Lung cancer is one of the leading causes of cancer death worldwide. microRNAs have been shown to be a novel class of regulators in lung cancer. Here, we explored the role of miR-153 in the pathogenesis of lung cancer and its therapeutic potential. miR-153 was significantly decreased in lung cancer tissues than the adjacent tissues. The protein and mRNA levels of protein kinase B (AKT), which were shown to promote tumor growth, were both increased in lung cancer tissues than adjacent tissues. Overexpression of miR-153 significantly inhibited AKT protein expression, which were abrogated by co-transfection of AMO-153, the specific inhibitor of miR-153. Luciferase assay showed that transfection of miR-153 markedly suppressed the fluorescent intensity of chimeric vectors carrying the 3'UTR of AKT1, while produced no effect on the mutant construct, indicating that AKT is regulated by miR-153. Overexpression of miR-153 significantly inhibited the proliferation and migration, and promoted apoptosis of cultured lung cancer cells in vitro, and suppressed the growth of xenograft tumors in vivo. Interestingly, lung cancer cells with lower endogenous miR-153 expression are more sensitive to ectopic overexpressed miR-153. The IC50 of miR-153 on lung cancer cells is positive correlated with the endogenous miR-153 level, while negative correlated with AKT level. Knockdown of AKT expression suppressed lung cancer cell proliferation. In summary, miR-153 exerted anti-tumor activity in lung cancer by targeting on AKT. The sensitivity of lung cancer cells to miR-153 is determined by its endogenous miR-153 level.
Several studies have confirmed the role of microRNAs in regulating ischemia/reperfusion-induced cardiac injury (I/R-I). MiR-17-5p has been regarded as an oncomiR in the development of cancer. However, its potential role in cardiomyocytes has not been exploited. The aim of this study is to investigate the role of miR-17-5p in I/R-I and the underlying mechanism through targeting Stat3, a key surviving factor in cardiomyocytes.
Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and high-lethality fibrotic lung disease characterized by excessive fibroblast proliferation, extracellular matrix accumulation, and, ultimately, loss of lung function. Although dysregulation of some microRNAs (miRs) has been shown to play important roles in the pathophysiological processes of IPF, the role of miRs in fibrotic lung diseases is not well understood. In this study, we found downregulation of miR-26a in the lungs of mice with experimental pulmonary fibrosis and in IPF, which resulted in posttranscriptional derepression of connective tissue growth factor (CTGF), and induced collagen production. More importantly, inhibition of miR-26a in the lungs caused pulmonary fibrosis in vivo, whereas overexpression of miR-26a repressed transforming growth factor (TGF)-?1-induced fibrogenesis in MRC-5 cells and attenuated experimental pulmonary fibrosis in mice. Our study showed that miR-26a was downregulated by TGF-?1-mediated phosphorylation of Smad3. Moreover, miR-26a inhibited the nuclear translocation of p-Smad3 through directly targeting Smad4, which determines the nuclear translocation of p-Smad2/Smad3. Taken together, our experiments demonstrated the antifibrotic effects of miR-26a in fibrotic lung diseases and suggested a new strategy for the prevention and treatment of IPF using miR-26a. The current study also uncovered a novel positive feedback loop between miR-26a and p-Smad3, which is involved in pulmonary fibrosis.
Bone marrow mesenchymal stem cells (BMSCs) emerge as a promising approach for treating heart diseases. However, the effects of BMSCs-based therapy on cardiac electrophysiology disorders after myocardial infarction were largely unclear. This study was aimed to investigate whether BMSCs transplantation prevents cardiac arrhythmias and reverses potassium channels remodelling in post-infarcted hearts. Myocardial infarction was established in male SD rats, and BMSCs were then intramyocardially transplanted into the infarcted hearts after 3 days. Cardiac electrophysiological properties in the border zone were evaluated by western blotting and whole-cell patch clamp technique after 2 weeks. We found that BMSCs transplantation ameliorated the increased heart weight index and the impaired LV function. The survival of infarcted rats was also improved after BMSCs transplantation. Importantly, electrical stimulation-induced arrhythmias were less observed in BMSCs-transplanted infarcted rats compared with rats without BMSCs treatment. Furthermore, BMSCs transplantation effectively inhibited the prolongation of action potential duration and the reduction of transient and sustained outward potassium currents in ventricular myocytes in post-infarcted rats. Consistently, BMSCs-transplanted infarcted hearts exhibited the increased expression of K(V)4.2, K(V)4.3, K(V)1.5 and K(V)2.1 proteins when compared to infarcted hearts. Moreover, intracellular free calcium level, calcineurin and nuclear NFATc3 protein expression were shown to be increased in infarcted hearts, which was inhibited by BMSCs transplantation. Collectively, BMSCs transplantation prevented ventricular arrhythmias by reversing cardiac potassium channels remodelling in post-infarcted hearts.
Preeclampsia is a serious complication in pregnancy. Dysregulation of trophoblast cell proliferation and invasion is a major pathological alteration observed in preeclampsia. Recently, microRNAs were shown to participate in the pathogenesis of preeclampsia. In this study we explored the effect of miR-20a on the proliferation and invasion of trophoblast cells and the underlying mechanism. We verified the distribution of miR-20a in human placenta by in situ hybridization. Real time PCR data showed that the level of miR-20a increased by 2.6 folds in human preeclampsia than normal tissues. We then cultured trophoblast-like JEG-3 cells and evaluated the effect of miR-20a on JEG-3 cell proliferation, migration and invasion. Overexpression of miR-20a significantly inhibited the proliferation, migration and invasion of cultured JEG-3 cells, which were abolished by co-transfection of AMO-20a. Transfection of miR-20a also inhibited JEG-3 cell xenograft tumor growth in nude mice. Luciferase assay technique was used to identify the direct regulation of miR-20a on Forkhead Box Protein A1(FOXA1). Transfection of miR-20a markedly reduced the luciferase activity of the chimeric plasmid containing the 3'UTR of FOXA1, indicating FOXA1 is the target of miR-20a. Furthermore, transfection of miR-20a inhibited both protein and mRNA expression of FOXA1 in JEG-3 cells. In summary, the upregulated miR-20a in human preeclampsia tissue can inhibit the proliferative and invasive activities of trophoblast cells by repressing the expression of FOXA1.
Atrial fibrillation (AF) is a highly prevalent arrhythmia with pronounced morbidity and mortality. Inward-rectifier K+ current (IK1) is believed to be an important regulator of reentrant-spiral dynamics and a major component of AF-related electrical remodeling. MicroRNA-26 (miR-26) is predicted to target the gene encoding KIR2.1, KCNJ2. We found that miR-26 was downregulated in atrial samples from AF animals and patients and this downregulation was accompanied by upregulation of IK1/KIR2.1 protein. miR-26 overexpression suppressed expression of KCNJ2/KIR2.1. In contrast, miR-26 knockdown, inhibition, or binding-site mutation enhanced KCNJ2/KIR2.1 expression, establishing KCNJ2 as a miR-26 target. Knockdown of endogenous miR-26 promoted AF in mice, whereas adenovirus-mediated expression of miR-26 reduced AF vulnerability. Kcnj2-specific miR-masks eliminated miR-26-mediated reductions in Kcnj2, abolishing miR-26s protective effects, while coinjection of a Kcnj2-specific miR-mimic prevented miR-26 knockdown-associated AF in mice. Nuclear factor of activated T cells (NFAT), a known actor in AF-associated remodeling, was found to negatively regulate miR-26 transcription. Our results demonstrate that miR-26 controls the expression of KCNJ2 and suggest that this downregulation may promote AF.
We previously reported that 15-lipoxygenase (15-LO) induced by hypoxia catalyzed the conversion of arachidonic acid (AA) into 15-hydroxyeicosatetraenoic acid (15-HETE), which plays an essential role in the development of hypoxic pulmonary arterial hypertension (HPH). However, the mechanisms by which hypoxia up-regulated 15-LO are still unclear. Heme oxygenase-1 (HO-1), an oxygen-dependent enzyme regulating vascular tone and cell proliferation, was implicated in HPH and was promoted by hypoxia. Therefore, the present study was carried out to determine whether hypoxia induced the expression of 15-LO via the HO-1 pathway. To test this hypothesis, we studied the role of HO-1 in HPH and 15-LO/15-HETE expression We found increased right ventricular systolic pressure and pulmonary arteries (PAs) reactivity to vasoconstrictors as well as intima-to-media ratio of PAs in HO-1 overexpressing transgenic mice. Moreover, HO-1 up-regulated 15-LO transcription and translation as well as 15-HETE in both transgenic mice and cultured pulmonary arterial smooth muscle cells (PASMCs). Results from immunoprecipitation and immunocytochemistry showed the interaction and colocalization of HO-1 and 15-LO. Together, these data suggest that HO-1 is an important upstream mediator in the hypoxia-induced 15-LO up-regulation during HPH. Unveiling the relevance of HO-1 signaling in PHP provides attractive treatment targets for HPH.
Background/Aims: Arsenic trioxide (As2O3) is a highly effective agent for treatment of acute promyelocytic leukemia (APL). However, consecutively administered As2O3 induces serious adverse cardiac effects, including long QT syndrome (LQTs) and even sudden cardiac death. Previous studies have shown that genistein (Gen) exerts anti-oxidant, anti-inflammatory, and anti-apoptotic effects. The present study aimed to explore the potential protective effects of Gen on As2O3-induced adverse cardiac effects, and to elucidate the underlying molecular mechanisms. Methods: A rat model of As2O3-induced QT prolongation was generated by intravenous injection with As2O3. Surface electrocardiogram (ECG) and hemodynamics were employed to assess the LQTs and cardiac function. Intracellular calcium concentration ([Ca(2+)]i) and mitochondrial membrane potential (??m) were measured by confocal microscopy, and cardiomyocytes apoptosis were assessed by TUNEL assay. Western blot was applied to determine protein levels. Results: We found for the first time that treatment with Gen significantly reversed LQTs and dose-dependently improved As2O3-induced impairment of cardiac function. As2O3 elevated [Ca(2+)]i and Gen mitigated this effect. Meanwhile, Gen significantly reversed As2O3-mediated cardiomyocytes apoptosis. Furthermore, Gen dose-dependently inhibited the phosphorylated JNK and p38-MAPK (pp38-MAPK), and blocked ??m collapse, and further decreased cleaved caspase-3. Conclusion: Gen protects against the adverse cardiac effects of As2O3 partly by mitigating cardiomyocytes apoptosis induced by As2O3 through attenuating intracellular calcium overload and downregulating protein expression of p-JNK and pp38-MAPK to ameliorate the damage of ??m leading to suppression of caspase-3 activation. Gen might be used as an adjunction therapy in APL patients receiving As2O3 treatment to avoid, at least to minimize, the adverse cardiac effects of As2O3.
Estrogen deficiency is associated with increased incidence of cardiovascular diseases. But merely estrogen supplementary treatment can induce many severe complications such as breast cancer. The present study was designed to elucidate molecular mechanisms underlying increased susceptibility of arrhythmogenesis during myocardial infarction with estrogen deprivation, which provides us a new target to cure cardiac disease accompanied with estrogen deprivation. We successfully established a rat model of myocardial ischemia (MI) accompanied with estrogen deprivation by coronary artery ligation and ovariectomy (OVX). Vulnerability and mortality of ventricular arrhythmias increased in estrogen deficiency rats compared to non estrogen deficiency rats when suffered MI, which was associated with down-regulation of microRNA-151-5p (miR-151-5p). Luciferase Reporter Assay demonstrated that miR-151-5p can bind to the 3-UTR of FXYD1 (coding gene of phospholemman, PLM) and inhibit its expression. We found that the expression of PLM was increased in (OVX+MI) group compared with MI group. More changes such as down-regulation of Kir2.1/IK1, calcium overload had emerged in (OVX+MI) group compared to MI group merely. Transfection of miR-151-5p into primary cultured myocytes decreased PLM levels and [Ca(2+)]i, however, increased Kir2.1 levels. These effects were abolished by the antisense oligonucleotides against miR-151-5p. Co-immunoprecipitation and immunofluorescent experiments confirmed the co-localization between Kir2.1 and PLM in rat ventricular tissue. We conclude that the increased ventricular arrhythmias vulnerability in response to acute myocardial ischemia in rat is critically dependent upon down-regulation of miR-151-5p. These findings support the proposal that miR-151-5p could be a potential therapeutic target for the prevention of ischemic arrhythmias in the subjects with estrogen deficiency.
Bone marrow mesenchymal stem cells (BMSCs) are capable of homing to and repair damaged myocardial tissues. Apoptosis of BMSCs in response to various pathological stimuli leads to the attenuation of healing ability of BMSCs. Plenty of evidence has shown that elevated homocysteine level is a novel independent risk factor of cardiovascular diseases. The present study was aimed to investigate whether homocysteine may induce apoptosis of BMSCs and its underlying mechanisms. Here we uncovered that homocysteine significantly inhibited the cellular viability of BMSCs. Furthermore, TUNEL, AO/EB, Hoechst 333342 and Live/Death staining demonstrated the apoptotic morphological appearance of BMSCs after homocysteine treatment. A distinct increase of ROS level was also observed in homocysteine-treated BMSCs. The blockage of ROS by DMTU and NAC prevented the apoptosis of BMSCs induced by homocysteine, indicating ROS was involved in the apoptosis of BMSCs. Moreover, homocysteine also caused the depolarization of mitochondrial membrane potential of BMSCs. Furthermore, apoptotic appearance and mitochondrial membrane potential depolarization in homocysteine-treated BMSCs was significantly reversed by JNK inhibitor but not p38 MAPK and ERK inhibitors. Western blot also confirmed that p-JNK was significantly activated after exposing BMSCs to homocysteine. Homocysteine treatment caused a significant reduction of BMSCs-secreted VEGF and IGF-1 in the culture medium. Collectively, elevated homocysteine induced the apoptosis of BMSCs via ROS-induced the activation of JNK signal, which provides more insight into the molecular mechanisms of hyperhomocysteinemia-related cardiovascular diseases.
We have found that 15-hydroxyeicosatetraenoic acid (15-HETE) induced by hypoxia was an important mediator in the regulation of hypoxic pulmonary hypertension, including the pulmonary vasoconstriction and remodeling. However, the underlying mechanisms of the remodeling induced by 15-HETE are poorly understood. In this study, we performed immunohistochemistry, pulmonary artery endothelial cells migration and tube formation, pulmonary artery smooth muscle cells bromodeoxyuridine incorporation, and cell cycle analysis to determine the role of 15-HETE in hypoxia-induced pulmonary vascular remodeling. We found that hypoxia induced pulmonary vascular medial hypertrophy and intimal endothelial cells migration and angiogenesis, which were mediated by 15-HETE. Moreover, 15-HETE regulated the cell cycle progression and made more smooth muscle cells from the G(0)/G(1) phase to the G(2)/M+S phase and enhanced the microtubule formation in cell nucleus. In addition, we found that the Rho-kinase pathway was involved in 15-HETE-induced endothelial cells tube formation and migration and smooth muscle cell proliferation. Together, these results show that 15-HETE mediates hypoxia-induced pulmonary vascular remodeling and stimulates angiogenesis via the Rho-kinase pathway.
Interstitial fibrosis plays a causal role in the development of heart failure after chronic myocardial infarction (MI), and anti-fibrotic therapy represents a promising strategy to mitigate this pathological process. The purpose of this study was to investigate the effect of long-term administration of scutellarin (Scu) on cardiac interstitial fibrosis of myocardial infarct rats and the underlying mechanisms.
Cardiac electrophysiological function is under the regulatory control of the sympathetic nervous system. In addition to classical ?-adrenoceptors (?-AR, including ?(1)- and ?(2)- subtypes), ?(3)-AR is also expressed in human heart and shows its distinctive functions. This study is aimed to elucidate the role of ?(3)-AR in the regulation of atrial fibrillation (AF), especially its role in rapid pacing-induced atrial electrical remodeling in rabbits. The rapid atrial pacing model was established by embedding electrodes in the right atrium pacing at a speed of 600 beats per minute. The protein level of ?(3)-AR in the atria was found significantly upregulated by western blot. The atrial effective refractory period (AERP) and its rate adaptation were decreased after pacing which were further shortened by BRL37344, a selective ?(3)-AR agonist, leading to the increase of AF inducibility and duration. Similarly, ?(3)-AR activation induced time-dependent shortening of action potential duration (APD), together with decrease of L-type calcium current (I(Ca,L)) and increase of inward rectifier potassium current (I(K1)) and transient outward potassium current (I(to)) in rapid pacing atrial myocytes. Meanwhile, all the effects were abolished by specific ?(3)-AR antagonist, SR59230A. In summary, our study represents that activation of ?(3)-AR promotes the atrial electrical remodeling process by altering the balance of ion channels in atrial myocytes, which provides new insights into the pharmacological role of ?(3)-AR in heart diseases.
The present study was designed to investigate the cardiac benefits of M? muscarinic receptor (M?-mAChR) overexpression and whether these effects are related to the regulation of the inward rectifying K? channel by microRNA-1 (miR-1) in a conditional overexpression mouse model. A cardiac-specific M?-mAChR transgenic mouse model was successfully established for the first time in this study using microinjection, and the overexpression was confirmed by both reverse transcriptase-polymerase chain reaction and Western blot techniques. We demonstrated that M?-mAChR overexpression dramatically reduced the incidence of arrhythmias and decreased the mortality in a mouse model of myocardial ischemia-reperfusion (I/R). By using whole-cell patch techniques, M?-mAChR overexpression significantly shortened the action potential duration and restored the membrane repolarization by increasing the inward rectifying K? current. By using Western blot techniques, M?-mAChR overexpression also rescued the expression of the inward rectifying K? channel subunit Kir2.1 after myocardial I/R injury. This result was accompanied by suppression of upregulation miR-1. We conclude that M?-mAChR overexpression reduced the incidence of arrhythmias and mortality after myocardial I/R by protecting the myocardium from ischemia in mice. This effect may be mediated by increasing the inward rectifying K? current by downregulation of arrhythmogenic miR-1 expression, which might partially be a novel strategy for antiarrhythmias, leading to sudden cardiac death.
Recent genome-wide association studies (GWAS) revealed that a 9p21.3 locus was associated with type 2 diabetes. In this study, we carried out a large-scale case-control study in the GeneID Chinese Han population to 1) further replicate the association of 9p21.3 type 2 diabetes GWAS single nucleotide polymorphisms (SNPs) and 2) assess the association of these SNPs with coronary artery disease.
A characteristic of both clinical and experimental atrial fibrillation (AF) is atrial electric remodeling associated with profound reduction of L-type Ca(2+) current and shortening of the action potential duration. The possibility that microRNAs (miRNAs) may be involved in this process has not been tested. Accordingly, we assessed the potential role of miRNAs in regulating experimental AF.
The present study was designed to study the effects of As(2)O(3) on QT interval prolongation and to explore the potential ionic mechanisms in isolated rat ventricular cardiomyocytes. The rats of As(2)O(3) group were treated with 0.8 mg·kg(-1)·d(-1) As(2)O(3) intravenously for 7 days consecutively and the control group with saline. The ECG was recorded to calculate heart rate-corrected QT interval (QTc). Single cardiomyocytes were isolated by using collagenase II, and the action potential duration (APD) and ion currents were recorded by whole-cell patch clamp. [Ca(2+)](i) was examined by confocal laser scanning microscopy. Our data showed that both QTc and APD were prolonged significantly after As(2)O(3)treatment. Meanwhile, As(2)O(3) suppressed I(K1) and shifted the reversal potential to more positive direction. Moreover, the density of I(Ca,L) was augmented significantly, and the steady-state activation curve became more negative, whereas, the inactivation and reactivation of I(Ca,L) were not changed notably after As(2)O(3) administration. Furthermore, the maximal [Ca(2+)](i) was enhanced obviously by either KCl or caffeine stimulation in As(2)O(3)-treated cardiomyocytes. Our results show that the potential mechanism of As(2)O(3)-induced QT interval prolongation in rat might be relative to disturbing the fine balance of transmembrane currents (increasing I(Ca,L) and decreasing I(K1)) and causing APD prolongation.
Activation of muscarinic M(3) mucarinic acetylcholine receptors (M(3)-mAChRs) has been previously shown to confer short-term cardioprotection against ischaemic injuries. However, it is not known whether activation of these receptors can provide delayed cardioprotection. Consequently, the present study was undertaken to investigate whether stimulation of M(3)-mAChRs can induce delayed preconditioning in rats, and to characterize the potential mechanism.
The calcium-sensing receptor (CaR) is a G protein-coupled receptor. The CaR stimulation elicits phospholipase C-mediated inositol triphosphate formation, leading to an elevation in the level of intracellular calcium released from endoplasmic reticulum (ER). Depletion of ER Ca(2+) leads to ER stress, which is thought to induce apoptosis. Intracellular calcium overload-induced apoptosis in cardiac myocytes during hypoxia-reoxygenation (H/Re) has been demonstrated. However, the links between CaR, ER stress and apoptosis during H/Re are unclear. This study hypothesized that the CaR could induce apoptosis in neonatal rat cardiomyocytes during H/Re via the ER stress pathway. Neonatal rat cardiomyocytes were subjected to 3 hr of hypoxia, followed by 6 hr of reoxygenation. CaR expression was elevated and the number of apoptotic cells was significantly increased, as shown by transferase-mediated dUTP nick end-labelling, with exposure to CaCl(2), a CaR activator, during H/Re. The intracellular calcium concentration was significantly elevated and the Ca(2+) concentration in the ER was dramatically decreased during H/Re with CaCl(2); both intracellular and ER calcium concentrations were detected by laser confocal microscopy. Expression of GRP78 (glucose-regulated protein 78), the cleavage products of ATF6 (activating transcription factor 6), phospho-PERK [pancreatic ER kinase (PKR)-like ER kinase], the activated fragments of caspase-12, and phospho-JNK (c-Jun NH(2)-terminal kinase) were increased following exposure to CaCl(2) during H/Re. Our results confirmed that the activated CaR can induce cardiomyocyte apoptosis via ER stress-associated apoptotic pathways during H/Re.
Tanshinone IIA is an active component of a traditional Chinese medicine based on Salvia miltiorrhiza, which reduces sudden cardiac death by suppressing ischaemic arrhythmias. However, the mechanisms underlying the anti-arrhythmic effects remain unclear.
Hyperhomocysteinemia has been proposed as an important risk factor for cardiac arrhythmias and ischemia worldwide. However, the cellular mechanism underlying toxic effects of homocysteine on hearts remains conjectural. It is well known that aberrant sodium channels can promote the development of cardiac arrhythmias and ischemic injury. So the present study was to investigate toxic effects of homocysteine on sodium currents recorded in human atrial cells. Human atrial myocytes were acutely enzymatically isolated and the whole-cell patch clamp technique was employed to record sodium currents and membrane potential in human atrial cells in the absence and presence of homocysteine. We found that in human atrial myocytes, sodium currents were significantly increased by pathological concentration of homocysteine with the maximum activation potential shifted toward the positive potential. However, physiological concentration of homocysteine did not have any effects on sodium currents. The time constants for time-dependent activation (tau(act)) and inactivation (tau(inact)) of sodium currents were both markedly shortened by elevated homocysteine levels. The further channel kinetic data showed that elevated homocysteine levels shifted the inactivation curve towards positive potential and accelerated the recovery from inactivation of sodium channel, but did not affect the activation of sodium channel. Additionally, the resting membrane potential of human atrial myocytes was obviously depolarized by elevated homocysteine levels in the current clamp model. Taken together, the data presented in this study first revealed that increased homocysteine levels caused the abnormality of sodium currents in human atrial cells by slowing the inactivation and promote the recovery of sodium channels, which provides a better understanding of hyperhomocysteinemia associated cardiac arrhythmias and ischemia.
Despite prolongation of the QTc interval in humans during cerebral ischemia, little is known about the mechanisms that underlie these actions. Cerebral ischemic model was established by middle cerebral artery occlusion (MCAO) for 24 h. In rat ventricular myocytes, the effect of cerebral ischemia on action potential duration (APD) and underlying electrophysiologic mechanisms were investigated by whole-cell patch clamp. We demonstrated that heart rate-corrected QT interval and APD were prolonged with frequent occurrence of ventricular tachyarrhythmias in a rat model of MCAO. The I(Na) density was overall smaller in cerebral ischemic myocytes relative to sham myocytes (P < 0.01). The Nav1.5 protein and mRNA levels (pore-forming subunit for I(Na) ) were decreased by about 20% (P < 0.01) in cerebral ischemic rat hearts than those in sham-operated rat hearts. Peak transient outward K(+) current (I(to)) at +60 mV was found decreased by approximately 32.3% (P < 0.01) in cerebral ischemic rats. The peak amplitude of L-type Ca(2+) current (I(Ca,L)) was increased and the inactivation kinetics were slowed (P < 0.01). Protein level of the pore-forming subunit for I(to) was decreased, but that for I(Ca,L) was increased. The inward rectifier K(+) current (I(K1)) at -120 mV and its protein level were unaffected. Our study represents the first documentation of I(Na), I(to) and I(Ca,L) channelopathy as the major ionic mechanism for cerebral ischemic QT prolongation.
Recent studies have revealed the critical role of microRNAs (miRNAs) in regulating cardiac injury. Among them, the cardiac enriched microRNA-1(miR-1) has been extensively investigated and proven to be detrimental to cardiac myocytes. However, solid in vivo evidence for the role of miR-1 in cardiac injury is still missing and the potential therapeutic advantages of systemic knockdown of miR-1 expression remained unexplored. In this study, miR-1 transgenic (miR-1 Tg) mice and locked nucleic acid modified oligonucleotide against miR-1 (LNA-antimiR-1) were used to explore the effects of miR-1 on cardiac ischemia/reperfusion injury (30 min ischemia followed by 24 h reperfusion). The cardiac miR-1 level was significantly increased in miR-1 Tg mice, and suppressed in LNA-antimiR-1 treated mice. When subjected to ischemia/reperfusion injury, miR-1 overexpression exacerbated cardiac injury, manifested by increased LDH, CK levels, caspase-3 expression, apoptosis and cardiac infarct area. On the contrary, LNA-antimiR-1 treatment significantly attenuated cardiac ischemia/reperfusion injury. The expression of PKC? and HSP60 was significantly repressed by miR-1 and enhanced by miR-1 knockdown, which may be a molecular mechanism for the role miR-1 in cardiac injury. Moreover, luciferase assay confirmed the direct regulation of miR-1 on protein kinase C epsilon (PKC?) and heat shock protein 60 (HSP60). In summary, this study demonstrated that miR-1 is a causal factor for cardiac injury and systemic LNA-antimiR-1 therapy is effective in ameliorating the problem.
The protective role of M(3)-mAChR against apoptosis has been identified previously. However, the underlying mechanisms remain unclear. This study was performed to clarify the signaling pathways of the anti-apoptotic effect mediated by activation of M(3)-mAChR in cultured cardiac H9c2 cells.
Cardiac interstitial fibrosis is a major cause of the deteriorated performance of the heart in patients with chronic myocardial infarction. MicroRNAs (miRs) have recently been proven to be a novel class of regulators of cardiovascular diseases, including those associated with cardiac fibrosis. This study aimed to explore the role of miR-101 in cardiac fibrosis and the underlying mechanisms.
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