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Svagusa T, Sikiric S, Milavic M, Sepac A, Seiwerth S, Milicic D, Gasparovic H, Biocina B, Rudez I, Sutlic Z, Manola S, Varvodic J, Udovicic M, Urlic M, Ivankovic S, Plestina S, Paic F, Kulic A, Bakovic P, Sedlic F. Heart failure in patients is associated with downregulation of mitochondrial quality control genes. Eur J Clin Invest 2023; 53:e14054. [PMID: 37403271 DOI: 10.1111/eci.14054] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 05/27/2023] [Accepted: 06/15/2023] [Indexed: 07/06/2023]
Abstract
BACKGROUND Mitochondrial dysfunction is one of key factors causing heart failure. We performed a comprehensive analysis of expression of mitochondrial quality control (MQC) genes in heart failure. METHODS Myocardial samples were obtained from patients with ischemic and dilated cardiomyopathy in a terminal stage of heart failure and donors without heart disease. Using quantitative real-time PCR, we analysed a total of 45 MQC genes belonging to mitochondrial biogenesis, fusion-fission balance, mitochondrial unfolded protein response (UPRmt), translocase of the inner membrane (TIM) and mitophagy. Protein expression was analysed by ELISA and immunohistochemistry. RESULTS The following genes were downregulated in ischemic and dilated cardiomyopathy: COX1, NRF1, TFAM, SIRT1, MTOR, MFF, DNM1L, DDIT3, UBL5, HSPA9, HSPE1, YME1L, LONP1, SPG7, HTRA2, OMA1, TIMM23, TIMM17A, TIMM17B, TIMM44, PAM16, TIMM22, TIMM9, TIMM10, PINK1, PARK2, ROTH1, PARL, FUNDC1, BNIP3, BNIP3L, TPCN2, LAMP2, MAP1LC3A and BECN1. Moreover, MT-ATP8, MFN2, EIF2AK4 and ULK1 were downregulated in heart failure from dilated, but not ischemic cardiomyopathy. VDAC1 and JUN were only genes that exhibited significantly different expression between ischemic and dilated cardiomyopathy. Expression of PPARGC1, OPA1, JUN, CEBPB, EIF2A, HSPD1, TIMM50 and TPCN1 was not significantly different between control and any form of heart failure. TOMM20 and COX proteins were downregulated in ICM and DCM. CONCLUSIONS Heart failure in patients with ischemic and dilated cardiomyopathy is associated with downregulation of large number of UPRmt, mitophagy, TIM and fusion-fission balance genes. This indicates multiple defects in MQC and represents one of potential mechanisms underlying mitochondrial dysfunction in patients with heart failure.
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Affiliation(s)
- T Svagusa
- Department of Cardiovascular Diseases, Dubrava Clinical Hospital, Zagreb, Croatia
| | - S Sikiric
- Department of Pathology, University of Zagreb School of Medicine, Zagreb, Croatia
| | - M Milavic
- Department of Pathology, University of Zagreb School of Medicine, Zagreb, Croatia
| | - A Sepac
- Department of Pathology, University of Zagreb School of Medicine, Zagreb, Croatia
- Department of Pathology and Cytology, University Hospital Center Zagreb, Zagreb, Croatia
| | - S Seiwerth
- Department of Pathology, University of Zagreb School of Medicine, Zagreb, Croatia
- Department of Pathology and Cytology, University Hospital Center Zagreb, Zagreb, Croatia
| | - D Milicic
- Department of Internal Medicine, University of Zagreb School of Medicine, Zagreb, Croatia
- Department of Cardiovascular Diseases, University Hospital Center Zagreb, Zagreb, Croatia
| | - H Gasparovic
- Department of Surgery, University of Zagreb School of Medicine, Zagreb, Croatia
- Department of Cardiac Surgery, University Hospital Center Zagreb, Zagreb, Croatia
| | - B Biocina
- Department of Surgery, University of Zagreb School of Medicine, Zagreb, Croatia
- Department of Cardiac Surgery, University Hospital Center Zagreb, Zagreb, Croatia
| | - I Rudez
- Department of Surgery, University of Zagreb School of Medicine, Zagreb, Croatia
- Department of Cardiac and Transplant Surgery, Dubrava Clinical Hospital, Zagreb, Croatia
| | - Z Sutlic
- Department of Surgery, University of Zagreb School of Medicine, Zagreb, Croatia
- Department of Cardiac and Transplant Surgery, Dubrava Clinical Hospital, Zagreb, Croatia
| | - S Manola
- Department of Cardiovascular Diseases, Dubrava Clinical Hospital, Zagreb, Croatia
| | - J Varvodic
- Department of Cardiac and Transplant Surgery, Dubrava Clinical Hospital, Zagreb, Croatia
| | - M Udovicic
- Department of Cardiovascular Diseases, Dubrava Clinical Hospital, Zagreb, Croatia
- Department of Internal Medicine, University of Zagreb School of Medicine, Zagreb, Croatia
| | - M Urlic
- Department of Cardiac Surgery, University Hospital Center Zagreb, Zagreb, Croatia
| | - S Ivankovic
- Department of Cardiac Surgery, University Hospital Center Split, Split, Croatia
| | - S Plestina
- Department of Pathophysiology, University of Zagreb School of Medicine, Zagreb, Croatia
- Department of Oncology, University Hospital Centre Zagreb, Zagreb, Croatia
| | - F Paic
- Department of Medical Biology, University of Zagreb School of Medicine, Zagreb, Croatia
| | - A Kulic
- Department of Oncology, University Hospital Centre Zagreb, Zagreb, Croatia
| | - P Bakovic
- Department of Pathophysiology, University of Zagreb School of Medicine, Zagreb, Croatia
| | - F Sedlic
- Department of Pathophysiology, University of Zagreb School of Medicine, Zagreb, Croatia
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Svaguša T, Martinić M, Martinić M, Kovačević L, Šepac A, Miličić D, Bulum J, Starčević B, Sirotković-Skerlev M, Seiwerth F, Kulić A, Sedlić F. Mitochondrial unfolded protein response, mitophagy and other mitochondrial quality control mechanisms in heart disease and aged heart. Croat Med J 2020. [PMID: 32378379 PMCID: PMC7230417 DOI: 10.3325/cmj.2020.61.126] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mitochondria are involved in crucial homeostatic processes in the cell: the production of adenosine triphosphate and reactive oxygen species, and the release of pro-apoptotic molecules. Thus, cell survival depends on the maintenance of proper mitochondrial function by mitochondrial quality control. The most important mitochondrial quality control mechanisms are mitochondrial unfolded protein response, mitophagy, biogenesis, and fusion-fission dynamics. This review deals with mitochondrial quality control in heart diseases, especially myocardial infarction and heart failure. Some previous studies have demonstrated that the activation of mitochondrial quality control mechanisms may be beneficial for the heart, while others have shown that it may lead to heart damage. Our aim was to describe the mechanisms by which mitochondrial quality control contributes to heart protection or damage and to provide evidence that may resolve the seemingly contradictory results from the previous studies.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Filip Sedlić
- Filip Sedlić, Department of Pathophysiology, University of Zagreb School of Medicine, Kišpatićeva 12, 10 000 Zagreb, Croatia,
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Tanno S, Yamamoto K, Kurata Y, Adachi M, Inoue Y, Otani N, Mishima M, Yamamoto Y, Kuwabara M, Ogino K, Miake J, Ninomiya H, Shirayoshi Y, Okada F, Yamamoto K, Hisatome I. Protective Effects of Topiroxostat on an Ischemia-Reperfusion Model of Rat Hearts. Circ J 2018; 82:1101-1111. [PMID: 29491325 DOI: 10.1253/circj.cj-17-1049] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Ischemia/reperfusion (I/R) injury triggers cardiac dysfunctions via creating reactive oxygen species (ROS). Because xanthine oxidase (XO) is one of the major enzymes that generate ROS, inhibition of XO is expected to suppress ROS-induced I/R injury. However, it remains unclear whether XO inhibition really yields cardioprotection during I/R. The protective effects of the XO inhibitors, topiroxostat and allopurinol, on cardiac I/R injury were evaluated.Methods and Results:Using isolated rat hearts, ventricular functions, occurrence of arrhythmias, XO activities and thiobarbituric acid reactive substances (TBARS) productions and myocardial levels of adenine nucleotides before and after I/R, and cardiomyocyte death markers during reperfusion, were evaluated. Topiroxostat prevented left ventricular dysfunctions and facilitated recovery from arrhythmias during I/R. Allopurinol and the antioxidant, N-acetylcysteine (NAC), exhibited similar effects at higher concentrations. Topiroxostat inhibited myocardial XO activities and TBARS productions after I/R. I/R decreased myocardial levels of ATP, ADP and AMP, but increased that of xanthine. While topiroxostat, allopurinol or NAC did not change myocardial levels of ATP, ADP or AMP after I/R, all of the agents decreased the level of xanthine. They also decreased releases of CPK and LDH during reperfusion. CONCLUSIONS Topiroxostat showed protective effects against I/R injury with higher potency than allopurinol or NAC. It dramatically inhibited XO activity and TBARS production, suggesting suppression of ROS generation.
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Affiliation(s)
- Shogo Tanno
- Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science
| | - Kenshiro Yamamoto
- Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science
| | | | - Maya Adachi
- Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science
| | - Yumiko Inoue
- Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science
| | - Naoyuki Otani
- Department of Clinical Pharmacology and Therapeutics, Oita University Faculty of Medicine
| | - Mutsuo Mishima
- Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science
| | - Yasutaka Yamamoto
- Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science
| | - Masanari Kuwabara
- University of Colorado, Denver, School of Medicine, Division of Renal Diseases and Hypertension
| | - Kazuhide Ogino
- Department of Clinical Laboratory, Tottori University Hospital
| | - Junichiro Miake
- Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University
| | | | - Yasuaki Shirayoshi
- Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science
| | - Futoshi Okada
- Division of Pathological Biochemistry, Faculty of Medicine, Tottori University
| | - Kazuhiro Yamamoto
- Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University
| | - Ichiro Hisatome
- Division of Regenerative Medicine and Therapeutics, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Graduate School of Medical Science
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Kloner RA, Brown DA, Csete M, Dai W, Downey JM, Gottlieb RA, Hale SL, Shi J. New and revisited approaches to preserving the reperfused myocardium. Nat Rev Cardiol 2017; 14:679-693. [PMID: 28748958 PMCID: PMC5991096 DOI: 10.1038/nrcardio.2017.102] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Early coronary artery reperfusion improves outcomes for patients with ST-segment elevation myocardial infarction (STEMI), but morbidity and mortality after STEMI remain unacceptably high. The primary deficits seen in these patients include inadequate pump function, owing to rapid infarction of muscle in the first few hours of treatment, and adverse remodelling of the heart in the months that follow. Given that attempts to further reduce myocardial infarct size beyond early reperfusion in clinical trials have so far been disappointing, effective therapies are still needed to protect the reperfused myocardium. In this Review, we discuss several approaches to preserving the reperfused heart, such as therapies that target the mechanisms involved in mitochondrial bioenergetics, pyroptosis, and autophagy, as well as treatments that harness the cardioprotective properties of inhaled anaesthetic agents. We also discuss potential therapies focused on correcting the no-reflow phenomenon and its effect on healing and adverse left ventricular remodelling.
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Affiliation(s)
- Robert A Kloner
- Cardiovascular Research Institute, Huntington Medical Research Institutes, 99 North El Molino Avenue, Pasadena, California 91101, USA
- Division of Cardiovascular Medicine and Department of Medicine, Keck School of Medicine, University of Southern California, 1975 Zonal Avenue, Los Angeles, California 90033, USA
| | - David A Brown
- Department of Human Nutrition, Foods, and Exercise, 1981 Kraft Drive, Blacksburg, Virginia 24060, USA
- Virginia Tech Center for Drug Discovery, Virginia Tech, 1981 Kraft Drive, Blacksburg, Virginia 24060, USA
- Virginia Tech Metabolic Phenotyping Core, Virginia Tech, 1981 Kraft Drive, Blacksburg, Virginia 24060, USA
| | - Marie Csete
- Cardiovascular Research Institute, Huntington Medical Research Institutes, 99 North El Molino Avenue, Pasadena, California 91101, USA
- Department of Anesthesiology, Keck School of Medicine, University of Southern California, Los Angeles, California 90017, USA
| | - Wangde Dai
- Cardiovascular Research Institute, Huntington Medical Research Institutes, 99 North El Molino Avenue, Pasadena, California 91101, USA
- Division of Cardiovascular Medicine and Department of Medicine, Keck School of Medicine, University of Southern California, 1975 Zonal Avenue, Los Angeles, California 90033, USA
| | - James M Downey
- Department of Physiology and Cell Biology, University of South Alabama, 5851 USA Drive North, Mobile, Alabama 36688, USA
| | - Roberta A Gottlieb
- Department of Medicine, Barbra Streisand Women's Heart Center, Heart Institute of Cedars-Sinai, Cedars-Sinai Medical Center, 127 South San Vicente Boulevard, Los Angeles, California 90048, USA
| | - Sharon L Hale
- Cardiovascular Research Institute, Huntington Medical Research Institutes, 99 North El Molino Avenue, Pasadena, California 91101, USA
| | - Jianru Shi
- Cardiovascular Research Institute, Huntington Medical Research Institutes, 99 North El Molino Avenue, Pasadena, California 91101, USA
- Division of Cardiovascular Medicine and Department of Medicine, Keck School of Medicine, University of Southern California, 1975 Zonal Avenue, Los Angeles, California 90033, USA
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Abstract
Part I of this review discussed the similarities between embryogenesis, mammalian adaptions to hypoxia (primarily driven by hypoxia-inducible factor-1 [HIF-1]), ischemia-reperfusion injury (and its relationship with reactive oxygen species), hibernation, diving animals, cancer, and sepsis, and it focused on the common characteristics that allow cells and organisms to survive in these states. Part II of this review describes techniques by which researchers gain insight into subcellular energetics and identify potential future tools for clinicians. In particular, P nuclear magnetic resonance to measure high-energy phosphates, serum lactate measurements, the use of near-infrared spectroscopy to measure the oxidation state of cytochrome aa3, and the ability of the protoporphyrin IX-triplet state lifetime technique to measure mitochondrial oxygen tension are discussed. In addition, this review discusses novel treatment strategies such as hyperbaric oxygen, preconditioning, exercise training, therapeutic gases, as well as inhibitors of HIF-1, HIF prolyl hydroxylase, and peroxisome proliferator-activated receptors.
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Affiliation(s)
- Robert H Thiele
- From the Department of Anesthesiology, University of Virginia, Charlottesville, Virginia
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Teixeira G, Chiari P, Fauconnier J, Abrial M, Couture-Lepetit E, Harisseh R, Pillot B, Lacampagne A, Tourneur Y, Gharib A, Ovize M. Involvement of Cyclophilin D and Calcium in Isoflurane-induced Preconditioning. Anesthesiology 2015; 123:1374-84. [PMID: 26460965 DOI: 10.1097/aln.0000000000000876] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BACKGROUND The mitochondrial permeability transition pore (PTP) has been established as an important mediator of ischemia-reperfusion-induced cell death. The matrix protein cyclophilin D (CypD) is the best known regulator of PTP opening. Therefore, the authors hypothesized that isoflurane, by inhibiting the respiratory chain complex I, another regulator of PTP, might reinforce the myocardial protection afforded by CypD inhibition. METHODS Adult mouse or isolated cardiomyocytes from wild-type or CypD knockout (CypD-KO) mice were subjected to ischemia or hypoxia followed by reperfusion or reoxygenation. Infarct size was assessed in vivo. Mitochondrial membrane potential and PTP opening were assessed using tetramethylrhodamine methyl ester perchlorate and calcein-cobalt fluorescence, respectively. Fluo-4 AM and rhod-2 AM staining allowed the measurement, by confocal microscopy, of Ca transient and Ca transfer from sarcoplasmic reticulum (SR) to mitochondria after caffeine stimulation. RESULTS Both inhibition of CypD and isoflurane significantly reduced infarct size (-50 and -37%, respectively) and delayed PTP opening (+63% each). Their combination had no additive effect (n = 6/group). CypD-KO mice displayed endogenous protection against ischemia-reperfusion. Isoflurane depolarized the mitochondrial membrane (-28%, n = 5), decreased oxidative phosphorylation (-59%, n = 5), and blunted the caffeine-induced Ca transfer from SR to mitochondria (-22%, n = 7) in the cardiomyocytes of wild-type mice. Importantly, this transfer was spontaneously decreased in the cardiomyocytes of CypD-KO mice (-25%, n = 4 to 5). CONCLUSIONS The results suggest that the partial inhibitory effect of isoflurane on respiratory complex I is insufficient to afford a synergy to CypD-induced protection. Isoflurane attenuates the Ca transfer from SR to mitochondria, which is also the prominent role of CypD, and finally prevents PTP opening.
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Affiliation(s)
- Geoffrey Teixeira
- From INSERM UMR-1060, CarMeN Laboratory, Université Lyon-1, Faculté de Médecine Rockefeller, Lyon, France (G.T., P.C., M.A., E.C.-L., R.H., B.P., Y.T., A.G., M.O.); Service d'Anesthésie Réanimation, Hôpital Louis Pradel, Hospices Civils de Lyon, Lyon, France (P.C.); INSERM UMR-1046, Université Montpellier 1, Université Montpellier 2, Centre Hospitalier Universitaire de Montpellier, Montpellier, France (J.F., A.L.); and Service d'Explorations Fonctionnelles Cardiovasculaires and CIC de Lyon, Hôpital Louis Pradel, Hospices Civils de Lyon, Lyon, France (M.O.)
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7
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Abstract
BACKGROUND Anesthetic cardioprotection reduces myocardial infarct size after ischemia-reperfusion injury. Currently, the role of microRNA in this process remains unknown. MicroRNAs are short, noncoding nucleotide sequences that negatively regulate gene expression through degradation or suppression of messenger RNA. In this study, the authors uncovered the functional role of microRNA-21 (miR-21) up-regulation after anesthetic exposure. METHODS MicroRNA and messenger RNA expression changes were analyzed by quantitative real-time polymerase chain reaction in cardiomyocytes after exposure to isoflurane. Lactate dehydrogenase release assay and propidium iodide staining were conducted after inhibition of miR-21. miR-21 target expression was analyzed by Western blot. The functional role of miR-21 was confirmed in vivo in both wild-type and miR-21 knockout mice. RESULTS Isoflurane induces an acute up-regulation of miR-21 in both in vivo and in vitro rat models (n = 6, 247.8 ± 27.5% and 258.5 ± 9.0%), which mediates protection to cardiomyocytes through down-regulation of programmed cell death protein 4 messenger RNA (n = 3, 82.0 ± 4.9% of control group). This protective effect was confirmed by knockdown of miR-21 and programmed cell death protein 4 in vitro. In addition, the protective effect of isoflurane was abolished in miR-21 knockout mice in vivo, with no significant decrease in infarct size compared with nonexposed controls (n = 8, 62.3 ± 4.6% and 56.2 ± 3.2%). CONCLUSIONS The authors demonstrate for the first time that isoflurane mediates protection of cardiomyocytes against oxidative stress via an miR-21/programmed cell death protein 4 pathway. These results reveal a novel mechanism by which the damage done by ischemia/reperfusion injury may be decreased.
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Abstract
BACKGROUND The impact of volatile anesthetics on patients with inherited long QT syndrome (LQTS) is not well understood. This is further complicated by the different genotypes underlying LQTS. No studies have reported on the direct effects of volatile anesthetics on specific LQTS-associated mutations. We investigated the effects of isoflurane on a common LQTS type 1 mutation, A341V, with an unusually severe phenotype. METHODS Whole cell potassium currents (IKs) were recorded from HEK293 and HL-1 cells transiently expressing/coexpressing wild-type KCNQ1 (α-subunit), mutant KCNQ1, wild-type KCNE1 (β-subunit), and fusion KCNQ1 + KCNE1. Current was monitored in the absence and presence of clinically relevant concentration of isoflurane (0.54 ± 0.05 mM, 1.14 vol %). Computer simulations determined the resulting impact on the cardiac action potential. RESULTS Isoflurane had significantly greater inhibitory effect on A341V + KCNE1 (62.2 ± 3.4%, n = 8) than on wild-type KCNQ1 + KCNE1 (40.7 ± 4.5%; n = 9) in transfected HEK293 cells. Under heterozygous conditions, isoflurane inhibited A341V + KCNQ1 + KCNE1 by 65.2 ± 3.0% (n = 13) and wild-type KCNQ1 + KCNE1 (2:1 ratio) by 32.0 ± 4.5% (n = 11). A341V exerted a dominant negative effect on IKs. Similar differential effects of isoflurane were also observed in experiments using the cardiac HL-1 cells. Mutations of the neighboring F340 residue significantly attenuated the effects of isoflurane, and fusion proteins revealed the modulatory effect of KCNE1. Action potential simulations revealed a stimulation frequency-dependent effect of A341V. CONCLUSIONS The LQTS-associated A341V mutation rendered the IKs channel more sensitive to the inhibitory effects of isoflurane compared to wild-type IKs in transfected cell lines; F340 is a key residue for anesthetic action.
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9
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KCNE2 modulates cardiac L-type Ca2+ channel. J Mol Cell Cardiol 2014; 72:208-18. [DOI: 10.1016/j.yjmcc.2014.03.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 03/05/2014] [Accepted: 03/18/2014] [Indexed: 11/19/2022]
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Zhao YL, Xiang Q, Shi QY, Li SY, Tan L, Wang JT, Jin XG, Luo AL. GABAergic excitotoxicity injury of the immature hippocampal pyramidal neurons' exposure to isoflurane. Anesth Analg 2011; 113:1152-60. [PMID: 21918167 DOI: 10.1213/ane.0b013e318230b3fd] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Certain anesthetics exhibit neurotoxicity in the brains of immature but not mature animals. γ-Aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the adult brain, is excitatory on immature neurons via its action at the GABAA receptor, depolarizing the membrane potential and inducing a cytosolic Ca2+ increase ([Ca2+]i), because of a reversed transmembrane chloride gradient. Recent experimental data from several rodent studies have demonstrated that exposure to isoflurane during an initial phase causes neuronal excitotoxicity and apoptosis. GABAA receptor-mediated synaptic voltage-dependent calcium channels' (VDCCs) overactivation and Ca2+ influx are involved in these neural changes. METHODS We monitored [Ca2+]i using Fluo-4 AM fluorescence imaging. Using whole-cell patch clamp techniques, IVDCC (voltage-dependent calcium channel currents) were recorded from primary cultures of rat hippocampal neurons (5-day culture) exposed to isoflurane. To further investigate the neurotoxicity of high cytosolic-free calcium after isoflurane in a dose- and time-dependent manner, the possibility of increased caspase-3 levels was evaluated by Western blot and quantitative real-time polymerase chain reaction. Statistical significance was assessed using the Student t test or 1-way analysis of variance followed by the Tukey post hoc test. RESULTS Under control conditions, isoflurane enhanced the GABA-induced [Ca2+]i increase in a dose-dependent manner. Dantrolene and nicardipine markedly inhibited this enhancement mediated by isoflurane. Moreover, in Ca2+-free media, pretreatment with isoflurane did not show any influence on the caffeine-induced increase of [Ca2+]i. Similarly, using whole-cell recording, isoflurane increased the peak amplitude of IVDCC in the cultured neurons from rat hippocampus by depolarization pulses. Isoflurane (0.25, 0.5, 0.75, and 1 minimum alveolar concentration [MAC]) potentiated IVDCC peak current amplitude by 109.11%±9.03%, 120.56%±11.46%, 141.33%±13.87%, and 146.78%±15.87%, respectively. To analyze variation in protein levels, the effect of treatments with isoflurane on caspase-3 activity was dose- and time-dependent, reaching a maximal caspase-3 activity after exposure to 1 MAC for 6 hours (P<0.001). However, in the mRNA levels, hippocampal caspase-3 mRNA levels began to be significantly increased in isoflurane-treated developing rat hippocampal neurons after 6 hours of exposure to 0.25 MAC isoflurane (P<0.001). CONCLUSIONS Isoflurane-mediated enhancement of GABA-triggered [Ca2+]i release results from membrane depolarization with subsequent activation of VDCCs and further Ca2+-induced Ca2+ release from the ryanodine-sensitizing Ca2+ store. An increase in [Ca2+]i, caused by activation of the GABAA receptor and opening of VDCCs, is necessary for isoflurane-induced calcium overload of immature rat hippocampal neurons, which may be involved in the mechanism of an isoflurane-induced neurotoxic effect in the developing rodent brain.
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Affiliation(s)
- Y L Zhao
- Department of Anesthesiology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, 1095 JieFang Rd., Wuhan, Hubei, 430030, China
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Mikuni I, Torres CG, Bienengraeber MW, Kwok WM. Partial restoration of the long QT syndrome associated KCNQ1 A341V mutant by the KCNE1 β-subunit. Biochim Biophys Acta Gen Subj 2011; 1810:1285-93. [PMID: 21854832 DOI: 10.1016/j.bbagen.2011.07.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 07/19/2011] [Accepted: 07/29/2011] [Indexed: 12/27/2022]
Abstract
BACKGROUND The A341V mutation in the pore-forming KCNQ1 subunit of the slowly activating delayed-rectifier potassium current (IKs) underlies a common form of the long QT syndrome, and is associated with an unusually severe phenotype. However, there is controversy regarding the underlying mechanism responsible for the clinically observed phenotype. We investigated the biophysical characteristics of A341V in a cardiac environment by utilizing a cardiac cell line, and in particular the impact of the KCNE1 β-subunit. METHODS Whole-cell current were recorded from transiently transfected HL-1 cells, a cardiac cell line. Mutant KCNQ1 and KCNE1 were constructed by site-directed mutagenesis. RESULTS The A341V mutant resulted in a non-functional channel when expressed alone. When co-expressed with wild type KCNE1, A341V produced a slowly activating current, with a smaller current density, slower rates of activation, and a depolarized shift in its activation curve compared to the wild type KCNQ1+KCNE1. Confocal microscopy confirmed the surface expression of GFP-tagged A341V, suggesting a functionally defective protein. A T58A mutation in KCNE1 abolished functional restoration of A341V. Under heterozygous conditions, the expression of A341V+KCNQ1+KCNE1 reduced but did not abolish the electrophysiological changes observed in A341V+KCNE1. A dominant negative effect of A341V was also observed. Action potential simulations revealed that the A341V mutation is arrhythmogenic. CONCLUSIONS The KCNE1 β-subunit partially rescued the non-functional A341V mutant, with electrophysiological properties distinct from the wild type IKs. GENERAL SIGNIFICANCE The severity of the A341V phenotype may be due to a combination of a significant suppression of the IKs with altered biophysical characteristics.
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Affiliation(s)
- Ikuomi Mikuni
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Cheng Q, Sedlic F, Pravdic D, Bosnjak ZJ, Kwok WM. Biphasic effect of nitric oxide on the cardiac voltage-dependent anion channel. FEBS Lett 2010; 585:328-34. [PMID: 21156174 DOI: 10.1016/j.febslet.2010.12.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 11/20/2010] [Accepted: 12/03/2010] [Indexed: 02/04/2023]
Abstract
Nitric oxide (NO·) effects on the cardiac mitochondrial voltage-dependent anion channel (VDAC) are unknown. The effects of exogenous NO· on VDAC purified from rat hearts were investigated in this study. When incorporated into lipid bilayers, VDAC was inhibited directly by an NO· donor, PAPA NONOate, in a concentration-dependent biphasic manner. This was prevented by an NO· scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. The effect paralleled that of NO() in delaying the opening of the mitochondrial permeability transition (PT) pore. These biphasic effects on the cardiac VDAC and the mitochondrial PT pore reveal a tandem impact of NO() on the two mitochondrial entities.
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Affiliation(s)
- Qunli Cheng
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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González G, Zaldívar D, Carrillo E, Hernández A, García M, Sánchez J. Pharmacological preconditioning by diazoxide downregulates cardiac L-type Ca(2+) channels. Br J Pharmacol 2010; 161:1172-85. [PMID: 20636393 PMCID: PMC2998696 DOI: 10.1111/j.1476-5381.2010.00960.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 05/18/2010] [Accepted: 06/29/2010] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND AND PURPOSE Pharmacological preconditioning (PPC) with mitochondrial ATP-sensitive K(+) (mitoK(ATP) ) channel openers such as diazoxide, leads to cardioprotection against ischaemia. However, effects on Ca(2+) homeostasis during PPC, particularly changes in Ca(2+) channel activity, are poorly understood. We investigated the effects of PPC on cardiac L-type Ca(2+) channels. EXPERIMENTAL APPROACH PPC was induced in isolated hearts and enzymatically dissociated cardiomyocytes from adult rats by preincubation with diazoxide. We measured reactive oxygen species (ROS) production and Ca(2+) signals associated with action potentials using fluorescent probes, and L-type currents using a whole-cell patch-clamp technique. Levels of the α(1c) subunit of L-type channels in the cellular membrane were measured by Western blot. KEY RESULTS PPC was accompanied by a 50% reduction in α(1c) subunit levels, and by a reversible fall in L-type current amplitude and Ca(2+) transients. These effects were prevented by the ROS scavenger N-acetyl-L-cysteine (NAC), or by the mitoK(ATP) channel blocker 5-hydroxydecanoate (5-HD). PPC significantly reduced infarct size, an effect blocked by NAC and 5-HD. Nifedipine also conferred protection against infarction when applied during the reperfusion period. Downregulation of the α(1c) subunit and Ca(2+) channel function were prevented in part by the protease inhibitor leupeptin. CONCLUSIONS AND IMPLICATIONS PPC downregulated the α(1c) subunit, possibly through ROS. Downregulation involved increased degradation of the Ca(2+) channel, which in turn reduced Ca(2+) influx, which may attenuate Ca(2+) overload during reperfusion.
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Affiliation(s)
- G González
- Departamento de Farmacología, Centro de Investigación y de Estudios Avanzados del I.P.N. México, México
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Sedlic F, Sepac A, Pravdic D, Camara AKS, Bienengraeber M, Brzezinska AK, Wakatsuki T, Bosnjak ZJ. Mitochondrial depolarization underlies delay in permeability transition by preconditioning with isoflurane: roles of ROS and Ca2+. Am J Physiol Cell Physiol 2010; 299:C506-15. [PMID: 20519447 DOI: 10.1152/ajpcell.00006.2010] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During reperfusion, the interplay between excess reactive oxygen species (ROS) production, mitochondrial Ca(2+) overload, and mitochondrial permeability transition pore (mPTP) opening, as the crucial mechanism of cardiomyocyte injury, remains intriguing. Here, we investigated whether an induction of a partial decrease in mitochondrial membrane potential (DeltaPsi(m)) is an underlying mechanism of protection by anesthetic-induced preconditioning (APC) with isoflurane, specifically addressing the interplay between ROS, Ca(2+), and mPTP opening. The magnitude of APC-induced decrease in DeltaPsi(m) was mimicked with the protonophore 2,4-dinitrophenol (DNP), and the addition of pyruvate was used to reverse APC- and DNP-induced decrease in DeltaPsi(m). In cardiomyocytes, DeltaPsi(m), ROS, mPTP opening, and cytosolic and mitochondrial Ca(2+) were measured using confocal microscope, and cardiomyocyte survival was assessed by Trypan blue exclusion. In isolated cardiac mitochondria, antimycin A-induced ROS production and Ca(2+) uptake were determined spectrofluorometrically. In cells exposed to oxidative stress, APC and DNP increased cell survival, delayed mPTP opening, and attenuated ROS production, which was reversed by mitochondrial repolarization with pyruvate. In isolated mitochondria, depolarization by APC and DNP attenuated ROS production, but not Ca(2+) uptake. However, in stressed cardiomyocytes, a similar decrease in DeltaPsi(m) attenuated both cytosolic and mitochondrial Ca(2+) accumulation. In conclusion, a partial decrease in DeltaPsi(m) underlies cardioprotective effects of APC by attenuating excess ROS production, resulting in a delay in mPTP opening and an increase in cell survival. Such decrease in DeltaPsi(m) primarily attenuates mitochondrial ROS production, with consequential decrease in mitochondrial Ca(2+) uptake.
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Affiliation(s)
- Filip Sedlic
- Department of Anesthesiology and Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin53226, USA.
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