2343448 DOI: 10.1113/jphysiol.2003.045260] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Cardiac troponin I (cTnI) is a phosphoprotein subunit of the troponin-tropomyosin complex that is thought to inhibit cardiac muscle contraction during diastole. To investigate the contributions of cTnI phosphorylation to cardiac regulation, transgenic mice were created with the phosphorylation sites of cTnI mutated to alanine. Activation of protein kinase C (PKC) by perfusion of hearts with phorbol-12-myristate-13-acetate (PMA) or endothelin-1 (ET-1) inhibited the maximum ATPase rate by up to 25 % and increased the Ca2+ sensitivity of ATPase activity and of isometric tension by up to 0.15 pCa units. PKC activation no longer altered cTnI phosphorylation, depressed ATPase rates or enhanced myofilament Ca2+ sensitivity in transgenic mice expressing cTnI that could not be phosphorylated on serines43/45 and threonine144 (PKC sites). Modest changes in myosin regulatory light chain phosphorylation occurred in all mouse lines, but increases in myofilament Ca2+ sensitivity required the presence of phosphorylatable cTnI. For comparison, the beta-adrenergic agonist isoproterenol caused a 38 % increase in maximum ATPase rate and a 0.12 pCa unit decrease in myofilament Ca2+ sensitivity. These beta-adrenergic effects were absent in transgenic mice expressing cTnI that could not be phosphorylated on serines23/24 (protein kinase A, PKA, sites). Overall, the results indicate that PKC and PKA exert opposing effects on actomyosin function by phosphorylating cTnI on distinct sites. A primary role of PKC phosphorylation of cTnI may be to reduce the requirements of the contractile apparatus for both Ca2+ and ATP, thereby promoting efficient ATP utilisation during contraction.
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Affiliation(s)
- YeQing Pi
- Department of Physiology, University of Wisconsin, Madison, WI 53706 USA
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Nagasaka T, Izumi M, Hori M, Ozaki H, Karaki H. Positive inotropic effect of endothelin-1 in the neonatal mouse right ventricle. Eur J Pharmacol 2003; 472:197-204. [PMID: 12871754 DOI: 10.1016/s0014-2999(03)01936-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In neonatal mouse right ventricles, endothelin-1 (ET-1, 1-300 nM) induced a dose-dependent increase in twitch contractions and the dose-response curve was shifted to the right by BQ-123 (10 microM), an endothelin ET(A) receptor antagonist. The ET-1 (100 nM)-induced positive inotropy was accompanied by an increase in [Ca(2+)](i) transients without any change in the [Ca(2+)](i)-force relationship. Ryanodine (1 microM) partially decreased the [Ca(2+)](i) transients and contractile force, but did not affect the ET-1 (100 nM)-induced positive inotropy. Reduction of [Na(+)](o) elicited an increase in contractile force, and this effect was significantly inhibited by KB-R7943 (30 microM), an inhibitor of the Na(+)-Ca(2+) exchanger. KB-R7943 (30 microM) almost completely suppressed the positive inotropic effect of ET-1. Activation of protein kinase C (PKC) by phorbol 12,13-dibutylate (100 nM) decreased the contractile force, an effect which was suppressed by bisindolylmaleimide I (3 microM). On the other hand, the ET-1-induced positive inotropic effect was unaffected by bisindolylmaleimide I (3 microM). These results suggest that the positive inotropic effect of ET-1 in neonatal mouse right ventricles is caused by the increase in [Ca(2+)](i) transients through activation of the endothelin ET(A) receptor and the increase in Ca(2+) influx via the Na(+)-Ca(2+) exchanger during an action potential. Furthermore, the ET-1-induced positive inotropy is independent of the effects of PKC, which makes it distinct from the ET-1-mediated pathways reported for cardiac tissues in other species.
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Affiliation(s)
- Tsuyoshi Nagasaka
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo, Tokyo 113-8657, Japan
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48
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Chau WH, Lee WH, Lau WH, Kwan YW, Au ALS, Raymond K. Role of Na+/H+ exchanger in acetylcholine-mediated pulmonary artery contraction of spontaneously hypertensive rats. Eur J Pharmacol 2003; 464:177-87. [PMID: 12620512 DOI: 10.1016/s0014-2999(03)01424-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Compared to sympathetic nervous system, the role of parasympathetic innervation on tone development, especially under diseased conditions, of the pulmonary artery is relatively unknown. In this study, the contractile effect of acetylcholine and the type(s) of muscarinic (M) receptor involved in the pulmonary artery (1st intralobar branch; endothelium-denuded, under resting tension) of the normotensive Wistar-Kyoto (WKY) and age-matched (male, 22-26 weeks old) Spontaneously hypertensive rats (SHR) were investigated. Cumulative administration of acetylcholine (> or =0.1 microM) caused a concentration-dependent increase in tension (antagonised by p-fluoro-hexahydro-sila-difenidol and 4-diphenylacetoxy-N-methylpiperidine, both are selective muscarinic M(3) receptor antagonists) and the magnitude of maximum contraction (expressed as % of 50 mM [K(+)](o)-induced contraction) was markedly enhanced in the presence of neostigmine (10 microM, an anti-cholinesterase) (acetylcholine 30 microM, SHR: 72% vs. 35%; WKY: 32% vs. 20%). In SHR only, acetylcholine-elicited contraction was suppressed by 1-[beta-[3-(4-Methoxyphenyl)-propoxyl]-4-methoxyphenethyl]-1H-imidazole (SK&F 96365, 1 microM), amiloride (500 microM), ethyl-isopropyl-amiloride (EIPA, 10 microM), 2-[2-[4-(4-Nitrobenzyloxy)phenyl]ethyl]isothiourea (KB-R 7943, 5 microM), 2,4-dichlorobenzamil (10 microM), and an equal molar substitution of [Na(+)](o) (< or =30 mM) with choline or N-methyl-D-glucamine. In nominally [Ca(2+)](o)-free, EGTA (0.5 mM)-containing Krebs' solution, acetylcholine (> or =3 microM) only elicited a small contraction. In conclusion, muscarinic M(3) receptor activation is responsible for the pulmonary artery contraction induced by acetylcholine, with a greater magnitude observed in SHR. The exaggerated contraction in SHR is probably due to an influx of [Na(+)](o) through the Na(+)/H(+) exchanger and the store-operated channels (SOC) into smooth muscle cells. Elevation of cytosolic [Na(+)](i) subsequently leads to an influx of [Ca(2+)](o) through the reverse mode of the Na(+)/Ca(2+) exchanger seems to play a permissive role in mediating the exaggerated contractile response of acetylcholine recorded in the SHR.
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Affiliation(s)
- Wing Han Chau
- School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, PR China
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Ceccarelli F, Scavuzzo MC, Giusti L, Bigini G, Costa B, Carnicelli V, Zucchi R, Lucacchini A, Mazzoni MR. ETA receptor-mediated Ca2+ mobilisation in H9c2 cardiac cells. Biochem Pharmacol 2003; 65:783-93. [PMID: 12628492 DOI: 10.1016/s0006-2952(02)01624-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Expression and pharmacological properties of endothelin receptors (ETRs) were investigated in H9c2 cardiomyoblasts. The mechanism of receptor-mediated modulation of intracellular Ca(2+) concentration ([Ca(2+)](i)) was examined by measuring fluorescence increase of Fluo-3-loaded cells with flow cytometry. Binding assays showed that [125I]endothelin-1 (ET-1) bound to a single class of high affinity binding sites in cardiomyoblast membranes. Endothelin-3 (ET-3) displaced bound [125I]ET-1 in a biphasic manner, in contrast to an ET(B)-selective agonist, IRL-1620, that was ineffective. The ET(B)-selective antagonist, BQ-788, inhibited [125I]ET-1 binding in a monophasic manner and with low potency. An ET(A)-selective antagonist, BQ-123, competed [125I]ET-1 binding in a monophasic manner. This antagonist was found to be 13-fold more potent than BQ-788. Immunoblotting analysis using anti-ET(A) and -ET(B) antibodies confirmed a predominant expression of the ET(A) receptor. ET-1 induced a concentration-dependent increase of Fluo-3 fluorescence in cardiomyoblasts resuspended in buffer containing 1mM CaCl(2). Treatment of cells with antagonists, PD-145065 and BQ-123, or a phospholipase C-beta inhibitor, U-73122, abolished ET-1-mediated increases in fluorescence. The close structural analogue of U-73122, U-73343, caused a minimal effect on the concentration-response curve of ET-1. ET-3 produced no major increase of Fluo-3 fluorescence. Removal of extracellular Ca(2+) resulted in a shift to the right of the ET-1 concentration-response curve. Both the L-type voltage-operated Ca(2+) channel blocker, nifedipine, and the ryanodine receptor inhibitor, dantrolene, reduced the efficacy of ET-1. Two protein kinase C inhibitors reduced both potency and efficacy of ET-1. Our results demonstrate that ET(A) receptors are expressed and functionally coupled to rise of [Ca(2+)](i) in H9c2 cardiomyoblasts. ET-1-induced [Ca(2+)](i) increase is triggered by Ca(2+) release from intracellular inositol 1,4,5-trisphosphate-gated stores; plasma membrane Ca(2+) channels and ryanodine receptors participate in sustaining the Ca(2+) response. Regulation of channel opening by protein kinase C is also involved in the process of [Ca(2+)](i) increase.
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Affiliation(s)
- Francesca Ceccarelli
- Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, Italy
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Ju YJ, Wang CM, Hung AC, Lo JC, Lin HJ, Sun SH. Endothelin-1 stimulated capacitative Ca2+ entry through ET(A) receptors of a rat brain-derived type-1 astrocyte cell line, IA-1g1. Cell Signal 2003; 15:197-207. [PMID: 12464391 DOI: 10.1016/s0898-6568(02)00079-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The present study demonstrated that endotheline-1 (ET-1) stimulated a biphasic (transient and sustained) increase in [Ca(2+)](i) and signaling was blocked by BQ123 and inhibited by BQ788. RT-PCR analysis revealed that ET(A) was expressed more than ET(B) mRNA-suggesting that ET(A) is the major receptor. Simply reintroducing Ca(2+) in the buffer stimulated a sustained increase in [Ca(2+)](i) and the effect was inhibited by U73122, thapsigargin (TG), miconazole and SKF96365. When measured in Ca(2+)-free buffer, the ET-1-stimulated Ca(2+) transient decreased by 73% and the reintroduction of Ca(2+) induced a large sustained increase in [Ca(2+)](i). These effects were not affected by nifedipine, but were inhibited by miconazole and SKF96365-indicating that the sustained increase in [Ca(2+)](i) mediated by ET-1 was mostly due to capacitative Ca(2+) entry (CCE). The ET-1-induced CCE was inhibited by phorbol ester (PMA) but was enhanced by GF109203X; it was also enhanced by 8-bromo-cyclic AMP (8-Br-cAMP) but was inhibited by H89. Thus, protein kinase C (PKC) negatively regulated and cAMP-dependent protein kinase (PKA) positively regulated the ET-1-mediated CCE in these cells.
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Affiliation(s)
- You Jing Ju
- Institute of Neuroscience, College of Life Science, National Yang Ming University, #155, Section 2, Li-Non Street, Shi-Pai, Taipei, Taiwan, ROC
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