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Mesirca P, Chemin J, Barrère C, Torre E, Gallot L, Monteil A, Bidaud I, Diochot S, Lazdunski M, Soong TW, Barrère-Lemaire S, Mangoni ME, Nargeot J. Selective blockade of Ca v1.2 (α1C) versus Ca v1.3 (α1D) L-type calcium channels by the black mamba toxin calciseptine. Nat Commun 2024; 15:54. [PMID: 38167790 PMCID: PMC10762068 DOI: 10.1038/s41467-023-43502-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 11/10/2023] [Indexed: 01/05/2024] Open
Abstract
L-type voltage-gated calcium channels are involved in multiple physiological functions. Currently available antagonists do not discriminate between L-type channel isoforms. Importantly, no selective blocker is available to dissect the role of L-type isoforms Cav1.2 and Cav1.3 that are concomitantly co-expressed in the heart, neuroendocrine and neuronal cells. Here we show that calciseptine, a snake toxin purified from mamba venom, selectively blocks Cav1.2 -mediated L-type calcium currents (ICaL) at concentrations leaving Cav1.3-mediated ICaL unaffected in both native cardiac myocytes and HEK-293T cells expressing recombinant Cav1.2 and Cav1.3 channels. Functionally, calciseptine potently inhibits cardiac contraction without altering the pacemaker activity in sino-atrial node cells, underscoring differential roles of Cav1.2- and Cav1.3 in cardiac contractility and automaticity. In summary, calciseptine is a selective L-type Cav1.2 Ca2+ channel blocker and should be a valuable tool to dissect the role of these L-channel isoforms.
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Affiliation(s)
- Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France.
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France.
| | - Jean Chemin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Christian Barrère
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Laura Gallot
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Arnaud Monteil
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
- Department of Physiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Sylvie Diochot
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
- Université Côte d'Azur, CNRS, IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), FHU InovPain (Fédération Hospitalo-Universitaire "Innovative Solutions in Refractory Chronic Pain"), F-06560, Valbonne, France
| | - Michel Lazdunski
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
- Université Côte d'Azur, CNRS, IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), FHU InovPain (Fédération Hospitalo-Universitaire "Innovative Solutions in Refractory Chronic Pain"), F-06560, Valbonne, France
| | - Tuck Wah Soong
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Stéphanie Barrère-Lemaire
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Joël Nargeot
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France.
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France.
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2
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Fender H, Walter K, Kiper AK, Plačkić J, Kisko TM, Braun MD, Schwarting RKW, Rohrbach S, Wöhr M, Decher N, Kockskämper J. Calcium Handling Remodeling Underlies Impaired Sympathetic Stress Response in Ventricular Myocardium from Cacna1c Haploinsufficient Rats. Int J Mol Sci 2023; 24:9795. [PMID: 37372947 DOI: 10.3390/ijms24129795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 05/27/2023] [Accepted: 05/31/2023] [Indexed: 06/29/2023] Open
Abstract
CACNA1C encodes the pore-forming α1C subunit of the L-type Ca2+ channel, Cav1.2. Mutations and polymorphisms of the gene are associated with neuropsychiatric and cardiac disease. Haploinsufficient Cacna1c+/- rats represent a recently developed model with a behavioral phenotype, but its cardiac phenotype is unknown. Here, we unraveled the cardiac phenotype of Cacna1c+/- rats with a main focus on cellular Ca2+ handling mechanisms. Under basal conditions, isolated ventricular Cacna1c+/- myocytes exhibited unaltered L-type Ca2+ current, Ca2+ transients (CaTs), sarcoplasmic reticulum (SR) Ca2+ load, fractional release, and sarcomere shortenings. However, immunoblotting of left ventricular (LV) tissue revealed reduced expression of Cav1.2, increased expression of SERCA2a and NCX, and augmented phosphorylation of RyR2 (at S2808) in Cacna1c+/- rats. The β-adrenergic agonist isoprenaline increased amplitude and accelerated decay of CaTs and sarcomere shortenings in both Cacna1c+/- and WT myocytes. However, the isoprenaline effect on CaT amplitude and fractional shortening (but not CaT decay) was impaired in Cacna1c+/- myocytes exhibiting both reduced potency and efficacy. Moreover, sarcolemmal Ca2+ influx and fractional SR Ca2+ release after treatment with isoprenaline were smaller in Cacna1c+/- than in WT myocytes. In Langendorff-perfused hearts, the isoprenaline-induced increase in RyR2 phosphorylation at S2808 and S2814 was attenuated in Cacna1c+/- compared to WT hearts. Despite unaltered CaTs and sarcomere shortenings, Cacna1c+/- myocytes display remodeling of Ca2+ handling proteins under basal conditions. Mimicking sympathetic stress with isoprenaline unmasks an impaired ability to stimulate Ca2+ influx, SR Ca2+ release, and CaTs caused, in part, by reduced phosphorylation reserve of RyR2 in Cacna1c+/- cardiomyocytes.
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Affiliation(s)
- Hauke Fender
- Institute of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, University of Marburg, 35032 Marburg, Germany
| | - Kim Walter
- Institute of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, University of Marburg, 35032 Marburg, Germany
| | - Aytug K Kiper
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, 35037 Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), University of Marburg, 35032 Marburg, Germany
| | - Jelena Plačkić
- Institute of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, University of Marburg, 35032 Marburg, Germany
| | - Theresa M Kisko
- Behavioral Neuroscience, Experimental and Biological Psychology, University of Marburg, 35032 Marburg, Germany
| | - Moria D Braun
- Behavioral Neuroscience, Experimental and Biological Psychology, University of Marburg, 35032 Marburg, Germany
| | - Rainer K W Schwarting
- Center for Mind, Brain and Behavior (CMBB), University of Marburg, 35032 Marburg, Germany
- Behavioral Neuroscience, Experimental and Biological Psychology, University of Marburg, 35032 Marburg, Germany
| | - Susanne Rohrbach
- Institute of Physiology, University of Gießen, 35392 Giessen, Germany
| | - Markus Wöhr
- Center for Mind, Brain and Behavior (CMBB), University of Marburg, 35032 Marburg, Germany
- Behavioral Neuroscience, Experimental and Biological Psychology, University of Marburg, 35032 Marburg, Germany
- Social and Affective Neuroscience Research Group, Laboratory of Biological Psychology, Research Unit Brain and Cognition, Faculty of Psychology and Educational Sciences, KU Leuven, B-3000 Leuven, Belgium
- Leuven Brain Institute, KU Leuven, B-3000 Leuven, Belgium
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, 35037 Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), University of Marburg, 35032 Marburg, Germany
| | - Jens Kockskämper
- Institute of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, Biochemical and Pharmacological Center (BPC) Marburg, University of Marburg, 35032 Marburg, Germany
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3
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Guarina L, Moghbel AN, Pourhosseinzadeh MS, Cudmore RH, Sato D, Clancy CE, Santana LF. Biological noise is a key determinant of the reproducibility and adaptability of cardiac pacemaking and EC coupling. J Gen Physiol 2022; 154:213185. [PMID: 35482009 PMCID: PMC9059386 DOI: 10.1085/jgp.202012613] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 03/16/2022] [Accepted: 04/07/2022] [Indexed: 12/23/2022] Open
Abstract
Each heartbeat begins with the generation of an action potential in pacemaking cells in the sinoatrial node. This signal triggers contraction of cardiac muscle through a process termed excitation-contraction (EC) coupling. EC coupling is initiated in dyadic structures of cardiac myocytes, where ryanodine receptors in the junctional sarcoplasmic reticulum come into close apposition with clusters of CaV1.2 channels in invaginations of the sarcolemma. Cooperative activation of CaV1.2 channels within these clusters causes a local increase in intracellular Ca2+ that activates the juxtaposed ryanodine receptors. A salient feature of healthy cardiac function is the reliable and precise beat-to-beat pacemaking and amplitude of Ca2+ transients during EC coupling. In this review, we discuss recent discoveries suggesting that the exquisite reproducibility of this system emerges, paradoxically, from high variability at subcellular, cellular, and network levels. This variability is attributable to stochastic fluctuations in ion channel trafficking, clustering, and gating, as well as dyadic structure, which increase intracellular Ca2+ variance during EC coupling. Although the effects of these large, local fluctuations in function and organization are sometimes negligible at the macroscopic level owing to spatial-temporal summation within and across cells in the tissue, recent work suggests that the "noisiness" of these intracellular Ca2+ events may either enhance or counterintuitively reduce variability in a context-dependent manner. Indeed, these noisy events may represent distinct regulatory features in the tuning of cardiac contractility. Collectively, these observations support the importance of incorporating experimentally determined values of Ca2+ variance in all EC coupling models. The high reproducibility of cardiac contraction is a paradoxical outcome of high Ca2+ signaling variability at subcellular, cellular, and network levels caused by stochastic fluctuations in multiple processes in time and space. This underlying stochasticity, which counterintuitively manifests as reliable, consistent Ca2+ transients during EC coupling, also allows for rapid changes in cardiac rhythmicity and contractility in health and disease.
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Affiliation(s)
- Laura Guarina
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | - Ariana Neelufar Moghbel
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | | | - Robert H Cudmore
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | - Daisuke Sato
- Department of Pharmacology, University of California Davis School of Medicine, Davis, CA
| | - Colleen E Clancy
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
| | - Luis Fernando Santana
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA
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4
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Huang ZX, Qiu ZE, Chen L, Hou XC, Zhu YX, Zhou WL, Zhang YL. Cellular mechanism underlying the facilitation of contractile response induced by IL-25 in mouse tracheal smooth muscle. Am J Physiol Lung Cell Mol Physiol 2022; 323:L27-L36. [PMID: 35537103 DOI: 10.1152/ajplung.00468.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Asthma is a common heterogeneous respiratory disease characterized by airway inflammation and airway hyperresponsiveness (AHR) which is associated with abnormality in smooth muscle contractility. The epithelial cell-derived cytokine IL-25 is implicated in type 2 immune pathology including asthma, whereas the underlying mechanisms have not been fully elucidated. This study aims to investigate the effects of IL-25 on mouse tracheal smooth muscle contractility and elucidate the cellular mechanisms. Incubation with IL-25 augmented the contraction of mouse tracheal smooth muscles, which could be suppressed by the L-type voltage-dependent Ca2+ channel (L-VDCC) blocker nifedipine. Furthermore, IL-25 enhanced the cytosolic Ca2+ signals and triggered up-regulation of α1C L-VDCC (CaV1.2) in primary cultured mouse tracheal smooth muscle cells. Knocking down IL-17RA/IL-17RB receptors or inhibiting the transforming growth factor-β-activated kinase 1 (TAK1)-tumor progression locus 2 (TPL2)-MAPK kinase 1/2 (MEK1/2)-ERK1/2-activating protein-1 (AP-1) signaling pathways suppressed the IL-25-elicited up-regulation of CaV1.2 and hyperreactivity in tracheal smooth muscles. Moreover, inhibition of TPL2, ERK1/2 or L-VDCC alleviated the AHR symptom induced by IL-25 in a murine model. This study revealed that IL-25 potentiated the contraction of tracheal smooth muscle and evoked AHR via activation of TPL2-ERK1/2-CaV1.2 signaling, providing novel targets for the treatment of asthma with a high-IL-25 phenotype.
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Affiliation(s)
- Ze-Xin Huang
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhuo-Er Qiu
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Lei Chen
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xiao-Chun Hou
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yun-Xin Zhu
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wen-Liang Zhou
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yi-Lin Zhang
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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5
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Ning S, Hua L, Ji Z, Fan D, Meng X, Li Z, Wang Q, Guo Z. Protein 4.1 family and ion channel proteins interact to regulate the process of heart failure in rats. Acta Histochem 2021; 123:151748. [PMID: 34271280 DOI: 10.1016/j.acthis.2021.151748] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 02/06/2023]
Abstract
Heart failure (HF) is a major cause of death in cardiovascular diseases worldwide, and its molecular mechanisms and effective prevention strategies remain to be further studied. The myocardial cytoskeleton plays a pivotal role in many heart diseases. However, little is known about the function of the membrane cytoskeleton 4.1 protein family and related regulatory mechanisms in the pathogenesis of HF. In this study, we detected the localization and expression of the protein 4.1 family and ion channel proteins in a rat HF model induced by doxorubicin (DOX), and studied the interactions between them. Our results showed that compared with the control group, the HF group displayed an increased expression level of protein 4.1R and decreased levels of protein 4.1 G and 4.1 N. The Nav1.5 protein levels were significantly increased, while the SERCA2a and Cav1.2 protein levels were significantly decreased in the HF group. Furthermore, there is co-localization and interaction between protein 4.1R and Nav1.5, protein 4.1 G and SERCA2a, protein 4.1 N and Cav1.2, respectively. Taken together, the results indicated that the protein 4.1 family might be involved in the occurrence and development of HF through its interaction with ion channel proteins, suggesting that 4.1 proteins may serve as a novel therapeutic target for HF.
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Affiliation(s)
- Shuwei Ning
- Zhengzhou Key Laboratory, Zhengzhou No. 7 People's Hospital, Zhengzhou, 450016, China
| | - Lei Hua
- Zhengzhou Key Laboratory, Zhengzhou No. 7 People's Hospital, Zhengzhou, 450016, China
| | - Zhenyu Ji
- Henan Academy of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, 450052, China
| | - Dandan Fan
- Henan Academy of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, 450052, China
| | - Xiangguang Meng
- Zhengzhou Key Laboratory, Zhengzhou No. 7 People's Hospital, Zhengzhou, 450016, China
| | - Zhiying Li
- Zhengzhou Key Laboratory, Zhengzhou No. 7 People's Hospital, Zhengzhou, 450016, China
| | - Qian Wang
- Zhengzhou Key Laboratory, Zhengzhou No. 7 People's Hospital, Zhengzhou, 450016, China
| | - Zhikun Guo
- Zhengzhou Key Laboratory, Zhengzhou No. 7 People's Hospital, Zhengzhou, 450016, China; Henan Key Laboratory of Medical Tissue Regeneration, Xinxiang Medical University, Xinxiang, 453003, China.
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6
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Knyrim M, Rabe S, Grossmann C, Gekle M, Schreier B. Influence of miR-221/222 on cardiomyocyte calcium handling and function. Cell Biosci 2021; 11:160. [PMID: 34404451 PMCID: PMC8369661 DOI: 10.1186/s13578-021-00676-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/02/2021] [Indexed: 11/10/2022] Open
Abstract
Background Cardiovascular disease is the leading cause of death worldwide. Cardiac electrical remodeling including altered ion channel expression and imbalance of calcium homeostasis can have detrimental effects on cardiac function. While it has been extensively reported that miR-221/222 are involved in structural remodeling, their role in electrical remodeling still has to be evaluated. We previously reported that subunits of the L-type Ca2+ channel (LTCC) are direct targets of miR-221/222. Furthermore, HL-1 cells transfected with miR-221 or -222 mimics showed a reduction in LTCC current density while the voltage-dependence of activation was not altered. The aim of the present study was to determine the influence of miR-221/222 on cardiomyocyte calcium handling and function. Results Transient transfection of HL-1 cells with miR-221/222 mimics led to slower depolarization-dependent Ca2+ entry and increased proportion of non-responding cells. Angiotensin II-induced Ca2+ release from the SR was not affected by miR-221/222. In miR-222-transfected neonatal cardiomyocytes the isoprenaline-induced positive inotropic effect on the intracellular Ca2+ transient was lost and the positive chronotropic effect on spontaneous beating activity was strongly reduced. This could have severe consequences for cardiomyocytes and could lead to a reduced contractility and systolic dysfunction of the whole heart. Conclusions This study adds a new role of miR-221/222 in cardiomyocytes by showing the impact on β-adrenergic regulation of LTCC function, calcium handling and beating frequency. Together with the previous report that miR-221/222 reduce GIRK1/4 function and LTCC current density, it expands our knowledge about the role of these miRs on cardiac ion channel regulation. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-021-00676-4.
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Affiliation(s)
- Maria Knyrim
- Julius-Bernstein-Institute of Physiology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 6, 06110, Halle (Saale), Germany.
| | - Sindy Rabe
- Julius-Bernstein-Institute of Physiology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 6, 06110, Halle (Saale), Germany
| | - Claudia Grossmann
- Julius-Bernstein-Institute of Physiology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 6, 06110, Halle (Saale), Germany
| | - Michael Gekle
- Julius-Bernstein-Institute of Physiology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 6, 06110, Halle (Saale), Germany
| | - Barbara Schreier
- Julius-Bernstein-Institute of Physiology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 6, 06110, Halle (Saale), Germany
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7
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Abstract
Steroid hormones bind receptors in the cell nucleus and in the cell membrane. The most widely studied class of steroid hormone receptors are the nuclear receptors, named for their function as ligand-dependent transcription factors in the cell nucleus. Nuclear receptors, such as estrogen receptor alpha, can also be anchored to the plasma membrane, where they respond to steroids by activating signaling pathways independent of their function as transcription factors. Steroids can also bind integral membrane proteins, such as the G protein-coupled estrogen receptor. Membrane estrogen and progestin receptors have been cloned and characterized in vitro and influence the development and function of many organ systems. Membrane androgen receptors were cloned and characterized in vitro, but their function as androgen receptors in vivo is unresolved. We review the identity and function of membrane proteins that bind estrogens, progestins, and androgens. We discuss evidence that membrane glucocorticoid and mineralocorticoid receptors exist, and whether glucocorticoid and mineralocorticoid nuclear receptors act at the cell membrane. In many cases, integral membrane steroid receptors act independently of nuclear steroid receptors, even though they may share a ligand.
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Affiliation(s)
- Lindsey S Treviño
- Department of Population Sciences, Division of Health Equities, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA
| | - Daniel A Gorelick
- Center for Precision Environmental Health, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Correspondence: Daniel A Gorelick, PhD, One Baylor Plaza, Alkek Building N1317.07, Houston, TX, 77030-3411, USA.
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8
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Han JW, Kang C, Kim Y, Lee MG, Kim JY. Isoproterenol-induced hypertrophy of neonatal cardiac myocytes and H9c2 cell is dependent on TRPC3-regulated Ca V1.2 expression. Cell Calcium 2020; 92:102305. [PMID: 33069962 DOI: 10.1016/j.ceca.2020.102305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/24/2020] [Accepted: 09/25/2020] [Indexed: 02/07/2023]
Abstract
CaV1.2 and transient receptor potential canonical channel 3 (TRPC3) are two proteins known to have important roles in pathological cardiac hypertrophy; however, such roles still remain unclear. A better understanding of these roles is important for furthering the clinical understanding of heart failure. We previously reported that Trpc3-knockout (KO) mice are resistant to pathologic hypertrophy and that their CaV1.2 protein expression is reduced. In this study, we aimed to examine the relationship between these two proteins and characterize their role in neonatal cardiomyocytes. We measured CaV1.2 expression in the hearts of wild-type (WT) and Trpc3-/- mice, and examined the effects of Trpc3 knockdown and overexpression in the rat cell line H9c2. We also compared the hypertrophic responses of neonatal cardiomyocytes cultured from Trpc3-/- mice to a representative hypertrophy-causing drug, isoproterenol (ISO), and measured the activity of nuclear factor of activated T cells 3 (NFAT3) in neonatal cardiomyocytes (NCMCs). We inhibited the L-type current with nifedipine, and measured the intracellular calcium concentration using Fura-2 with 1-oleoyl-2-acetyl-sn-glycerol (OAG)-induced Ba2+ influx. When using the Trpc3-mediated Ca2+ influx, both intracellular calcium concentration and calcium influx were reduced in Trpc3-KO myocytes. Not only was the expression of CaV1.2 greatly reduced in Trpc3-KO cardiac lysate, but the size of the CaV1.2 currents in NCMCs was also greatly reduced. When NCMCs were treated with Trpc3 siRNA, it was confirmed that the expression of CaV1.2 and the intracellular nuclear transfer activity of NFAT decreased. In H9c2 cells, the ISO activated- and verapamil inhibited- Ca2+ influxes were dramatically attenuated by Trpc3 siRNA treatment. In addition, it was confirmed that both the expression of CaV1.2 and the size of H9c2 cells were regulated according to the expression and activation level of TRPC3. We found that after stimulation with ISO, cell hypertrophy occurred in WT myocytes, while the increase in size of Trpc3-KO myocytes was greatly reduced. These results suggest that not only the cell hypertrophy process in neonatal cardiac myocytes and H9c2 cells were regulated according to the expression level of CaV1.2, but also that the expression level of CaV1.2 was regulated by TRPC3 through the activation of NFAT.
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Affiliation(s)
- Jung Woo Han
- Department of Pharmacology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, South Korea.
| | - Choeun Kang
- Department of Pharmacology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, South Korea.
| | - Yonjung Kim
- Department of Pharmacology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, South Korea.
| | - Min Goo Lee
- Department of Pharmacology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, South Korea.
| | - Joo Young Kim
- Department of Pharmacology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, South Korea.
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9
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Ren AJ, Chen C, Zhang S, Liu M, Wei C, Wang K, Ma X, Song Y, Wang R, Zhang H, Chen YX, Wu H, Xie Z, Zhang Y, Zhang WJ. Zbtb20 deficiency causes cardiac contractile dysfunction in mice. FASEB J 2020; 34:13862-13876. [PMID: 32844471 DOI: 10.1096/fj.202000160rr] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 08/04/2020] [Accepted: 08/07/2020] [Indexed: 12/15/2022]
Abstract
The zinc-finger protein ZBTB20 regulates development and metabolism in multiple systems, and is essential for postnatal survival in mice. However, its potential role in the cardiovascular system remains undefined. Here, we demonstrate that ZBTB20 is critically involved in the regulation of cardiac contractility and blood pressure in mice. At the age of 16 days, the relatively healthy Zbtb20-null mice exhibited hypotension without obvious change of heart rate or other evidence for heart failure. Moreover, Zbtb20 deletion led to a marked reduction in heart size, left ventricular wall thickness, and cell size of cardiomyocytes, which was largely proportional to the decreased body growth. Notably, echocardiographic and hemodynamic analyses showed that cardiac contractility was greatly impaired in the absence of ZBTB20. Mechanistically, ZBTB20 deficiency decreased cardiac ATP contents, and compromised the enzyme activity of mitochondrial complex I in heart as well as L-type calcium current density in cardiomyocytes. Furthermore, the developmental activation of some mitochondrial function-related genes was significantly attenuated in Zbtb20-null myocardium, which included Hspb8, Ckmt2, Cox7a1, Tfrc, and Ogdhl. Put together, these results suggest that ZBTB20 plays a crucial role in the regulation of heart development, energy metabolism, and contractility.
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Affiliation(s)
- An-Jing Ren
- Department of Pathophysiology, Naval Medical University, Shanghai, China
| | - Chao Chen
- Institute of Vascular Medicine, Peking University Third Hospital, Beijing, China
| | - Sha Zhang
- Department of Pathophysiology, Naval Medical University, Shanghai, China.,Department of Cardiovascular Diseases, Changhai Hospital, Naval Medical University, Shanghai, China
| | - Mengna Liu
- Department of Pathophysiology, Naval Medical University, Shanghai, China
| | - Chunchun Wei
- Department of Pathophysiology, Naval Medical University, Shanghai, China
| | - Kai Wang
- Department of Pathophysiology, Naval Medical University, Shanghai, China
| | - Xianhua Ma
- Department of Pathophysiology, Naval Medical University, Shanghai, China
| | - Yao Song
- Institute of Vascular Medicine, Peking University Third Hospital, Beijing, China
| | - Rui Wang
- Department of Pathophysiology, Naval Medical University, Shanghai, China
| | - Hai Zhang
- Department of Pathophysiology, Naval Medical University, Shanghai, China
| | - Yu-Xia Chen
- Department of Pathophysiology, Naval Medical University, Shanghai, China
| | - Hong Wu
- Department of Cardiovascular Diseases, Changhai Hospital, Naval Medical University, Shanghai, China
| | - Zhifang Xie
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Youyi Zhang
- Institute of Vascular Medicine, Peking University Third Hospital, Beijing, China
| | - Weiping J Zhang
- Department of Pathophysiology, Naval Medical University, Shanghai, China.,NHC Key Laboratory of Hormones and Development, Tianjin Institute of Endocrinology, Tianjin Medical University Chu Hsien-I Memorial Hospital, Tianjin, China
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10
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Lee DP, Tan WLW, Anene-Nzelu CG, Lee CJM, Li PY, Luu TDA, Chan CX, Tiang Z, Ng SL, Huang X, Efthymios M, Autio MI, Jiang J, Fullwood MJ, Prabhakar S, Lieberman Aiden E, Foo RSY. Robust CTCF-Based Chromatin Architecture Underpins Epigenetic Changes in the Heart Failure Stress-Gene Response. Circulation 2020; 139:1937-1956. [PMID: 30717603 DOI: 10.1161/circulationaha.118.036726] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND The human genome folds in 3 dimensions to form thousands of chromatin loops inside the nucleus, encasing genes and cis-regulatory elements for accurate gene expression control. Physical tethers of loops are anchored by the DNA-binding protein CTCF and the cohesin ring complex. Because heart failure is characterized by hallmark gene expression changes, it was recently reported that substantial CTCF-related chromatin reorganization underpins the myocardial stress-gene response, paralleled by chromatin domain boundary changes observed in CTCF knockout. METHODS We undertook an independent and orthogonal analysis of chromatin organization with mouse pressure-overload model of myocardial stress (transverse aortic constriction) and cardiomyocyte-specific knockout of Ctcf. We also downloaded published data sets of similar cardiac mouse models and subjected them to independent reanalysis. RESULTS We found that the cardiomyocyte chromatin architecture remains broadly stable in transverse aortic constriction hearts, whereas Ctcf knockout resulted in ≈99% abolition of global chromatin loops. Disease gene expression changes correlated instead with differential histone H3K27-acetylation enrichment at their respective proximal and distal interacting genomic enhancers confined within these static chromatin structures. Moreover, coregulated genes were mapped out as interconnected gene sets on the basis of their multigene 3D interactions. CONCLUSIONS This work reveals a more stable genome-wide chromatin framework than previously described. Myocardial stress-gene transcription responds instead through H3K27-acetylation enhancer enrichment dynamics and gene networks of coregulation. Robust and intact CTCF looping is required for the induction of a rapid and accurate stress response.
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Affiliation(s)
- Dominic Paul Lee
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Wilson Lek Wen Tan
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Chukwuemeka George Anene-Nzelu
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Chang Jie Mick Lee
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Peter Yiqing Li
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Tuan Danh Anh Luu
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Cheryl Xueli Chan
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Zenia Tiang
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Shi Ling Ng
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Xingfan Huang
- Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (X.H., E.L.A.)
- Center for Theoretical Biological Physics and Department of Computer Science, Rice University, Houston, TX (X.H., E.L.A.)
| | - Motakis Efthymios
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Matias I Autio
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
| | - Jianming Jiang
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
- Department of Biochemistry, School of Medicine (J.J.), National University of Singapore
| | - Melissa Jane Fullwood
- Cancer Science Institute (M.J.F.), National University of Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore (M.J.F.)
| | - Shyam Prabhakar
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
| | - Erez Lieberman Aiden
- Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX (X.H., E.L.A.)
- Center for Theoretical Biological Physics and Department of Computer Science, Rice University, Houston, TX (X.H., E.L.A.)
| | - Roger Sik-Yin Foo
- Genome Institute of Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., C.X.C., Z.T., S.L.N., M.E., M.I.A., S.P., R.S.-Y.F.)
- Cardiovascular Research Institute, National University Health System, Centre for Translational Medicine, Singapore (D.P.L., W.L.W.T., C.G.A.-N., C.J.M.L., P.Y.L., T.L.D.A., C.X.C., Z.T., S.L.N., M.E., M.I.A., J.J., R.S.-Y.F.)
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11
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Sato D, Hernández-Hernández G, Matsumoto C, Tajada S, Moreno CM, Dixon RE, O'Dwyer S, Navedo MF, Trimmer JS, Clancy CE, Binder MD, Santana LF. A stochastic model of ion channel cluster formation in the plasma membrane. J Gen Physiol 2019; 151:1116-1134. [PMID: 31371391 PMCID: PMC6719406 DOI: 10.1085/jgp.201912327] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 07/05/2019] [Accepted: 07/08/2019] [Indexed: 12/24/2022] Open
Abstract
Ion channels are often found arranged into dense clusters in the plasma membranes of excitable cells, but the mechanisms underlying the formation and maintenance of these functional aggregates are unknown. Here, we tested the hypothesis that channel clustering is the consequence of a stochastic self-assembly process and propose a model by which channel clusters are formed and regulated in size. Our hypothesis is based on statistical analyses of the size distributions of the channel clusters we measured in neurons, ventricular myocytes, arterial smooth muscle, and heterologous cells, which in all cases were described by exponential functions, indicative of a Poisson process (i.e., clusters form in a continuous, independent, and memory-less fashion). We were able to reproduce the observed cluster distributions of five different types of channels in the membrane of excitable and tsA-201 cells in simulations using a computer model in which channels are "delivered" to the membrane at randomly assigned locations. The model's three parameters represent channel cluster nucleation, growth, and removal probabilities, the values of which were estimated based on our experimental measurements. We also determined the time course of cluster formation and membrane dwell time for CaV1.2 and TRPV4 channels expressed in tsA-201 cells to constrain our model. In addition, we elaborated a more complex version of our model that incorporated a self-regulating feedback mechanism to shape channel cluster formation. The strong inference we make from our results is that CaV1.2, CaV1.3, BK, and TRPV4 proteins are all randomly inserted into the plasma membranes of excitable cells and that they form homogeneous clusters that increase in size until they reach a steady state. Further, it appears likely that cluster size for a diverse set of membrane-bound proteins and a wide range of cell types is regulated by a common feedback mechanism.
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Affiliation(s)
- Daisuke Sato
- Department of Pharmacology, University of California School of Medicine, Davis, CA
| | | | - Collin Matsumoto
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA
| | - Sendoa Tajada
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA
| | - Claudia M Moreno
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA
| | - Rose E Dixon
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA
| | - Samantha O'Dwyer
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA
| | - Manuel F Navedo
- Department of Pharmacology, University of California School of Medicine, Davis, CA
| | - James S Trimmer
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA
| | - Colleen E Clancy
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA
| | - Marc D Binder
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA
| | - L Fernando Santana
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA
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12
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Abstract
Most cells in the body acquire iron via receptor-mediated endocytosis of transferrin, the circulating iron transport protein. When cellular iron levels are sufficient, the uptake of transferrin decreases to limit further iron assimilation and prevent excessive iron accumulation. In iron overload conditions, such as hereditary hemochromatosis and thalassemia major, unregulated iron entry into the plasma overwhelms the carrying capacity of transferrin, resulting in non-transferrin-bound iron (NTBI), a redox-active, potentially toxic form of iron. Plasma NTBI is rapidly cleared from the circulation primarily by the liver and other organs (e.g., pancreas, heart, and pituitary) where it contributes significantly to tissue iron overload and related pathology. While NTBI is usually not detectable in the plasma of healthy individuals, it does appear to be a normal constituent of brain interstitial fluid and therefore likely serves as an important source of iron for most cell types in the CNS. A growing body of literature indicates that NTBI uptake is mediated by non-transferrin-bound iron transporters such as ZIP14, L-type and T-type calcium channels, DMT1, ZIP8, and TRPC6. This review provides an overview of NTBI uptake by various tissues and cells and summarizes the evidence for and against the roles of individual transporters in this process.
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Affiliation(s)
- Mitchell D Knutson
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA.
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13
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McKinnon D, Rosati B. Transmural gradients in ion channel and auxiliary subunit expression. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:165-186. [PMID: 27702655 DOI: 10.1016/j.pbiomolbio.2016.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/30/2016] [Indexed: 12/11/2022]
Abstract
Evolution has acted to shape the action potential in different regions of the heart in order to produce a maximally stable and efficient pump. This has been achieved by creating regional differences in ion channel expression levels within the heart as well as differences between equivalent cardiac tissues in different species. These region- and species-dependent differences in channel expression are established by regulatory evolution, evolution of the regulatory mechanisms that control channel expression levels. Ion channel auxiliary subunits are obvious targets for regulatory evolution, in order to change channel expression levels and/or modify channel function. This review focuses on the transmural gradients of ion channel expression in the heart and the role that regulation of auxiliary subunit expression plays in generating and shaping these gradients.
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Affiliation(s)
- David McKinnon
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Barbara Rosati
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, 11794, USA.
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14
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Cheli VT, Santiago González DA, Smith J, Spreuer V, Murphy GG, Paez PM. L-type voltage-operated calcium channels contribute to astrocyte activation In vitro. Glia 2016; 64:1396-415. [PMID: 27247164 DOI: 10.1002/glia.23013] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 03/11/2016] [Accepted: 05/12/2016] [Indexed: 12/20/2022]
Abstract
We have found a significant upregulation of L-type voltage-operated Ca(++) channels (VOCCs) in reactive astrocytes. To test if VOCCs are centrally involved in triggering astrocyte reactivity, we used in vitro models of astrocyte activation in combination with pharmacological inhibitors, siRNAs and the Cre/lox system to reduce the activity of L-type VOCCs in primary cortical astrocytes. The endotoxin lipopolysaccharide (LPS) as well as high extracellular K(+) , glutamate, and ATP promote astrogliosis in vitro. L-type VOCC inhibitors drastically reduce the number of reactive cells, astrocyte hypertrophy, and cell proliferation after these treatments. Astrocytes transfected with siRNAs for the Cav1.2 subunit that conducts L-type Ca(++) currents as well as Cav1.2 knockout astrocytes showed reduce Ca(++) influx by ∼80% after plasma membrane depolarization. Importantly, Cav1.2 knock-down/out prevents astrocyte activation and proliferation induced by LPS. Similar results were found using the scratch wound assay. After injuring the astrocyte monolayer, cells extend processes toward the cell-free scratch region and subsequently migrate and populate the scratch. We found a significant increase in the activity of L-type VOCCs in reactive astrocytes located in the growing line in comparison to quiescent astrocytes situated away from the scratch. Moreover, the migration of astrocytes from the scratching line as well as the number of proliferating astrocytes was reduced in Cav1.2 knock-down/out cultures. In summary, our results suggest that Cav1.2 L-type VOCCs play a fundamental role in the induction and/or proliferation of reactive astrocytes, and indicate that the inhibition of these Ca(++) channels may be an effective way to prevent astrocyte activation. GLIA 2016. GLIA 2016;64:1396-1415.
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Affiliation(s)
- Veronica T Cheli
- Department of Pharmacology and Toxicology, Hunter James Kelly Research Institute, School of Medicine and Biomedical Sciences, SUNY, University at Buffalo. NYS Center of Excellence, 701 Ellicott St., Buffalo, New York
| | - Diara A Santiago González
- Department of Pharmacology and Toxicology, Hunter James Kelly Research Institute, School of Medicine and Biomedical Sciences, SUNY, University at Buffalo. NYS Center of Excellence, 701 Ellicott St., Buffalo, New York
| | - Jessica Smith
- Department of Pharmacology and Toxicology, Hunter James Kelly Research Institute, School of Medicine and Biomedical Sciences, SUNY, University at Buffalo. NYS Center of Excellence, 701 Ellicott St., Buffalo, New York
| | - Vilma Spreuer
- Department of Pharmacology and Toxicology, Hunter James Kelly Research Institute, School of Medicine and Biomedical Sciences, SUNY, University at Buffalo. NYS Center of Excellence, 701 Ellicott St., Buffalo, New York
| | - Geoffrey G Murphy
- Department of Physiology, Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, Michigan
| | - Pablo M Paez
- Department of Pharmacology and Toxicology, Hunter James Kelly Research Institute, School of Medicine and Biomedical Sciences, SUNY, University at Buffalo. NYS Center of Excellence, 701 Ellicott St., Buffalo, New York
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15
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Ke F, Zhang L, Liu Z, Liu J, Yan S, Xu Z, Bai J, Zhu H, Lou F, Wang H, Shi Y, Jiang Y, Su B, Wang H. Autocrine interleukin-6 drives skin-derived mesenchymal stem cell trafficking via regulating voltage-gated Ca(2+) channels. Stem Cells 2015; 32:2799-810. [PMID: 24906203 DOI: 10.1002/stem.1763] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 04/01/2014] [Accepted: 04/09/2014] [Indexed: 12/13/2022]
Abstract
Mesenchymal stem cells (MSCs) have demonstrated promising therapeutic potential for a variety of diseases including autoimmune disorders. A fundamental requirement for MSC-mediated in vivo immunosuppression is their effective trafficking. However the mechanism underlying MSC trafficking remains elusive. Here we report that skin-derived MSCs (S-MSCs) secrete high levels of interleukin-6 (IL-6) in inflammatory conditions. Disruption of the il6 or its signaling transducer gp130 blocks voltage-gated calcium (Ca(2+) ) channels (VGCC) critically required for cell contraction involved in the sequential adhesion and de-adhesion events during S-MSC migration. Deletion of il6 gene leads to a severe defect in S-MSC's trafficking and immunosuppressive function in vivo. Thus, this unexpected requirement of autocrine IL-6 for activating Ca(2+) channels uncovers a previously unrecognized link between the IL-6 signaling and the VGCC and provides novel mechanistic insights for the trafficking and immunomodulatory activities of S-MSCs.
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Affiliation(s)
- Fang Ke
- Shanghai Institute of Immunology, Institute of Medical Sciences, Institute of Health Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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16
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Wang HZ, Rosati B, Gordon C, Valiunas V, McKinnon D, Cohen IS, Brink PR. Inhibition of histone deacetylase (HDAC) by 4-phenylbutyrate results in increased junctional conductance between rat corpora smooth muscle cells. Front Pharmacol 2015; 6:9. [PMID: 25691868 PMCID: PMC4315027 DOI: 10.3389/fphar.2015.00009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 01/11/2015] [Indexed: 01/02/2023] Open
Abstract
4-phenylbutyrate (4-PB) has been shown to increase the protein content in a number of cells types. One such protein is Connexin43 (Cx43). We show here that 4-phenylbutyrate exposure results in significantly elevated cell to cell coupling, as determined by dual whole cell patch clamp. Incubation with 5 mM 4PB for 24 h or more nearly doubles junctional conductance. Interestingly, mRNA levels for Cx43 declined with exposure to 4-PB while western blot analysis revealed not significant change in protein levels. These data are most consistent with stabilization of the existing Cx43 pool or alterations in the number of functional channels within an existing pool of active and silent channels. These data represent a baseline for testing the efficacy of increased connexin mediated coupling in a variety of multicellular functions including erectile function.
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Affiliation(s)
- Hong Zhan Wang
- Department of Physiology and Biophysics, Stony Brook University Stony Brook, NY, USA
| | - Barbara Rosati
- Department of Physiology and Biophysics, Stony Brook University Stony Brook, NY, USA ; Department of Physiology and Biophysics, Molecular Cardiology Institute, Stony Brook University Stony Brook, NY, USA
| | - Chris Gordon
- Department of Physiology and Biophysics, Stony Brook University Stony Brook, NY, USA
| | - Virginijus Valiunas
- Department of Physiology and Biophysics, Stony Brook University Stony Brook, NY, USA ; Department of Physiology and Biophysics, Molecular Cardiology Institute, Stony Brook University Stony Brook, NY, USA
| | - David McKinnon
- Department of Physiology and Biophysics, Molecular Cardiology Institute, Stony Brook University Stony Brook, NY, USA ; Department of Neurobiology and Behavior, Stony Brook University Stony Brook, NY, USA
| | - Ira S Cohen
- Department of Physiology and Biophysics, Stony Brook University Stony Brook, NY, USA ; Department of Physiology and Biophysics, Molecular Cardiology Institute, Stony Brook University Stony Brook, NY, USA
| | - Peter R Brink
- Department of Physiology and Biophysics, Stony Brook University Stony Brook, NY, USA ; Department of Physiology and Biophysics, Molecular Cardiology Institute, Stony Brook University Stony Brook, NY, USA
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17
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Cheli VT, Santiago González DA, Spreuer V, Paez PM. Voltage-gated Ca2+ entry promotes oligodendrocyte progenitor cell maturation and myelination in vitro. Exp Neurol 2014; 265:69-83. [PMID: 25542980 DOI: 10.1016/j.expneurol.2014.12.012] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 11/14/2014] [Accepted: 12/12/2014] [Indexed: 11/16/2022]
Abstract
We have previously shown that the expression of voltage-operated Ca(++) channels (VOCCs) is highly regulated in the oligodendroglial lineage and is essential for proper oligodendrocyte progenitor cell (OPC) migration. Here we assessed the role of VOCCs, in particular the L-type, in oligodendrocyte maturation. We used pharmacological treatments to activate or block voltage-gated Ca(++) uptake and siRNAs to specifically knock down the L-type VOCC in primary cultures of mouse OPCs. Activation of VOCCs by plasma membrane depolarization increased OPC morphological differentiation as well as the expression of mature oligodendrocyte markers. On the contrary, inhibition of L-type Ca(++) channels significantly delayed OPC development. OPCs transfected with siRNAs for the Cav1.2 subunit that conducts L-type Ca(++) currents showed reduce Ca(++) influx by ~75% after plasma membrane depolarization, indicating that Cav1.2 is heavily involved in mediating voltage-operated Ca(++) entry in OPCs. Cav1.2 knockdown induced a decrease in the proportion of oligodendrocytes that expressed myelin proteins, and an increase in cells that retained immature oligodendrocyte markers. Moreover, OPC proliferation, but not cell viability, was negatively affected after L-type Ca(++) channel knockdown. Additionally, we have tested the ability of L-type VOCCs to facilitate axon-glial interaction during the first steps of myelin formation using an in vitro co-culture system of OPCs with cortical neurons. Unlike control OPCs, Cav1.2 deficient oligodendrocytes displayed a simple morphology, low levels of myelin proteins expression and appeared to be less capable of establishing contacts with neurites and axons. Together, this set of in vitro experiments characterizes the involvement of L-type VOCCs on OPC maturation as well as the role played by these Ca(++) channels during the early phases of myelination.
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Affiliation(s)
- V T Cheli
- Hunter James Kelly Research Institute, Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, SUNY, University at Buffalo, NYS Center of Excellence, 701 Ellicott St., Buffalo, NY 14203, USA
| | - D A Santiago González
- Hunter James Kelly Research Institute, Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, SUNY, University at Buffalo, NYS Center of Excellence, 701 Ellicott St., Buffalo, NY 14203, USA
| | - V Spreuer
- Hunter James Kelly Research Institute, Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, SUNY, University at Buffalo, NYS Center of Excellence, 701 Ellicott St., Buffalo, NY 14203, USA
| | - P M Paez
- Hunter James Kelly Research Institute, Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, SUNY, University at Buffalo, NYS Center of Excellence, 701 Ellicott St., Buffalo, NY 14203, USA.
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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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A rare mutation of CACNA1C in a patient with bipolar disorder, and decreased gene expression associated with a bipolar-associated common SNP of CACNA1C in brain. Mol Psychiatry 2014; 19:890-4. [PMID: 23979604 PMCID: PMC4151967 DOI: 10.1038/mp.2013.107] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 07/07/2013] [Accepted: 07/10/2013] [Indexed: 12/15/2022]
Abstract
Timothy Syndrome (TS) is caused by very rare exonic mutations of the CACNA1C gene that produce delayed inactivation of Cav1.2 voltage-gated calcium channels during cellular action potentials, with greatly increased influx of calcium into the activated cells. The major clinical feature of this syndrome is a long QT interval that results in cardiac arrhythmias. However, TS also includes cognitive impairment, autism and major developmental delays in many of the patients. We observed the appearance of bipolar disorder (BD) in a patient with a previously reported case of TS, who is one of the very few patients to survive childhood. This is most interesting because the common single-nucleotide polymorphism (SNP) most highly associated with BD is rs1006737, which we show here is a cis-expression quantitative trait locus for CACNA1C in human cerebellum, and the risk allele (A) is associated with decreased expression. To combine the CACNA1C perturbations in the presence of BD in this patient and in patients with the common CACNA1C SNP risk allele, we would propose that either increase or decrease in calcium influx in excitable cells can be associated with BD. In treatment of BD with calcium channel blocking drugs, we would predict better response in patients without the risk allele, because they have increased CACNA1C expression.
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20
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Aziz R, Beymer M, Negrón AL, Newshan A, Yu G, Rosati B, McKinnon D, Fukuda M, Lin RZ, Mayer C, Boehm U, Acosta-Martínez M. Galanin-like peptide (GALP) neurone-specific phosphoinositide 3-kinase signalling regulates GALP mRNA levels in the hypothalamus of males and luteinising hormone levels in both sexes. J Neuroendocrinol 2014; 26:426-38. [PMID: 24796383 PMCID: PMC4076824 DOI: 10.1111/jne.12163] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/23/2014] [Accepted: 04/28/2014] [Indexed: 12/31/2022]
Abstract
Galanin-like peptide (GALP) neurones participate in the metabolic control of reproduction and are targets of insulin and leptin regulation. Phosphoinositide 3-kinase (PI3K) is common to the signalling pathways utilised by both insulin and leptin. Therefore, we investigated whether PI3K signalling in neurones expressing GALP plays a role in the transcriptional regulation of the GALP gene and in the metabolic control of luteinising hormone (LH) release. Accordingly, we deleted PI3K catalytic subunits p110α and p110β via conditional gene targeting (cKO) in mice (GALP-p110α/β cKO). To monitor PI3K signalling in GALP neurones, these animals were also crossed with Cre-dependent FoxO1GFP reporter mice. Compared to insulin-infused control animals, the PI3K-Akt-dependent FoxO1GFP nuclear exclusion in GALP neurones was abolished in GALP-p110α/β cKO mice. We next used food deprivation to investigate whether the GALP-neurone specific ablation of PI3K activity affected the susceptibility of the gonadotrophic axis to negative energy balance. Treatment did not affect LH levels in either sex. However, a significant genotype effect on LH levels was observed in females. By contrast, no genotype effect on LH levels was observed in males. A sex-specific genotype effect on hypothalamic GALP mRNA was observed, with fed and fasted GALP-p110α/β cKO males having lower GALP mRNA expression compared to wild-type fed males. Finally, the effects of gonadectomy and steroid hormone replacement on GALP mRNA levels were investigated. Compared to vehicle-treated mice, steroid hormone replacement reduced mediobasal hypothalamus GALP expression in wild-type and GALP-p110α/β cKO animals. In addition, within the castrated and vehicle-treated group and compared to wild-type mice, LH levels were lower in GALP-p110α/β cKO males. Double immunofluorescence using GALP-Cre/R26-YFP mice showed androgen and oestrogen receptor co-localisation within GALP neurones. Our data demonstrate that GALP neurones are direct targets of steroid hormones and that PI3K signalling regulates hypothalamic GALP mRNA expression and LH levels in a sex-specific fashion.
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Affiliation(s)
- R Aziz
- Department of Physiology and Biophysics, Medical Center, Stony Brook University, Stony Brook, NY, USA
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21
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Hofmann F, Flockerzi V, Kahl S, Wegener JW. L-type CaV1.2 calcium channels: from in vitro findings to in vivo function. Physiol Rev 2014; 94:303-26. [PMID: 24382889 DOI: 10.1152/physrev.00016.2013] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The L-type Cav1.2 calcium channel is present throughout the animal kingdom and is essential for some aspects of CNS function, cardiac and smooth muscle contractility, neuroendocrine regulation, and multiple other processes. The L-type CaV1.2 channel is built by up to four subunits; all subunits exist in various splice variants that potentially affect the biophysical and biological functions of the channel. Many of the CaV1.2 channel properties have been analyzed in heterologous expression systems including regulation of the L-type CaV1.2 channel by Ca(2+) itself and protein kinases. However, targeted mutations of the calcium channel genes confirmed only some of these in vitro findings. Substitution of the respective serines by alanine showed that β-adrenergic upregulation of the cardiac CaV1.2 channel did not depend on the phosphorylation of the in vitro specified amino acids. Moreover, well-established in vitro phosphorylation sites of the CaVβ2 subunit of the cardiac L-type CaV1.2 channel were found to be irrelevant for the in vivo regulation of the channel. However, the molecular basis of some kinetic properties, such as Ca(2+)-dependent inactivation and facilitation, has been approved by in vivo mutagenesis of the CaV1.2α1 gene. This article summarizes recent findings on the in vivo relevance of well-established in vitro results.
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Striessnig J, Pinggera A, Kaur G, Bock G, Tuluc P. L-type Ca 2+ channels in heart and brain. ACTA ACUST UNITED AC 2014; 3:15-38. [PMID: 24683526 PMCID: PMC3968275 DOI: 10.1002/wmts.102] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
L-type calcium channels (Cav1) represent one of the three major classes (Cav1–3) of voltage-gated calcium channels. They were identified as the target of clinically used calcium channel blockers (CCBs; so-called calcium antagonists) and were the first class accessible to biochemical characterization. Four of the 10 known α1 subunits (Cav1.1–Cav1.4) form the pore of L-type calcium channels (LTCCs) and contain the high-affinity drug-binding sites for dihydropyridines and other chemical classes of organic CCBs. In essentially all electrically excitable cells one or more of these LTCC isoforms is expressed, and therefore it is not surprising that many body functions including muscle, brain, endocrine, and sensory function depend on proper LTCC activity. Gene knockouts and inherited human diseases have allowed detailed insight into the physiological and pathophysiological role of these channels. Genome-wide association studies and analysis of human genomes are currently providing even more hints that even small changes of channel expression or activity may be associated with disease, such as psychiatric disease or cardiac arrhythmias. Therefore, it is important to understand the structure–function relationship of LTCC isoforms, their differential contribution to physiological function, as well as their fine-tuning by modulatory cellular processes.
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Affiliation(s)
- Jörg Striessnig
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Alexandra Pinggera
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Gurjot Kaur
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Gabriella Bock
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Petronel Tuluc
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
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Cardiac functions of voltage-gated Ca(2+) channels: role of the pharmacoresistant type (E-/R-Type) in cardiac modulation and putative implication in sudden unexpected death in epilepsy (SUDEP). Rev Physiol Biochem Pharmacol 2014; 167:115-39. [PMID: 25280639 DOI: 10.1007/112_2014_21] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Voltage-gated Ca(2+) channels (VGCCs) are ubiquitous in excitable cells. These channels play key roles in many physiological events like cardiac regulation/pacemaker activity due to intracellular Ca(2+) transients. In the myocardium, the Cav1 subfamily (L-type: Cav1.2 and Cav1.3) is the main contributor to excitation-contraction coupling and/or pacemaking, whereas the Cav3 subfamily (T-type: Cav3.1 and Cav3.2) is important in rhythmically firing of the cardiac nodal cells. No established cardiac function has been attributed to the Cav2 family (E-/R-type: Cav2.3) despite accumulating evidence of cardiac dysregulation observed upon deletion of the Cav2.3 gene, the only member of this family so far detected in cardiomyocytes. In this review, we summarize the pathophysiological changes observed after ablation of the E-/R-type VGCC and propose a cardiac mechanism of action for this channel. Also, considering the role played by this channel in epilepsy and its reported sensitivity to antiepileptic drugs, a putative involvement of this channel in the cardiac mechanism of sudden unexpected death in epilepsy is also discussed.
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24
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Cox RH, Fromme SJ. A naturally occurring truncated Cav1.2 α1-subunit inhibits Ca2+ current in A7r5 cells. Am J Physiol Cell Physiol 2013; 305:C896-905. [PMID: 23926129 DOI: 10.1152/ajpcell.00217.2013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Alternative splicing of the voltage-gated Ca(2+) (CaV) α1-subunit adds to the functional diversity of Ca(2+) channels. A variant with a 73-nt deletion in exon 15 of the Cav1.2 α1-subunit (Cav1.2Δ73) produced by alternative splicing that predicts a truncated protein has been described, but its function, if any, is unknown. We sought to determine if, by analogy to other truncated CaV α1-subunits, Cav1.2Δ73 acts as an inhibitor of wild-type Cav1.2 currents. HEK-293 cells were transfected with Cav1.2Δ73 in a pIRES vector with CD8 or in pcDNA3.1 with a V5/his COOH-terminal tag plus β2 and α2δ1 accessory subunits and pEGFP. Production of Cav1.2Δ73 protein was confirmed by Western blotting and immunofluorescence. Voltage-clamp studies revealed the absence of functional channels in transfected cells. In contrast, cells transfected with full-length Cav1.2 plus accessory subunits and pEGFP exhibited robust Ca(2+) currents. A7r5 cells exhibited endogenous Cav1.2-based currents that were greatly reduced (>80%) without a change in voltage-dependent activation when transfected with Cav1.2Δ73-IRES-CD8 compared with empty vector or pIRES-CD8 controls. Transfection of A7r5 cells with an analogous Cav2.3Δ73-IRES-CD8 had no effect on Ca(2+) currents. Immunofluorescence showed intracellular, but not plasma membrane, localization of Cav1.2Δ73-V5/his, as well as colocalization with an endoplasmic reticulum marker, ER Organelle Lights. Expression of Cav1.2Δ73 α1-subunits in A7r5 cells inhibits endogenous Cav1.2 currents. The fact that this variant arises naturally by alternative splicing raises the possibility that it may represent a physiological mechanism to modulate Cav1.2 functional activity.
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Affiliation(s)
- Robert H Cox
- Program in Cardiovascular Studies, Lankenau Institute for Medical Research, Main Line Health System, Wynnewood, Pennsylvania
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25
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Zhang SS, Shaw RM. Multilayered regulation of cardiac ion channels. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1833:876-85. [PMID: 23103513 PMCID: PMC3568256 DOI: 10.1016/j.bbamcr.2012.10.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 10/12/2012] [Accepted: 10/12/2012] [Indexed: 12/27/2022]
Abstract
Essential to beat-to-beat heart function is the ability for cardiomyocytes to propagate electrical excitation and generate contractile force. Both excitation and contractility depend on specific ventricular ion channels, which include the L-type calcium channel (LTCC) and the connexin 43 (Cx43) gap junction. Each of these two channels is localized to a distinct subdomain of the cardiomyocyte plasma membrane. In this review, we focus on regulatory mechanisms that govern the lifecycles of LTCC and Cx43, from their biogenesis in the nucleus to directed delivery to T-tubules and intercalated discs, respectively. We discuss recent findings on how alternative promoter usage, tissue-specific transcription, and alternative splicing determine precise ion channel expression levels within a cardiomyocyte. Moreover, recent work on microtubule and actin-dependent trafficking for Cx43 and LTCC are introduced. Lastly, we discuss how human cardiac disease phenotypes can be attributed to defects in distinct mechanisms of channel regulation at the level of gene expression and channel trafficking. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction.
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Affiliation(s)
- Shan-Shan Zhang
- University of California, San Francisco, San Francisco, CA 94158, USA
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26
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Guo Y, Rosati B, Scarlata S. α-Synuclein increases the cellular level of phospholipase Cβ1. Cell Signal 2012; 24:1109-14. [PMID: 22286107 DOI: 10.1016/j.cellsig.2012.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 12/30/2011] [Accepted: 01/12/2012] [Indexed: 12/22/2022]
Abstract
α-Synuclein is a conserved protein that is a key component in neurodegenerative plaques [1,2]. α-Synuclein binds strongly to phospholipase Cβ (PLCβ) and promotes Ca2+ release in cells. Here, we show that expression of α-synuclein increases the cellular level of PLCβ1 in two neuronal cell lines: PC12 and SK-N-S-SH. The increase in PLCβ1 is not accompanied by changes in the level of RNA or in ubiquitination. Instead, we find that α-synuclein protects PLCβ1 from trypsin digestion and from degradation by the Ca(+2) activated protease calpain. Calpain removes the C-terminal region of the enzyme which mediates activation by Gα(q). We find that in SK-N-SH cells, α-synuclein reduced degradation of PLCβ1 by calpain during Ca2+ signaling allowing the enzyme to remain sensitive to Gα(q) activation. Taken together, our studies show that α-synuclein protects the integrity of PLCβ1 and its ability to be activated by Gα(q), which may in turn impact Ca2+ signaling.
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Affiliation(s)
- Yuanjian Guo
- Department of Physiology & Biophysics, Stony Book University, Stony Brook, NY 11794-8661, USA
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27
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Goonasekera SA, Hammer K, Auger-Messier M, Bodi I, Chen X, Zhang H, Reiken S, Elrod JW, Correll RN, York AJ, Sargent MA, Hofmann F, Moosmang S, Marks AR, Houser SR, Bers DM, Molkentin JD. Decreased cardiac L-type Ca²⁺ channel activity induces hypertrophy and heart failure in mice. J Clin Invest 2011; 122:280-90. [PMID: 22133878 DOI: 10.1172/jci58227] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 10/12/2011] [Indexed: 02/06/2023] Open
Abstract
Antagonists of L-type Ca²⁺ channels (LTCCs) have been used to treat human cardiovascular diseases for decades. However, these inhibitors can have untoward effects in patients with heart failure, and their overall therapeutic profile remains nebulous given differential effects in the vasculature when compared with those in cardiomyocytes. To investigate this issue, we examined mice heterozygous for the gene encoding the pore-forming subunit of LTCC (calcium channel, voltage-dependent, L type, α1C subunit [Cacna1c mice; referred to herein as α1C⁻/⁺ mice]) and mice in which this gene was loxP targeted to achieve graded heart-specific gene deletion (termed herein α1C-loxP mice). Adult cardiomyocytes from the hearts of α1C⁻/⁺ mice at 10 weeks of age showed a decrease in LTCC current and a modest decrease in cardiac function, which we initially hypothesized would be cardioprotective. However, α1C⁻/⁺ mice subjected to pressure overload stimulation, isoproterenol infusion, and swimming showed greater cardiac hypertrophy, greater reductions in ventricular performance, and greater ventricular dilation than α1C⁺/⁺ controls. The same detrimental effects were observed in α1C-loxP animals with a cardiomyocyte-specific deletion of one allele. More severe reductions in α1C protein levels with combinatorial deleted alleles produced spontaneous cardiac hypertrophy before 3 months of age, with early adulthood lethality. Mechanistically, our data suggest that a reduction in LTCC current leads to neuroendocrine stress, with sensitized and leaky sarcoplasmic reticulum Ca²⁺ release as a compensatory mechanism to preserve contractility. This state results in calcineurin/nuclear factor of activated T cells signaling that promotes hypertrophy and disease.
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Affiliation(s)
- Sanjeewa A Goonasekera
- Department of Pediatrics, University of Cincinnati, Cincinnati Children's Hospital Medical Center, Howard Hughes Medical Institute, Cincinnati, Ohio 45229, USA
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