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Ottolia M, John S, Hazan A, Goldhaber JI. The Cardiac Na + -Ca 2+ Exchanger: From Structure to Function. Compr Physiol 2021; 12:2681-2717. [PMID: 34964124 DOI: 10.1002/cphy.c200031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Ca2+ homeostasis is essential for cell function and survival. As such, the cytosolic Ca2+ concentration is tightly controlled by a wide number of specialized Ca2+ handling proteins. One among them is the Na+ -Ca2+ exchanger (NCX), a ubiquitous plasma membrane transporter that exploits the electrochemical gradient of Na+ to drive Ca2+ out of the cell, against its concentration gradient. In this critical role, this secondary transporter guides vital physiological processes such as Ca2+ homeostasis, muscle contraction, bone formation, and memory to name a few. Herein, we review the progress made in recent years about the structure of the mammalian NCX and how it relates to function. Particular emphasis will be given to the mammalian cardiac isoform, NCX1.1, due to the extensive studies conducted on this protein. Given the degree of conservation among the eukaryotic exchangers, the information highlighted herein will provide a foundation for our understanding of this transporter family. We will discuss gene structure, alternative splicing, topology, regulatory mechanisms, and NCX's functional role on cardiac physiology. Throughout this article, we will attempt to highlight important milestones in the field and controversial topics where future studies are required. © 2021 American Physiological Society. Compr Physiol 12:1-37, 2021.
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Affiliation(s)
- Michela Ottolia
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Scott John
- Department of Medicine (Cardiology), UCLA, Los Angeles, California, USA
| | - Adina Hazan
- Smidt Heart Institute, Cedars Sinai Medical Center, Los Angeles, California, USA
| | - Joshua I Goldhaber
- Smidt Heart Institute, Cedars Sinai Medical Center, Los Angeles, California, USA
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MicroRNA-214 in Health and Disease. Cells 2021; 10:cells10123274. [PMID: 34943783 PMCID: PMC8699121 DOI: 10.3390/cells10123274] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/16/2021] [Accepted: 11/20/2021] [Indexed: 12/24/2022] Open
Abstract
MicroRNAs (miRNAs) are endogenously expressed, non-coding RNA molecules that mediate the post-transcriptional repression and degradation of mRNAs by targeting their 3′ untranslated region (3′-UTR). Thousands of miRNAs have been identified since their first discovery in 1993, and miR-214 was first reported to promote apoptosis in HeLa cells. Presently, miR-214 is implicated in an extensive range of conditions such as cardiovascular diseases, cancers, bone formation and cell differentiation. MiR-214 has shown pleiotropic roles in contributing to the progression of diseases such as gastric and lung cancers but may also confer cardioprotection against excessive fibrosis and oxidative damage. These contrasting functions are achieved through the diverse cast of miR-214 targets. Through silencing or overexpressing miR-214, the detrimental effects can be attenuated, and the beneficial effects promoted in order to improve health outcomes. Therefore, discovering novel miR-214 targets and understanding how miR-214 is dysregulated in human diseases may eventually lead to miRNA-based therapies. MiR-214 has also shown promise as a diagnostic biomarker in identifying breast cancer and coronary artery disease. This review provides an up-to-date discussion of miR-214 literature by describing relevant roles in health and disease, areas of disagreement, and the future direction of the field.
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Liu T, Zhao J, Ibarra C, Garcia MU, Uhlén P, Nistér M. Glycosylation controls sodium-calcium exchanger 3 sub-cellular localization during cell cycle. Eur J Cell Biol 2018. [PMID: 29526322 DOI: 10.1016/j.ejcb.2018.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
The Na+/Ca2+ exchanger (NCX) is a membrane antiporter that has been identified in the plasma membrane, the inner membrane of the nuclear envelope and in the membrane of the endoplasmic reticulum (ER). In humans, three genes have been identified, encoding unique NCX proteins. Although extensively studied, the NCX's sub-cellular localization and mechanisms regulating the activity of different subtypes are still ambiguous. Here we investigated the subcellular localization of the NCX subtype 3 (NCX3) and its impact on the cell cycle. Two phenotypes, switching from one to the other during the cell cycle, were detected. One phenotype was NCX3 in the plasma membrane during S and M phase, and the other was NCX3 in the ER membrane during resting and interphase. Glycosylation of NCX3 at the N45 site was required for targeting the protein to the plasma membrane, and the N45 site functioned as an on-off switch for the translocation of NCX3 to either the plasma membrane or the membrane of the ER. Introduction of an N-glycosylation deficient NCX3 mutant led to an arrest of cells in the G0/G1 phase of the cell cycle. This was accompanied by accumulation of de-glycosylated NCX3 in the cytosol (that is in the ER), where it transported calcium ions (Ca2+) from the cytosol to the ER. These results, obtained in transfected HEK293T and HeLa and confirmed endogenously in SH-SY5Y cells, suggest that cells can use a dynamic Ca2+ signaling toolkit in which the NCX3 sub-cellular localization changes in synchrony with the cell cycle.
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Affiliation(s)
- Tong Liu
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden
| | - Jian Zhao
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden.
| | - Cristian Ibarra
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Maxime U Garcia
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden
| | - Per Uhlén
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Monica Nistér
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden.
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Bali A, Gupta S, Singh N, Jaggi AS. Implicating the role of plasma membrane localized calcium channels and exchangers in stress-induced deleterious effects. Eur J Pharmacol 2013; 714:229-38. [DOI: 10.1016/j.ejphar.2013.06.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/16/2013] [Accepted: 06/08/2013] [Indexed: 10/26/2022]
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Mirza MA, Lane S, Yang Z, Karaoli T, Akosah K, Hossack J, McDuffie M, Wang J, Zhang XQ, Song J, Cheung JY, Tucker AL. Phospholemman deficiency in postinfarct hearts: enhanced contractility but increased mortality. Clin Transl Sci 2012; 5:235-42. [PMID: 22686200 DOI: 10.1111/j.1752-8062.2012.00403.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Phospholemman (PLM) regulates [Na(+) ](i), [Ca(2+)](i) and contractility through its interactions with Na(+)-K(+)-ATPase (NKA) and Na(+) /Ca(2+) exchanger (NCX1) in the heart. Both expression and phosphorylation of PLM are altered after myocardial infarction (MI) and heart failure. We tested the hypothesis that absence of PLM regulation of NKA and NCX1 in PLM-knockout (KO) mice is detrimental. Three weeks after MI, wild-type (WT) and PLM-KO hearts were similarly hypertrophied. PLM expression was lower but fractional phosphorylation was higher in WT-MI compared to WT-sham hearts. Left ventricular ejection fraction was severely depressed in WT-MI but significantly less depressed in PLM-KO-MI hearts despite similar infarct sizes. Compared with WT-sham myocytes, the abnormal [Ca(2+) ], transient and contraction amplitudes observed in WT-MI myocytes were ameliorated by genetic absence of PLM. In addition, NCX1 current was depressed in WT-MI but not in PLM-KO-MI myocytes. Despite improved myocardial and myocyte performance, PLM-KO mice demonstrated reduced survival after MI. Our findings indicate that alterations in PLM expression and phosphorylation are important adaptations post-MI, and that complete absence of PLM regulation of NKA and NCX1 is detrimental in post-MI animals.
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Affiliation(s)
- M Ayoub Mirza
- Cardiovascular Division, Department of Medicine, University of Virginia Medical Center, Charlottesville, Virginia, USA
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Roos KP, Jordan MC, Fishbein MC, Ritter MR, Friedlander M, Chang HC, Rahgozar P, Han T, Garcia AJ, MacLellan WR, Ross RS, Philipson KD. Hypertrophy and heart failure in mice overexpressing the cardiac sodium-calcium exchanger. J Card Fail 2007; 13:318-29. [PMID: 17517353 PMCID: PMC2017112 DOI: 10.1016/j.cardfail.2007.01.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2006] [Revised: 11/03/2006] [Accepted: 01/15/2007] [Indexed: 10/23/2022]
Abstract
BACKGROUND The cardiac sodium-calcium exchanger (NCX1) is a key sarcolemmal protein for the maintenance of calcium homeostasis in the heart. Because heart failure is associated with increased expression of NCX1, heterozygous (HET) and homozygous (HOM) transgenic mice overexpressing NCX1 were developed and evaluated. METHODS AND RESULTS The NCX1 transgenic mice display 2.3-fold (HET) and 3.1-fold (HOM) increases in exchanger activity from wild-type (WT) mice. Functional information was obtained by echocardiography and catheterizations before and after hemodynamic stress from pregnancy, treadmill exercise or transaortic constriction (TAC). HET and HOM mice exhibited hypertrophy and blunted responses with beta-adrenergic stimulation. Postpartum mice from all groups were hypertrophied, but only the HOM mice exhibited premature death from heart failure. HOM mice became exercise intolerant after 6 weeks of daily treadmill running. After 21 days TAC, HET, and HOM mice exhibited significant contractile dysfunction and 15% to 40% mortality with clinical evidence of heart failure. CONCLUSIONS Hemodynamic stress results in a compensated hypertrophy in WT mice, but NCX1 transgenic mice exhibit decreased contractile function and heart failure in proportion to their level of NCX1 expression. Thus exchanger overexpression in mice leads to abnormal calcium handling and a decompensatory transition to heart failure with stress.
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Affiliation(s)
- Kenneth P. Roos
- The Cardiovascular Research Laboratory Department of Physiology, David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
| | - Maria C. Jordan
- The Cardiovascular Research Laboratory Department of Physiology, David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
| | - Michael C. Fishbein
- The Cardiovascular Research Laboratory Department of Pathology David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
| | - Matthew R. Ritter
- Department of Cell Biology The Scripps Research Institute La Jolla, CA 92037
| | - Martin Friedlander
- Department of Cell Biology The Scripps Research Institute La Jolla, CA 92037
| | - Helen C. Chang
- The Cardiovascular Research Laboratory Department of Physiology, David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
| | - Paymon Rahgozar
- The Cardiovascular Research Laboratory Department of Physiology, David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
| | - Tieyan Han
- The Cardiovascular Research Laboratory Department of Physiology, David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
| | - Alejandro J. Garcia
- The Cardiovascular Research Laboratory Department of Medicine David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
| | - W. Robb MacLellan
- The Cardiovascular Research Laboratory Department of Medicine David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
| | - Robert S. Ross
- The Department of Medicine, UCSD School of Medicine and Veterans Administration San Diego Healthcare System, San Diego, CA 92161
| | - Kenneth D. Philipson
- The Cardiovascular Research Laboratory Department of Physiology, David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
- The Cardiovascular Research Laboratory Department of Medicine David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1751
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Török TL. Electrogenic Na+/Ca2+-exchange of nerve and muscle cells. Prog Neurobiol 2007; 82:287-347. [PMID: 17673353 DOI: 10.1016/j.pneurobio.2007.06.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 04/12/2007] [Accepted: 06/12/2007] [Indexed: 12/19/2022]
Abstract
The plasma membrane Na(+)/Ca(2+)-exchanger is a bi-directional electrogenic (3Na(+):1Ca(2+)) and voltage-sensitive ion transport mechanism, which is mainly responsible for Ca(2+)-extrusion. The Na(+)-gradient, required for normal mode operation, is created by the Na(+)-pump, which is also electrogenic (3Na(+):2K(+)) and voltage-sensitive. The Na(+)/Ca(2+)-exchanger operational modes are very similar to those of the Na(+)-pump, except that the uncoupled flux (Na(+)-influx or -efflux?) is missing. The reversal potential of the exchanger is around -40 mV; therefore, during the upstroke of the AP it is probably transiently activated, leading to Ca(2+)-influx. The Na(+)/Ca(2+)-exchange is regulated by transported and non-transported external and internal cations, and shows ATP(i)-, pH- and temperature-dependence. The main problem in determining the role of Na(+)/Ca(2+)-exchange in excitation-secretion/contraction coupling is the lack of specific (mode-selective) blockers. During recent years, evidence has been accumulated for co-localisation of the Na(+)-pump, and the Na(+)/Ca(2+)-exchanger and their possible functional interaction in the "restricted" or "fuzzy space." In cardiac failure, the Na(+)-pump is down-regulated, while the exchanger is up-regulated. If the exchanger is working in normal mode (Ca(2+)-extrusion) during most of the cardiac cycle, upregulation of the exchanger may result in SR Ca(2+)-store depletion and further impairment in contractility. If so, a normal mode selective Na(+)/Ca(2+)-exchange inhibitor would be useful therapy for decompensation, and unlike CGs would not increase internal Na(+). In peripheral sympathetic nerves, pre-synaptic alpha(2)-receptors may regulate not only the VSCCs but possibly the reverse Na(+)/Ca(2+)-exchange as well.
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Affiliation(s)
- Tamás L Török
- Department of Pharmacodynamics, Semmelweis University, P.O. Box 370, VIII. Nagyvárad-tér 4, H-1445 Budapest, Hungary.
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Hudecova S, Kubovcakova L, Kvetnansky R, Kopacek J, Pastorekova S, Novakova M, Knezl V, Tarabova B, Lacinova L, Sulova Z, Breier A, Jurkovicova D, Krizanova O. Modulation of expression of Na+/Ca2+ exchanger in heart of rat and mouse under stress. Acta Physiol (Oxf) 2007; 190:127-36. [PMID: 17394575 DOI: 10.1111/j.1748-1716.2007.01673.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIM The Na(+)/Ca(2+) exchanger (NCX) is a major Ca(2+) extrusion system in the plasma membrane of cardiomyocytes and an important component participating on the excitation-contraction coupling process in muscle cells. NCX1 isoform is the most abundant in the heart and is known to be changed after development of ischaemia or myocardial infarction. Objective of this study was to investigate the effect of stress factors (immobilization, cold and short-term hypoxia) on the expression of NCX1, in vivo, in the heart of rat and mouse. METHODS We compared gene expression and protein levels of control and stressed animals. The activity of NCX was measured by the whole cell configuration using the patch clamp. We also measured physiological parameters of the heart in physiological conditions and under ischaemia-reperfusion to compare response of control and stressed hearts. RESULTS We have found that only strong stress stimulus (hypoxia, immobilization) applied repeatedly for several days elevated the NCX1 mRNA level. Cold, which is a weaker stressor that activates mainly sympathoneural, and only marginally adrenomedullary system did not affect the gene expression of NCX1. Thus, from these results it appears that hormones produced by the adrenal medulla (mainly adrenaline) might be involved in this process. To study possible mechanism of the NCX1 regulation by stress, we focused on the possible role of the hypothalamo-pituitary-adrenocortical pathway in the activation of catecholamine synthesis in the adrenal medulla. We have already published that cortisol affects activity, but not the gene expression of NCX1. In this work, we used corticotropin-releasing hormone (CRH) knockout mice, where secretion of corticosterone and subsequently adrenaline is significantly suppressed. As no increase in NCX1 mRNA was observed in CRH knockout mice due to immobilization stress, we proposed that adrenaline (probably regulated via corticosterone) is involved in the regulation of NCX1 gene expression during stress. CONCLUSIONS The gene expression and protein levels of the NCX1 are increased by the strong stress stimuli, e.g. hypoxia, or immobilization stress. The activity of NCX1 is decreased. Based on these results, we assume that the gene expression of NCX is increased as a consequence of suppressed activity of this transport system.
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Affiliation(s)
- S Hudecova
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia
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Seehase M, Quentin T, Wiludda E, Hellige G, Paul T, Schiffmann H. Gene Expression of the Na +–Ca 2+ Exchanger, SERCA2a and Calsequestrin after Myocardial Ischemia in the Neonatal Rabbit Heart. Neonatology 2006; 90:174-84. [PMID: 16645265 DOI: 10.1159/000092888] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Accepted: 10/04/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND Neonatal hearts are less susceptible to developing myocardial dysfunction after hypoxia and/or ischemia than adult hearts. Differences in intracellular calcium homeostasis may be responsible for reduced calcium overload of the immature myocardium leading to the observed protection against ischemia. OBJECTIVE To assess differences in baseline and post-ischemic gene expression of calcium handling proteins after ischemia in neonatal and adult rabbit hearts. METHODS We used isolated antegrade perfused rabbit hearts (age 2 days, 28 days, n = 32), which were exposed to ischemia and hypothermia simulating myocardial stunning comparable to neonatal asphyxia. Gene and protein expression of the sodium-calcium exchanger (NCX), the sarco-endoplasmatic reticulum Ca2+-ATPase 2a (SERCA) and calsequestrin (CSQ) were measured using quantitative real-time PCR and Western blotting. RESULTS After ischemia and reperfusion in neonatal and adult hearts, a significant decrease in myocardial performance was recorded. At the mRNA level, significant differences in the baseline expression of NCX, SERCA and CSQ between neonatal and adult hearts were observed. In neonatal post-ischemic hearts, NCX and CSQ expression were significantly higher at the mRNA level than in controls. In contrast, SERCA expression remained unchanged in neonatal hearts and decreased in adult hearts compared to the non-ischemic controls. CONCLUSION These findings suggest that changes in gene expression of calcium handling proteins may be involved in the different susceptibility of neonatal compared to adult hearts to developing myocardial dysfunction after ischemia.
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Affiliation(s)
- Matthias Seehase
- Department of Pediatric Cardiology and Pediatric Intensive Care, Georg-August-Universitat, Gottingen, Germany
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Keller M, Pignier C, Niggli E, Egger M. Mechanisms of Na+-Ca2+ exchange inhibition by amphiphiles in cardiac myocytes: importance of transbilayer movement. J Membr Biol 2005; 198:159-75. [PMID: 15216417 DOI: 10.1007/s00232-004-0668-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2003] [Revised: 03/01/2004] [Indexed: 10/26/2022]
Abstract
The membrane lipid environment and lipid signaling pathways are potentially involved in the modulation of the activity of the cardiac Na(+)-Ca(2+) exchanger (NCX). In the present study biophysical mechanisms of interactions of amphiphiles with the NCX and the functional consequences were examined. For this purpose, intracellular Ca(2+) concentration jumps were generated by laser-flash photolysis of caged Ca(2+) in guinea-pig ventricular myocytes and Na(+)-Ca(2+) exchange currents ( I(Na/Ca)) were recorded in the whole-cell configuration of the patch-clamp technique. The inhibitory effect of amphiphiles increased with the length of the aliphatic chain between C(7) and C(10) and was more potent with cationic or anionic head groups than with uncharged head groups. Long-chain cationic amines (C(12)) exhibited a cut-off in their efficacy in I(Na/Ca) inhibition. Analysis of the time-course, comparison with the Ni(2+)-induced I(Na/Ca) block and confocal laser scanning microscopy experiments with fluorescent lipid analogs (C(6)- and C(12)-NBD-labeled analogs) suggested that amphiphiles need to be incorporated into the membrane. Furthermore, NCX block appears to require transbilayer movement of the amphiphile to the inner leaflet ("flip"). We conclude that both, hydrophobic and electrostatic interactions between the lipids and the NCX may be important factors for the modulation by lipids and could be relevant in cardiac diseases where the lipid metabolism is altered.
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Affiliation(s)
- M Keller
- Department of Physiology, University of Bern, CH-3012, Bern, Switzerland
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Eigel BN, Gursahani H, Hadley RW. Na+/Ca2+ exchanger plays a key role in inducing apoptosis after hypoxia in cultured guinea pig ventricular myocytes. Am J Physiol Heart Circ Physiol 2004; 287:H1466-75. [PMID: 15155263 DOI: 10.1152/ajpheart.00874.2003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Altered Na(+)/Ca(2+) exchanger (NCX) protein expression or activity is thought to contribute to various aspects of cardiac pathology. In guinea pig ventricular myocytes, NCX-mediated Ca(2+) entry is almost entirely responsible for Ca(2+) overload during hypoxia-reoxygenation. Because Ca(2+) overload is a common initiator of apoptosis, the purpose of this study was to test the hypotheses that NCX activity is critically involved in initiating apoptosis after hypoxia-reoxygenation and that hypoxia-reoxygenation-induced apoptosis can be modulated by changes in NCX protein expression or activity. An NCX antisense oligonucleotide was used to reduce NCX protein expression in cultured adult guinea pig ventricular myocytes. Caspase-3 activation and cytochrome c release were used as markers of apoptosis. Hypoxia-reoxygenation-induced apoptosis was significantly decreased in antisense-treated myocytes compared with untreated control or nonsense-treated myocytes. Pretreatment of cultured myocytes for 24 h with either endothelin-1 or phenylephrine was found to increase both NCX protein expression and evoked NCX activity as well as enhance hypoxia-reoxygenation-induced apoptosis. Control experiments demonstrated that endothelin-1 and phenylephrine did not induce apoptosis on their own nor did they enhance the apoptotic response in a model of Ca(2+)-dependent, NCX-independent apoptosis. Additional control experiments demonstrated that the NCX antisense oligonucleotide did not alter the apoptotic response of myocytes to either H(2)O(2) or isoproterenol. Taken together, these data suggest that the NCX has a critical and specific role in the initiation of apoptosis after hypoxia-reoxygenation in guinea pig myocytes and that hypoxia-reoxygenation-induced apoptosis is quite sensitive to changes in NCX activity.
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Affiliation(s)
- B N Eigel
- Dept. of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, MS-371 UKMC, Lexington, KY 40536-0298, USA
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Min JY, Sullivan MF, Yan X, Feng X, Chu V, Wang JF, Amende I, Morgan JP, Philipson KD, Hampton TG. Overexpression of Na+/Ca2+ exchanger gene attenuates postinfarction myocardial dysfunction. Am J Physiol Heart Circ Physiol 2002; 283:H2466-71. [PMID: 12388257 DOI: 10.1152/ajpheart.01062.2001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We monitored myocardial function in postinfarcted wild-type (WT) and transgenic (TG) mouse hearts with overexpression of the cardiac Na(+)/Ca(2+) exchanger. Five weeks after infarction, cardiac function was better maintained in TG than WT mice [left ventricular (LV) systolic pressure: WT, 41 +/- 2; TG, 58 +/- 3 mmHg; P < 0.05; maximum rising rate of LV pressure (+dP/dt(max)): WT, 3,750 +/- 346; TG, 5,075 +/- 334 mmHg/s; P < 0.05]. The isometric contractile response to beta-adrenergic stimulation was greater in papillary muscles from TG than WT mice (WT, 13.2 +/- 0.9; TG, 16.3 +/- 1.0 mN/mm(2) at 10(-4) M isoproterenol). The sarcoplasmic reticulum (SR) Ca(2+) content investigated by rapid cooling contractures in papillary muscles was greater in TG than WT mouse hearts. We conclude that myocardial function is better preserved in TG mice 5 wk after infarction, which results from enhanced SR Ca(2+) content via overexpression of the Na(+)/Ca(2+) exchanger.
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Affiliation(s)
- Jiang-Yong Min
- Cardiovascular Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA
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Wang Z, Nolan B, Kutschke W, Hill JA. Na+-Ca2+ exchanger remodeling in pressure overload cardiac hypertrophy. J Biol Chem 2001; 276:17706-11. [PMID: 11279089 DOI: 10.1074/jbc.m100544200] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Perturbations of Ca(2+) metabolism are central to the pathogenesis of cardiac hypertrophy. The electrogenic Na(+)-Ca(2+) exchanger mediates a substantial component of transmembrane Ca(2+) movement in cardiac myocytes and is up-regulated in heart failure. However, the role of the exchanger in the pathogenesis of cardiac hypertrophy is poorly understood. Thoracic aortic banding in mice induced 50-60% increases in heart mass and cardiomyocyte size. Despite the absence of myocardial dysfunction, steady-state NCX1 transcript and protein levels were increased to an extent similar to that reported in heart failure. As recent studies indicate that calcineurin is critical to the expression of Na(+)-Ca(2+) exchanger genes, we inhibited calcineurin with cyclosporin. Calcineurin inhibition blunted the increases in NCX1 transcript and protein levels and eliminated the increases in heart mass and cell volume normally associated with pressure overload. To examine the functional significance of these changes, we measured Na(+)-Ca(2+) exchanger current in two independent ways. Surprisingly, exchanger current density was decreased in hypertrophied myocytes, and this down-regulation was eliminated by calcineurin inhibition. Together, these data reveal a role for Na(+)-Ca(2+) exchanger current in the electrical remodeling of hypertrophy and implicate calcineurin signaling therein. In addition, these data suggest the Na(+)-Ca(2+) exchanger is functionally regulated in hypertrophy.
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Affiliation(s)
- Z Wang
- Department of Internal Medicine, the Interdisciplinary Graduate Program in Molecular Biology, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA
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