MicroRNAs as a therapeutic target for cardiovascular diseases

Inhibition of microRNA-497 ameliorates anoxia/reoxygenation injury in cardiomyocytes by suppressing cell apoptosis and enhancing autophagy

MiR-497 is predicted to target anti-apoptosis gene Bcl2 and autophagy gene microtubule-associated protein 1 light chain 3 B (LC3B), but the functional consequence of miR-497 in response to anoxia/reoxygenation (AR) or ischemia/reperfusion (IR) remains unknown. This study was designed to investigate the influences of miR-497 on myocardial AR or IR injury. We noted that miR-497 was enriched in cardiac tissues, while its expression was dynamically changed in murine hearts subjected to myocardial infarction and in neonatal rat cardiomyocytes (NRCs) subjected to AR. Forced expression of miR-497 (miR-497 mimic) induced apoptosis in NRCs as determined by Hoechst staining and TUNEL assay. In response to AR, silencing of miR-497 using a miR-497 sponge significantly reduced cell apoptosis and enhanced autophagic flux. Furthermore, the infarct size induced by IR in adenovirus (Ad)-miR-497 sponge infected mice was significantly smaller than in mice receiving Ad-vector or vehicle treatment, while Ad-miR-497 increased infarct size. The expression of Bcl-2 and LC3B-II in NRCs or in murine heart was significantly decreased by miR-497 mimic and enhanced by miR-497 sponge. These findings demonstrate that inhibition of miR-497 holds promise for limiting myocardial IR injury.

Emerging role of hydrogen sulfide-microRNA crosstalk in cardiovascular diseases

Despite an obnoxious smell and toxicity at a high dose, hydrogen sulfide (H2S) is emerging as a cardioprotective gasotransmitter. H2S mitigates pathological cardiac remodeling by regulating several cellular processes including fibrosis, hypertrophy, apoptosis, and inflammation. These encouraging findings in rodents led to initiation of a clinical trial using a H2S donor in heart failure patients. However, the underlying molecular mechanisms by which H2S mitigates cardiac remodeling are not completely understood. Empirical evidence suggest that H2S may regulate signaling pathways either by directly influencing a gene in the cascade or interacting with nitric oxide (another cardioprotective gasotransmitter) or both. Recent studies revealed that H2S may ameliorate cardiac dysfunction by up- or downregulating specific microRNAs. MicroRNAs are noncoding, conserved, regulatory RNAs that modulate gene expression mostly by translational inhibition and are emerging as a therapeutic target for cardiovascular disease (CVD). Few microRNAs also regulate H2S biosynthesis. The inter-regulation of microRNAs and H2S opens a new avenue for exploring the H2S-microRNA crosstalk in CVD. This review embodies regulatory mechanisms that maintain the physiological level of H2S, exogenous H2S donors used for increasing the tissue levels of H2S, H2S-mediated regulation of CVD, H2S-microRNAs crosstalk in relation to the pathophysiology of heart disease, clinical trials on H2S, and future perspectives for H2S as a therapeutic agent for heart failure.

Circulating miR155 expression level is positive with blood pressure parameters: Potential markers of target-organ damage

OBJECTIVES

The aim of this study is to evaluate the relationship of miR155 with office and ambulatory blood pressure (BP) parameters and left ventricular hypertrophy (LVH) in patients with hypertension and healthy controls.

METHODS

We assessed the expression level of the miR155 in 50 patients with essential hypertension and 30 healthy individuals. All patients underwent two-dimensional echocardiography, office BP monitoring and ambulatory blood pressure monitoring (ABPM). Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was used to evaluate the expression of selected miR155. The miR155 correlations between BP parameters and left ventricular mass index (LVMI) were assessed using the Spearman correlation coefficient.

RESULTS

We observed higher expression level of miR155 (33.22 ± 2.59 vs. 27.30 ± 1.76; p < 0.001) in hypertensive patients compared with healthy control individuals, as well as in LVH to nLVH group (33.00 ± 2.78 vs. 27.28 ± 1.76; p < 0.001). MiR155 expression level showed significant positive correlations with office measurement of systolic blood pressure (SBP) (r = 0.634, p < 0.001), diastolic blood pressure (DBP) (r = 0.222, p < 0.05), pulse pressure (PP) (r = 0.564, p < 0.001), respectively. And explored miR155 expression level in relation to 24-h ABPM parameters showed significant positive correlation with 24 h mean SBP (r = 0.67, p < 0.001), 24 h mean DBP (r = 0.257, p < 0.05), 24 h mean PP (r = 0.597, p < 0.001), respectively, as well as with LVMI (r = 0.591, p < 0.001).

CONCLUSION

Circulating miR155 may possibly represent potential non-invasive marker of hypertension and target organ damage (TOD) in essential hypertensive patients.

Oncostatin M-induced cardiomyocyte dedifferentiation regulates the progression of diabetic cardiomyopathy through B-Raf/Mek/Erk signaling pathway

It has been reported that oncostatin M (OSM) could initiate cardiomyocyte dedifferentiation both in vivo and in vitro. OSM-induced cardiomyocyte dedifferentiation might be a new target for the treatment of diabetic cardiomyopathy (DCM). This study was designed to determine the role of OSM in cardiomyocyte dedifferentiation and the progression of DCM. A mouse DCM model was established to evaluate the effects of OSM in vivo. Echocardiography was applied to determine cardiac function. Sirius red staining was used to detect fibrosis area. Transmission electron microscopy was used to evaluate mitochondria impairment. Real-time polymerase chain reaction and western blot analysis were performed to detect relative mRNA expressions and cardiomyocyte dedifferentiation-related protein expressions, respectively. OSM treatment induced similar impaired cardiac function and cardiac ultrastructure impairment to those detected in DCM mice. The expressions of dedifferentiation markers of cardiomyocyte (Runx1, and α-SM-actin) were up-regulated in the OSM-treated mice compared with those in the control group. To further demonstrate the important role of OSM, OSM receptor knockout (Oβ(ko)) mice were used. In Oβ(ko) mice, cardiomyocytes dedifferentiation markers of c-kit, Runx1, and atrial natriuretic peptide were down-regulated, with attenuated DCM injury and abrogated OSM/B-Raf/Mek/Erk signaling pathway. In conclusion, OSM-induced cardiomyocyte dedifferentiation plays a crucial role in the progression of DCM. The mechanism of OSM-induced cardiomyocyte dedifferentiation is associated with B-Raf/Mek/Erk signaling pathway through the OSM receptor Oβ.

Anti-obesity and anti-diabetic effects of flavonoid derivative (Fla-CN) via microRNA in high fat diet induced obesity mice

3-O-[(E)-4-(4-cyanophenyl)-2-oxobut-3-en-1-yl]kaempferol (Fla-CN), a semi-synthesized flavonoid derivative of tiliroside, reduces whole-body adiposity, ameliorates metabolic lipid disorder, improves insulin sensitivity and benefits other disorders characterized by insulin resistance in high fat diet induced obesity mice. The improvement of insulin sensitivity and the reduction of weight gain are correlated with the changes of leptin and adiponectin levels. As a result, Fla-CN treatment could increase the expressions of pAMPK and miR-27 in the liver and adipose tissues. Meanwhile, we discovered that the expressions of various adipogenesis genes were downregulated, which were target genes of miR-27. This is the first report for the action of miR-27 by flavonoid derivative in rodents. The action of Fla-CN might be through multiple approaches including AMPK activation and enhancement in miR-27 expression.

Therapeutic Angiogenesis by Ultrasound-Mediated MicroRNA-126-3p Delivery

OBJECTIVE

MicroRNAs are involved in many critical functions, including angiogenesis. Ultrasound-targeted microbubble destruction (UTMD) is a noninvasive technique for targeted vascular transfection of plasmid DNA and may be well suited for proangiogenic microRNA delivery. We aimed to investigate UTMD of miR-126-3p for therapeutic angiogenesis in chronic ischemia.

APPROACH AND RESULTS

The angiogenic potential of miR-126-3p was tested in human umbilical vein endothelial cells in vitro. UTMD of miR-126-3p was tested in vivo in Fischer-344 rats before and after chronic left femoral artery ligation, evaluating target knockdown, miR-126-3p and miR-126-5p expression, phosphorylated Tie2 levels, microvascular perfusion, and vessel density. In vitro, miR-126-3p-transfected human umbilical vein endothelial cells showed repression of sprouty-related protein-1 and phosphatidylinositol-3-kinase regulatory subunit 2, negative regulators of vascular endothelial growth factor and angiopoietin-1 signaling, increased phosphorylated Tie2 mediated by knockdown of phosphatidylinositol-3-kinase regulatory subunit 2 and greater angiogenic potential mediated by both vascular endothelial growth factor/vascular endothelial growth factor R2 and angiopoietin-1 /Tie2 effects. UTMD of miR-126-3p resulted in targeted vascular transfection, peaking early after delivery and lasting for >3 days, and resulting in inhibition of sprouty-related protein-1 and phosphatidylinositol-3-kinase regulatory subunit 2, with minimal uptake in remote organs. Finally, UTMD of miR-126-3p to chronic ischemic hindlimb muscle resulted in improved perfusion, vessel density, enhanced arteriolar formation, pericyte coverage, and phosphorylated Tie2 levels, without affecting miR-126-5p or delta-like 1 homolog levels.

CONCLUSIONS

UTMD of miR-126 results in improved tissue perfusion and vascular density in the setting of chronic ischemia by repressing sprouty-related protein-1 and phosphatidylinositol-3-kinase regulatory subunit 2 and enhancing vascular endothelial growth factor and angiopoietin-1 signaling, with no effect on miR-126-5p. UTMD is a promising platform for microRNA delivery, with applications for therapeutic angiogenesis.

Silencing of miR-195 reduces diabetic cardiomyopathy in C57BL/6 mice

AIMS/HYPOTHESIS

MicroRNAs (miRs) have been suggested as potential therapeutic targets for heart diseases. Inhibition of miR-195 prevents apoptosis in cardiomyocytes stimulated with palmitate and transgenic overexpression of miR-195 induces cardiac hypertrophy and heart failure. We investigated whether silencing of miR-195 reduces diabetic cardiomyopathy in a mouse model of streptozotocin (STZ)-induced type 1 diabetes.

METHODS

Type 1 diabetes was induced in C57BL/6 mice (male, 2 months old) by injections of STZ.

RESULTS

MiR-195 expression was increased and levels of its target proteins (B cell leukaemia/lymphoma 2 and sirtuin 1) were decreased in STZ-induced type 1 and db/db type 2 diabetic mouse hearts. Systemically delivering an anti-miR-195 construct knocked down miR-195 expression in the heart, reduced caspase-3 activity, decreased oxidative stress, attenuated myocardial hypertrophy and improved myocardial function in STZ-induced mice with a concurrent upregulation of B cell leukaemia/lymphoma 2 and sirtuin 1. Diabetes reduced myocardial capillary density and decreased maximal coronary blood flow in mice. Knockdown of miR-195 increased myocardial capillary density and improved maximal coronary blood flow in diabetic mice. Upregulation of miR-195 sufficiently induced apoptosis in cardiomyocytes and attenuated the angiogenesis of cardiac endothelial cells in vitro. Furthermore, inhibition of miR-195 prevented apoptosis in cardiac endothelial cells in response to NEFA, an important feature of diabetes.

CONCLUSIONS/INTERPRETATION

Therapeutic silencing of miR-195 reduces myocardial hypertrophy and improves coronary blood flow and myocardial function in diabetes, at least in part by reducing oxidative damage, inhibiting apoptosis and promoting angiogenesis. Thus, miR-195 may represent an alternative therapeutic target for diabetic heart diseases.

Local MicroRNA Modulation Using a Novel Anti-miR-21-Eluting Stent Effectively Prevents Experimental In-Stent Restenosis

OBJECTIVE

Despite advances in stent technology for vascular interventions, in-stent restenosis (ISR) because of myointimal hyperplasia remains a major complication.

APPROACH AND RESULTS

We investigated the regulatory role of microRNAs in myointimal hyperplasia/ISR, using a humanized animal model in which balloon-injured human internal mammary arteries with or without stenting were transplanted into Rowett nude rats, followed by microRNA profiling. miR-21 was the only significantly upregulated candidate. In addition, miR-21 expression was increased in human tissue samples from patients with ISR compared with coronary artery disease specimen. We systemically repressed miR-21 via intravenous fluorescein-tagged-locked nucleic acid-anti-miR-21 (anti-21) in our humanized myointimal hyperplasia model. As expected, suppression of vascular miR-21 correlated dose dependently with reduced luminal obliteration. Furthermore, anti-21 did not impede reendothelialization. However, systemic anti-miR-21 had substantial off-target effects, lowering miR-21 expression in liver, heart, lung, and kidney with concomitant increase in serum creatinine levels. We therefore assessed the feasibility of local miR-21 suppression using anti-21-coated stents. Compared with bare-metal stents, anti-21-coated stents effectively reduced ISR, whereas no significant off-target effects could be observed.

CONCLUSION

This study demonstrates the efficacy of an anti-miR-coated stent for the reduction of ISR.

The effects of phosphodiesterase-5 inhibitor sildenafil against post-resuscitation myocardial and intestinal microcirculatory dysfunction by attenuating apoptosis and regulating microRNAs expression: essential role of nitric oxide syntheses signaling

Background

Recent experimental and clinical studies have indicated the cardioprotective role of sildenafil during ischemia/reperfusion (I/R) injury. Sildenafil has been shown to attenuate postresuscitation myocardial dysfunction in piget models of ventricular fibrillation. This study was designed to investigate if administration of sildenafil will attenuate post-resuscitation myocardial dysfunction by attenuating apoptosis and regulating miRNA expressions, furthermore, ameliorating the severity of post-microcirculatory dysfunction.

Methods

Twenty-four male pigs (weighing 30 ± 2 kg) were randomly divided into groups, sildenafil pretreatment (n = 8), saline (n = 8) and sham operation (sham, n = 8). Sildenafil pretreatment consisted of 0.5 mg/kg sildenafil, administered once intraperitoneally 30 min prior to ventricular fibrillation (VF). Eight minutes of untreated VF was followed by defibrillation in anesthetized, closed-chest pigs. Hemodynamic status and blood samples were obtained at 0 min, 0.5, 1, 2, 4 and 6 h after return of spontaneous circulation (ROSC). Surviving pigs were euthanatized at 24 h after ROSC, and hearts were removed for analysis by electron microscopy, western blotting, quantitative real-time polymerase chain reaction (PCR), and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Intestinal microcirculatory blood flow was visualized by a sidestream dark-field imaging device at baseline and 0.5, 1, 2, 4, and 6 h after ROSC.

Results

Compared with the saline group, the sildenafil group had a higher 24-hour survival (7/8 versus 3/8 survivors, p < 0.05) and a better outcome in hemodynamic parameters. The protective effect of sildenafil also correlated with reduced cardiomyocyte apoptosis, as evidenced by reduced TUNEL-positive cells, increased anti-apoptotic Bcl-2/Bax ratio and inhibited caspase-3 activity in myocardium. Additionally, sildenafil treatment inhibited the increases in the microRNA-1 levels and alleviated the decreases in the microRNA-133a levels which negatively regulates pro-apoptotic genes. At 6 h after ROSC, post-resuscitation perfused vessel density and microcirculatory flow index were significantly lower in the saline group than in the sildenafil group.

Conclusions

The major findings of this study are as follows: (1) sildenafil improved post-resuscitation perfusion of the heart, and thus reduced cardiac myocyte apoptosis and improved cardiac function; (2) sildenafil treatment inhibited the increases in the microRNA-1 levels, but alleviated the decreases in the microRNA-133a levels.

Induction of autophagy markers is associated with attenuation of miR-133a in diabetic heart failure patients undergoing mechanical unloading

Autophagy is ubiquitous in all forms of heart failure and cardioprotective miR-133a is attenuated in human heart failure. Previous reports from heart failure patients undergoing left ventricular assist device (LVAD) implantation demonstrated that autophagy is upregulated in the LV of the failing human heart. Studies in the murine model show that diabetes downregulates miR-133a. However, the role of miR-133a in the regulation of autophagy in diabetic hearts is unclear. We tested the hypothesis that diabetes exacerbates cardiac autophagy by inhibiting miR-133a in heart failure patients undergoing LVAD implantation. The miRNA assay was performed on the LV of 15 diabetic (D) and 6 non-diabetic (ND) heart failure patients undergoing LVAD implantation. Four ND with highly upregulated and 5 D with highly downregulated miR-133a were analyzed for autophagy markers (Beclin1, LC3B, ATG3) and their upstream regulators (mTOR and AMPK), and hypertrophy marker (beta-myosin heavy chain) by RT-qPCR, Western blotting and immunofluorescence. Our results demonstrate that attenuation of miR-133a in diabetic hearts is associated with the induction of autophagy and hypertrophy, and suppression of mTOR without appreciable difference in AMPK activity. In conclusion, attenuation of miR-133a contributes to the exacerbation of diabetes mediated cardiac autophagy and hypertrophy in heart failure patients undergoing LVAD implantation.

Harnessing fetal and adult genetic reprograming for therapy of heart disease

Heart is the first organ formed during organogenesis. The fetal heart undergoes several structural and functional modifications to form the four-chambered mammalian heart. The adult heart shows different adaptations during compensatory and decompensatory heart failure. However, one common adaptation in the pathological heart is fetal reprogramming, where the adult heart expresses several genes and miRNAs which are active in the fetal stage. The fetal reprogramming in the failing heart raises several questions, such as whether the switch of adult to fetal genetic programming is an adaptive response to cope with adverse remodeling of the heart, does the expression of fetal genes protect the heart during compensatory and/or decompensatory heart failure, does repressing the fetal gene in the failing heart is protective to the heart? To answer these questions, we need to understand the expression of genes and miRNAs that are reprogrammed in the failing heart. In view of this, we provided an overview of differentially expressed genes and miRNAs, and their regulation in this review. Further, we elaborated novel strategies for a plausible future therapy of cardiovascular diseases.

MicroRNA-23a participates in estrogen deficiency induced gap junction remodeling of rats by targeting GJA1

Increased incidence of arrhythmias in women after menopause has been widely documented, which is considered to be related to estrogen (E2) deficiency induced cardiac electrophysiological abnormalities. However, its molecular mechanism remains incompletely clear. In the present study, we found cardiac conduction blockage in post-menopausal rats. Thereafter, the results showed that cardiac gap junctions were impaired and Connexin43 (Cx43) expression was reduced in the myocardium of post-menopausal rats. The phenomenon was also observed in ovariectomized (OVX) rats, which was attenuated by E2 supplement. Further study displayed that microRNA-23a (miR-23a) level was significantly increased in both post-menopausal and OVX rats, which was reversed by daily E2 treatment after OVX. Importantly, forced overexpression of miR-23a led to gap junction impairment and Cx43 downregulation in cultured cardiomyocytes, which was rescued by suppressing miR-23a by transfection of miR-23a specific inhibitory oligonucleotide (AMO-23a). GJA1 was identified as the target gene of miR-23a by luciferase assay and miRNA-masking antisense ODN (miR-Mask) assay. We also found that E2 supplement could reverse cardiac conduction blockage, Cx43 downregulation, gap junction remodeling and miR-23a upregulation in post-menopausal rats. These findings provide the evidence that miR-23a mediated repression of Cx43 participates in estrogen deficiency induced damages of cardiac gap junction, and highlights a new insight into molecular mechanism of post-menopause related arrhythmia at the microRNA level.

MicroRNAs are potential prognostic and therapeutic targets in diabetic osteoarthritis

Osteoarthritis is an aging-related degenerative disease that severely influences the elders' life quality. However, there have been few clinical approaches available until now. Currently, more knowledge of the pathology of osteoarthritis has been illustrated. Especially, diabetes can be the only predictor of osteoarthritis. Due to its outstanding characteristics, MicroRNA has been considered as an efficient target in treating diseases. In this review, we will discuss a new insight focusing on the roles of microRNA in the progression of osteoarthritis-induced by diabetes, especially type II diabetes mellitus.

The emerging role of microRNAs in cardiovascular disease

Cardiovascular disease remains the most prevalent cause of human morbidity and mortality in ageing Western societies. Basic and translational scientific efforts have focused on the development and improvement of diagnostic and therapeutic strategies to limit the burden of associated diseases, such as stroke and myocardial infarction, and diabetes mellitus and arterial hypertension. Progress in molecular medicine and biology has unravelled a complex epigenetic and post-transcriptional gene-regulating machinery in humans which may limit disease development. An increasing number of attractive molecular strategies, which use the potential of modulating noncoding RNAs, have surfaced over the last decade. Currently, the most extensively studied gene-regulating RNA subspecies are microRNAs, which have been shown to adjust the translational output of coding transcripts by enforcing their degradation and inhibiting their translation into protein. Key findings indicate that microRNAs act as crucial regulators in the majority of human pathologies. Thus, recent research has focused on detecting and modulating microRNAs for therapeutic and biomarker purposes. This review focuses on main and repeated discoveries regarding the role and the therapeutic and biomarker feasibility of microRNAs during cardiovascular disease development and exacerbation.

miR-24 limits aortic vascular inflammation and murine abdominal aneurysm development

Identification and treatment of abdominal aortic aneurysm (AAA) remain among the most prominent challenges in vascular medicine. MicroRNAs (miRNAs) are crucial regulators of cardiovascular pathology and represent intriguing targets to limit AAA expansion. Here we show, by using two established murine models of AAA disease along with human aortic tissue and plasma analysis, that miR-24 is a key regulator of vascular inflammation and AAA pathology. In vivo and in vitro studies reveal chitinase 3-like 1 (Chi3l1) to be a major target and effector under the control of miR-24, regulating cytokine synthesis in macrophages as well as their survival, promoting aortic smooth muscle cell migration and cytokine production, and stimulating adhesion molecule expression in vascular endothelial cells. We further show that modulation of miR-24 alters AAA progression in animal models, and that miR-24 and CHI3L1 represent novel plasma biomarkers of AAA disease progression in humans.

Abdominal aortic aneurysm (AAA) is a potentially fatal and often asymptomatic disease whose causes remain unclear. Here the authors show that a microRNA, miR-24, and its target, the glycoprotein chitinase 3-like 1, represent key regulators of AAA development.

Differential expression of dicer, miRNAs, and inflammatory markers in diabetic Ins2+/- Akita hearts

Diabetic cardiomyopathy is a leading cause of morbidity and mortality, and Insulin2 mutant (Ins2+/-) Akita is a genetic mice model of diabetes relevant to humans. Dicer, miRNAs, and inflammatory cytokines are associated with heart failure. However, the differential expression of miRNAs, dicer, and inflammatory molecules are not clear in diabetic cardiomyopathy of Akita. We measured the levels of miRNAs, dicer, pro-inflammatory tumor necrosis factor alpha (TNFα), and anti-inflammatory interleukin 10 (IL-10) in C57BL/6J (WT) and Akita hearts. The results revealed increased heart to body weight ratio and robust expression of brain natriuretic peptide (BNP: a hypertrophy marker) suggesting cardiac hypertrophy in Akita. The multiplex RT-PCR, qPCR, and immunoblotting showed up regulation of dicer, whereas miRNA array elicited spread down regulation of miRNAs in Akita including dramatic down regulation of let-7a, miR-130, miR-142-3p, miR-148, miR-338, miR-345-3p, miR-384-3p, miR-433, miR-450, miR-451, miR-455, miR-494, miR-499, miR-500, miR-542-3p, miR-744, and miR-872. Conversely, miR-295 is induced in Akita. Cardiac TNFα is upregulated at mRNA (RT-PCR and qPCR), protein (immunoblotting), and cellular (immunohistochemistry and confocal microscopy) levels, and is robust in hypertrophic cardiomyocytes suggesting direct association of TNFα with hypertrophy. Contrary to TNFα, cardiac IL-10 is downregulated in Akita. In conclusion, induction of dicer and TNFα, and attenuation of IL-10 and majority of miRNA are associated with cardiomyopathy in Akita and could be used for putative therapeutic target for heart failure in diabetics.

Relationship between downregulation of miRNAs and increase of oxidative stress in the development of diabetic cardiac dysfunction: junctin as a target protein of miR-1

Oxidative stress is involved in the etiology of diabetes-induced cardiac dysfunction while microRNAs (miRNAs) are known as regulators for genes involved in cardiac remodeling. However, a functional link between miRNAs and diabetes-induced cardiac dysfunction remains to be investigated. Here, we aimed to identify whether the expression levels of miRNAs are associated with oxidative stress/diabetic heart and if proteins responsible from contractile activity during diabetes might be directly modulated by miRNAs. Diabetic cardiomyopathy developed with streptozotocin, is characterized with marked changes in sarcomere and mitochondria, depressed left ventricular developed pressure, and a massive oxidative stress that is particularly evident in the heart. miRNA profiling was performed in freshly isolated left ventricular cells from diabetic rats. Using microarray analysis, we identified marked changes in the expression of 43 miRNAs (37 of them were downregulated while 6 miRNAs were upregulated) out of examined total of 351 miRNAs. Among them, 6 miRNAs were further validated by real-time PCR. The expression levels of miR-1, miR-499, miR-133a, and miR-133b were markedly depressed in the diabetic cardiomyocytes while miR-21 level increased and miR-16 level was unchanged. Notably, normalization of cardiac function and oxidant/antioxidant level after N-acetylcysteine (NAC)-treatment of diabetic rats resulted with a significant restoration in the expression levels of miR-499, miR-1, miR-133a, and miR-133b in the myocardium. Since changes in the level of muscle-specific miR-1 has been implicated in cardiac diseases and its specific molecular targets involved in its action, in part, associated with oxidative stress are limited, we first examined the protein levels of some SR-associated proteins such as junctin and triadin. Junctin but not triadin is markedly overexpressed in diabetic cardiomyocytes while its level was normalized in NAC-treated diabetics. Luciferase reporter assay showed that junctin is targetted by miR-1. Taken together, our data demonstrates that intervention with an antioxidant treatment for 4-week leads to significant cardioprotection against diabetes-induced injury, controlling oxidant/antioxidant level, which may directly control the levels of some miRNAs including miR-1 and its target protein junctin, which is involved in the development of diabetic cardiomyopathy.

Generating double knockout mice to model genetic intervention for diabetic cardiomyopathy in humans

Diabetes is a rapidly increasing disease that enhances the chances of heart failure twofold to fourfold (as compared to age and sex matched nondiabetics) and becomes a leading cause of morbidity and mortality. There are two broad classifications of diabetes: type1 diabetes (T1D) and type2 diabetes (T2D). Several mice models mimic both T1D and T2D in humans. However, the genetic intervention to ameliorate diabetic cardiomyopathy in these mice often requires creating double knockout (DKO). In order to assess the therapeutic potential of a gene, that specific gene is either overexpressed (transgenic expression) or abrogated (knockout) in the diabetic mice. If the genetic mice model for diabetes is used, it is necessary to create DKO with transgenic/knockout of the target gene to investigate the specific role of that gene in pathological cardiac remodeling in diabetics. One of the important genes involved in extracellular matrix (ECM) remodeling in diabetes is matrix metalloproteinase-9 (Mmp9). Mmp9 is a collagenase that remains latent in healthy hearts but induced in diabetic hearts. Activated Mmp9 degrades extracellular matrix (ECM) and increases matrix turnover causing cardiac fibrosis that leads to heart failure. Insulin2 mutant (Ins2+/-) Akita is a genetic model for T1D that becomes diabetic spontaneously at the age of 3-4 weeks and show robust hyperglycemia at the age of 10-12 weeks. It is a chronic model of T1D. In Ins2+/- Akita, Mmp9 is induced. To investigate the specific role of Mmp9 in diabetic hearts, it is necessary to create diabetic mice where Mmp9 gene is deleted. Here, we describe the method to generate Ins2+/-/Mmp9-/- (DKO) mice to determine whether the abrogation of Mmp9 ameliorates diabetic cardiomyopathy.

Mechanical stretch via transforming growth factor-β1 activates microRNA-208a to regulate hypertrophy in cultured rat cardiac myocytes

BACKGROUND/PURPOSE

MicroRNA-208a (miR208a) and mechanical stress play a key role in cardiac hypertrophy. The relationship between miR208a and mechanical stress in cultured cardiomyocytes has not been investigated. The molecular mechanisms underlying miR208a-induced hypertrophy of cardiomyocytes by mechanical stress is poorly understood. This study investigated whether miR208a is a critical regulator in cardiomyocyte hypertrophy under mechanical stretch.

METHODS

Neonatal rat cardiomyocytes grown on a flexible membrane base were stretched at 60 cycles/minute. MiR real-time quantitative assays were used to quantify miRs. A quantitative sandwich enzyme immunoassay technique was used to measure transforming growth factor-β1 (TGF-β1). A (3)H-proline incorporation assay was used to measure protein synthesis.

RESULTS

Mechanical stretch significantly enhanced miR208a expression. Stretch significantly induced cardiomyocyte hypertrophic protein expression such as β-myosin heavy chain (MHCβ), thyroid hormone receptor-associated protein 100, myostatin, connexin 40, GATA4, and brain natriuretic peptide. MHCα was not induced by stretch. Overexpression of miR208a significantly increased MHCβ protein expression while pretreatment with antagomir208a significantly attenuated MHCβ protein expression induced by stretch and overexpression of miR208a. Mechanical stretch significantly increased the secretion of TGF-β1 from cultured cardiomyocytes. Exogenous addition of TGF-β1 recombinant protein significantly increased miR208a expression and pretreatment with TGF-β1 antibody attenuated miR208a expression induced by stretch. Mechanical stretch and overexpression of miR208a increased protein synthesis while antagomir208a attenuated protein synthesis induced by stretch and overexpression of miR208a.

CONCLUSION

Cyclic stretch enhances miR208a expression in cultured rat cardiomyocytes. MiR208a plays a role in stretch-induced cardiac hypertrophy. The stretch-induced miR208a is mediated by TGF-β1.

Molecular basis of organ fibrosis: potential therapeutic approaches

Fibrosis, a non-physiological wound healing in multiple organs, is associated with end-stage pathological symptoms of a wide variety of vascular injury and inflammation related diseases. In response to chemical, immunological and physical insults, the body's defense system and matrix synthetic machinery respond to healing the wound and maintain tissue homeostasis. However, uncontrolled wound healing leads to scarring or fibrosis, a pathological condition characterized by excessive synthesis and accumulation of extracellular matrix proteins, loss of tissue homeostasis and organ failure. Understanding the actual cause of pathological wound healing and identification of igniter(s) of fibrogenesis would be helpful to design novel therapeutic approaches to control pathological wound healing and to prevent fibrosis related morbidity and mortality. In this article, we review the significance of a few key cytokines (TGF-β, IFN-γ, IL-10) transcriptional activators (Sp1, Egr-1, Smad3), repressors (Smad7, Fli-1, PPAR-γ, p53, Klotho) and epigenetic modulators (acetyltransferase, methyltransferases, deacetylases, microRNAs) involved in major matrix protein collagen synthesis under pathological stage of wound healing, and the potentiality of these regulators as therapeutic targets for fibrosis treatment. The significance of endothelial to mesenchymal transition (EndMT) and senescence, two newly emerged fields in fibrosis research, has also been discussed.

Cardiac matrix: a clue for future therapy

Cardiac muscle is unique because it contracts ceaselessly throughout the life and is highly resistant to fatigue. The marvelous nature of the cardiac muscle is attributed to its matrix that maintains structural and functional integrity and provides ambient micro-environment required for mechanical, cellular and molecular activities in the heart. Cardiac matrix dictates the endothelium myocyte (EM) coupling and contractility of cardiomyocytes. The matrix metalloproteinases (MMPs) and their tissue inhibitor of metalloproteinases (TIMPs) regulate matrix degradation that determines cardiac fibrosis and myocardial performance. We have shown that MMP-9 regulates differential expression of micro RNAs (miRNAs), calcium cycling and contractility of cardiomyocytes. The differential expression of miRNAs is associated with angiogenesis, hypertrophy and fibrosis in the heart. MMP-9, which is involved in the degradation of cardiac matrix and induction of fibrosis, is also implicated in inhibition of survival and differentiation of cardiac stem cells (CSC). Cardiac matrix is distinct because it renders mechanical properties and provides a framework essential for differentiation of cardiac progenitor cells (CPC) into specific lineage. Cardiac matrix regulates myocyte contractility by EM coupling and calcium transients and also directs miRNAs required for precise regulation of continuous and synchronized beating of cardiomyocytes that is indispensible for survival. Alteration in the matrix homeostasis due to induction of MMPs, altered expression of specific miRNAs or impaired signaling for contractility of cardiomyocytes leads to catastrophic effects. This review describes the mechanisms by which cardiac matrix regulates myocardial performance and suggests future directions for the development of treatment strategies in cardiovascular diseases.

MicroRNA-29b regulation of abdominal aortic aneurysm development

Tremendous efforts have been initiated to elucidate the molecular and pathophysiological characteristics of abdominal aortic aneurysm (AAA) disease, which is a significant contributor to morbidity and mortality in the Western world. Recently, a novel class of small noncoding RNAs, called microRNAs, was identified as important transcriptional and posttranscriptional inhibitors of gene expression thought to simultaneously "fine tune" the translational output of multiple target messenger RNAs (mRNAs) by promoting mRNA degradation or inhibiting translation. Several research groups were able to identify the miR-29 family, and miR-29b in particular, as crucial regulators of-not only vascular fibrosis-but also cardiac-, kidney-, liver-, and skin-fibrosis. The current review briefly points out data indicating a causal role for miR-29 in various diseases, while focusing on its potential benefit during AAA initiation and propagation.

Micromanaging abdominal aortic aneurysms

The contribution of abdominal aortic aneurysm (AAA) disease to human morbidity and mortality has increased in the aging, industrialized world. In response, extraordinary efforts have been launched to determine the molecular and pathophysiological characteristics of the diseased aorta. This work aims to develop novel diagnostic and therapeutic strategies to limit AAA expansion and, ultimately, rupture. Contributions from multiple research groups have uncovered a complex transcriptional and post-transcriptional regulatory milieu, which is believed to be essential for maintaining aortic vascular homeostasis. Recently, novel small noncoding RNAs, called microRNAs, have been identified as important transcriptional and post-transcriptional inhibitors of gene expression. MicroRNAs are thought to "fine tune" the translational output of their target messenger RNAs (mRNAs) by promoting mRNA degradation or inhibiting translation. With the discovery that microRNAs act as powerful regulators in the context of a wide variety of diseases, it is only logical that microRNAs be thoroughly explored as potential therapeutic entities. This current review summarizes interesting findings regarding the intriguing roles and benefits of microRNA expression modulation during AAA initiation and propagation. These studies utilize disease-relevant murine models, as well as human tissue from patients undergoing surgical aortic aneurysm repair. Furthermore, we critically examine future therapeutic strategies with regard to their clinical and translational feasibility.

miR-145 regulates myofibroblast differentiation and lung fibrosis

The expression of smooth muscle actin-α (SMA-α) by fibroblasts defines phenotypic transition to myofibroblasts and is a primary contributor to contractile force generation by these differentiated cells. Although the regulation of SMA-α expression has been the focus of many studies, there is presently only limited information concerning miRNA regulation of lung myofibroblast differentiation and the involvement of these miRNAs in pulmonary fibrosis. To determine the role of miR-145 in regulating lung myofibroblast differentiation and pulmonary fibrosis. Wild-type and miR-145(-/-) mice were studied. Lung fibrosis models and cell culture systems were employed. miR-145 mimics or inhibitors were transfected into pulmonary fibroblasts. Fibrogenic and contractile activities of lung fibroblasts were determined. We found that miR-145 expression is upregulated in TGF-β1-treated lung fibroblasts. miR-145 expression is also increased in the lungs of patients with idiopathic pulmonary fibrosis as compared to in normal human lungs. Overexpression of miR-145 in lung fibroblasts increased SMA-α expression, enhanced contractility, and promoted formation of focal and fibrillar adhesions. In contrast, miR-145 deficiency diminished TGF-β1 induced SMA-α expression. miR-145 did not affect the activity of TGF-β1, but promoted the activation of latent TGF-β1. miR-145 targets KLF4, a known negative regulator of SMA-α expression. Finally, we found that miR-145(-/-) mice are protected from bleomycin-induced pulmonary fibrosis. miR-145 plays an important role in the differentiation of lung myofibroblasts. miR-145 deficiency is protective against bleomycin-induced lung fibrosis, suggesting that miR-145 may be a potential target in the development of novel therapies to treat pathological fibrotic disorders.

The therapeutic effect of rosuvastatin on cardiac remodelling from hypertrophy to fibrosis during the end-stage hypertension in rats

End-stage hypertensive heart disease is an increasing cause of cardiac mortality. Therefore, the current study focused on the cardiac remodelling from hypertrophy to fibrosis in old-aged spontaneously hypertensive rats (SHRs), and explored the therapeutic effects of Rosuvastatin and its possible mechanism(s) of action. Spontaneously hypertensive rats at age 52 weeks were randomly divided into three groups, the first two to receive Rosuvastatin at a dose of 20 mg/kg/day and 40 mg/kg/day, respectively, and the third to receive placebo, which was to be compared with Wistar-Kyoto as controls. After 2-month treatment, SBP, heart to body weight ratio (HW/BW%) and echocardiographic features were evaluated, followed by haematoxylin and eosin and Masson trichrome staining in conjunction with qPCR of foetal gene expressions. Transferase-mediated dUTP nick-end labelling assay and immunofluorescent labelling for active caspase-3 were used to detect the apoptotic cardiomyocytes. Signaling pathways involved were examined by using western blot. Old-aged SHR developed end-stage hypertensive heart disease characterized by significant enhancement of HW/BW%, LVAWd and LVPWd, and decreased LVEF and LVFS, accompanied by cardiomyocytes enlargement and fibrosis along with activation of foetal gene programme. Cardiac apoptosis increased significantly during the transition process. Rosuvastatin reduced hypertrophy significantly via AT₁ Receptor-PKCβ2/α-ERK-c-fos pathway; protected myocardium against apoptosis via Akt-FOXO1, Bcl-2 family and survivin pathways and consequently suppressed the caspase-3 activity. The present study revealed that old-aged SHRs developed cardiac remodelling from hypertrophy to fibrosis via cardiac apoptosis during the end stage of hypertensive heart disease. These pathological changes might be the consequence of activation of AT₁ Receptor-PKCβ2/α-ERK-c-fos and AKT-FOXO1/Bcl-2/survivin/Caspase3 signaling. Rosuvastatin effectively attenuated the structural changes by reversing the signaling transductions involved.

Predictors and prevention of diabetic cardiomyopathy

Despite our cognizance that diabetes can enhance the chances of heart failure, causes multiorgan failure,and contributes to morbidity and mortality, it is rapidly increasing menace worldwide. Less attention has been paid to alert prediabetics through determining the comprehensive predictors of diabetic cardiomyopathy (DCM) and ameliorating DCM using novel approaches. DCM is recognized as asymptomatic progressing structural and functional remodeling in the heart of diabetics, in the absence of coronary atherosclerosis and hypertension. The three major stages of DCM are: (1) early stage, where cellular and metabolic changes occur without obvious systolic dysfunction; (2) middle stage, which is characterized by increased apoptosis, a slight increase in left ventricular size, and diastolic dysfunction and where ejection fraction (EF) is <50%; and (3) late stage, which is characterized by alteration in microvasculature compliance, an increase in left ventricular size, and a decrease in cardiac performance leading to heart failure. Recent investigations have revealed that DCM is multifactorial in nature and cellular, molecular, and metabolic perturbations predisposed and contributed to DCM. Differential expression of microRNA (miRNA), signaling molecules involved in glucose metabolism, hyperlipidemia, advanced glycogen end products, cardiac extracellular matrix remodeling, and alteration in survival and differentiation of resident cardiac stem cells are manifested in DCM. A sedentary lifestyle and high fat diet causes obesity and this leads to type 2 diabetes and DCM. However, exercise training improves insulin sensitivity, contractility of cardiomyocytes, and cardiac performance in type 2 diabetes. These findings provide new clues to diagnose and mitigate DCM. This review embodies developments in the field of DCM with the aim of elucidating the future perspectives of predictors and prevention of DCM.

MicroRNAs and atherosclerosis: new actors for an old movie

To date, cardiovascular diseases (CVDs) are the leading causes of morbidity and mortality worldwide. MicroRNAs (miRNAs) are endogenous, short, non-coding RNA sequences able to regulate gene expression principally at the post-transcriptional level. Initially, they were thought to be involved only in developmental timing of worms. Their involvement in human biology was recently discovered and many studies have been performed to demonstrate the role of miRNA in human cancer. Since the first observation in 2005 of their implication in cardiac biology, many studies have demonstrated their role in the genetic modulation of cardiovascular development and in cardiovascular diseases such as cardial remodeling and heart failure, cardiac arrhythmias, cardiac ischaemia, cardiac fibrosis, atherosclerosis and stroke. Thus, the aim of this review is to describe the role of miRNA in atherosclerosis development and evolution and to individuate their role as potential therapeutic target.

MicroRNAs: a new ray of hope for diabetes mellitus

Diabetes mellitus has become one of the most common chronic diseases, thereby posing a major challenge to global health. Characterized by high levels of blood glucose (hyperglycemia), diabetes usually results from a loss of insulin-producing β-cells in the pancreas, leading to a deficiency of insulin (type 1 diabetes), or loss of insulin sensitivity (type 2 diabetes). Both types of diabetes have serious secondary complications, such as microvascular abnormalities, cardiovascular dysfunction, and kidney failure. Various complex factors, such as genetic and environmental factors, are associated with the pathophysiology of diabetes. Over the past two decades, the role of small, single-stranded noncoding microRNAs in various metabolic disorders, especially diabetes mellitus and its complications, has gained widespread attention in the scientific community. Discovered first as an endogenous regulator of development in the nematode Caenorhabditis elegans, these small RNAs post-transcriptionally suppress mRNA target expression. In this review, we discuss the potential roles of different microRNAs in diabetes and diabetes-related complications.

Role of microRNAs in cardiac remodelling: new insights and future perspectives

Cardiac remodelling is a key process in the progression of cardiovascular disease, implemented in myocardial infarction, valvular heart disease, myocarditis, dilated cardiomyopathy, atrial fibrillation and heart failure. Fibroblasts, extracellular matrix proteins, coronary vasculature, cardiac myocytes and ionic channels are all involved in this remodelling process. MicroRNAs (miRNAs) represent a sizable sub-group of small non-coding RNAs, which degrade or inhibit the translation of their target mRNAs, thus regulating gene expression and play an important role in a wide range of biologic processes. Recent studies have reported that miRNAs are aberrantly expressed in the cardiovascular system under some pathological conditions. Indeed, in vitro and in vivo models have revealed that miRNAs are essential for cardiac development and remodelling. Clinically, there is increasing evidence of the potential diagnostic role of miRNAs as potential diagnostic biomarkers and they may represent a novel therapeutic target in several cardiovascular disorders. This paper provides an overview of the impact of several miRNAs in electrical and structural remodelling of the cardiac tissue, and the diagnostic and therapeutic potential of miRNA in cardiovascular disease.

MicroRNA-21 blocks abdominal aortic aneurysm development and nicotine-augmented expansion

Identification and treatment of abdominal aortic aneurysm (AAA) remains among the most prominent challenges in vascular medicine. MicroRNAs are crucial regulators of cardiovascular pathology and represent possible targets for the inhibition of AAA expansion. We identified microRNA-21 (miR-21) as a key modulator of proliferation and apoptosis of vascular wall smooth muscle cells during development of AAA in two established murine models. In both models (AAA induced by porcine pancreatic elastase or infusion of angiotensin II), miR-21 expression increased as AAA developed. Lentiviral overexpression of miR-21 induced cell proliferation and decreased apoptosis in the aortic wall, with protective effects on aneurysm expansion. miR-21 overexpression substantially decreased expression of the phosphatase and tensin homolog (PTEN) protein, leading to increased phosphorylation and activation of AKT, a component of a pro-proliferative and antiapoptotic pathway. Systemic injection of a locked nucleic acid-modified antagomir targeting miR-21 diminished the pro-proliferative impact of down-regulated PTEN, leading to a marked increase in the size of AAA. Similar results were seen in mice with AAA augmented by nicotine and in human aortic tissue samples from patients undergoing surgical repair of AAA (with more pronounced effects observed in smokers). Modulation of miR-21 expression shows potential as a new therapeutic option to limit AAA expansion and vascular disease progression.

Comprehensive exploration of the effects of miRNA SNPs on monocyte gene expression

We aimed to assess whether pri-miRNA SNPs (miSNPs) could influence monocyte gene expression, either through marginal association or by interacting with polymorphisms located in 3'UTR regions (3utrSNPs). We then conducted a genome-wide search for marginal miSNPs effects and pairwise miSNPs × 3utrSNPs interactions in a sample of 1,467 individuals for which genome-wide monocyte expression and genotype data were available. Statistical associations that survived multiple testing correction were tested for replication in an independent sample of 758 individuals with both monocyte gene expression and genotype data. In both studies, the hsa-mir-1279 rs1463335 was found to modulate in cis the expression of LYZ and in trans the expression of CNTN6, CTRC, COPZ2, KRT9, LRRFIP1, NOD1, PCDHA6, ST5 and TRAF3IP2 genes, supporting the role of hsa-mir-1279 as a regulator of several genes in monocytes. In addition, we identified two robust miSNPs × 3utrSNPs interactions, one involving HLA-DPB1 rs1042448 and hsa-mir-219-1 rs107822, the second the H1F0 rs1894644 and hsa-mir-659 rs5750504, modulating the expression of the associated genes.

As some of the aforementioned genes have previously been reported to reside at disease-associated loci, our findings provide novel arguments supporting the hypothesis that the genetic variability of miRNAs could also contribute to the susceptibility to human diseases.

Mechanical stretch via transforming growth factor-β1 activates microRNA208a to regulate endoglin expression in cultured rat cardiac myoblasts

AIMS

MicroRNAs (miRNAs) play a role in cardiac remodelling. MiR208a is essential for the expression of the genes involved in cardiac hypertrophy and fibrosis. The mechanism of regulation of miR208a involved in cardiac hypertrophy by mechanical stress is still unclear. We sought to investigate the mechanism of regulation of miR208a and the target gene of miR208a in cardiac cells by mechanical stretch.

METHODS AND RESULTS

Rat H9c2 cells (cardiac myoblasts) grown on a flexible membrane base were stretched via vacuum to 20% of maximum elongation at 60 cycles/min. Mechanical stretch significantly enhanced miR208a expression after 4 h of stretch. Exogenous addition of transforming growth factor-β1 (TGF-β1) increased miR208a expression, and pre-treatment with TGF-β1 antibody attenuated the miR208a expression induced by stretch. Mechanical stretch significantly increased endoglin and collagen I expression for 6-24 h. Exogenous addition of TGF-β1 and overexpression of miR208a up-regulated endoglin and collagen I expression, while antagomir208a and Smad3/4 inhibitor attenuated endoglin and collagen I expression induced by stretch. Mechanical stretch and TGF-β1 increased Smad3/4-DNA binding activity and miR208a promoter activity, and TGF-β1 antibody and Smad3/4 inhibitor decreased the Smad3/4-DNA binding activity and miR208a promoter activity induced by stretch.

CONCLUSION

Cyclic mechanical stretch enhances miR208a expression in cultured rat cardiac myoblasts. The stretch-induced miR208a is mediated by TGF-β1. Mir208a activates endoglin expression and may result in cardiac fibrosis.

Computational analysis and predictive modeling of small molecule modulators of microRNA

Background

MicroRNAs (miRNA) are small endogenously transcribed regulatory RNA which modulates gene expression at a post transcriptional level. These small RNAs have now been shown to be critical regulators in a number of biological processes in the cell including pathophysiology of diseases like cancers. The increasingly evident roles of microRNA in disease processes have also motivated attempts to target them therapeutically. Recently there has been immense interest in understanding small molecule mediated regulation of RNA, including microRNA.

Results

We have used publicly available datasets of high throughput screens on small molecules with potential to inhibit microRNA. We employed computational methods based on chemical descriptors and machine learning to create predictive computational models for biological activity of small molecules. We further used a substructure based approach to understand common substructures potentially contributing to the activity.

Conclusion

We generated computational models based on Naïve Bayes and Random Forest towards mining small RNA binding molecules from large molecular datasets. We complement this with substructure based approach to identify and understand potentially enriched substructures in the active dataset. We use this approach to identify miRNA binding potential of a set of approved drugs, suggesting a probable novel mechanism of off-target activity of these drugs. To the best of our knowledge, this is the first and most comprehensive computational analysis towards understanding RNA binding activities of small molecules and predictive modeling of these activities.

MicroRNA-133a regulates DNA methylation in diabetic cardiomyocytes

We tested the hypothesis that miR-133a regulates DNA methylation by inhibiting Dnmt-1 (maintenance) and Dnmt-3a and -3b (de novo) methyl transferases in diabetic hearts by using Ins2(+/-) Akita (diabetic) and C57BL/6J (WT), mice and HL1 cardiomyocytes. The specific role of miR-133a in DNA methylation in diabetes was assessed by two treatment groups (1) scrambled, miR-133a mimic, anti-miR-133a, and (2) 5mM glucose (CT), 25 mM glucose (HG) and HG+miR-133a mimic. The levels of miR-133a, Dnmt-1, -3a and -3b were measured by multiplex RT-PCR, qPCR and Western blotting. The results revealed that miR-133a is inhibited but Dnmt-1 and -3b are induced in Akita suggesting that attenuation of miR-133a induces both maintenance (Dnmt-1) - and de novo - methylation (Dnmt-3b) in diabetes. The up regulation of Dnmt-3a in Akita hearts elicits intricate and antagonizing interaction between Dnmt-3a and -3b. In cardiomyocytes, over expression of miR-133a inhibits but silencing of miR-133a induces Dnmt-1, -3a and -3b elucidating the involvement of miR-133a in regulation of DNA methylation. The HG treatment up regulates only Dnmt-1 and not Dnmt-3a and -3b suggesting that acute hyperglycemia triggers only maintenance methylation. The over expression of miR-133a mitigates glucose mediated induction of Dnmt-1 illustrating the role of miR-133a in regulation of DNA methylation in diabetes.

miR-31 is a negative regulator of fibrogenesis and pulmonary fibrosis

Aberrant expression of miRNAs is closely associated with initiation and progression of pathological processes, including diabetes, cancer, and cardiovascular disease. However, the role of miRNAs in lung fibrosis is not well characterized. We sought to determine the role of miR-31 in regulating the fibrogenic, contractile, and migratory activities of lung fibroblasts and modulating of pulmonary fibrosis in vivo. In vivo lung fibrosis models and ex vivo cell culture systems were employed. Real-time PCR and Western blot analysis were used to determine gene expression levels. miR-31 mimics or inhibitors were transfected into pulmonary fibroblasts. Fibrogenic, contractile, and migratory activities of lung fibroblasts were determined. We found that miR-31 expression is reduced in the lungs of mice with experimental pulmonary fibrosis and in IPF fibroblasts. miR-31 inhibits the profibrotic activity of TGF-β1 in normal lung fibroblasts and diminishes the fibrogenic, contractile, and migratory activities of IPF fibroblasts. In these experiments, miR-31 was shown to directly target integrin α(5) and RhoA, two proteins that have been shown to regulate activation of fibroblasts. We found that levels of integrin α(5) and RhoA are up-regulated in fibrotic mouse lungs. Knockdown of integrin α(5) and RhoA attenuated fibrogenic, contractile, and migratory activities of IPF fibroblasts, in a manner similar to that observed with miR-31. We also found that introduction of miR-31 ameliorated experimental lung fibrosis in mice. Our data suggest that miR-31 is an important regulator of the pathological activities of lung fibroblasts and may be a potential target in the development of novel therapies to treat pathological fibrotic disorders, including pulmonary fibrosis.

MicroRNA-mediated regulation of gene expression is affected by disease-associated SNPs within the 3'-UTR via altered RNA structure

Single nucleotide polymorphisms (SNPs) in microRNAs (miRNAs) or their target sites (miR-SNPs) within the 3′-UTR of mRNAs are increasingly thought to play a major role in pathological dysregulation of gene expression. Here, we studied the functional role of miR-SNPs on miRNA-mediated post-transcriptional regulation of gene expression. First, analyses were performed on a SNP located in the miR-155 target site within the 3′-UTR of the Angiotensin II type 1 receptor (AGTR1; rs5186, A > C) mRNA. Second, a SNP in the 3′-UTR of the muscle RAS oncogene homolog (MRAS; rs9818870, C > T) mRNA was studied which is located outside of binding sites of miR-195 and miR-135. Using these SNPs we investigated their effects on local RNA structure, on local structural accessibility and on functional miRNA binding, respectively. Systematic computational RNA folding analyses of the allelic mRNAs in either case predicted significant changes of local RNA structure in the vicinity of the cognate miRNA binding sites. Consistently, experimental in vitro probing of RNA showing differential cleavage patterns and reporter gene-based assays indicated functional differences of miRNA-mediated regulation of the two AGTR1 and MRAS alleles. In conclusion, we describe a novel model explaining the functional influence of 3′-UTR-located SNPs on miRNA-mediated control of gene expression via SNP-related changes of local RNA structure in non-coding regions of mRNA. This concept substantially extends the meaning of disease-related SNPs identified in non protein-coding transcribed sequences within or close to miRNA binding sites.

Molecular basis of cardiac endothelial-to-mesenchymal transition (EndMT): differential expression of microRNAs during EndMT

Fibroblasts are responsible for producing the majority of collagen and other extracellular matrix (ECM) proteins in tissues. In the injured tissue, transforming growth factor-β (TGF-β)-activated fibroblasts or differentiated myofibroblasts synthesize excessive ECM proteins and play a pivotal role in the pathogenesis of fibrosis in heart, kidney and other organs. Recent studies suggest that fibroblast-like cells, derived from endothelial cells by endothelial-to-mesenchymal transition (EndMT), contribute to the pathogenesis of cardiac fibrosis. The molecular basis of EndMT, however, is poorly understood. Here, we investigated the molecular basis of EndMT in mouse cardiac endothelial cells (MCECs) in response to TGF-β2. MCECs exposed to TGF-β2 underwent EndMT as evidenced by morphologic changes, lack of acetylated-low density lipoprotein (Ac-LDL) uptake, and the presence of alpha-smooth muscle actin (α-SMA) staining. Treatment with SB431542, a small molecule inhibitor of TGF-β-receptor I (TβRI) kinase, but not PD98059, a MEK inhibitor, completely blocked TGF-β2-induced EndMT. The transcript and protein levels of α-SMA, Snail and β-catenin as well as acetyltransferase p300 (ATp300) were elevated in EndMT derived fibroblast-like cells. Importantly, microRNA (miRNA) array data revealed that the expression levels of specific miRNAs, known to be dysregulated in different cardiovascular diseases, were altered during EndMT. The protein level of cellular p53, a bonafide target of miR-125b, was downregulated in EndMT-derived fibroblast-like cells. Here, we report for the first time, the differential expression of miRNAs during cardiac EndMT. These results collectively suggest that TβRI serine-threonine kinase-induced TGF-β signaling and microRNAs, the epigenetic regulator of gene expression at the posttranscriptional level, are involved in EndMT and promote profibrotic signaling in EndMT-derived fibroblast-like cells. Pharmacologic agents that restrict the progression of cardiac EndMT, a phenomenon that is found in adults only in the pathological conditions, in targeting specific miRNA may be helpful in preventing and treating cardiac fibrosis.

MicroRNA-199a* regulates the expression of cyclooxygenase-2 in human chondrocytes

OBJECTIVE

Cyclooxygenase-2 (COX-2) expression is associated with the pathogenesis of chronic inflammation and pain in osteoarthritis (OA). A study was undertaken to determine whether interleukin-1β (IL-1β)-mediated induction of COX-2 can be regulated by microRNAs (miRNAs) in OA.

METHODS

Human chondrocytes were stimulated with IL-1β in vitro. Total RNA was prepared using Trizol reagent. Gene expression was quantified using TaqMan Assays and miRNA targets were identified using bioinformatics. Transfection with reporter construct and premiRNA and antimiRNA was employed to verify suppression of target mRNA. Expression of COX-2 proteins was determined by immunoblotting. The role of activated p38-MAPKs was evaluated using specific inhibitor.

RESULTS

The 3'UTR of COX-2 mRNA contained the 'seed-matched' sequences for miR-199a* and miR-101_3. Increased expression of COX-2 correlated with the downregulation of miR-199a* and miR-101_3 in IL-1β-stimulated normal and OA chondrocytes. miR-199a* directly suppressed the luciferase activity of a COX-2 3'UTR reporter construct and inhibited the IL-1β-induced expression of COX-2 protein in OA chondrocytes. Modulation of miR-199a* expression also caused significant inhibition of IL-1β-induced upregulation of mPGES1 and prostaglandin E(2) production in OA chondrocytes. Activation of p38-MAPK downregulated the expression of miR-199a* and induced COX-2 expression. Treatment with antimiR-101_3 increased COX-2 expression in IL-1β-stimulated chondrocytes, but overexpression of miR-101_3 had no significant effect on COX-2 protein expression.

CONCLUSIONS

miR-199a* is a direct regulator of COX-2 expression in OA chondrocytes. IL-1β-induced activation of p38-MAPK correlates inversely with miR199a* expression levels. miR-199a* may be an important regulator of human cartilage homeostasis and a new target for OA therapy.

Inhibition of microRNA-29b reduces murine abdominal aortic aneurysm development

MicroRNAs (miRs) regulate gene expression at the posttranscriptional level and play crucial roles in vascular integrity. As such, they may have a role in modifying abdominal aortic aneurysm (AAA) expansion, the pathophysiological mechanisms of which remain incompletely explored. Here, we investigate the role of miRs in 2 murine models of experimental AAA: the porcine pancreatic elastase (PPE) infusion model in C57BL/6 mice and the AngII infusion model in Apoe-/- mice. AAA development was accompanied by decreased aortic expression of miR-29b, along with increased expression of known miR-29b targets, Col1a1, Col3a1, Col5a1, and Eln, in both models. In vivo administration of locked nucleic acid anti-miR-29b greatly increased collagen expression, leading to an early fibrotic response in the abdominal aortic wall and resulting in a significant reduction in AAA progression over time in both models. In contrast, overexpression of miR-29b using a lentiviral vector led to augmented AAA expansion and significant increase of aortic rupture rate. Cell culture studies identified aortic fibroblasts as the likely vascular cell type mediating the profibrotic effects of miR-29b modulation. A similar pattern of reduced miR-29b expression and increased target gene expression was observed in human AAA tissue samples compared with that in organ donor controls. These data suggest that therapeutic manipulation of miR-29b and its target genes holds promise for limiting AAA disease progression and protecting from rupture.

Short-RNA selective binding of oligonucleotides modified using adenosine and guanosine derivatives that possess cyclohexyl phosphates as substituents

We have developed new artificial oligonucleotides which distinguish short RNA targets from long ones. The modification of the 5' termini of oligonucleotides by using adenosine derivatives that possess a bulky cyclohexyl phosphate moiety at their base moiety and a phosphate group at the position of their 5'-hydroxyl group maximized their short RNA selectivity. The 2'-O-methyl-RNA (5'-XC(m)A(m)A(m)C(m)C(m)U(m)A(m)C(m)U(m)) having these modifications exhibits ca. 10 °C higher T(m) in the duplexes with the complementary short RNA (3'-GUUGGAUGA-5') than with the long RNA (3'-AUUAUAUGUUGGAUGAUGGUUA-5'). The oligodeoxynucleotides having the same modification exhibited similar selectivity. Such short-RNA selective binding of terminally modified oligonucleotides can be employed to distinguish between mature microRNAs and pre-microRNAs.

Novel microRNA prosurvival cocktail for improving engraftment and function of cardiac progenitor cell transplantation

BACKGROUND

Although stem cell therapy has provided a promising treatment for myocardial infarction, the low survival of the transplanted cells in the infarcted myocardium is possibly a primary reason for failure of long-term improvement. Therefore, the development of novel prosurvival strategies to boost stem cell survival will be of significant benefit to this field.

METHODS AND RESULTS

Cardiac progenitor cells (CPCs) were isolated from transgenic mice, which constitutively express firefly luciferase and green fluorescent protein. The CPCs were transduced with individual lentivirus carrying the precursor of miR-21, miR-24, and miR-221, a cocktail of these 3 microRNA precursors, or green fluorescent protein as a control. After challenge in serum free medium, CPCs treated with the 3 microRNA cocktail showed significantly higher viability compared with untreated CPCs. After intramuscular and intramyocardial injections, in vivo bioluminescence imaging showed that microRNA cocktail-treated CPCs survived significantly longer after transplantation. After left anterior descending artery ligation, microRNA cocktail-treated CPCs boost the therapeutic efficacy in terms of functional recovery. Histological analysis confirmed increased myocardial wall thickness and CPC engraftment in the myocardium with the microRNA cocktail. Finally, we used bioinformatics analysis and experimental validation assays to show that Bim, a critical apoptotic activator, is an important target gene of the microRNA cocktail, which collectively can bind to the 3'UTR region of Bim and suppress its expression.

CONCLUSIONS

We have demonstrated that a microRNA prosurvival cocktail (miR-21, miR-24, and miR-221) can improve the engraftment of transplanted cardiac progenitor cells and therapeutic efficacy for treatment of ischemic heart disease.

MicroRNA-134 as a potential plasma biomarker for the diagnosis of acute pulmonary embolism

Background

Acute pulmonary embolism (APE) remains a diagnostic challenge due to a variable clinical presentation and the lack of a reliable screening tool. MicroRNAs (miRNAs) regulate gene expression in a wide range of pathophysiologic processes. Circulating miRNAs are emerging biomarkers in heart failure, type 2 diabetes and other disease states; however, using plasma miRNAs as biomarkers for the diagnosis of APE is still unknown.

Methods

Thirty-two APE patients, 32 healthy controls, and 22 non-APE patients (reported dyspnea, chest pain, or cough) were enrolled in this study. The TaqMan miRNA microarray was used to identify dysregulated miRNAs in the plasma of APE patients. The TaqMan-based miRNA quantitative real-time reverse transcription polymerase chain reactions were used to validate the dysregulated miRNAs. The receiver-operator characteristic (ROC) curve analysis was conducted to evaluate the diagnostic accuracy of the miRNA identified as the candidate biomarker.

Results

Plasma miRNA-134 (miR-134) level was significantly higher in the APE patients than in the healthy controls or non-APE patients. The ROC curve showed that plasma miR-134 was a specific diagnostic predictor of APE with an area under the curve of 0.833 (95% confidence interval, 0.737 to 0.929; P < 0.001).

Conclusions

Our findings indicated that plasma miR-134 could be an important biomarker for the diagnosis of APE. Because of this finding, large-scale investigations are urgently needed to pave the way from basic research to clinical utilization.

MicroRNA-1 transfected embryonic stem cells enhance cardiac myocyte differentiation and inhibit apoptosis by modulating the PTEN/Akt pathway in the infarcted heart

microRNAs (miRs) have emerged as critical modulators of various physiological processes including stem cell differentiation. Indeed, miR-1 has been reported to play an integral role in the regulation of cardiac muscle progenitor cell differentiation. However, whether overexpression of miR-1 in embryonic stem (ES) cells (miR-1-ES cells) will enhance cardiac myocyte differentiation following transplantation into the infarcted myocardium is unknown. In the present study, myocardial infarction (MI) was produced in C57BL/6 mice by left anterior descending artery ligation. miR-1-ES cells, ES cells, or culture medium (control) was transplanted into the border zone of the infarcted heart, and 2 wk post-MI, cardiac myocyte differentiation, adverse ventricular remodeling, and cardiac function were assessed. We provide evidence demonstrating enhanced cardiac myocyte commitment of transplanted miR-1-ES cells in the mouse infarcted heart as compared with ES cells. Assessment of apoptosis revealed that overexpression of miR-1 in transplanted ES cells protected host myocardium from MI-induced apoptosis through activation of p-AKT and inhibition of caspase-3, phosphatase and tensin homolog, and superoxide production. A significant reduction in interstitial and vascular fibrosis was quantified in miR-1-ES cell and ES cell transplanted groups compared with control MI. However, no statistical significance between miR-1-ES cell and ES cell groups was observed. Finally, mice receiving miR-1-ES cell transplantation post-MI had significantly improved heart function compared with respective controls (P < 0.05). Our data suggest miR-1 drives cardiac myocyte differentiation from transplanted ES cells and inhibits apoptosis post-MI, ultimately giving rise to enhanced cardiac repair, regeneration, and function.

The therapeutic potential of microRNAs: disease modulators and drug targets

MiRNAs are a class of small, naturally occurring RNA molecules that play critical roles in modulating numerous biological pathways by regulating gene expression. The knowledge that miRNA expression is dysregulated in many pathological disease processes, including cancer, has led to a rapidly expanding body of literature as we try to unveil their mechanism of action. Their putative role as oncogenes or tumour suppressor genes presents a wonderful opportunity to provide targeted cancer treatment strategies. Additionally, their documented function in a host of benign diseases broadens the potential market for miRNA-based therapeutics. The present review outlines the underlying rationales for considering mi(cro)RNAs as therapeutic agents or targets. We highlight the potential of manipulating miRNAs for the treatment of many common diseases, particularly cancers. Finally, we summarize the challenges that need to be overcome to fully harness the potential of miRNA-based therapies so they become the next generation of pharmaceutical products.

A unique microRNA signature associated with plaque instability in humans

BACKGROUND AND PURPOSE

Atherosclerotic plaque rupture is considered the most important mechanism that underlies the onset of stroke, myocardial infarction, and sudden death. Several evidences demonstrated the pivotal role of inflammatory processes in plaque destabilization. MicroRNAs (miRNAs) are small endogenous RNAs and represent a new important class of gene regulators. Nevertheless, no data exist about the expression profile of miRNAs in atherosclerotic plaques. Thus, the aim of this study was to investigate the expression level of miRNAs in human plaques and to correlate it with clinical features of plaque destabilization.

METHODS

Two separate groups of plaques were collected from patients who underwent carotid endarterectomy in Chieti (n=15) and Ancona (n=38) Hospitals. All the plaques were subdivided in symptomatic (n=22) and asymptomatic (n=31) according to the presence/absence of stroke.

RESULTS

First, on the plaques collected at Chieti Hospital, we performed large-scale analysis of miRNA expression. Between the 41 miRNAs examined, we discovered profound differences in the expression of 5 miRNAs (miRNA-100, miRNA-127, miRNA-145, miRNA-133a, and miRNA-133b) in symptomatic versus asymptomatic plaques. Remarkably, when we repeated the analysis on the Ancona plaque subset, all these 5 miRNAs confirmed to be significantly more expressed in the symptomatic plaques. Finally, in vitro experiments on endothelial cells transfected with miRNA-145 and miRNA-133a confirmed the importance of these miRNAs in the modulation of stroke-related proteins.

CONCLUSIONS

These results are the first to report alterations in the expression of specific miRNAs in human atherosclerotic plaques and suggest that miRNAs may have an important role in regulating the evolution of atherosclerotic plaque toward instability and rupture. Furthermore, by identifying the specific miRNA signature for stroke now, we are able to use computer algorithms to identify previously unrecognized molecular targets.

Clarifying mammalian RISC assembly in vitro

Background

Argonaute, the core component of the RNA induced silencing complex (RISC), binds to mature miRNAs and regulates gene expression at transcriptional or post-transcriptional level. We recently reported that Argonaute 2 (Ago2) also assembles into complexes with miRNA precursors (pre-miRNAs). These Ago2:pre-miRNA complexes are catalytically active in vitro and constitute non-canonical RISCs.

Results

The use of pre-miRNAs as guides by Ago2 bypasses Dicer activity and complicates in vitro RISC reconstitution. In this work, we characterized Ago2:pre-miRNA complexes and identified RNAs that are targeted by miRNAs but not their corresponding pre-miRNAs. Using these target RNAs we were able to recapitulate in vitro pre-miRNA processing and canonical RISC loading, and define the minimal factors required for these processes.

Conclusions

Our results indicate that Ago2 and Dicer are sufficient for processing and loading of miRNAs into RISC. Furthermore, our studies suggest that Ago2 binds primarily to the 5'- and alternatively, to the 3'-end of select pre-miRNAs.

Rupture of vulnerable atherosclerotic plaques: microRNAs conducting the orchestra?

MicroRNAs (miRNAs) are tiny, endogenous nucleotides that bind to mRNA and induce translation repression within metazoan cells. Since their discovery in 1993 in Caenorhabditis elegans and the demonstration of miRNAs in Homo sapiens in 2000, research has been fruitful in deciphering the role of these nucleotides in development, tissue homeostasis, and pathologic processes. In humans, around 700 human miRNA nucleotides have been verified, which interfere with 30% of all genes. Recently, the role of miRNA in cardiovascular research gained attention and the involvement of miRNAs in several cardiovascular diseases has been identified. In this review, we focus on the role of miRNAs in atherosclerosis and in particular on the potential role of miRNAs in the development of vulnerable atherosclerotic plaques. The role of miRNA in the main characteristics of these plaques, inflammation, angiogenesis, and apoptosis will be discussed. Finally, the future perspectives and miRNA-based diagnostic and therapeutic potentials will be highlighted.

MicroRNA expression analysis: clinical advantage of propranolol reveals key microRNAs in myocardial infarction

Background

As playing important roles in gene regulation, microRNAs (miRNAs) are believed as indispensable involvers in the pathogenesis of myocardial infarction (MI) that causes significant morbidity and mortality. Working on a hypothesis that modulation of only some key members in the miRNA superfamily could benefit ischemic heart, we proposed a microarray based network biology approach to identify them with the recognized clinical effect of propranolol as a prompt.

Methods

A long-term MI model of rat was established in this study. The microarray technology was applied to determine the global miRNA expression change intervened by propranolol. Multiple network analyses were sequentially applied to evaluate the regulatory capacity, efficiency and emphasis of the miRNAs which dysexpression in MI were significantly reversed by propranolol.

Results

Microarray data analysis indicated that long-term propranolol administration caused 18 of the 31 dysregulated miRNAs in MI undergoing reversed expression, implying that intentional modulation of miRNA expression might show favorable effects for ischemic heart. Our network analysis identified that, among these miRNAs, the prime players in MI were miR-1, miR-29b and miR-98. Further finding revealed that miR-1 focused on regulation of myocyte growth, yet miR-29b and miR-98 stressed on fibrosis and inflammation, respectively.

Conclusion

Our study illustrates how a combination of microarray technology and functional protein network analysis can be used to identify disease-related key miRNAs.

Role for miR-204 in human pulmonary arterial hypertension

Reduced miR-204 expression facilitates the excessive proliferation and apoptosis resistance of pulmonary artery smooth muscle cells characteristic of human pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is characterized by enhanced proliferation and reduced apoptosis of pulmonary artery smooth muscle cells (PASMCs). Because microRNAs have been recently implicated in the regulation of cell proliferation and apoptosis, we hypothesized that these regulatory molecules might be implicated in the etiology of PAH. In this study, we show that miR-204 expression in PASMCs is down-regulated in both human and rodent PAH. miR-204 down-regulation correlates with PAH severity and accounts for the proliferative and antiapoptotic phenotypes of PAH-PASMCs. STAT3 activation suppresses miR-204 expression, and miR-204 directly targets SHP2 expression, thereby SHP2 up-regulation, by miR-204 down-regulation, activates the Src kinase and nuclear factor of activated T cells (NFAT). STAT3 also directly induces NFATc2 expression. NFAT and SHP2 were needed to sustain PAH-PASMC proliferation and resistance to apoptosis. Finally, delivery of synthetic miR-204 to the lungs of animals with PAH significantly reduced disease severity. This study uncovers a new regulatory pathway involving miR-204 that is critical to the etiology of PAH and indicates that reestablishing miR-204 expression should be explored as a potential new therapy for this disease.