201
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Goette A, Hammwöhner M, Bukowska A. [Upstream therapy for atrial fibrillation]. Herzschrittmacherther Elektrophysiol 2014; 25:33-40. [PMID: 24519662 DOI: 10.1007/s00399-014-0303-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In recent years a tremendous amount has been learned about the pathophysiology of atrial fibrillation (AF) which induces electrophysiological changes in the right and left atrium. Besides calcium-dependent tissue changes which are induced by activation of proteases and phosphatases, such as calpain and calcineurin, concomitant cardiac diseases activate the atrial angiotensin II system. Experiments have shown positive effects of statins in AF models. In contrast, clinical studies have provided heterogeneous results. Of note, several studies have shown that therapy with angiotensin II receptor blockers or statins does not influence the recurrence of AF.
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Affiliation(s)
- Andreas Goette
- Medizinische Klinik II, St. Vincenz-Krankenhaus Paderborn GmbH, Am Busdorf 2, 33098, Paderborn, Deutschland,
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202
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Role of Small-Conductance Calcium-Activated Potassium Channels in Atrial Electrophysiology and Fibrillation in the Dog. Circulation 2014; 129:430-40. [DOI: 10.1161/circulationaha.113.003019] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Recent evidence points to functional Ca
2+
-dependent K
+
(SK) channels in the heart that may govern atrial fibrillation (AF) risk, but the underlying mechanisms are unclear. This study addressed the role of SK channels in atrial repolarization and AF persistence in a canine AF model.
Methods and Results—
Electrophysiological variables were assessed in dogs subjected to atrial remodeling by 7-day atrial tachypacing (AT-P), as well as controls. Ionic currents and single-channel properties were measured in isolated canine atrial cardiomyocytes by patch clamp. NS8593, a putative selective SK blocker, suppressed SK current with an IC
50
of ≈5 μmol/L, without affecting Na
+
, Ca
2+
, or other K
+
currents. Whole-cell SK current sensitive to NS8593 was significantly larger in pulmonary vein (PV) versus left atrial (LA) cells, without a difference in SK single-channel open probability (
P
o
), whereas AT-P enhanced both whole-cell SK currents and single-channel
P
o
. SK-current block increased action potential duration in both PV and LA cells after AT-P; but only in PV cells in absence of AT-P. SK2 expression was more abundant at both mRNA and protein levels for PV versus LA in control dogs, in both control and AT-P; AT-P upregulated only SK1 at the protein level. Intravenous administration of NS8593 (5 mg/kg) significantly prolonged atrial refractoriness and reduced AF duration without affecting the Wenckebach cycle length, left ventricular refractoriness, or blood pressure.
Conclusions—
SK currents play a role in canine atrial repolarization, are larger in PVs than LA, are enhanced by atrial-tachycardia remodeling, and appear to participate in promoting AF maintenance. These results are relevant to the potential mechanisms underlying the association between SK single-nucleotide polymorphisms and AF and suggest SK blockers as potentially interesting anti-AF drugs.
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203
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Liu H, Chen GX, Liang MY, Qin H, Rong J, Yao JP, Wu ZK. Atrial fibrillation alters the microRNA expression profiles of the left atria of patients with mitral stenosis. BMC Cardiovasc Disord 2014; 14:10. [PMID: 24461008 PMCID: PMC3909014 DOI: 10.1186/1471-2261-14-10] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Accepted: 01/22/2014] [Indexed: 12/22/2022] Open
Abstract
Background Structural changes of the left and right atria associated with atrial fibrillation (AF) in mitral stenosis (MS) patients are well known, and alterations in microRNA (miRNA) expression profiles of the right atria have also been investigated. However, miRNA changes in the left atria still require delineation. This study evaluated alterations in miRNA expression profiles of left atrial tissues from MS patients with AF relative to those with normal sinus rhythm (NSR). Methods Sample tissues from left atrial appendages were obtained from 12 MS patients (6 with AF) during mitral valve replacement surgery. From these tissues, miRNA expression profiles were created and analyzed using a human miRNA microarray. Results were validated via reverse-transcription and quantitative PCR for 5 selected miRNAs. Potential miRNA targets were predicted and their functions and potential pathways analyzed via the miRFocus database. Results The expression levels of 22 miRNAs differed between the AF and NSR groups. Relative to NSR patients, in those with AF the expression levels of 45% (10/22) of these miRNAs were significantly higher, while those of the balance (55%, 12/22) were significantly lower. Potential miRNA targets and molecular pathways were identified. Conclusions AF alters the miRNA expression profiles of the left atria of MS patients. These findings may be useful for the biological understanding of AF in MS patients.
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Affiliation(s)
| | | | | | | | | | | | - Zhong-kai Wu
- Second Department of Cardiac Surgery, First Affiliated Hospital of Sun Yat-Sen University, 58 Zhongshan II Road, Guangzhou 510080, China.
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204
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Santulli G, Iaccarino G, De Luca N, Trimarco B, Condorelli G. Atrial fibrillation and microRNAs. Front Physiol 2014; 5:15. [PMID: 24478726 PMCID: PMC3900852 DOI: 10.3389/fphys.2014.00015] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 01/08/2014] [Indexed: 12/17/2022] Open
Abstract
Atrial fibrillation (AF) is the most common sustained arrhythmia, especially in the elderly, and has a significant genetic component. Recently, several independent investigators have demonstrated a functional role for small non-coding RNAs (microRNAs) in the pathophysiology of this cardiac arrhythmia. This report represents a systematic and updated appraisal of the main studies that established a mechanistic association between specific microRNAs and AF, focusing both on the regulation of electrical and structural remodeling of cardiac tissue.
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Affiliation(s)
- Gaetano Santulli
- Department of Advanced Biomedical Sciences, "Federico II" University Hospital Naples, Italy ; Department of Translational Medical Sciences, "Federico II" University Hospital Naples, Italy ; Columbia University Medical Center, College of Physicians & Surgeons, New York Presbyterian Hospital - Manhattan New York, NY, USA
| | - Guido Iaccarino
- Department of Medicine and Surgery, University of Salerno Salerno, Italy ; IRCCS "Multimedica," Milano, Italy
| | - Nicola De Luca
- Department of Translational Medical Sciences, "Federico II" University Hospital Naples, Italy
| | - Bruno Trimarco
- Department of Advanced Biomedical Sciences, "Federico II" University Hospital Naples, Italy
| | - Gianluigi Condorelli
- Humanitas Clinical and Research Center Rozzano (Milan), Italy ; University of Milan Milan, Italy
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205
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Li N, Chiang DY, Wang S, Wang Q, Sun L, Voigt N, Respress JL, Ather S, Skapura DG, Jordan VK, Horrigan FT, Schmitz W, Müller FU, Valderrabano M, Nattel S, Dobrev D, Wehrens XHT. Ryanodine receptor-mediated calcium leak drives progressive development of an atrial fibrillation substrate in a transgenic mouse model. Circulation 2014; 129:1276-1285. [PMID: 24398018 DOI: 10.1161/circulationaha.113.006611] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND The progression of atrial fibrillation (AF) from paroxysmal to persistent forms remains a major clinical challenge. Abnormal sarcoplasmic reticulum (SR) Ca(2+) leak via the ryanodine receptor type 2 (RyR2) has been observed as a source of ectopic activity in various AF models. However, its potential role in progression to long-lasting spontaneous AF (sAF) has never been tested. This study was designed to test the hypothesis that enhanced RyR2-mediated Ca(2+) release underlies the development of a substrate for sAF and to elucidate the underlying mechanisms. METHODS AND RESULTS CREM-IbΔC-X transgenic (CREM) mice developed age-dependent progression from spontaneous atrial ectopy to paroxysmal and eventually long-lasting AF. The development of sAF in CREM mice was preceded by enhanced diastolic Ca(2+) release, atrial enlargement, and marked conduction abnormalities. Genetic inhibition of Ca(2+)/calmodulin-dependent protein kinase II-mediated RyR2-S2814 phosphorylation in CREM mice normalized open probability of RyR2 channels and SR Ca(2+) release, delayed the development of spontaneous atrial ectopy, fully prevented sAF, suppressed atrial dilation, and forestalled atrial conduction abnormalities. Hyperactive RyR2 channels directly stimulated the Ca(2+)-dependent hypertrophic pathway nuclear factor of activated T cell/Rcan1-4, suggesting a role for the nuclear factor of activated T cell/Rcan1-4 system in the development of a substrate for long-lasting AF in CREM mice. CONCLUSIONS RyR2-mediated SR Ca(2+) leak directly underlies the development of a substrate for sAF in CREM mice, the first demonstration of a molecular mechanism underlying AF progression and sAF substrate development in an experimental model. Our work demonstrates that the role of abnormal diastolic Ca(2+) release in AF may not be restricted to the generation of atrial ectopy but extends to the development of atrial remodeling underlying the AF substrate.
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Affiliation(s)
- Na Li
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX
| | - David Y Chiang
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX.,TBMM program, Baylor College of Medicine, Houston, TX
| | - Sufen Wang
- Department of Cardiology, The Methodist Hospital, Houston, TX
| | - Qiongling Wang
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX
| | - Liang Sun
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX
| | - Niels Voigt
- Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany.,Division of Experimental Cardiology, Heidelberg University, Mannheim, Germany
| | - Jonathan L Respress
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX
| | - Sameer Ather
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX
| | - Darlene G Skapura
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX
| | - Valerie K Jordan
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX
| | - Frank T Horrigan
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX
| | - Wilhelm Schmitz
- Institute of Pharmacology and Toxicology, University of Münster, Germany
| | - Frank U Müller
- Institute of Pharmacology and Toxicology, University of Münster, Germany
| | - Miguel Valderrabano
- Division of Experimental Cardiology, Heidelberg University, Mannheim, Germany
| | - Stanley Nattel
- Department of Medicine, Montreal Heart Institute and Université de Montréal, Quebec, Canada
| | - Dobromir Dobrev
- Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany.,Division of Experimental Cardiology, Heidelberg University, Mannheim, Germany
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Department of Molecular Physiology&Biophysics, Baylor College of Medicine, Houston, TX.,Department of Medicine.Cardiology), Baylor College of Medicine, Houston, TX
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206
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Postoperative arrhythmias after cardiac surgery: incidence, risk factors, and therapeutic management. Cardiol Res Pract 2014; 2014:615987. [PMID: 24511410 PMCID: PMC3912619 DOI: 10.1155/2014/615987] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 10/16/2013] [Indexed: 01/16/2023] Open
Abstract
Arrhythmias are a known complication after cardiac surgery and represent a major cause of morbidity, increased length of hospital stay, and economic costs. However, little is known about incidence, risk factors, and treatment of early postoperative arrhythmias. Both tachyarrhythmias and bradyarrhythmias can present in the postoperative period. In this setting, atrial fibrillation is the most common heart rhythm disorder. Postoperative atrial fibrillation is often self-limiting, but it may require anticoagulation therapy and either a rate or rhythm control strategy. However, ventricular arrhythmias and conduction disturbances can also occur. Sustained ventricular arrhythmias in the recovery period after cardiac surgery may warrant acute treatment and long-term preventive strategy in the absence of reversible causes. Transient bradyarrhythmias may be managed with temporary pacing wires placed at surgery, but significant and persistent atrioventricular block or sinus node dysfunction can occur with the need for permanent pacing. We provide a complete and updated review about mechanisms, risk factors, and treatment strategies for the main postoperative arrhythmias.
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207
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Wang Q, Hu W, Lei M, Wang Y, Yan B, Liu J, Zhang R, Jin Y. MiR-17-5p impairs trafficking of H-ERG K+ channel protein by targeting multiple er stress-related chaperones during chronic oxidative stress. PLoS One 2013; 8:e84984. [PMID: 24386440 PMCID: PMC3875566 DOI: 10.1371/journal.pone.0084984] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 11/29/2013] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND To investigate if microRNAs (miRNAs) play a role in regulating h-ERG trafficking in the setting of chronic oxidative stress as a common deleterious factor for many cardiac disorders. METHODS We treated neonatal rat ventricular myocytes and HEK293 cells with stable expression of h-ERG with H2O2 for 12 h and 48 h. Expression of miR-17-5p seed miRNAs was quantified by real-time RT-PCR. Protein levels of chaperones and h-ERG trafficking were measured by Western blot analysis. Luciferase reporter gene assay was used to study miRNA and target interactions. Whole-cell patch-clamp techniques were employed to record h-ERG K(+) current. RESULTS H-ERG trafficking was impaired by H2O2 after 48 h treatment, accompanied by reciprocal changes of expression between miR-17-5p seed miRNAs and several chaperones (Hsp70, Hsc70, CANX, and Golga2), with the former upregulated and the latter downregulated. We established these chaperones as targets for miR-17-5p. Application miR-17-5p inhibitor rescued H2O2-induced impairment of h-ERG trafficking. Upregulation of endogenous by H2O2 or forced miR-17-5p expression either reduced h-ERG current. Sequestration of AP1 by its decoy molecule eliminated the upregulation of miR-17-5p, and ameliorated impairment of h-ERG trafficking. CONCLUSIONS Collectively, deregulation of the miR-17-5p seed family miRNAs can cause severe impairment of h-ERG trafficking through targeting multiple ER stress-related chaperones, and activation of AP1 likely accounts for the deleterious upregulation of these miRNAs, in the setting of prolonged duration of oxidative stress. These findings revealed the role of miRNAs in h-ERG trafficking, which may contribute to the cardiac electrical disturbances associated with oxidative stress.
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Affiliation(s)
- Qi Wang
- The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, P. R. China
| | - Weina Hu
- The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, P. R. China
| | - Mingming Lei
- The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, P. R. China
| | - Yong Wang
- The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, P. R. China
| | - Bing Yan
- The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, P. R. China
| | - Jun Liu
- The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, P. R. China
| | - Ren Zhang
- The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, P. R. China
| | - Yuanzhe Jin
- The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, P. R. China
- * E-mail:
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208
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Lessons from the heart: mirroring electrophysiological characteristics during cardiac development to in vitro differentiation of stem cell derived cardiomyocytes. J Mol Cell Cardiol 2013; 67:12-25. [PMID: 24370890 DOI: 10.1016/j.yjmcc.2013.12.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 11/14/2013] [Accepted: 12/13/2013] [Indexed: 01/12/2023]
Abstract
The ability of human pluripotent stem cells (hPSCs) to differentiate into any cell type of the three germ layers makes them a very promising cell source for multiple purposes, including regenerative medicine, drug discovery, and as a model to study disease mechanisms and progression. One of the first specialized cell types to be generated from hPSC was cardiomyocytes (CM), and differentiation protocols have evolved over the years and now allow for robust and large-scale production of hPSC-CM. Still, scientists are struggling to achieve the same, mainly ventricular, phenotype of the hPSC-CM in vitro as their adult counterpart in vivo. In vitro generated cardiomyocytes are generally described as fetal-like rather than adult. In this review, we compare the in vivo development of cardiomyocytes to the in vitro differentiation of hPSC into CM with focus on electrophysiology, structure and contractility. Furthermore, known epigenetic changes underlying the differences between adult human CM and CM differentiated from pluripotent stem cells are described. This should provide the reader with an extensive overview of the current status of human stem cell-derived cardiomyocyte phenotype and function. Additionally, the reader will gain insight into the underlying signaling pathways and mechanisms responsible for cardiomyocyte development.
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209
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Shi KH, Tao H, Yang JJ, Wu JX, Xu SS, Zhan HY. Role of microRNAs in atrial fibrillation: New insights and perspectives. Cell Signal 2013; 25:2079-84. [DOI: 10.1016/j.cellsig.2013.06.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 06/08/2013] [Accepted: 06/14/2013] [Indexed: 01/15/2023]
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210
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Zhao Z, Liu T, Wang X, Li G. MicroRNAs as novel antiarrhythmic targets for atrial fibrillation. Int J Cardiol 2013; 168:e135-7. [PMID: 23978363 DOI: 10.1016/j.ijcard.2013.08.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Revised: 07/28/2013] [Accepted: 08/03/2013] [Indexed: 10/26/2022]
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211
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Zhang SG, Liu CY, Li L, Sun TW, Luo YG, Yun WJ, Zhang JY. Examination of artificial MiRNA mimics with centered-site complementarity for gene targeting. PLoS One 2013; 8:e72062. [PMID: 24013456 PMCID: PMC3754971 DOI: 10.1371/journal.pone.0072062] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 07/07/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND MiRNA primarily acts to repress gene expression at the post-transcriptional level through imperfect complementarity of its 5' region to the "seed site" in the 3' untranslated region of target mRNAs, with its "3'-supplementary site" and "center site" also playing important roles under certain circumstances. The aim of this study was to test if artificial miRNA mimics (miR-Mimics) that are designed to target the "centered sites" without "seed sites" complementarity are able to repress gene expression as natural miRNAs. METHODS We designed miR-Mimics carrying centered-site matches (CS-miR-Mimics) or seed-site matches (SS-miR-Mimics) and siRNA to two antiapoptotic genes BCL2 and AKT1. We tested the gene targeting of these constructs using real-time RT-PCR and Western blot to quantify mRNA and protein levels of BCL2 and AKT1, respectively, luciferase reporter gene assay to investigate the interaction between miR-Mimics and their target sites, and cell survival assay to study the functional outcomes of the miR-Mimics. RESULTS We found that CS-miR-Mimic, SS-miR-Mimic and siRNA, all down regulated the mRNA and protein levels of their cognate target BCL2 or AKT1 in a concentration-dependent manner. Luciferase reporter gene assay further confirmed the functional interactions of CS-miR-Mimic, SS-miR-Mimic and siRNA with their target sites. We then observed that the miR-Mimics and siRNAs were all able to induce cell death, as indicated by the reduced survival rate of cells. CONCLUSIONS We have provided evidence for the feasibility of CS-miR-Mimics for post-transcriptional repression of genes, which can be designed to have reduced numbers of seed type off-target sites compared to the number of target sites from an average endogenous seed-site miRNA. CS-miR-Mimics may be a novel approach for miRNA research requiring miRNA gain-of-function.
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Affiliation(s)
- Shu-Guang Zhang
- Department of MICU, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, P. R. China
| | - Chun-Yan Liu
- Department of Pediatrics, the Second Affiliated Hospital, Zhengzhou University, Zhengzhou, P. R. China
| | - Li Li
- Department of Emergency, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, P. R. China
| | - Tong-Wen Sun
- Department of MICU, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, P. R. China
| | - Yong-Gang Luo
- Department of MICU, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, P. R. China
| | - Wen-Jing Yun
- Department of MICU, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, P. R. China
| | - Jin-Ying Zhang
- Department of Cardiology, the First Affiliated Hospital, Zhengzhou University, Zhengzhou, P. R. China
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212
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Elzenaar I, Pinto YM, van Oort RJ. MicroRNAs in Heart Failure: New Targets in Disease Management. Clin Pharmacol Ther 2013; 94:480-9. [DOI: 10.1038/clpt.2013.138] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 07/08/2013] [Indexed: 12/20/2022]
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