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Arancibia F, De Giorgis D, Medina F, Hermosilla T, Simon F, Varela D. Role of the Ca V1.2 distal carboxy terminus in the regulation of L-type current. Channels (Austin) 2024; 18:2338782. [PMID: 38691022 PMCID: PMC11067984 DOI: 10.1080/19336950.2024.2338782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 03/31/2024] [Indexed: 05/03/2024] Open
Abstract
L-type calcium channels are essential for the excitation-contraction coupling in cardiac muscle. The CaV1.2 channel is the most predominant isoform in the ventricle which consists of a multi-subunit membrane complex that includes the CaV1.2 pore-forming subunit and auxiliary subunits like CaVα2δ and CaVβ2b. The CaV1.2 channel's C-terminus undergoes proteolytic cleavage, and the distal C-terminal domain (DCtermD) associates with the channel core through two domains known as proximal and distal C-terminal regulatory domain (PCRD and DCRD, respectively). The interaction between the DCtermD and the remaining C-terminus reduces the channel activity and modifies voltage- and calcium-dependent inactivation mechanisms, leading to an autoinhibitory effect. In this study, we investigate how the interaction between DCRD and PCRD affects the inactivation processes and CaV1.2 activity. We expressed a 14-amino acid peptide miming the DCRD-PCRD interaction sequence in both heterologous systems and cardiomyocytes. Our results show that overexpression of this small peptide can displace the DCtermD and replicate the effects of the entire DCtermD on voltage-dependent inactivation and channel inhibition. However, the effect on calcium-dependent inactivation requires the full DCtermD and is prevented by overexpression of calmodulin. In conclusion, our results suggest that the interaction between DCRD and PCRD is sufficient to bring about the current inhibition and alter the voltage-dependent inactivation, possibly in an allosteric manner. Additionally, our data suggest that the DCtermD competitively modifies the calcium-dependent mechanism. The identified peptide sequence provides a valuable tool for further dissecting the molecular mechanisms that regulate L-type calcium channels' basal activity in cardiomyocytes.
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Affiliation(s)
- Felipe Arancibia
- Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Chile, Santiago, Chile
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Daniela De Giorgis
- Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Chile, Santiago, Chile
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Franco Medina
- Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Chile, Santiago, Chile
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Tamara Hermosilla
- Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Chile, Santiago, Chile
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Felipe Simon
- Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Chile, Santiago, Chile
- Laboratory of Integrative Physiopathology, Faculty of Life Sciences, Universidad Andres Bello, Santiago, Chile
- Millennium Institute on Immunology and Immunotherapy, Santiago, Chile
| | - Diego Varela
- Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Chile, Santiago, Chile
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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Htet M, Lei S, Bajpayi S, Gangrade H, Arvanitis M, Zoitou A, Murphy S, Chen EZ, Koleini N, Lin BL, Kwon C, Tampakakis E. A transcriptional enhancer regulates cardiac maturation. NATURE CARDIOVASCULAR RESEARCH 2024; 3:666-684. [PMID: 39196225 DOI: 10.1038/s44161-024-00484-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 05/02/2024] [Indexed: 08/29/2024]
Abstract
Cardiomyocyte maturation is crucial for generating adult cardiomyocytes and the application of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). However, regulation at the cis-regulatory element level and its role in heart disease remain unclear. Alpha-actinin 2 (ACTN2) levels increase during CM maturation. In this study, we investigated a clinically relevant, conserved ACTN2 enhancer's effects on CM maturation using hPSC and mouse models. Heterozygous ACTN2 enhancer deletion led to abnormal CM morphology, reduced function and mitochondrial respiration. Transcriptomic analyses in vitro and in vivo showed disrupted CM maturation and upregulated anabolic mammalian target for rapamycin (mTOR) signaling, promoting senescence and hindering maturation. As confirmation, ACTN2 enhancer deletion induced heat shock protein 90A expression, a chaperone mediating mTOR activation. Conversely, targeting the ACTN2 enhancer via enhancer CRISPR activation (enCRISPRa) promoted hPSC-CM maturation. Our studies reveal the transcriptional enhancer's role in cardiac maturation and disease, offering insights into potentially fine-tuning gene expression to modulate cardiomyocyte physiology.
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Grants
- K99 HL155840 NHLBI NIH HHS
- 2023- MSCRFL-5984 Maryland Stem Cell Research Fund (MSCRF)
- 5K08HL166690 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- CDA34660077 American Heart Association (American Heart Association, Inc.)
- R00 HL155840 NHLBI NIH HHS
- TPA1058685 American Heart Association (American Heart Association, Inc.)
- T32HL007227 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- HL-145135 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- R01HL156947 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- K08 HL145135 NHLBI NIH HHS
- MSCRFD-6139 Maryland Stem Cell Research Fund (MSCRF)
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Affiliation(s)
- Myo Htet
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
| | - Shunyao Lei
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Sheetal Bajpayi
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
| | - Harshi Gangrade
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
| | - Marios Arvanitis
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Department of Genetic Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Asimina Zoitou
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Sean Murphy
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
| | - Elaine Zhelan Chen
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Navid Koleini
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
| | - Brian Leei Lin
- Department of Cell Biology, Neurobiology, and Anatomy and Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Chulan Kwon
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Institute of Cell Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Emmanouil Tampakakis
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA.
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA.
- Department of Genetic Medicine, Johns Hopkins University, Baltimore, MD, USA.
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3
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Ojima K, Kigaki M, Ichimura E, Suzuki T, Kobayashi K, Muroya S, Nishimura T. Endogenous slow and fast myosin dynamics in myofibers isolated from mice expressing GFP-Myh7 and Kusabira Orange-Myh1. Am J Physiol Cell Physiol 2022; 323:C520-C535. [PMID: 35759444 DOI: 10.1152/ajpcell.00415.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Skeletal muscle consists of slow and fast myofibers in which different myosin isoforms are expressed. Approximately 300 myosins form a single thick filament in the myofibrils, where myosin is continuously exchanged. However, endogenous slow and fast myosin dynamics have not been fully understood. To elucidate those dynamics, here we generated mice expressing green fluorescence protein-tagged slow myosin heavy chain (GFP-Myh7) and Kusabira Orange fluorescence protein-tagged fast myosin heavy chain (KuO-Myh1). First, these mice enabled us to distinguish between GFP- and KuO-myofibers under fluorescence microscopy: GFP-Myh7 and KuO-Myh1 were exclusively expressed in slow myofibers and fast myofibers, respectively. Next, to monitor endogenous myosin dynamics, fluorescence recovery after photobleaching (FRAP) was conducted. The mobile fraction (Mf) of GFP-Myh7 and that of KuO-Myh1 were almost constant values independent of the regions of the myofibers and the muscle portions where the myofibers were isolated. Intriguingly, proteasome inhibitor treatment significantly decreased the Mf in GFP-Myh7 but not in KuO-Myh1 myofibers, indicating that the response to a disturbance in protein turnover depended on muscle fiber type. Taken together, the present results indicated that the mice we generated are promising tools not only for distinguishing between GFP- and KuO-myofibers but also for studying the dynamics of endogenous myosin isoforms by live-cell fluorescence imaging.
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Affiliation(s)
- Koichi Ojima
- Muscle Biology Research Unit, Division of Animal Products Research, Institute of Livestock and Grassland Science, NARO, Tsukuba, Ibaraki, Japan
| | - Masahiro Kigaki
- Research Faculty of Agriculture, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Emi Ichimura
- Research Faculty of Agriculture, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Takahiro Suzuki
- Laboratory of Muscle and Meat Science, Department of Animal and Marine Bioresource Sciences, Faculty of Agriculture, Graduate School of Agriculture, Kyushu University, Fukuoka, Japan
| | - Ken Kobayashi
- Research Faculty of Agriculture, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Susumu Muroya
- Muscle Biology Research Unit, Division of Animal Products Research, Institute of Livestock and Grassland Science, NARO, Tsukuba, Ibaraki, Japan
| | - Takanori Nishimura
- Research Faculty of Agriculture, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
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Preferential Expression of Ca2+-Stimulable Adenylyl Cyclase III in the Supraventricular Area, Including Arrhythmogenic Pulmonary Vein of the Rat Heart. Biomolecules 2022; 12:biom12050724. [PMID: 35625651 PMCID: PMC9138642 DOI: 10.3390/biom12050724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/16/2022] [Accepted: 05/19/2022] [Indexed: 12/10/2022] Open
Abstract
Ectopic excitability in pulmonary veins (PVs) is the major cause of atrial fibrillation. We previously reported that the inositol trisphosphate receptor in rat PV cardiomyocytes cooperates with the Na+-Ca2+ exchanger to provoke ectopic automaticity in response to norepinephrine. Here, we focused on adenylyl cyclase (AC) as another effector of norepinephrine stimulation. RT-PCR, immunohistochemistry, and Western blotting revealed that the abundant expression of Ca2+-stimulable AC3 was restricted to the supraventricular area, including the PVs. All the other AC isotypes hardly displayed any region-specific expressions. Immunostaining of isolated cardiomyocytes showed an enriched expression of AC3 along the t-tubules in PV myocytes. The cAMP-dependent response of L-type Ca2+ currents in the PV and LA cells is strengthened by the 0.1 mM intracellular Ca2+ condition, unlike in the ventricular cells. The norepinephrine-induced automaticity of PV cardiomyocytes was reversibly suppressed by 100 µM SQ22536, an adenine-like AC inhibitor. These findings suggest that the specific expression of AC3 along t-tubules may contribute to arrhythmogenic automaticity in rat PV cardiomyocytes.
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Abstract
Each heartbeat is initiated by the action potential, an electrical signal that depolarizes the plasma membrane and activates a cycle of calcium influx via voltage-gated calcium channels, calcium release via ryanodine receptors, and calcium reuptake and efflux via calcium-ATPase pumps and sodium-calcium exchangers. Agonists of the sympathetic nervous system bind to adrenergic receptors in cardiomyocytes, which, via cascading signal transduction pathways and protein kinase A (PKA), increase the heart rate (chronotropy), the strength of myocardial contraction (inotropy), and the rate of myocardial relaxation (lusitropy). These effects correlate with increased intracellular concentration of calcium, which is required for the augmentation of cardiomyocyte contraction. Despite extensive investigations, the molecular mechanisms underlying sympathetic nervous system regulation of calcium influx in cardiomyocytes have remained elusive over the last 40 years. Recent studies have uncovered the mechanisms underlying this fundamental biologic process, namely that PKA phosphorylates a calcium channel inhibitor, Rad, thereby releasing inhibition and increasing calcium influx. Here, we describe an updated model for how signals from adrenergic agonists are transduced to stimulate calcium influx and contractility in the heart.
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Affiliation(s)
- Arianne Papa
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Jared Kushner
- Division of Cardiology, Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA;
| | - Steven O Marx
- Division of Cardiology, Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA;
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
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6
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Al Katat A, Zhao J, Calderone A, Parent L. Sympathetic Stimulation Upregulates the Ca 2+ Channel Subunit, Ca Vα2δ1, via the β1 and ERK 1/2 Pathway in Neonatal Ventricular Cardiomyocytes. Cells 2022; 11:188. [PMID: 35053304 PMCID: PMC8774121 DOI: 10.3390/cells11020188] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 12/29/2021] [Accepted: 01/03/2022] [Indexed: 02/04/2023] Open
Abstract
Intracellular Ca2+ overload secondary to chronic hemodynamic stimuli promotes the recruitment of Ca2+-dependent signaling implicated in cardiomyocyte hypertrophy. The present study tested the hypothesis that sympathetic-mediated hypertrophy of neonatal rat ventricular cardiomyocytes (NRVMs) translated to an increase in calcium influx secondary to the upregulation of CaV1.2 channel subunits. Confocal imaging of norepinephrine (NE)-treated NRVMs revealed a hypertrophic response compared to untreated NRVMs. L-type CaV1.2 peak current density was increased 4-fold following a 24-h stimulation with NE. NE-treated NRVMs exhibited a significant upregulation of CaVα2δ1 and CaVβ3 protein levels without significant changes of CaVα1C and CaVβ2 protein levels. Pre-treatment with the β1-blocker metoprolol failed to inhibit hypertrophy or CaVβ3 upregulation whereas CaVα2δ1 protein levels were significantly reduced. NE promoted the phosphorylation of ERK 1/2, and the response was attenuated by the β1-blocker. U0126 pre-treatment suppressed NE-induced ERK1/2 phosphorylation but failed to attenuate hypertrophy. U0126 inhibition of ERK1/2 phosphorylation prevented NE-mediated upregulation of CaVα2δ1, whereas CaVβ3 protein levels remained elevated. Thus, β1-adrenergic receptor-mediated recruitment of the ERK1/2 plays a seminal role in the upregulation of CaVα2δ1 in NRVMs independent of the concomitant hypertrophic response. However, the upregulation of CaVβ3 protein levels may be directly dependent on the hypertrophic response of NRVMs.
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Affiliation(s)
- Aya Al Katat
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Université de Montréal, Montréal, QC H3T 1J4, Canada; (A.A.K.); (A.C.)
- Research Center, Montreal Heart Institute, 5000 Rue Belanger, Montréal, QC H1T 1C8, Canada;
| | - Juan Zhao
- Research Center, Montreal Heart Institute, 5000 Rue Belanger, Montréal, QC H1T 1C8, Canada;
| | - Angelino Calderone
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Université de Montréal, Montréal, QC H3T 1J4, Canada; (A.A.K.); (A.C.)
- Research Center, Montreal Heart Institute, 5000 Rue Belanger, Montréal, QC H1T 1C8, Canada;
| | - Lucie Parent
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Université de Montréal, Montréal, QC H3T 1J4, Canada; (A.A.K.); (A.C.)
- Research Center, Montreal Heart Institute, 5000 Rue Belanger, Montréal, QC H1T 1C8, Canada;
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Vinogradova TM, Lakatta EG. Dual Activation of Phosphodiesterase 3 and 4 Regulates Basal Cardiac Pacemaker Function and Beyond. Int J Mol Sci 2021. [PMID: 34445119 DOI: 10.3390/ijms22168414.pmid:34445119;pmcid:pmc8395138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
The sinoatrial (SA) node is the physiological pacemaker of the heart, and resting heart rate in humans is a well-known risk factor for cardiovascular disease and mortality. Consequently, the mechanisms of initiating and regulating the normal spontaneous SA node beating rate are of vital importance. Spontaneous firing of the SA node is generated within sinoatrial nodal cells (SANC), which is regulated by the coupled-clock pacemaker system. Normal spontaneous beating of SANC is driven by a high level of cAMP-mediated PKA-dependent protein phosphorylation, which rely on the balance between high basal cAMP production by adenylyl cyclases and high basal cAMP degradation by cyclic nucleotide phosphodiesterases (PDEs). This diverse class of enzymes includes 11 families and PDE3 and PDE4 families dominate in both the SA node and cardiac myocardium, degrading cAMP and, consequently, regulating basal cardiac pacemaker function and excitation-contraction coupling. In this review, we will demonstrate similarities between expression, distribution, and colocalization of various PDE subtypes in SANC and cardiac myocytes of different species, including humans, focusing on PDE3 and PDE4. Here, we will describe specific targets of the coupled-clock pacemaker system modulated by dual PDE3 + PDE4 activation and provide evidence that concurrent activation of PDE3 + PDE4, operating in a synergistic manner, regulates the basal cardiac pacemaker function and provides control over normal spontaneous beating of SANCs through (PDE3 + PDE4)-dependent modulation of local subsarcolemmal Ca2+ releases (LCRs).
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Affiliation(s)
- Tatiana M Vinogradova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institute of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institute of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
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Dual Activation of Phosphodiesterase 3 and 4 Regulates Basal Cardiac Pacemaker Function and Beyond. Int J Mol Sci 2021; 22:ijms22168414. [PMID: 34445119 PMCID: PMC8395138 DOI: 10.3390/ijms22168414] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/01/2021] [Accepted: 08/02/2021] [Indexed: 11/17/2022] Open
Abstract
The sinoatrial (SA) node is the physiological pacemaker of the heart, and resting heart rate in humans is a well-known risk factor for cardiovascular disease and mortality. Consequently, the mechanisms of initiating and regulating the normal spontaneous SA node beating rate are of vital importance. Spontaneous firing of the SA node is generated within sinoatrial nodal cells (SANC), which is regulated by the coupled-clock pacemaker system. Normal spontaneous beating of SANC is driven by a high level of cAMP-mediated PKA-dependent protein phosphorylation, which rely on the balance between high basal cAMP production by adenylyl cyclases and high basal cAMP degradation by cyclic nucleotide phosphodiesterases (PDEs). This diverse class of enzymes includes 11 families and PDE3 and PDE4 families dominate in both the SA node and cardiac myocardium, degrading cAMP and, consequently, regulating basal cardiac pacemaker function and excitation-contraction coupling. In this review, we will demonstrate similarities between expression, distribution, and colocalization of various PDE subtypes in SANC and cardiac myocytes of different species, including humans, focusing on PDE3 and PDE4. Here, we will describe specific targets of the coupled-clock pacemaker system modulated by dual PDE3 + PDE4 activation and provide evidence that concurrent activation of PDE3 + PDE4, operating in a synergistic manner, regulates the basal cardiac pacemaker function and provides control over normal spontaneous beating of SANCs through (PDE3 + PDE4)-dependent modulation of local subsarcolemmal Ca2+ releases (LCRs).
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9
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Reconstitution of β-adrenergic regulation of Ca V1.2: Rad-dependent and Rad-independent protein kinase A mechanisms. Proc Natl Acad Sci U S A 2021; 118:2100021118. [PMID: 34001616 DOI: 10.1073/pnas.2100021118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
L-type voltage-gated CaV1.2 channels crucially regulate cardiac muscle contraction. Activation of β-adrenergic receptors (β-AR) augments contraction via protein kinase A (PKA)-induced increase of calcium influx through CaV1.2 channels. To date, the full β-AR cascade has never been heterologously reconstituted. A recent study identified Rad, a CaV1.2 inhibitory protein, as essential for PKA regulation of CaV1.2. We corroborated this finding and reconstituted the complete pathway with agonist activation of β1-AR or β2-AR in Xenopus oocytes. We found, and distinguished between, two distinct pathways of PKA modulation of CaV1.2: Rad dependent (∼80% of total) and Rad independent. The reconstituted system reproduces the known features of β-AR regulation in cardiomyocytes and reveals several aspects: the differential regulation of posttranslationally modified CaV1.2 variants and the distinct features of β1-AR versus β2-AR activity. This system allows for the addressing of central unresolved issues in the β-AR-CaV1.2 cascade and will facilitate the development of therapies for catecholamine-induced cardiac pathologies.
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Segura E, Mehta A, Marsolais M, Quan XR, Zhao J, Sauvé R, Spafford JD, Parent L. An ancestral MAGUK protein supports the modulation of mammalian voltage-gated Ca 2+ channels through a conserved Ca Vβ-like interface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183439. [PMID: 32814116 DOI: 10.1016/j.bbamem.2020.183439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/11/2020] [Accepted: 08/03/2020] [Indexed: 01/09/2023]
Abstract
Eukaryote voltage-gated Ca2+ channels of the CaV2 channel family are hetero-oligomers formed by the pore-forming CaVα1 protein assembled with auxiliary CaVα2δ and CaVβ subunits. CaVβ subunits are formed by a Src homology 3 (SH3) domain and a guanylate kinase (GK) domain connected through a HOOK domain. The GK domain binds a conserved cytoplasmic region of the pore-forming CaVα1 subunit referred as the "AID". Herein we explored the phylogenetic and functional relationship between CaV channel subunits in distant eukaryotic organisms by investigating the function of a MAGUK protein (XM_004990081) cloned from the choanoflagellate Salpingoeca rosetta (Sro). This MAGUK protein (Sroβ) features SH3 and GK structural domains with a 25% primary sequence identity to mammalian CaVβ. Recombinant expression of its cDNA with mammalian high-voltage activated Ca2+ channel CaV2.3 in mammalian HEK cells produced robust voltage-gated inward Ca2+ currents with typical activation and inactivation properties. Like CaVβ, Sroβ prevents fast degradation of total CaV2.3 proteins in cycloheximide assays. The three-dimensional homology model predicts an interaction between the GK domain of Sroβ and the AID motif of the pore-forming CaVα1 protein. Substitution of AID residues Trp (W386A) and Tyr (Y383A) significantly impaired co-immunoprecipitation of CaV2.3 with Sroβ and functional upregulation of CaV2.3 currents. Likewise, a 6-residue deletion within the GK domain of Sroβ, similar to the locus found in mammalian CaVβ, significantly reduced peak current density. Altogether our data demonstrate that an ancestor MAGUK protein reconstitutes the biophysical and molecular features responsible for channel upregulation by mammalian CaVβ through a minimally conserved molecular interface.
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Affiliation(s)
- Emilie Segura
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Canada; Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada
| | - Amrit Mehta
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Mireille Marsolais
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada
| | - Xin R Quan
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Juan Zhao
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada
| | - Rémy Sauvé
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Canada
| | - J David Spafford
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Lucie Parent
- Département de Pharmacologie et Physiologie, Faculté de Médecine, Canada; Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H1T 1C8, Canada.
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11
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Ednie AR, Bennett ES. Intracellular O-linked glycosylation directly regulates cardiomyocyte L-type Ca 2+ channel activity and excitation-contraction coupling. Basic Res Cardiol 2020; 115:59. [PMID: 32910282 DOI: 10.1007/s00395-020-00820-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 08/17/2020] [Indexed: 12/20/2022]
Abstract
Cardiomyocyte L-type Ca2+ channels (Cavs) are targets of signaling pathways that modulate channel activity in response to physiologic stimuli. Cav regulation is typically transient and beneficial but chronic stimulation can become pathologic; therefore, gaining a more complete understanding of Cav regulation is of critical importance. Intracellular O-linked glycosylation (O-GlcNAcylation), which is the result of two enzymes that dynamically add and remove single N-acetylglucosamines to and from intracellular serine/threonine residues (OGT and OGA respectively), has proven to be an increasingly important post-translational modification that contributes to the regulation of many physiologic processes. However, there is currently no known role for O-GlcNAcylation in the direct regulation of Cav activity nor is its contribution to cardiac electrical signaling and EC coupling well understood. Here we aimed to delineate the role of O-GlcNAcylation in regulating cardiomyocyte L-type Cav activity and its subsequent effect on EC coupling by utilizing a mouse strain possessing an inducible cardiomyocyte-specific OGT-null-transgene. Ablation of the OGT-gene in adult cardiomyocytes (OGTKO) reduced OGT expression and O-GlcNAcylation by > 90%. Voltage clamp recordings indicated an ~ 40% reduction in OGTKO Cav current (ICa), but with increased efficacy of adrenergic stimulation, and Cav steady-state gating and window current were significantly depolarized. Consistently, OGTKO cardiomyocyte intracellular Ca2+ release and contractility were diminished and demonstrated greater beat-to-beat variability. Additionally, we show that the Cav α1 and β2 subunits are O-GlcNAcylated while α2δ1 is not. Echocardiographic analyses indicated that the reductions in OGTKO cardiomyocyte Ca2+ handling and contractility were conserved at the whole-heart level as evidenced by significantly reduced left-ventricular contractility in the absence of hypertrophy. The data indicate, for the first time, that O-GlcNAc signaling is a critical and direct regulator of cardiomyocyte ICa achieved through altered Cav expression, gating, and response to adrenergic stimulation; these mechanisms have significant implications for understanding how EC coupling is regulated in health and disease.
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Affiliation(s)
- Andrew R Ednie
- Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, 143 Biological Sciences II, 3640 Colonel Glenn Hwy, Dayton, OH, 45435, USA.
| | - Eric S Bennett
- Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, 143 Biological Sciences II, 3640 Colonel Glenn Hwy, Dayton, OH, 45435, USA
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12
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Function of Adenylyl Cyclase in Heart: the AKAP Connection. J Cardiovasc Dev Dis 2018; 5:jcdd5010002. [PMID: 29367580 PMCID: PMC5872350 DOI: 10.3390/jcdd5010002] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/09/2018] [Accepted: 01/11/2018] [Indexed: 12/13/2022] Open
Abstract
Cyclic adenosine monophosphate (cAMP), synthesized by adenylyl cyclase (AC), is a universal second messenger that regulates various aspects of cardiac physiology from contraction rate to the initiation of cardioprotective stress response pathways. Local pools of cAMP are maintained by macromolecular complexes formed by A-kinase anchoring proteins (AKAPs). AKAPs facilitate control by bringing together regulators of the cAMP pathway including G-protein-coupled receptors, ACs, and downstream effectors of cAMP to finely tune signaling. This review will summarize the distinct roles of AC isoforms in cardiac function and how interactions with AKAPs facilitate AC function, highlighting newly appreciated roles for lesser abundant AC isoforms.
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13
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Folci A, Steinberger A, Lee B, Stanika R, Scheruebel S, Campiglio M, Ramprecht C, Pelzmann B, Hell JW, Obermair GJ, Heine M, Di Biase V. Molecular mimicking of C-terminal phosphorylation tunes the surface dynamics of Ca V1.2 calcium channels in hippocampal neurons. J Biol Chem 2017; 293:1040-1053. [PMID: 29180451 PMCID: PMC5777246 DOI: 10.1074/jbc.m117.799585] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 11/03/2017] [Indexed: 11/26/2022] Open
Abstract
L-type voltage-gated CaV1.2 calcium channels (CaV1.2) are key regulators of neuronal excitability, synaptic plasticity, and excitation-transcription coupling. Surface-exposed CaV1.2 distributes in clusters along the dendrites of hippocampal neurons. A permanent exchange between stably clustered and laterally diffusive extra-clustered channels maintains steady-state levels of CaV1.2 at dendritic signaling domains. A dynamic equilibrium between anchored and diffusive receptors is a common feature among ion channels and is crucial to modulate signaling transduction. Despite the importance of this fine regulatory system, the molecular mechanisms underlying the surface dynamics of CaV1.2 are completely unexplored. Here, we examined the dynamic states of CaV1.2 depending on phosphorylation on Ser-1700 and Ser-1928 at the channel C terminus. Phosphorylation at these sites is strongly involved in CaV1.2-mediated nuclear factor of activated T cells (NFAT) signaling, long-term potentiation, and responsiveness to adrenergic stimulation. We engineered CaV1.2 constructs mimicking phosphorylation at Ser-1700 and Ser-1928 and analyzed their behavior at the membrane by immunolabeling protocols, fluorescence recovery after photobleaching, and single particle tracking. We found that the phosphomimetic S1928E variant increases the mobility of CaV1.2 without altering the steady-state maintenance of cluster in young neurons and favors channel stabilization later in differentiation. Instead, mimicking phosphorylation at Ser-1700 promoted the diffusive state of CaV1.2 irrespective of the differentiation stage. Together, these results reveal that phosphorylation could contribute to the establishment of channel anchoring mechanisms depending on the neuronal differentiation state. Finally, our findings suggest a novel mechanism by which phosphorylation at the C terminus regulates calcium signaling by tuning the content of CaV1.2 at signaling complexes.
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Affiliation(s)
- Alessandra Folci
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Angela Steinberger
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Boram Lee
- the Department of Pharmacology, University of California, Davis, California 95616
| | - Ruslan Stanika
- the Department of Physiology and Medical Physics, Medical University of Innsbruck, 6020 Innsbruck, Austria, and
| | - Susanne Scheruebel
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Marta Campiglio
- the Department of Physiology and Medical Physics, Medical University of Innsbruck, 6020 Innsbruck, Austria, and
| | - Claudia Ramprecht
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Brigitte Pelzmann
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria
| | - Johannes W Hell
- the Department of Pharmacology, University of California, Davis, California 95616
| | - Gerald J Obermair
- the Department of Physiology and Medical Physics, Medical University of Innsbruck, 6020 Innsbruck, Austria, and
| | - Martin Heine
- the Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Valentina Di Biase
- From the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria,
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14
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Raifman TK, Kumar P, Haase H, Klussmann E, Dascal N, Weiss S. Protein kinase C enhances plasma membrane expression of cardiac L-type calcium channel, Ca V1.2. Channels (Austin) 2017; 11:604-615. [PMID: 28901828 DOI: 10.1080/19336950.2017.1369636] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
L-type-voltage-dependent Ca2+ channels (L-VDCCs; CaV1.2, α1C), crucial in cardiovascular physiology and pathology, are modulated via activation of G-protein-coupled receptors and subsequently protein kinase C (PKC). Despite extensive study, key aspects of the mechanisms leading to PKC-induced Ca2+ current increase are unresolved. A notable residue, Ser1928, located in the distal C-terminus (dCT) of α1C was shown to be phosphorylated by PKC. CaV1.2 undergoes posttranslational modifications yielding full-length and proteolytically cleaved CT-truncated forms. We have previously shown that, in Xenopus oocytes, activation of PKC enhances α1C macroscopic currents. This increase depended on the isoform of α1C expressed. Only isoforms containing the cardiac, long N-terminus (L-NT), were upregulated by PKC. Ser1928 was also crucial for the full effect of PKC. Here we report that, in Xenopus oocytes, following PKC activation the amount of α1C protein expressed in the plasma membrane (PM) increases within minutes. The increase in PM content is greater with full-length α1C than in dCT-truncated α1C, and requires Ser1928. The same was observed in HL-1 cells, a mouse atrium cell line natively expressing cardiac α1C, which undergoes the proteolytic cleavage of the dCT, thus providing a native setting for exploring the effects of PKC in cardiomyocytes. Interestingly, activation of PKC preferentially increased the PM levels of full-length, L-NT α1C. Our findings suggest that part of PKC regulation of CaV1.2 in the heart involves changes in channel's cellular fate. The mechanism of this PKC regulation appears to involve the C-terminus of α1C, possibly corroborating the previously proposed role of NT-CT interactions within α1C.
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Affiliation(s)
- Tal Keren Raifman
- a Department of Physiology and Pharmacology , Sackler School of Medicine, Tel Aviv University , Tel Aviv , Israel.,b Department of Physiotherapy , Zfat Academic College , Zfat , Israel
| | - Prabodh Kumar
- a Department of Physiology and Pharmacology , Sackler School of Medicine, Tel Aviv University , Tel Aviv , Israel
| | - Hannelore Haase
- c Max Delbruck Center for Molecular Medicine (MDC) , Berlin , Germany
| | - Enno Klussmann
- c Max Delbruck Center for Molecular Medicine (MDC) , Berlin , Germany
| | - Nathan Dascal
- a Department of Physiology and Pharmacology , Sackler School of Medicine, Tel Aviv University , Tel Aviv , Israel
| | - Sharon Weiss
- a Department of Physiology and Pharmacology , Sackler School of Medicine, Tel Aviv University , Tel Aviv , Israel
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15
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Bourdin B, Briot J, Tétreault MP, Sauvé R, Parent L. Negatively charged residues in the first extracellular loop of the L-type Ca V1.2 channel anchor the interaction with the Ca Vα2δ1 auxiliary subunit. J Biol Chem 2017; 292:17236-17249. [PMID: 28864774 PMCID: PMC5655503 DOI: 10.1074/jbc.m117.806893] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/18/2017] [Indexed: 12/20/2022] Open
Abstract
Voltage-gated L-type CaV1.2 channels in cardiomyocytes exist as heteromeric complexes. Co-expression of CaVα2δ1 with CaVβ/CaVα1 proteins reconstitutes the functional properties of native L-type currents, but the interacting domains at the CaV1.2/CaVα2δ1 interface are unknown. Here, a homology-based model of CaV1.2 identified protein interfaces between the extracellular domain of CaVα2δ1 and the extracellular loops of the CaVα1 protein in repeats I (IS1S2 and IS5S6), II (IIS5S6), and III (IIIS5S6). Insertion of a 9-residue hemagglutinin epitope in IS1S2, but not in IS5S6 or in IIS5S6, prevented the co-immunoprecipitation of CaV1.2 with CaVα2δ1. IS1S2 contains a cluster of three conserved negatively charged residues Glu-179, Asp-180, and Asp-181 that could contribute to non-bonded interactions with CaVα2δ1. Substitutions of CaV1.2 Asp-181 impaired the co-immunoprecipitation of CaVβ/CaV1.2 with CaVα2δ1 and the CaVα2δ1-dependent shift in voltage-dependent activation gating. In contrast, single substitutions in CaV1.2 in neighboring positions in the same loop (179, 180, and 182–184) did not significantly alter the functional up-regulation of CaV1.2 whole-cell currents. However, a negatively charged residue at position 180 was necessary to convey the CaVα2δ1-mediated shift in the activation gating. We also found a more modest contribution from the positively charged Arg-1119 in the extracellular pore region in repeat III of CaV1.2. We conclude that CaV1.2 Asp-181 anchors the physical interaction that facilitates the CaVα2δ1-mediated functional modulation of CaV1.2 currents. By stabilizing the first extracellular loop of CaV1.2, CaVα2δ1 may up-regulate currents by promoting conformations of the voltage sensor that are associated with the channel's open state.
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Affiliation(s)
- Benoîte Bourdin
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Julie Briot
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada.,From the Département de Pharmacologie et Physiologie, Faculté de Médecine, and
| | - Marie-Philippe Tétreault
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Rémy Sauvé
- From the Département de Pharmacologie et Physiologie, Faculté de Médecine, and
| | - Lucie Parent
- Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada .,From the Département de Pharmacologie et Physiologie, Faculté de Médecine, and
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16
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Proteolytic cleavage and PKA phosphorylation of α 1C subunit are not required for adrenergic regulation of Ca V1.2 in the heart. Proc Natl Acad Sci U S A 2017; 114:9194-9199. [PMID: 28784807 DOI: 10.1073/pnas.1706054114] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Calcium influx through the voltage-dependent L-type calcium channel (CaV1.2) rapidly increases in the heart during "fight or flight" through activation of the β-adrenergic and protein kinase A (PKA) signaling pathway. The precise molecular mechanisms of β-adrenergic activation of cardiac CaV1.2, however, are incompletely known, but are presumed to require phosphorylation of residues in α1C and C-terminal proteolytic cleavage of the α1C subunit. We generated transgenic mice expressing an α1C with alanine substitutions of all conserved serine or threonine, which is predicted to be a potential PKA phosphorylation site by at least one prediction tool, while sparing the residues previously shown to be phosphorylated but shown individually not to be required for β-adrenergic regulation of CaV1.2 current (17-mutant). A second line included these 17 putative sites plus the five previously identified phosphoregulatory sites (22-mutant), thus allowing us to query whether regulation requires their contribution in combination. We determined that acute β-adrenergic regulation does not require any combination of potential PKA phosphorylation sites conserved in human, guinea pig, rabbit, rat, and mouse α1C subunits. We separately generated transgenic mice with inducible expression of proteolytic-resistant α1C Prevention of C-terminal cleavage did not alter β-adrenergic stimulation of CaV1.2 in the heart. These studies definitively rule out a role for all conserved consensus PKA phosphorylation sites in α1C in β-adrenergic stimulation of CaV1.2, and show that phosphoregulatory sites on α1C are not redundant and do not each fractionally contribute to the net stimulatory effect of β-adrenergic stimulation. Further, proteolytic cleavage of α1C is not required for β-adrenergic stimulation of CaV1.2.
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17
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Segura E, Bourdin B, Tétreault MP, Briot J, Allen BG, Mayer G, Parent L. Proteolytic cleavage of the hydrophobic domain in the Ca Vα2δ1 subunit improves assembly and activity of cardiac Ca V1.2 channels. J Biol Chem 2017; 292:11109-11124. [PMID: 28495885 DOI: 10.1074/jbc.m117.784355] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 04/24/2017] [Indexed: 11/06/2022] Open
Abstract
Voltage-gated L-type CaV1.2 channels in cardiomyocytes exist as heteromeric complexes with the pore-forming CaVα1, CaVβ, and CaVα2δ1 subunits. The full complement of subunits is required to reconstitute the native-like properties of L-type Ca2+ currents, but the molecular determinants responsible for the formation of the heteromeric complex are still being studied. Enzymatic treatment with phosphatidylinositol-specific phospholipase C, a phospholipase C specific for the cleavage of glycosylphosphatidylinositol (GPI)-anchored proteins, disrupted plasma membrane localization of the cardiac CaVα2δ1 prompting us to investigate deletions of its hydrophobic transmembrane domain. Patch-clamp experiments indicated that the C-terminally cleaved CaVα2δ1 proteins up-regulate CaV1.2 channels. In contrast, deleting the residues before the single hydrophobic segment (CaVα2δ1 Δ1059-1063) impaired current up-regulation. CaVα2δ1 mutants G1060I and G1061I nearly eliminated the cell-surface fluorescence of CaVα2δ1, indicated by two-color flow cytometry assays and confocal imaging, and prevented CaVα2δ1-mediated increase in peak current density and modulation of the voltage-dependent gating of CaV1.2. These impacts were specific to substitutions with isoleucine residues because functional modulation was partially preserved in CaVα2δ1 G1060A and G1061A proteins. Moreover, C-terminal fragments exhibited significantly altered mobility in denatured immunoblots of CaVα2δ1 G1060I and CaVα2δ1 G1061I, suggesting that these mutant proteins were impaired in proteolytic processing. Finally, CaVα2δ1 Δ1059-1063, but not CaVα2δ1 G1060A, failed to co-immunoprecipitate with CaV1.2. Altogether, our data support a model in which small neutral hydrophobic residues facilitate the post-translational cleavage of the CaVα2δ1 subunit at the predicted membrane interface and further suggest that preventing GPI anchoring of CaVα2δ1 averts its cell-surface expression, its interaction with CaVα1, and modulation of CaV1.2 currents.
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Affiliation(s)
- Emilie Segura
- From the Départements de Pharmacologie et Physiologie and.,the Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Benoîte Bourdin
- the Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Marie-Philippe Tétreault
- the Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Julie Briot
- From the Départements de Pharmacologie et Physiologie and.,the Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Bruce G Allen
- the Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada.,Médecine, Faculté de Médecine
| | - Gaétan Mayer
- the Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada.,the Faculté de Pharmacie, and
| | - Lucie Parent
- From the Départements de Pharmacologie et Physiologie and .,the Centre de Recherche de l'Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec H3C 3J7, Canada
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18
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Kashihara T, Nakada T, Kojima K, Takeshita T, Yamada M. Angiotensin II activates Ca V 1.2 Ca 2+ channels through β-arrestin2 and casein kinase 2 in mouse immature cardiomyocytes. J Physiol 2017; 595:4207-4225. [PMID: 28295363 DOI: 10.1113/jp273883] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/10/2017] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS Angiotensin II (AngII) is crucial in cardiovascular regulation in perinatal mammalians. Here we show that AngII increases twitch Ca2+ transients of mouse immature but not mature cardiomyocytes by robustly activating CaV 1.2 L-type Ca2+ channels through a novel signalling pathway involving angiotensin type 1 (AT1 ) receptors, β-arrestin2 and casein kinase 2. A β-arrestin-biased AT1 receptor agonist, TRV027, was as effective as AngII in activating L-type Ca2+ channels. Our results help understand the molecular mechanism by which AngII regulates the perinatal circulation and also suggest that β-arrestin-biased AT1 receptor agonists may be valuable therapeutics for paediatric heart failure. ABSTRACT Angiotensin II (AngII), the main effector peptide of the renin-angiotensin system, plays important roles in cardiovascular regulation in the perinatal period. Despite the well-known stimulatory effect of AngII on vascular contraction, little is known about regulation of contraction of the immature heart by AngII. Here we found that AngII significantly increased the peak amplitude of twitch Ca2+ transients by robustly activating L-type CaV 1.2 Ca2+ (CaV 1.2) channels in mouse immature but not mature cardiomyocytes. This response to AngII was mediated by AT1 receptors and β-arrestin2. A β-arrestin-biased AT1 receptor agonist was as effective as AngII in activating CaV 1.2 channels. Src-family tyrosine kinases (SFKs) and casein kinase 2α'β (CK2α'β) were sequentially activated when AngII activated CaV 1.2 channels. A cyclin-dependent kinase inhibitor, p27Kip1 (p27), inhibited CK2α'β, and AngII removed this inhibitory effect through phosphorylating tyrosine 88 of p27 via SFKs in cardiomyocytes. In a human embryonic kidney cell line, tsA201 cells, overexpression of CK2α'β but not c-Src directly activated recombinant CaV 1.2 channels composed of C-terminally truncated α1C , the distal C-terminus of α1C , β2C and α2 δ1 subunits, by phosphorylating threonine 1704 located at the interface between the proximal and the distal C-terminus of CaV 1.2α1C subunits. Co-immunoprecipitation revealed that CaV 1.2 channels, CK2α'β and p27 formed a macromolecular complex. Therefore, stimulation of AT1 receptors by AngII activates CaV 1.2 channels through β-arrestin2 and CK2α'β, thereby probably exerting a positive inotropic effect in the immature heart. Our results also indicated that β-arrestin-biased AT1 receptor agonists may be used as valuable therapeutics for paediatric heart failure in the future.
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Affiliation(s)
- Toshihide Kashihara
- Department of Molecular Pharmacology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - Tsutomu Nakada
- Department of Molecular Pharmacology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - Katsuhiko Kojima
- Department of Microbiology and Immunology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - Toshikazu Takeshita
- Department of Microbiology and Immunology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - Mitsuhiko Yamada
- Department of Molecular Pharmacology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
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19
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Bourdin B, Segura E, Tétreault MP, Lesage S, Parent L. Determination of the Relative Cell Surface and Total Expression of Recombinant Ion Channels Using Flow Cytometry. J Vis Exp 2016. [PMID: 27768059 DOI: 10.3791/54732] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Inherited or de novo mutations in cation-selective channels may lead to sudden cardiac death. Alteration in the plasma membrane trafficking of these multi-spanning transmembrane proteins, with or without change in channel gating, is often postulated to contribute significantly in this process. It has thus become critical to develop a method to quantify the change of the relative cell surface expression of cardiac ion channels on a large scale. Herein, a detailed protocol is provided to determine the relative total and cell surface expression of cardiac L-type calcium channels CaV1.2 and membrane-associated subunits in tsA-201 cells using two-color fluorescent cytometry assays. Compared with other microscopy-based or immunoblotting-based qualitative methods, flow cytometry experiments are fast, reproducible, and large-volume assays that deliver quantifiable end-points on large samples of live cells (ranging from 104 to 106 cells) with similar cellular characteristics in a single flow. Constructs were designed to constitutively express mCherry at the intracellular C-terminus (thus allowing a rapid assessment of the total protein expression) and express an extracellular-facing hemagglutinin (HA) epitope to estimate the cell surface expression of membrane proteins using an anti-HA fluorescence conjugated antibody. To avoid false negative, experiments were also conducted in permeabilized cells to confirm the accessibility and proper expression of the HA epitope. The detailed procedure provides: (1) design of tagged DNA (deoxyribonucleic acid) constructs, (2) lipid-mediated transfection of constructs in tsA-201 cells, (3) culture, harvest, and staining of non-permeabilized and permeabilized cells, and (4) acquisition and analysis of fluorescent signals. Additionally, the basic principles of flow cytometry are explained and the experimental design, including the choice of fluorophores, titration of the HA antibody and control experiments, is thoroughly discussed. This specific approach offers objective relative quantification of the total and cell surface expression of ion channels that can be extended to study ion pumps and plasma membrane transporters.
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Affiliation(s)
- Benoîte Bourdin
- Département de Physiologie Moléculaire et Intégrative, Montreal Heart Institute Research Centre
| | - Emilie Segura
- Département de Physiologie Moléculaire et Intégrative, Montreal Heart Institute Research Centre
| | | | - Sylvie Lesage
- Département de Microbiologie, Infectiologie, Immunologie, Centre de recherche de l'Hôpital Maisonneuve-Rosemont
| | - Lucie Parent
- Département de Physiologie Moléculaire et Intégrative, Montreal Heart Institute Research Centre;
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20
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Brandenburg S, Kohl T, Williams GSB, Gusev K, Wagner E, Rog-Zielinska EA, Hebisch E, Dura M, Didié M, Gotthardt M, Nikolaev VO, Hasenfuss G, Kohl P, Ward CW, Lederer WJ, Lehnart SE. Axial tubule junctions control rapid calcium signaling in atria. J Clin Invest 2016; 126:3999-4015. [PMID: 27643434 DOI: 10.1172/jci88241] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/09/2016] [Indexed: 11/17/2022] Open
Abstract
The canonical atrial myocyte (AM) is characterized by sparse transverse tubule (TT) invaginations and slow intracellular Ca2+ propagation but exhibits rapid contractile activation that is susceptible to loss of function during hypertrophic remodeling. Here, we have identified a membrane structure and Ca2+-signaling complex that may enhance the speed of atrial contraction independently of phospholamban regulation. This axial couplon was observed in human and mouse atria and is composed of voluminous axial tubules (ATs) with extensive junctions to the sarcoplasmic reticulum (SR) that include ryanodine receptor 2 (RyR2) clusters. In mouse AM, AT structures triggered Ca2+ release from the SR approximately 2 times faster at the AM center than at the surface. Rapid Ca2+ release correlated with colocalization of highly phosphorylated RyR2 clusters at AT-SR junctions and earlier, more rapid shortening of central sarcomeres. In contrast, mice expressing phosphorylation-incompetent RyR2 displayed depressed AM sarcomere shortening and reduced in vivo atrial contractile function. Moreover, left atrial hypertrophy led to AT proliferation, with a marked increase in the highly phosphorylated RyR2-pS2808 cluster fraction, thereby maintaining cytosolic Ca2+ signaling despite decreases in RyR2 cluster density and RyR2 protein expression. AT couplon "super-hubs" thus underlie faster excitation-contraction coupling in health as well as hypertrophic compensatory adaptation and represent a structural and metabolic mechanism that may contribute to contractile dysfunction and arrhythmias.
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21
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Tétreault MP, Bourdin B, Briot J, Segura E, Lesage S, Fiset C, Parent L. Identification of Glycosylation Sites Essential for Surface Expression of the CaVα2δ1 Subunit and Modulation of the Cardiac CaV1.2 Channel Activity. J Biol Chem 2016; 291:4826-43. [PMID: 26742847 DOI: 10.1074/jbc.m115.692178] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Indexed: 12/15/2022] Open
Abstract
Alteration in the L-type current density is one aspect of the electrical remodeling observed in patients suffering from cardiac arrhythmias. Changes in channel function could result from variations in the protein biogenesis, stability, post-translational modification, and/or trafficking in any of the regulatory subunits forming cardiac L-type Ca(2+) channel complexes. CaVα2δ1 is potentially the most heavily N-glycosylated subunit in the cardiac L-type CaV1.2 channel complex. Here, we show that enzymatic removal of N-glycans produced a 50-kDa shift in the mobility of cardiac and recombinant CaVα2δ1 proteins. This change was also observed upon simultaneous mutation of the 16 Asn sites. Nonetheless, the mutation of only 6/16 sites was sufficient to significantly 1) reduce the steady-state cell surface fluorescence of CaVα2δ1 as characterized by two-color flow cytometry assays and confocal imaging; 2) decrease protein stability estimated from cycloheximide chase assays; and 3) prevent the CaVα2δ1-mediated increase in the peak current density and voltage-dependent gating of CaV1.2. Reversing the N348Q and N812Q mutations in the non-operational sextuplet Asn mutant protein partially restored CaVα2δ1 function. Single mutation N663Q and double mutations N348Q/N468Q, N348Q/N812Q, and N468Q/N812Q decreased protein stability/synthesis and nearly abolished steady-state cell surface density of CaVα2δ1 as well as the CaVα2δ1-induced up-regulation of L-type currents. These results demonstrate that Asn-663 and to a lesser extent Asn-348, Asn-468, and Asn-812 contribute to protein stability/synthesis of CaVα2δ1, and furthermore that N-glycosylation of CaVα2δ1 is essential to produce functional L-type Ca(2+) channels.
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Affiliation(s)
| | - Benoîte Bourdin
- From the Départment de Physiologie Moléculaire et Intégrative, Faculté de Médecine, and
| | - Julie Briot
- From the Départment de Physiologie Moléculaire et Intégrative, Faculté de Médecine, and
| | - Emilie Segura
- From the Départment de Physiologie Moléculaire et Intégrative, Faculté de Médecine, and
| | - Sylvie Lesage
- Départment de Microbiologie, Infectiologie, and Immunologie, Faculté de Médecine, Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Céline Fiset
- Faculté de Pharmacie, Institut de Cardiologie de Montréal and
| | - Lucie Parent
- From the Départment de Physiologie Moléculaire et Intégrative, Faculté de Médecine, and
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22
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Xu J, Yu L, Minobe E, Lu L, Lei M, Kameyama M. PKA and phosphatases attached to the Ca(V)1.2 channel regulate channel activity in cell-free patches. Am J Physiol Cell Physiol 2015; 310:C136-41. [PMID: 26561637 DOI: 10.1152/ajpcell.00157.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 11/02/2015] [Indexed: 11/22/2022]
Abstract
Calmodulin (CaM) + ATP can reprime voltage-gated L-type Ca(2+) channels (Ca(V)1.2) in inside-out patches for activation, but this effect decreases time dependently. This suggests that the Ca(V)1.2 channel activity is regulated by additional cytoplasmic factors. To test this hypothesis, we examined the role of cAMP-dependent protein kinase A (PKA) and protein phosphatases in the regulation of Ca(V)1.2 channel activity in the inside-out mode in guinea pig ventricular myocytes. Ca(V)1.2 channel activity quickly disappeared after the patch was excised from the cell and recovered to only 9% of that in the cell-attached mode on application of CaM + ATP at 10 min after the inside out. However, immediate exposure of the excised patch to the catalytic subunit of PKA + ATP or the nonspecific phosphatase inhibitor okadaic acid significantly increased the Ca(V)1.2 channel activity recovery by CaM + ATP (114 and 96%, respectively) at 10 min. Interestingly, incubation of the excised patches with cAMP + ATP also increased CaM/ATP-induced Ca(V)1.2 channel activity recovery (108%), and this effect was blocked by the nonspecific protein kinase inhibitor K252a. The channel activity in the inside-out mode was not maintained by either catalytic subunit of PKA or cAMP + ATP in the absence of CaM, but was stably maintained in the presence of CaM for more than 40 min. These results suggest that PKA and phosphatase(s) attached on or near the Ca(V)1.2 channel regulate the basal channel activity, presumably through modulation of the dynamic CaM interaction with the channel.
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Affiliation(s)
- Jianjun Xu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Lifeng Yu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China; Department of Ethnopharmacology, School of Pharmacy, China Medical University, Shenyang, China; and
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Liting Lu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Laboratory of Environmental Biology, Northeastern University, Shenyang, China
| | - Ming Lei
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan;
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Godinho RO, Duarte T, Pacini ESA. New perspectives in signaling mediated by receptors coupled to stimulatory G protein: the emerging significance of cAMP efflux and extracellular cAMP-adenosine pathway. Front Pharmacol 2015; 6:58. [PMID: 25859216 PMCID: PMC4373373 DOI: 10.3389/fphar.2015.00058] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/06/2015] [Indexed: 12/25/2022] Open
Abstract
G protein-coupled receptors (GPCRs) linked to stimulatory G (Gs) proteins (GsPCRs) mediate increases in intracellular cyclic AMP as consequence of activation of nine adenylyl cyclases , which differ considerably in their cellular distribution and activation mechanisms. Once produced, cyclic AMP may act via distinct intracellular signaling effectors such as protein kinase A and the exchange proteins activated by cAMP (Epacs). More recently, attention has been focused on the efflux of cAMP through a specific transport system named multidrug resistance proteins that belongs to the ATP-binding cassette transporter superfamily. Outside the cell, cAMP is metabolized into adenosine, which is able to activate four distinct subtypes of adenosine receptors, members of the GPCR family: A1, A2A, A2B, and A3. Taking into account that this phenomenon occurs in numerous cell types, as consequence of GsPCR activation and increment in intracellular cAMP levels, in this review, we will discuss the impact of cAMP efflux and the extracellular cAMP-adenosine pathway on the regulation of GsPCR-induced cell response.
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Affiliation(s)
- Rosely O Godinho
- Disciplina Farmacologia Celular, Departamento de Farmacologia, Escola Paulista de Medicina, Universidade Federal de São Paulo São Paulo, Brazil
| | - Thiago Duarte
- Disciplina Farmacologia Celular, Departamento de Farmacologia, Escola Paulista de Medicina, Universidade Federal de São Paulo São Paulo, Brazil
| | - Enio S A Pacini
- Disciplina Farmacologia Celular, Departamento de Farmacologia, Escola Paulista de Medicina, Universidade Federal de São Paulo São Paulo, Brazil
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Balycheva M, Faggian G, Glukhov AV, Gorelik J. Microdomain-specific localization of functional ion channels in cardiomyocytes: an emerging concept of local regulation and remodelling. Biophys Rev 2015; 7:43-62. [PMID: 28509981 PMCID: PMC5425752 DOI: 10.1007/s12551-014-0159-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 12/18/2014] [Indexed: 12/26/2022] Open
Abstract
Cardiac excitation involves the generation of action potential by individual cells and the subsequent conduction of the action potential from cell to cell through intercellular gap junctions. Excitation of the cellular membrane results in opening of the voltage-gated L-type calcium ion (Ca2+) channels, thereby allowing a small amount of Ca2+ to enter the cell, which in turn triggers the release of a much greater amount of Ca2+ from the sarcoplasmic reticulum, the intracellular Ca2+ store, and gives rise to the systolic Ca2+ transient and contraction. These processes are highly regulated by the autonomic nervous system, which ensures the acute and reliable contractile function of the heart and the short-term modulation of this function upon changes in heart rate or workload. It has recently become evident that discrete clusters of different ion channels and regulatory receptors are present in the sarcolemma, where they form an interacting network and work together as a part of a macro-molecular signalling complex which in turn allows the specificity, reliability and accuracy of the autonomic modulation of the excitation-contraction processes by a variety of neurohormonal pathways. Disruption in subcellular targeting of ion channels and associated signalling proteins may contribute to the pathophysiology of a variety of cardiac diseases, including heart failure and certain arrhythmias. Recent methodological advances have made it possible to routinely image the topography of live cardiomyocytes, allowing the study of clustering functional ion channels and receptors as well as their coupling within a specific microdomain. In this review we highlight the emerging understanding of the functionality of distinct subcellular microdomains in cardiac myocytes (e.g. T-tubules, lipid rafts/caveolae, costameres and intercalated discs) and their functional role in the accumulation and regulation of different subcellular populations of sodium, Ca2+ and potassium ion channels and their contributions to cellular signalling and cardiac pathology.
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Affiliation(s)
- Marina Balycheva
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, 4th Floor National Heart and Lung Institute, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
- Cardiosurgery Department, University of Verona School of Medicine, Verona, Italy
| | - Giuseppe Faggian
- Cardiosurgery Department, University of Verona School of Medicine, Verona, Italy
| | - Alexey V Glukhov
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, 4th Floor National Heart and Lung Institute, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
| | - Julia Gorelik
- Department of Cardiovascular Sciences, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, 4th Floor National Heart and Lung Institute, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
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25
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Bourdin B, Shakeri B, Tétreault MP, Sauvé R, Lesage S, Parent L. Functional characterization of CaVα2δ mutations associated with sudden cardiac death. J Biol Chem 2014; 290:2854-69. [PMID: 25527503 DOI: 10.1074/jbc.m114.597930] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
L-type Ca(2+) channels play a critical role in cardiac rhythmicity. These ion channels are oligomeric complexes formed by the pore-forming CaVα1 with the auxiliary CaVβ and CaVα2δ subunits. CaVα2δ increases the peak current density and improves the voltage-dependent activation gating of CaV1.2 channels without increasing the surface expression of the CaVα1 subunit. The functional impact of genetic variants of CACNA2D1 (the gene encoding for CaVα2δ), associated with shorter repolarization QT intervals (the time interval between the Q and the T waves on the cardiac electrocardiogram), was investigated after recombinant expression of the full complement of L-type CaV1.2 subunits in human embryonic kidney 293 cells. By performing side-by-side high resolution flow cytometry assays and whole-cell patch clamp recordings, we revealed that the surface density of the CaVα2δ wild-type protein correlates with the peak current density. Furthermore, the cell surface density of CaVα2δ mutants S755T, Q917H, and S956T was not significantly different from the cell surface density of the CaVα2δ wild-type protein expressed under the same conditions. In contrast, the cell surface expression of CaVα2δ D550Y, CaVα2δ S709N, and the double mutant D550Y/Q917H was reduced, respectively, by ≈30-33% for the single mutants and by 60% for the latter. The cell surface density of D550Y/Q917H was more significantly impaired than protein stability, suggesting that surface trafficking of CaVα2δ was disrupted by the double mutation. Co-expression with D550Y/Q917H significantly decreased CaV1.2 currents as compared with results obtained with CaVα2δ wild type. It is concluded that D550Y/Q917H reduced inward Ca(2+) currents through a defect in the cell surface trafficking of CaVα2δ. Altogether, our results provide novel insight in the molecular mechanism underlying the modulation of CaV1.2 currents by CaVα2δ.
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Affiliation(s)
- Benoîte Bourdin
- From the Département de Physiologie, Montreal Heart Institute Research Centre, and
| | - Behzad Shakeri
- From the Département de Physiologie, Montreal Heart Institute Research Centre, and
| | | | - Rémy Sauvé
- From the Département de Physiologie, Montreal Heart Institute Research Centre, and
| | - Sylvie Lesage
- Département de Microbiologie, Infectiologie et Immunologie, Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Lucie Parent
- From the Département de Physiologie, Montreal Heart Institute Research Centre, and
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Weiss S, Oz S, Benmocha A, Dascal N. Regulation of cardiac L-type Ca²⁺ channel CaV1.2 via the β-adrenergic-cAMP-protein kinase A pathway: old dogmas, advances, and new uncertainties. Circ Res 2013; 113:617-31. [PMID: 23948586 DOI: 10.1161/circresaha.113.301781] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the heart, adrenergic stimulation activates the β-adrenergic receptors coupled to the heterotrimeric stimulatory Gs protein, followed by subsequent activation of adenylyl cyclase, elevation of cyclic AMP levels, and protein kinase A (PKA) activation. One of the main targets for PKA modulation is the cardiac L-type Ca²⁺ channel (CaV1.2) located in the plasma membrane and along the T-tubules, which mediates Ca²⁺ entry into cardiomyocytes. β-Adrenergic receptor activation increases the Ca²⁺ current via CaV1.2 channels and is responsible for the positive ionotropic effect of adrenergic stimulation. Despite decades of research, the molecular mechanism underlying this modulation has not been fully resolved. On the contrary, initial reports of identification of key components in this modulation were later refuted using advanced model systems, especially transgenic animals. Some of the cardinal debated issues include details of specific subunits and residues in CaV1.2 phosphorylated by PKA, the nature, extent, and role of post-translational processing of CaV1.2, and the role of auxiliary proteins (such as A kinase anchoring proteins) involved in PKA regulation. In addition, the previously proposed crucial role of PKA in modulation of unstimulated Ca²⁺ current in the absence of β-adrenergic receptor stimulation and in voltage-dependent facilitation of CaV1.2 remains uncertain. Full reconstitution of the β-adrenergic receptor signaling pathway in heterologous expression systems remains an unmet challenge. This review summarizes the past and new findings, the mechanisms proposed and later proven, rejected or disputed, and emphasizes the essential issues that remain unresolved.
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Affiliation(s)
- Sharon Weiss
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel-Aviv, Israel.
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27
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López-Contreras AJ, de la Morena ME, Ramos-Molina B, Lambertos A, Cremades A, Peñafiel R. The induction of cardiac ornithine decarboxylase by β2 -adrenergic agents is associated with calcium channels and phosphorylation of ERK1/2. J Cell Biochem 2013; 114:1978-86. [PMID: 23519605 DOI: 10.1002/jcb.24540] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 03/05/2013] [Indexed: 12/17/2022]
Abstract
The role that the induction of cardiac ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis, by beta-adrenergic agents may have in heart hypertrophy is a controversial issue. Besides, the signaling pathways related to cardiac ODC regulation have not been fully elucidated. Here we show that in Balb C mice the stimulation of cardiac ODC activity by adrenergic agents was mainly mediated by β2 -adrenergic receptors, and that this induction was lower in the hypertrophic heart. Interestingly, this stimulation was abolished by the L-calcium channel antagonists verapamil and nifedipine. In addition, whereas the treatment with β2 -adrenergic agents was associated to both the increases in ODC, ODC-antizyme inhibitor 1 (AZIN1), c-fos and c-myc mRNA levels and the phosphorylation of CREB and MAP kinases ERK1 and ERK2 (ERK1/2), the co-treatment with L-calcium channel blockers differentially prevented most of these changes. These results suggest that the stimulation of cardiac ODC by β2 -adrenergic agents is associated with the activation of MAP kinases through the participation of L-calcium channels, and that by itself p-CREB does not appear to be sufficient for the transcriptional activation of ODC. In addition, post-translational mechanisms related with the induction of AZIN1 appear to be related to the increase of cardiac ODC activity.
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Affiliation(s)
- Andrés J López-Contreras
- Faculty of Medicine, Department of Biochemistry and Molecular Biology B and Immunology, University of Murcia, Murcia, Spain
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28
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Calcium influx through L-type channels attenuates skeletal muscle contraction via inhibition of adenylyl cyclases. Eur J Pharmacol 2013; 720:326-34. [PMID: 24140436 DOI: 10.1016/j.ejphar.2013.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 09/25/2013] [Accepted: 10/10/2013] [Indexed: 11/23/2022]
Abstract
Skeletal muscle contraction is triggered by acetylcholine induced release of Ca(2+) from sarcoplasmic reticulum. Although this signaling pathway is independent of extracellular Ca(2+), L-type voltage-gated calcium channel (Cav) blockers have inotropic effects on frog skeletal muscles which occur by an unknown mechanism. Taking into account that skeletal muscle fiber expresses Ca(+2)-sensitive adenylyl cyclase (AC) isoforms and that cAMP is able to increase skeletal muscle contraction force, we investigated the role of Ca(2+) influx on mouse skeletal muscle contraction and the putative crosstalk between extracellular Ca(2+) and intracellular cAMP signaling pathways. The effects of Cav blockers (verapamil and nifedipine) and extracellular Ca(2+) chelator EGTA were evaluated on isometric contractility of mouse diaphragm muscle under direct electrical stimulus (supramaximal voltage, 2 ms, 0.1 Hz). Production of cAMP was evaluated by radiometric assay while Ca(2+) transients were assessed by confocal microscopy using L6 cells loaded with fluo-4/AM. Ca(2+) channel blockers verapamil and nifedipine had positive inotropic effect, which was mimicked by removal of extracellular Ca(+2) with EGTA or Ca(2+)-free Tyrode. While phosphodiesterase inhibitor IBMX potentiates verapamil positive inotropic effect, it was abolished by AC inhibitors SQ22536 and NYK80. Finally, the inotropic effect of verapamil was associated with increased intracellular cAMP content and mobilization of intracellular Ca(2+), indicating that positive inotropic effects of Ca(2+) blockers depend on cAMP formation. Together, our results show that extracellular Ca(2+) modulates skeletal muscle contraction, through inhibition of Ca(2+)-sensitive AC. The cross-talk between extracellular calcium and cAMP-dependent signaling pathways appears to regulate the extent of skeletal muscle contraction responses.
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29
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Demers-Giroux PO, Bourdin B, Sauvé R, Parent L. Cooperative activation of the T-type CaV3.2 channel: interaction between Domains II and III. J Biol Chem 2013; 288:29281-93. [PMID: 23970551 PMCID: PMC3795230 DOI: 10.1074/jbc.m113.500975] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 08/02/2013] [Indexed: 12/28/2022] Open
Abstract
T-type CaV3 channels are important mediators of Ca(2+) entry near the resting membrane potential. Little is known about the molecular mechanisms responsible for channel activation. Homology models based upon the high-resolution structure of bacterial NaV channels predict interaction between the S4-S5 helix of Domain II (IIS4-S5) and the distal S6 pore region of Domain II (IIS6) and Domain III (IIIS6). Functional intra- and inter-domain interactions were investigated with a double mutant cycle analysis. Activation gating and channel kinetics were measured for 47 single mutants and 20 pairs of mutants. Significant coupling energies (ΔΔG(interact) ≥ 1.5 kcal mol(-1)) were measured for 4 specific pairs of mutants introduced between IIS4-S5 and IIS6 and between IIS4-S5 and IIIS6. In agreement with the computer based models, Thr-911 in IIS4-S5 was functionally coupled with Ile-1013 in IIS6 during channel activation. The interaction energy was, however, found to be stronger between Val-907 in IIS4-S5 and Ile-1013 in IIS6. In addition Val-907 was significantly coupled with Asn-1548 in IIIS6 but not with Asn-1853 in IVS6. Altogether, our results demonstrate that the S4-S5 and S6 helices from adjacent domains are energetically coupled during the activation of a low voltage-gated T-type CaV3 channel.
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Affiliation(s)
- Pierre-Olivier Demers-Giroux
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Benoîte Bourdin
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Rémy Sauvé
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Lucie Parent
- From the Département de Physiologie, Membrane Protein Research Group, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
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Mika D, Leroy J, Fischmeister R, Vandecasteele G. Rôle des phosphodiestérases des nucléotides cycliques de types 3 et 4 dans le couplage excitation-contraction et les arythmies cardiaques. Med Sci (Paris) 2013; 29:617-22. [DOI: 10.1051/medsci/2013296014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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31
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Yang L, Katchman A, Samad T, Morrow J, Weinberg R, Marx SO. β-adrenergic regulation of the L-type Ca2+ channel does not require phosphorylation of α1C Ser1700. Circ Res 2013; 113:871-80. [PMID: 23825359 DOI: 10.1161/circresaha.113.301926] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
RATIONALE Sympathetic nervous system triggered activation of protein kinase A, which phosphorylates several targets within cardiomyocytes, augments inotropy, chronotropy, and lusitropy. An important target of β-adrenergic stimulation is the sarcolemmal L-type Ca(2+) channel, CaV1.2, which plays a key role in cardiac excitation-contraction coupling. The molecular mechanisms of β-adrenergic regulation of CaV1.2 in cardiomyocytes, however, are incompletely known. Recently, it has been postulated that proteolytic cleavage at Ala(1800) and protein kinase A phosphorylation of Ser(1700) are required for β-adrenergic modulation of CaV1.2. OBJECTIVE To assess the role of Ala(1800) in the cleavage of α1C and the role of Ser(1700) and Thr(1704) in mediating the adrenergic regulation of CaV1.2 in the heart. METHODS AND RESULTS Using a transgenic approach that enables selective and inducible expression in mice of FLAG-epitope-tagged, dihydropyridine-resistant CaV1.2 channels harboring mutations at key regulatory sites, we show that adrenergic regulation of CaV1.2 current and fractional shortening of cardiomyocytes do not require phosphorylation of either Ser(1700) or Thr(1704) of the α1C subunit. The presence of Ala(1800) and the (1798)NNAN(1801) motif in α1C is not required for proteolytic cleavage of the α1C C-terminus, and deletion of these residues did not perturb adrenergic modulation of CaV1.2 current. CONCLUSIONS These results show that protein kinase A phosphorylation of α1C Ser(1700) does not have a major role in the sympathetic stimulation of Ca(2+) current and contraction in the adult murine heart. Moreover, this new transgenic approach enables functional and reproducible screening of α1C mutants in freshly isolated adult cardiomyocytes in a reliable, timely, cost-effective manner.
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Affiliation(s)
- Lin Yang
- Division of Cardiology, Department of Medicine, College of Physicians and Surgeons, New York, NY 10032
| | - Alexander Katchman
- Division of Cardiology, Department of Medicine, College of Physicians and Surgeons, New York, NY 10032
| | - Tahmina Samad
- Division of Cardiology, Department of Medicine, College of Physicians and Surgeons, New York, NY 10032
| | - John Morrow
- Division of Cardiology, Department of Medicine, College of Physicians and Surgeons, New York, NY 10032
| | - Richard Weinberg
- Division of Cardiology, Department of Medicine, College of Physicians and Surgeons, New York, NY 10032
| | - Steven O Marx
- Division of Cardiology, Department of Medicine, College of Physicians and Surgeons, New York, NY 10032.,Department of Pharmacology Columbia University, College of Physicians and Surgeons, New York, NY 10032
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Kappel VD, Zanatta L, Postal BG, Silva FRMB. Rutin potentiates calcium uptake via voltage-dependent calcium channel associated with stimulation of glucose uptake in skeletal muscle. Arch Biochem Biophys 2013; 532:55-60. [PMID: 23395857 DOI: 10.1016/j.abb.2013.01.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 01/19/2013] [Accepted: 01/23/2013] [Indexed: 11/29/2022]
Abstract
Rutin is a flavonoid with several pharmacological properties and it has been demonstrated that rutin can modulate glucose homeostasis. In skeletal muscle, an increase in intracellular calcium concentration may induce glucose transporter-4 (GLUT-4) translocation with consequent glucose uptake. The aim of this study was to investigate the effect of rutin and intracellular pathways on calcium uptake as well as the involvement of calcium in glucose uptake in skeletal muscle. The results show that rutin significantly stimulated calcium uptake through voltage-dependent calcium channels as well as mitogen-activated kinase (MEK) and protein kinase A (PKA) signaling pathways. Also, rutin stimulated glucose uptake in the soleus muscle and this effect was mediated by extracellular calcium and calcium-calmodulin-dependent protein kinase II (CaMKII) activation. In conclusion, rutin significantly stimulates calcium uptake in rat soleus muscles. Furthermore, the increase in intracellular calcium concentration is involved in DNA activation by rutin. Also, rutin-induced glucose uptake via CaMKII may result in GLUT-4 translocation to the plasma membrane, characterizing an insulin-independent pathway. These findings indicate that rutin is a potential drug candidate for diabetes therapy.
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Affiliation(s)
- Virginia Demarchi Kappel
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis-Santa Catarina, Brazil
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Harvey RD, Hell JW. CaV1.2 signaling complexes in the heart. J Mol Cell Cardiol 2012; 58:143-52. [PMID: 23266596 DOI: 10.1016/j.yjmcc.2012.12.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 12/07/2012] [Accepted: 12/10/2012] [Indexed: 01/08/2023]
Abstract
L-type Ca(2+) channels (LTCCs) are essential for generation of the electrical and mechanical properties of cardiac muscle. Furthermore, regulation of LTCC activity plays a central role in mediating the effects of sympathetic stimulation on the heart. The primary mechanism responsible for this regulation involves β-adrenergic receptor (βAR) stimulation of cAMP production and subsequent activation of protein kinase A (PKA). Although it is well established that PKA-dependent phosphorylation regulates LTCC function, there is still much we do not understand. However, it has recently become clear that the interaction of the various signaling proteins involved is not left to completely stochastic events due to random diffusion. The primary LTCC expressed in cardiac muscle, CaV1.2, forms a supramolecular signaling complex that includes the β2AR, G proteins, adenylyl cyclases, phosphodiesterases, PKA, and protein phosphatases. In some cases, the protein interactions with CaV1.2 appear to be direct, in other cases they involve scaffolding proteins such as A kinase anchoring proteins and caveolin-3. Functional evidence also suggests that the targeting of these signaling proteins to specific membrane domains plays a critical role in maintaining the fidelity of receptor mediated LTCC regulation. This information helps explain the phenomenon of compartmentation, whereby different receptors, all linked to the production of a common diffusible second messenger, can vary in their ability to regulate LTCC activity. The purpose of this review is to examine our current understanding of the signaling complexes involved in cardiac LTCC regulation.
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Affiliation(s)
- Robert D Harvey
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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The proximal C-terminus of α1C subunits is necessary for junctional membrane targeting of cardiac L-type calcium channels. Biochem J 2012; 448:221-31. [DOI: 10.1042/bj20120773] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In cardiac myocytes, LTCCs (L-type calcium channels) form a functional signalling complex with ryanodine receptors at the JM (junctional membrane). Although the specific localization of LTCCs to the JM is critical for excitation–contraction coupling, their targeting mechanism is unclear. Transient transfection of GFP (green fluorescent protein)–α1S or GFP–α1C, but not P/Q-type calcium channel α1A, in dysgenic (α1S-null) GLT myotubes results in correct targeting of these LTCCs to the JMs and restoration of action-potential-induced Ca2+ transients. To identify the sequences of α1C responsible for JM targeting, we generated a range of α1C–α1A chimaeras, deletion mutants and alanine substitution mutants and studied their targeting properties in GLT myotubes. The results revealed that amino acids L1681QAGLRTL1688 and P1693EIRRAIS1700, predicted to form two adjacent α-helices in the proximal C-terminus, are necessary for the JM targeting of α1C. The efficiency of restoration of action-potential-induced Ca2+ transients in GLT myotubes was significantly decreased by mutations in the targeting motif. JM targeting was not disrupted by the distal C-terminus of α1C which binds to the second α-helix. Therefore we have identified a new structural motif in the C-terminus of α1C that mediates the targeting of cardiac LTCCs to JMs independently of the interaction between proximal and distal C-termini of α1C.
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Zanatta L, Goulart PB, Gonçalves R, Pierozan P, Winkelmann-Duarte EC, Woehl VM, Pessoa-Pureur R, Silva FRMB, Zamoner A. 1α,25-Dihydroxyvitamin D3 mechanism of action: Modulation of L-type calcium channels leading to calcium uptake and intermediate filament phosphorylation in cerebral cortex of young rats. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1708-19. [DOI: 10.1016/j.bbamcr.2012.06.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 06/15/2012] [Accepted: 06/18/2012] [Indexed: 12/22/2022]
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Abstract
3'-5'-Cyclic adenosine monophosphate (cAMP), generated by adenylyl cyclase (AC), serves as a second messenger in signaling pathways regulating many aspects of cardiac physiology, including contraction rate and action potential duration, and in the pathophysiology of hypertrophy and heart failure. A kinase-anchoring proteins localize the effect of cAMP in space and time by organizing receptors, AC, protein kinase A, and other components of the cAMP cascade into multiprotein complexes. In this review, we discuss how the interaction of A kinase-anchoring proteins with distinct AC isoforms affects cardiovascular physiology.
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Shakeri B, Bourdin B, Demers-Giroux PO, Sauvé R, Parent L. A quartet of leucine residues in the guanylate kinase domain of CaVβ determines the plasma membrane density of the CaV2.3 channel. J Biol Chem 2012; 287:32835-47. [PMID: 22846999 DOI: 10.1074/jbc.m112.387233] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ca(V)β subunits are formed by a Src homology 3 domain and a guanylate kinase-like (GK) domain connected through a variable HOOK domain. Complete deletion of the Src homology 3 domain (75 residues) as well as deletion of the HOOK domain (47 residues) did not alter plasma membrane density of Ca(V)2.3 nor its typical activation gating. In contrast, six-residue deletions in the GK domain disrupted cell surface trafficking and functional expression of Ca(V)2.3. Mutations of residues known to carry nanomolar affinity binding in the GK domain of Ca(V)β (P175A, P179A, M195A, M196A, K198A, S295A, R302G, R307A, E339G, N340G, and A345G) did not significantly alter cell surface targeting or gating modulation of Ca(V)2.3. Nonetheless, mutations of a quartet of leucine residues (either single or multiple mutants) in the α3, α6, β10, and α9 regions of the GK domain were found to significantly impair cell surface density of Ca(V)2.3 channels. Furthermore, the normalized protein density of Ca(V)2.3 was nearly abolished with the quadruple Ca(V)β3 Leu mutant L200G/L303G/L337G/L342G. Altogether, our observations suggest that the four leucine residues in Ca(V)β3 form a hydrophobic pocket surrounding key residues in the α-interacting domain of Ca(V)2.3. This interaction appears to play an essential role in conferring Ca(V)β-induced modulation of the protein density of Ca(V)α1 subunits in Ca(V)2 channels.
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Affiliation(s)
- Behzad Shakeri
- Département de Physiologie and the Membrane Protein Research Group, Université de Montréal, Montréal, Québec H3C 3J7, Canada
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38
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Özgen N, Lu Z, Boink GJJ, Lau DH, Shlapakova IN, Bobkov Y, Danilo P, Cohen IS, Rosen MR. Microtubules and angiotensin II receptors contribute to modulation of repolarization induced by ventricular pacing. Heart Rhythm 2012; 9:1865-72. [PMID: 22820054 DOI: 10.1016/j.hrthm.2012.07.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Indexed: 01/09/2023]
Abstract
BACKGROUND Left ventricular pacing (LVP) in canine heart alters ventricular activation, leading to reduced transient outward potassium current (I(to)), loss of the epicardial action potential notch, and T-wave vector displacement. These repolarization changes, referred to as cardiac memory, are initiated by locally increased angiotensin II (AngII) levels. In HEK293 cells in which Kv4.3 and KChIP2, the channel subunits contributing to I(to), are overexpressed with the AngII receptor 1 (AT1R), AngII induces a decrease in I(to) as the result of internalization of a Kv4.3/KChIP2/AT1R macromolecular complex. OBJECTIVE To test the hypothesis that in canine heart in situ, 2h LVP-induced decreases in membrane KChIP2, AT1R, and I(to) are prevented by blocking subunit trafficking. METHODS We used standard electrophysiological, biophysical, and biochemical methods to study 4 groups of dogs: (1) Sham, (2) 2h LVP, (3) LVP + colchicine (microtubule-disrupting agent), and (4) LVP + losartan (AT1R blocker). RESULTS The T-wave vector displacement was significantly greater in LVP than in Sham and was inhibited by colchicine or losartan. Epicardial biopsies showed significant decreases in KChIP2 and AT1R proteins in the membrane fraction after LVP but not after sham treatment, and these decreases were prevented by colchicine or losartan. Colchicine but not losartan significantly reduced microtubular polymerization. In isolated ventricular myocytes, AngII-induced I(to) reduction and loss of action potential notch were blocked by colchicine. CONCLUSIONS LVP-induced reduction of KChIP2 in plasma light membranes depends on an AngII-mediated pathway and intact microtubular status. Loss of I(to) and the action potential notch appear to derive from AngII-initiated trafficking of channel subunits.
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Affiliation(s)
- Nazira Özgen
- Department of Pharmacology, Columbia University, New York, New York 10032, USA
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39
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Antoni FA. New paradigms in cAMP signalling. Mol Cell Endocrinol 2012; 353:3-9. [PMID: 22085559 DOI: 10.1016/j.mce.2011.10.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 10/24/2011] [Accepted: 10/29/2011] [Indexed: 12/16/2022]
Abstract
Signalling through adenosine 3'5' monophosphate (cAMP) is known to be important in virtually every cell. The mapping of the human genome over the past two decades has revealed an unexpected complexity of cAMP signalling, which is shared from insects to mammals. A more recent technical advance is the ability to monitor intracellular cAMP levels at subcellular spatial resolution within the time-domains of fast biochemical reactions. Thus, new light has been shed on old paradigms, some of which turn out to be multiple new ones. The novel aspects of cAMP signalling are highlighted here: (1) agonist induced plasticity - showing how the repertory of cAMP signalling genes supports homeostatic adaptation; (2) sustained cAMP signalling after endocytosis; (3) pre-assembled receptor-Gs-adenylyl cyclase complexes. Finally, a hypothetical model of propagating neuronal cAMP signals travelling form dendrites to the cell body is presented.
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Affiliation(s)
- Ferenc A Antoni
- Division of Preclinical Research, EGIS PLC, Bökényföldi út 116, 1165 Budapest, Hungary.
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40
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Mika D, Leroy J, Vandecasteele G, Fischmeister R. [Role of cyclic nucleotide phosphodiesterases in the cAMP compartmentation in cardiac cells]. Biol Aujourdhui 2012; 206:11-24. [PMID: 22463992 DOI: 10.1051/jbio/2012003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Indexed: 11/15/2022]
Abstract
In the light of the knowledge accumulated over the years, it becomes clear that intracellular cAMP is not uniformly distributed within cardiomyocytes and that cAMP compartmentation is required for adequate processing and targeting of the information generated at the membrane. Localized cAMP signals may be generated by interplay between discrete production sites and restricted diffusion within the cytoplasm. In addition to specialized membrane structures that may limit cAMP spreading, degradation of the second messenger by cyclic nucleotide phosphodiesterases (PDEs) appears critical for the formation of dynamic microdomains that confer specificity of the response to various hormones. This review summarizes the main findings that support the cAMP compartmentation hypothesis in cardiac cells, with a special emphasis on PDEs. The respective roles of the four main cardiac cAMP-PDE families (PDE1 to PDE4) in the organization of cAMP microdomains and hormonal specificity in cardiac cells are reviewed. The evidence that these PDEs are modified in heart failure is summarized, and the implication for the progression of the disease is discussed. Finally, the potential benefits that could be awaited from the manipulation of specific PDE subtypes in heart failure are presented.
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Affiliation(s)
- Delphine Mika
- Inserm UMR-S 769- LabEx LERMIT, 92296 Châtenay-Malabry, France
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41
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PDEs create local domains of cAMP signaling. J Mol Cell Cardiol 2011; 52:323-9. [PMID: 21888909 DOI: 10.1016/j.yjmcc.2011.08.016] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 07/12/2011] [Accepted: 08/17/2011] [Indexed: 01/11/2023]
Abstract
In the light of the knowledge accumulated over the years, it becomes clear that intracellular cAMP is not uniformly distributed within cardiomyocytes and that cAMP compartmentation is required for adequate processing and targeting of the information generated at the membrane. Localized cAMP signals may be generated by interplay between discrete production sites and restricted diffusion within the cytoplasm. In addition to specialized membrane structures that may limit cAMP spreading, degradation of the second messenger by cyclic nucleotide phosphodiesterases (PDEs) appears critical for the formation of dynamic microdomains that confer specificity of the response to various hormones. This review will cover the role of the different cAMP-PDE isoforms in this process. This article is part of a Special Issue entitled "Local Signaling in Myocytes."
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42
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Leroy J, Richter W, Mika D, Castro LRV, Abi-Gerges A, Xie M, Scheitrum C, Lefebvre F, Schittl J, Mateo P, Westenbroek R, Catterall WA, Charpentier F, Conti M, Fischmeister R, Vandecasteele G. Phosphodiesterase 4B in the cardiac L-type Ca²⁺ channel complex regulates Ca²⁺ current and protects against ventricular arrhythmias in mice. J Clin Invest 2011; 121:2651-61. [PMID: 21670503 DOI: 10.1172/jci44747] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 04/20/2011] [Indexed: 11/17/2022] Open
Abstract
β-Adrenergic receptors (β-ARs) enhance cardiac contractility by increasing cAMP levels and activating PKA. PKA increases Ca²⁺-induced Ca²⁺ release via phosphorylation of L-type Ca²⁺ channels (LTCCs) and ryanodine receptor 2. Multiple cyclic nucleotide phosphodiesterases (PDEs) regulate local cAMP concentration in cardiomyocytes, with PDE4 being predominant for the control of β-AR-dependent cAMP signals. Three genes encoding PDE4 are expressed in mouse heart: Pde4a, Pde4b, and Pde4d. Here we show that both PDE4B and PDE4D are tethered to the LTCC in the mouse heart but that β-AR stimulation of the L-type Ca²⁺ current (ICa,L) is increased only in Pde4b-/- mice. A fraction of PDE4B colocalized with the LTCC along T-tubules in the mouse heart. Under β-AR stimulation, Ca²⁺ transients, cell contraction, and spontaneous Ca²⁺ release events were increased in Pde4b-/- and Pde4d-/- myocytes compared with those in WT myocytes. In vivo, after intraperitoneal injection of isoprenaline, catheter-mediated burst pacing triggered ventricular tachycardia in Pde4b-/- mice but not in WT mice. These results identify PDE4B in the CaV1.2 complex as a critical regulator of ICa,L during β-AR stimulation and suggest that distinct PDE4 subtypes are important for normal regulation of Ca²⁺-induced Ca²⁺ release in cardiomyocytes.
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43
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Fu Y, Westenbroek RE, Yu FH, Clark JP, Marshall MR, Scheuer T, Catterall WA. Deletion of the distal C terminus of CaV1.2 channels leads to loss of beta-adrenergic regulation and heart failure in vivo. J Biol Chem 2011; 286:12617-26. [PMID: 21216955 DOI: 10.1074/jbc.m110.175307] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
L-type calcium currents conducted by CaV1.2 channels initiate excitation-contraction coupling in cardiac and vascular smooth muscle. In the heart, the distal portion of the C terminus (DCT) is proteolytically processed in vivo and serves as a noncovalently associated autoinhibitor of CaV1.2 channel activity. This autoinhibitory complex, with A-kinase anchoring protein-15 (AKAP15) bound to the DCT, is hypothesized to serve as the substrate for β-adrenergic regulation in the fight-or-flight response. Mice expressing CaV1.2 channels with the distal C terminus deleted (DCT-/-) develop cardiac hypertrophy and die prematurely after E15. Cardiac hypertrophy and survival rate were improved by drug treatments that reduce peripheral vascular resistance and hypertension, consistent with the hypothesis that CaV1.2 hyperactivity in vascular smooth muscle causes hypertension, hypertrophy, and premature death. However, in contrast to expectation, L-type Ca2+ currents in cardiac myocytes from DCT-/- mice were dramatically reduced due to decreased cell-surface expression of CaV1.2 protein, and the voltage dependence of activation and the kinetics of inactivation were altered. CaV1.2 channels in DCT-/- myocytes fail to respond to activation of adenylyl cyclase by forskolin, and the localized expression of AKAP15 is reduced. Therefore, we conclude that the DCT of CaV1.2 channels is required in vivo for normal vascular regulation, cell-surface expression of CaV1.2 channels in cardiac myocytes, and β-adrenergic stimulation of L-type Ca2+ currents in the heart.
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Affiliation(s)
- Ying Fu
- Department of Pharmacology, University of Washington, Seattle, Washington 98195-7280, USA
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44
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Antzelevitch C, Dumaine R. Electrical Heterogeneity in the Heart: Physiological, Pharmacological and Clinical Implications. Compr Physiol 2011. [DOI: 10.1002/cphy.cp020117] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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45
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Beta-adrenergic-regulated phosphorylation of the skeletal muscle Ca(V)1.1 channel in the fight-or-flight response. Proc Natl Acad Sci U S A 2010; 107:18712-7. [PMID: 20937870 DOI: 10.1073/pnas.1012384107] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ca(V)1 channels initiate excitation-contraction coupling in skeletal and cardiac muscle. During the fight-or-flight response, epinephrine released by the adrenal medulla and norepinephrine released from sympathetic nerves increase muscle contractility by activation of the β-adrenergic receptor/cAMP-dependent protein kinase pathway and up-regulation of Ca(V)1 channels in skeletal and cardiac muscle. Although the physiological mechanism of this pathway is well defined, the molecular mechanism and the sites of protein phosphorylation required for Ca(V)1 channel regulation are unknown. To identify the regulatory sites of phosphorylation under physiologically relevant conditions, Ca(V)1.1 channels were purified from skeletal muscle and sites of phosphorylation on the α1 subunit were identified by mass spectrometry. Two phosphorylation sites were identified in the proximal C-terminal domain, serine 1575 (S1575) and threonine 1579 (T1579), which are conserved in cardiac Ca(V)1.2 channels (S1700 and T1704, respectively). In vitro phosphorylation revealed that Ca(V)1.1-S1575 is a substrate for both cAMP-dependent protein kinase and calcium/calmodulin-dependent protein kinase II, whereas Ca(V)1.1-T1579 is a substrate for casein kinase 2. Treatment of rabbits with isoproterenol to activate β-adrenergic receptors increased phosphorylation of S1575 in skeletal muscle Ca(V)1.1 channels in vivo, and treatment with propranolol to inhibit β-adrenergic receptors reduced phosphorylation. As S1575 and T1579 in Ca(V)1.1 channels and their homologs in Ca(V)1.2 channels are located at a key regulatory interface between the distal and proximal C-terminal domains, it is likely that phosphorylation of these sites in skeletal and cardiac muscle is directly involved in calcium channel regulation in response to the sympathetic nervous system in the fight-or-flight response.
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46
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Fuller MD, Emrick MA, Sadilek M, Scheuer T, Catterall WA. Molecular mechanism of calcium channel regulation in the fight-or-flight response. Sci Signal 2010; 3:ra70. [PMID: 20876873 PMCID: PMC3063709 DOI: 10.1126/scisignal.2001152] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During the fight-or-flight response, the sympathetic nervous system stimulates L-type calcium ion (Ca2+) currents conducted by Ca(V)1 channels through activation of β-adrenergic receptors, adenylyl cyclase, and phosphorylation by adenosine 3',5'-monophosphate-dependent protein kinase [also known as protein kinase A (PKA)], increasing contractility of skeletal and cardiac muscles. We reconstituted this regulation of cardiac Ca(V)1.2 channels in non-muscle cells by forming an autoinhibitory signaling complex composed of Ca(V)1.2Δ1800 (a form of the channel truncated at the in vivo site of proteolytic processing), its noncovalently associated distal carboxyl-terminal domain, the auxiliary α₂δ₁ and β(2b) subunits, and A-kinase anchoring protein 15 (AKAP15). A factor of 3.6 range of Ca(V)1.2 channel activity was observed from a minimum in the presence of protein kinase inhibitors to a maximum upon activation of adenylyl cyclase. Basal Ca(V)1.2 channel activity in unstimulated cells was regulated by phosphorylation of serine-1700 and threonine-1704, two residues located at the interface between the distal and the proximal carboxyl-terminal regulatory domains, whereas further stimulation of channel activity through the PKA signaling pathway only required phosphorylation of serine-1700. Our results define a conceptual framework for Ca(V)1.2 channel regulation and identify sites of phosphorylation that regulate channel activity.
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Affiliation(s)
- Matthew D. Fuller
- Department of Pharmacology, University of Washington, Box 357280, Seattle, WA 98195-7280, USA
| | - Michelle A. Emrick
- Department of Pharmacology, University of Washington, Box 357280, Seattle, WA 98195-7280, USA
| | - Martin Sadilek
- Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195-1700, USA
| | - Todd Scheuer
- Department of Pharmacology, University of Washington, Box 357280, Seattle, WA 98195-7280, USA
| | - William A. Catterall
- Department of Pharmacology, University of Washington, Box 357280, Seattle, WA 98195-7280, USA
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47
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Bourdin B, Marger F, Wall-Lacelle S, Schneider T, Klein H, Sauvé R, Parent L. Molecular determinants of the CaVbeta-induced plasma membrane targeting of the CaV1.2 channel. J Biol Chem 2010; 285:22853-63. [PMID: 20478999 DOI: 10.1074/jbc.m110.111062] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ca(V)beta subunits modulate cell surface expression and voltage-dependent gating of high voltage-activated (HVA) Ca(V)1 and Ca(V)2 alpha1 subunits. High affinity Ca(V)beta binding onto the so-called alpha interaction domain of the I-II linker of the Ca(V)alpha1 subunit is required for Ca(V)beta modulation of HVA channel gating. It has been suggested, however, that Ca(V)beta-mediated plasma membrane targeting could be uncoupled from Ca(V)beta-mediated modulation of channel gating. In addition to Ca(V)beta, Ca(V)alpha2delta and calmodulin have been proposed to play important roles in HVA channel targeting. Indeed we show that co-expression of Ca(V)alpha2delta caused a 5-fold stimulation of the whole cell currents measured with Ca(V)1.2 and Ca(V)beta3. To gauge the synergetic role of auxiliary subunits in the steady-state plasma membrane expression of Ca(V)1.2, extracellularly tagged Ca(V)1.2 proteins were quantified using fluorescence-activated cell sorting analysis. Co-expression of Ca(V)1.2 with either Ca(V)alpha2delta, calmodulin wild type, or apocalmodulin (alone or in combination) failed to promote the detection of fluorescently labeled Ca(V)1.2 subunits. In contrast, co-expression with Ca(V)beta3 stimulated plasma membrane expression of Ca(V)1.2 by a 10-fold factor. Mutations within the alpha interaction domain of Ca(V)1.2 or within the nucleotide kinase domain of Ca(V)beta3 disrupted the Ca(V)beta3-induced plasma membrane targeting of Ca(V)1.2. Altogether, these data support a model where high affinity binding of Ca(V)beta to the I-II linker of Ca(V)alpha1 largely accounts for Ca(V)beta-induced plasma membrane targeting of Ca(V)1.2.
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Affiliation(s)
- Benoîte Bourdin
- Institute of Neurophysiology and Center for Molecular Medicine, Cologne University, D-50931 Cologne, Germany
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Pang C, Crump SM, Jin L, Correll RN, Finlin BS, Satin J, Andres DA. Rem GTPase interacts with the proximal CaV1.2 C-terminus and modulates calcium-dependent channel inactivation. Channels (Austin) 2010; 4:192-202. [PMID: 20458179 DOI: 10.4161/chan.4.3.11867] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Rem, Rem2, Rad, and Gem/Kir (RGK) GTPases, comprise a subfamily of small Ras-related GTP-binding proteins, and have been shown to potently inhibit high voltage-activated Ca(2+) channel current following overexpression. Although the molecular mechanisms underlying RGK-mediated Ca(2+) channel regulation remains controversial, recent studies suggest that RGK proteins inhibit Ca(2+) channel currents at the plasma membrane in part by interactions with accessory channel β subunits. In this paper, we extend our understanding of the molecular determinants required for RGK-mediated channel regulation by demonstrating a direct interaction between Rem and the proximal C-terminus of Ca(V)1.2 (PCT), including the CB/IQ domain known to contribute to Ca(2+)/calmodulin (CaM)-mediated channel regulation. The Rem2 and Rad GTPases display similar patterns of PCT binding, suggesting that the Ca(V)1.2 C-terminus represents a common binding partner for all RGK proteins. In vitro Rem:PCT binding is disrupted by Ca(2+)/CaM, and this effect is not due to Ca(2+)/CaM binding to the Rem C-terminus. In addition, co-overexpression of CaM partially relieves Rem-mediated L-type Ca(2+) channel inhibition and slows the kinetics of Ca(2+)-dependent channel inactivation. Taken together, these results suggest that the association of Rem with the PCT represents a crucial molecular determinant in RGK-mediated Ca(2+) channel regulation and that the physiological function of the RGK GTPases must be re-evaluated. Rather than serving as endogenous inhibitors of Ca(2+) channel activity, these studies indicate that RGK proteins may play a more nuanced role, regulating Ca(2+) currents via modulation of Ca(2+)/CaM-mediated channel inactivation kinetics.
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Affiliation(s)
- Chunyan Pang
- Department of Molecular and Cellular Biochemistry and Physiology, University of Kentucky College of Medicine, Lexington, USA
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49
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Localised Ca channel phosphorylation modulates the distribution of L-type Ca current in cardiac myocytes. J Mol Cell Cardiol 2010; 49:121-31. [PMID: 20188735 DOI: 10.1016/j.yjmcc.2010.02.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 02/01/2010] [Accepted: 02/18/2010] [Indexed: 11/23/2022]
Abstract
The t-tubule network is central to excitation-contraction coupling in mammalian cardiac ventricular myocytes, with recent studies showing that the majority of Ca influx via the L-type Ca current (I(Ca)) occurs across the t-tubule membrane. The present study investigated whether tonic phosphorylation of the L-type Ca channel is different at the t-tubule and surface membranes, and if this could account for the high density of I(Ca) at the t-tubules. Ventricular myocytes were isolated from male Wistar rats and detubulated using formamide. I(Ca) was recorded using the whole cell patch clamp technique, and Ca transients were recorded using fluo-3 in conjunction with confocal microscopy. The protein kinase A (PKA) inhibitor H-89 (10micromol/L) and the CaMKII inhibitor KN-93 (5micromol/L) decreased the amplitude of I(Ca) in intact cells but had no effect on I(Ca) amplitude in detubulated cells. These inhibitors also decreased the amplitude of the Ca transient in intact cells but not in detubulated cells. Antibody staining for phosphorylated L-type Ca channel showed significantly higher phosphorylation at the t-tubules than at the surface membrane in intact cells. Thus it appears that tonic phosphorylation of the L-type Ca channel maintains the amplitude of I(Ca) and occurs predominantly at the t-tubules. This may have important implications in heart disease, in which changes of phosphorylation and t-tubule density have been reported.
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50
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Mechanisms of protein kinase A anchoring. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 283:235-330. [PMID: 20801421 DOI: 10.1016/s1937-6448(10)83005-9] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The second messenger cyclic adenosine monophosphate (cAMP), which is produced by adenylyl cyclases following stimulation of G-protein-coupled receptors, exerts its effect mainly through the cAMP-dependent serine/threonine protein kinase A (PKA). Due to the ubiquitous nature of the cAMP/PKA system, PKA signaling pathways underlie strict spatial and temporal control to achieve specificity. A-kinase anchoring proteins (AKAPs) bind to the regulatory subunit dimer of the tetrameric PKA holoenzyme and thereby target PKA to defined cellular compartments in the vicinity of its substrates. AKAPs promote the termination of cAMP signals by recruiting phosphodiesterases and protein phosphatases, and the integration of signaling pathways by binding additional signaling proteins. AKAPs are a heterogeneous family of proteins that only display similarity within their PKA-binding domains, amphipathic helixes docking into a hydrophobic groove formed by the PKA regulatory subunit dimer. This review summarizes the current state of information on compartmentalized cAMP/PKA signaling with a major focus on structural aspects, evolution, diversity, and (patho)physiological functions of AKAPs and intends to outline newly emerging directions of the field, such as the elucidation of AKAP mutations and alterations of AKAP expression in human diseases, and the validation of AKAP-dependent protein-protein interactions as new drug targets. In addition, alternative PKA anchoring mechanisms employed by noncanonical AKAPs and PKA catalytic subunit-interacting proteins are illustrated.
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