MicroRNAs are aberrantly expressed in hypertrophic heart: do they play a role in cardiac hypertrophy?

Electrochemical-based biosensors for microRNA detection: Nanotechnology comes into view

Nanotechnology plays an undeniable significant role in medical sciences, particularly in the field of biomedicine. Development of several diagnostic procedures in medicine has been possible through the beneficial application of nano-materials, among which electrochemical nano-biosensors can be mentioned. They can be employed to quantify various clinical biomarkers in detection, evaluation, and follow up stages of the illnesses. MicroRNAs, a group of regulatory short RNA fragments, added a new dimension to the management and diagnosis of several diseases. Mature miRNAs are single-stranded RNA molecules approximately 22 nucleotides in length, which regulate a vast range of biological functions from cellular proliferation and death to cancer development and progression. Recently, diagnostic value of miRNAs in various diseases has been demonstrated. There are many traditional methods for detection of miRNAs including northern blotting, quantitative real time PCR (qRT-PCR), microarray technology, nanotechnology-based approaches, and molecular biology tools including miRNA biosensors. In comparison with other techniques, electrochemical nucleic acid biosensor methods exhibit many interesting features, and could play an important role in the future nucleic acid analysis. This review paper provides an overview of some different types of nanotechnology-based biosensors for detection of miRNAs.

MicroRNA-21 abrogates palmitate-induced cardiomyocyte apoptosis through caspase-3/NF-κB signal pathways

Objective:

The aim of the study was to investigate the role of microRNA-21 (miR-21) in cardiomyocyte apoptosis and to determine a possible mechanism.

Methods:

H9c2 embryonic rat heart-derived cells were used in the study. Cell viability was determined using the 3-(4.5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, and flow cytometry was used to evaluate cell apoptosis. Reverse transcription-polymerase chain reaction and western blot assays were used to detect mRNA and protein expression of the apoptosis-related proteins and miR-21. ELISA was used to detect reactive oxygen species (ROS).

Results:

Palmitate exposure greatly reduced miR-21 expression in cardiomyocytes. Apoptosis increased when miR-21 was inhibited with or without palmitate exposure. Consistently, reduced apoptosis was observed when miR-21 was overexpressed in cardiomyocytes. Caspase-3 activity was reduced after palmitate exposure. Bcl-2 protein expression was increased in H9c2 cells when transfected with the miR-21 mimic. MiR-21 overexpression alone did not induce ROS or DNA fragmentation; however, in conjunction with palmitate exposure, miR-21 mimic reduced ROS and DNA fragmentation. Moreover, palmitate administration overcame the antioxidant effect of 3 mM N-acetylcysteine to significantly inhibit apoptosis, DNA fragmentation, and caspase-3 activity. The exposure to palmitate greatly reduced p65 and p-p38 expression in the nucleus. A p38 inhibitor had no effect on the expression of Bcl-2 and cleaved caspase-3 in H9c2 cells alone; however, when combined with exposure to palmitate the p38 inhibitor induced Bcl-2 expression and inhibited caspase-3 activity. The p38 inhibitor by itself did not induce apoptosis, ROS production, or DNA fragmentation in H9c2 cells, but when palmitate was included with the p38 inhibitor, apoptosis, ROS production, and DNA fragmentation were reduced.

Conclusion:

miR-21 protects cardiomyocytes from apoptosis that is induced by palmitate through the caspase-3/NF-κB signal pathways.

Targeting the highly abundant circular RNA circSlc8a1 in cardiomyocytes attenuates pressure overload induced hypertrophy

Aims

We and others have previously described the expression landscape of circular RNA (circRNA) in mouse and human hearts. However, the functional relevance of many of these abundantly expressed cardiomyocyte circRNA remains to be fully explored. Among the most abundant circRNA, one stems from the sodium-calcium exchanger gene, Slc8a1, exon 2 locus. Because of its very high abundance in cardiomyocytes we investigated the possible role of circSlc8a1 in the heart.

Methods and results

We performed a miRNA screen using an array of 752 miRNAs with RNA recovered from a pull-down of endogenous cardiomyocyte circSlc8a1. MicroRNA-133a (miR-133a), with a prior well-recognized role in cardiac hypertrophy, was highly enriched in the fraction of circSlc8a1 pull-down (adjusted P-value < 0.001). We, therefore, followed-up validation of the functional interaction between circSlc8a1 and miR-133 using luciferase assays and reciprocal pull-down assays. In vivo, AAV9-mediated RNAi knockdown of circSlc8a1 attenuates cardiac hypertrophy from pressure-overload, whereas forced cardiomyocyte specific overexpression of circSlc8a1 resulted in heart failure. Molecular analyses showed targets of miR-133a including serum response factor (Srf), connective tissue growth factor (Ctgf), adrenoceptor beta 1 (Adrb1), and adenylate cyclase 6 (Adcy6) to be regulated by circSlc8a1-directed intervention of knockdown and overexpression.

Conclusion

In summary, circSlc8a1 can function as an endogenous sponge for miR-133a in cardiomyocytes. We propose that circSlc8a1 may serve as a novel therapeutic target for cardiac hypertrophy.

The Effects of Regular Exercise on Circulating Cardiovascular-related MicroRNAs

The purpose of the present study was to examine the effects of regular exercise on the abundance of targeted circulating microRNAs (miRNAs). The present analysis examined 20 previously sedentary adults from the HERITAGE Family Study who completed 20 weeks of endurance exercise training. The expression of 53 miRNAs related to cardiovascular disease were measured in serum collected at baseline and post-training by performing RT-qPCR on the Human Cardiovascular Disease miRNA array (Qiagen, Germany). The effect of regular exercise on circulating miRNAs was assessed using paired t-tests of baseline and post-training expression levels. A false discovery rate threshold of 5% was used to determine significance. Regular exercise resulted in significantly decreased mean serum expression of nine miRNAs (miR-486-5p, let-7b-5p, miR-29c-3p, let-7e-5p, miR-93-5p, miR-7-5p, miR-25-3p, miR-92a-3p, and miR-29b-3p; fold change range: 0.64–83, p = 0.0002–0.01) and increased mean expression of five miRNAs (miR-142-3p, miR-221-3p, miR-126-3p, miR-146a-5p, and miR-27b-3p; fold change range: 1.41–3.60, p = 0.001–0.006). Enrichment analysis found that these 14 miRNAs target genes related to over 345 different biological pathways. These results provide further evidence of the effects of regular exercise on the circulating miRNA profile.

MiR-1/133 attenuates cardiomyocyte apoptosis and electrical remodeling in mice with viral myocarditis

BACKGROUND

The role of miR-1 and miR-133 in regulating the expression of potassium and calcium ion channels, and mediating cardiomyocyte apoptosis in mice with viral myocarditis (VMC) is investigated herein.

METHODS

Male Balb/c mice were randomly divided into groups: control group, VMC group, VMC + miR-1/133 mimics group, or VMC + miR-1/133 negative control (NC) group. VMC was induced with coxsackievirus B3 (CVB3). MiR-1/133 mimics ameliorated cardiac dysfunction in VMC mice and was compared to the VMC+NC group.

RESULTS

Hematoxylin and eosin staining showed a well-arranged myocardium without inflammatory cell infiltration in the myocardial matrix of the control group. However, in the VMC and VMC+NC groups, the myocardium was disorganized and swollen with necrosis, and the myocardial matrix was infiltrated with inflammatory cells. These changes were alleviated by miR-1/133 mimics. TUNEL staining revealed decreased cardiomyocyte apoptosis in the VMC + miR-1/133 mimics group compared with the VMC group. In addition, miR-1/133 mimics up-regulated the expression of miR-1 and miR-133, the potassium channel genes Kcnd2 and Kcnj2, as well as Bcl-2, and down-regulated the expression of the potassium channel suppressor gene Irx5, L-type calcium channel subunit gene a1c (Cacna1c), Bax, and caspase-9 in the myocardium of VMC mice. MiR-1/133 also up-regulated the protein levels of Kv4.2 and Kir2.1, and down-regulated the expression of CaV1.2 in the myocardium of VMC mice.

CONCLUSIONS

MiR-1 and miR-133 decreased cardiomyocyte apoptosis by mediating the expression of apoptosis-related genes in the hearts of VMC mice.

RETRACTED: Gastrodin protects rat cardiomyocytes H9c2 from hypoxia-induced injury by up-regulation of microRNA-21

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief and Author. The journal contacted the authors for their response to the following remark from Dr Elisabeth Bik regarding this paper: ‘This paper belongs to a set of over 400 papers (as per February 2020) that share very similar Western blots with tadpole-like shaped bands, the same background pattern, and striking similarities in title structures, paper layout, bar graph design, and - in a subset - flow cytometry panels. Despite these similarities, these papers are authored by researchers from different departments and institutes, with almost no overlap in authors’. The authors failed to respond to this directly but instead requested the journal to retract the paper on the basis that the data were not represented accurately and new results have shown inconsistency with what has been reported in this paper. The authors apologise for any misconceptions that this paper may have resulted in.

Sex-specific regulation of cardiac microRNAs targeting mitochondrial proteins in pressure overload

Background

Maladaptive remodeling in pressure overload (PO)-induced left ventricular hypertrophy (LVH) may lead to heart failure. Major sex differences have been reported in this process. The steroid hormone 17β-estradiol, along with its receptors ERα and ERβ, is thought to be crucial for sex differences and is expected to be protective, but this may not hold true for males. Increasing evidence demonstrates a major role for microRNAs (miRNAs) in PO-induced LVH. However, little is known about the effects of biological sex and ERβ on cardiac miRNA regulation and downstream mitochondrial targets. We aimed at the analysis of proteins involved in mitochondrial metabolism testing the hypothesis that they are the target of sex-specific miRNA regulation.

Methods

We employed the transverse aortic constriction model in mice and assessed the levels of five mitochondrial proteins, i.e., Auh, Crat, Decr1, Hadha, and Ndufs4.

Results

We found a significant decrease of the mitochondrial proteins primarily in the male overloaded heart compared with the corresponding control group. Following computational analysis to identify miRNAs putatively targeting these proteins, our in vitro experiments employing miRNA mimics demonstrated the presence of functional target sites for miRNAs in the 3′-untranslated region of the messenger RNAs coding for these proteins. Next, we assessed the levels of the functionally validated miRNAs under PO and found that their expression was induced only in the male overloaded heart. In contrast, there was no significant effect on miRNA expression in male mice with deficient ERβ.

Conclusion

We put forward that the male-specific induction of miRNAs and corresponding downregulation of downstream protein targets involved in mitochondrial metabolism may contribute to sex-specific remodeling in PO-induced LVH.

Molecular biomarkers in cardiac hypertrophy

Cardiac hypertrophy is characterized by an increase in myocyte size in the absence of cell division. This condition is thought to be an adaptive response to cardiac wall stress resulting from the enhanced cardiac afterload. The pathogenesis of heart dysfunction, which is one of the primary causes of morbidity and mortality in elderly people, is often associated with myocardial remodelling caused by cardiac hypertrophy. In order to well understand the potential mechanisms, we described the molecules involved in the development and progression of myocardial hypertrophy. Increasing evidence has indicated that micro‐RNAs are involved in the pathogenesis of cardiac hypertrophy. In addition, molecular biomarkers including vascular endothelial growth factor B, NAD‐dependent deacetylase sirtuin‐3, growth/differentiation factor 15 and glycoprotein 130, also play important roles in the development of myocardial hypertrophy. Knowing the regulatory mechanisms of these biomarkers in the heart may help identify new molecular targets for the treatment of cardiac hypertrophy.

Alteration in cardiac PI3K/Akt/mTOR and ERK signaling pathways with the use of growth hormone and swimming, and the roles of miR21 and miR133

Athletes misuse recombinant human growth hormone (r-hGH) to enhance their performance. Although r-hGH is known to increase cardiac hypertrophy, the underlying molecular mechanism remains unclear. The aim of the present study was to investigate the role of r-hGH in cardiac intracellular signaling pathways and of miR-21 and miR-133 expression in rat hearts during exercise. A total of 36 adult male Sprague-Dawley rats were divided into sedentary control (SC, n=9), swimming exercise (SE, n=8), r-hGH (GH, n=10) and swimming exercise plus r-hGH (SE-GH, n=9) groups. The exercise groups completed a 1-h swimming exercise 5 times a week for 8 weeks. Subcutaneous r-hGH was administered as 0.3 mg/kg/day. Phosphoinositide-3-kinase (PI3K), serine/threonine protein kinase 1 (AKT1), extracellular signal-regulated kinase (ERK), microRNA (miR)-21 and miR-133 expression was evaluated in ventricular muscle by real-time quantitative polymerase chain reaction. Protein expression of PI3K, AKT1, ERK and mechanistic target of rapamycin (mTOR) was also assessed by immunohistochemistry. Statistical differences were analyzed by two-way ANOVA. PI3K and AKT1 expression and the gene and protein levels was notably increased in the SE-GH group compared with in SC ventricular tissues (P<0.05). mTOR protein expression was higher in the GH, SE and SE-GH groups compared with in the SC group (P<0.05, <0.05 and <0.001, respectively). ERK gene/protein expression was similar across all groups. miR-21 and miR-133 levels in ventricular muscle were higher in the SE and GH groups than those in the SC group. In summary, growth hormone application coupled with swimming exercise appeared to affect the PI3K/AKT/mTOR signaling pathway in the left ventricular tissue of rats; however, ERK signaling pathway appeared inactive in physiological left ventricular hypertrophy caused by swimming and GH administration over 8 weeks. Furthermore, GH treatment resulted in increased miR-21 and miR-133 expression. Future study by our group will aim to assess the effects of higher dose GH treatment.

Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT₁R) is believed to mediate most functions of ANG II in the system. AT₁R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT₁R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT₁R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.

MicroRNA-21 ablation exacerbates aldosterone-mediated cardiac injury, remodeling, and dysfunction

Primary aldosteronism is characterized by excess aldosterone secretion by the adrenal gland independent of the renin-angiotensin system and accounts for ~10% of hypertensive patients. Excess aldosterone causes cardiac hypertrophy, fibrosis, inflammation, and hypertension. The molecular mechanisms that trigger the onset and progression of aldosterone-mediated cardiac injury remain incompletely understood. MicroRNAs (miRNAs) are endogenous, small, noncoding RNAs that have been implicated in multiple cardiac pathologies; however, their regulation and role in aldosterone-mediated cardiac injury and dysfunction remains mostly unknown. We previously reported that microRNA-21 (miR-21) is the most upregulated miRNA by excess aldosterone in the left ventricle in a rat experimental model of primary aldosteronism. To elucidate the role of miR-21 in aldosterone-mediated cardiac injury and dysfunction, miR-21 knockout mice and their wild-type littermates were treated with aldosterone infusion and salt in the drinking water for 2 or 8 wk. miR-21 genetic ablation exacerbated aldosterone/salt-mediated cardiac hypertrophy and cardiomyocyte cross-sectional area. Furthermore, miR-21 genetic ablation increased the cardiac expression of fibrosis and inflammation markers and fetal gene program. miR-21 genetic ablation increased aldosterone/salt-mediated cardiac dysfunction but did not affect aldosterone/salt-mediated hypertension. miR-21 target gene Sprouty 2 may be implicated in the cardiac effects of miR-21 genetic ablation. Our study shows that miR-21 genetic ablation exacerbates aldosterone/salt-mediated cardiac hypertrophy, injury, and dysfunction blood pressure independently. These results suggest that miR-21 plays a protective role in the cardiac pathology triggered by excess aldosterone. Furthermore, miR-21 supplementation may be a novel therapeutic approach to abolish or mitigate excess aldosterone-mediated cardiovascular deleterious effects in primary aldosteronism.

Inhibition of microRNA-143-3p attenuates myocardial hypertrophy by inhibiting inflammatory response

MicroRNA-143-3p (miR-143-3p) is involved in the initiation of inflammatory response and the progression of cardiovascular diseases. Myocardial hypertrophy is a common symptom in numerous cardiovascular diseases. In the current study, we attempted to demonstrate the role of miR-143-3p in the development of myocardial hypertrophy by focusing on its association with inflammation. Myocardial hypertrophy was induced by transverse aortic constriction (TAC) method in vivo and by H₂ O₂ administration in vitro. The expression status of miR-143-3p and downstream effectors were detected in animal heart tissues and H9c2 cells. Furthermore, the effect of miR-143-3p inhibition on H₂ O₂ -induced changes in ERK5/PPARδ/NF-κB axis was assessed. TAC induced oxidative stress and inflammation in rat heart tissues, which was associated with the increased expressions of miR-143-3p and p-ERK5. However, the up-regulated expression of miR-143-3p had no effect on the expression of ERK5, which was a direct target of miR-143-3p. The results of in vitro assays showed that H₂ O₂ administration increased the levels of miR-143-3p and p-EKR5 and induced the activation of NF-κB pathway. After the inhibition of miR-143-3p, the activation of EKR5 and NF-κB pathway was suppressed, whereas the expression of PPARδ was up-regulated. The current study demonstrated that miR-143-3p is crucial to the initiation of inflammatory response induced by myocardial hypertrophy. The activation of ERK5 following miR-143-3p up-regulation appears to be a complementary response to induce the subsequent anti-inflammatory signaling transduction, which needed further exploration.

Cardiac fibroblast-specific p38α MAP kinase promotes cardiac hypertrophy via a putative paracrine interleukin-6 signaling mechanism

Recent studies suggest that cardiac fibroblast-specific p38α MAPK contributes to the development of cardiac hypertrophy, but the underlying mechanism is unknown. Our study used a novel fibroblast-specific, tamoxifen-inducible p38α knockout (KO) mouse line to characterize the role of fibroblast p38α in modulating cardiac hypertrophy, and we elucidated the mechanism. Myocardial injury was induced in tamoxifen-treated Cre-positive p38α KO mice or control littermates via chronic infusion of the β-adrenergic receptor agonist isoproterenol. Cardiac function was assessed by pressure-volume conductance catheter analysis and was evaluated for cardiac hypertrophy at tissue, cellular, and molecular levels. Isoproterenol infusion in control mice promoted overt cardiac hypertrophy and dysfunction (reduced ejection fraction, increased end systolic volume, increased cardiac weight index, increased cardiomyocyte area, increased fibrosis, and up-regulation of myocyte fetal genes and hypertrophy-associated microRNAs). Fibroblast-specific p38α KO mice exhibited marked protection against myocardial injury, with isoproterenol-induced alterations in cardiac function, histology, and molecular markers all being attenuated. In vitro mechanistic studies determined that cardiac fibroblasts responded to damaged myocardium by secreting several paracrine factors known to induce cardiomyocyte hypertrophy, including IL-6, whose secretion was dependent upon p38α activity. In conclusion, cardiac fibroblast p38α contributes to cardiomyocyte hypertrophy and cardiac dysfunction, potentially via a mechanism involving paracrine fibroblast-to-myocyte IL-6 signaling.-Bageghni, S. A., Hemmings, K. E., Zava, N., Denton, C. P., Porter, K. E., Ainscough, J. F. X., Drinkhill, M. J., Turner, N. A. Cardiac fibroblast-specific p38α MAP kinase promotes cardiac hypertrophy via a putative paracrine interleukin-6 signaling mechanism.

Cardiac remodeling and pre-eclampsia: an overview of microRNA expression patterns

Pre-eclampsia (PE) is strongly associated with heart failure (HF) later in life. During PE pregnancy, the left ventricle undergoes concentric remodeling which often persists after delivery. This aberrant remodeling can induce a molecular signature that can be evaluated in terms of microRNAs (miRNAs) and which may help to explain the associated increased risk of HF. For this review, we performed a literature search of PubMed (National Center for Biotechnology Information), identifying studies on miRNA expression in concentric remodeling and on miRNA expression in PE. The miRNA data were stratified based on origin (isolated from humans or animals and from tissue or the circulation) and both datasets compared in order to generate a list of miRNA expression patterns in concentric remodeling and in PE. The nine miRNAs identified in both concentric remodeling and PE-complicated pregnancy were: miR-1, miR-18, miR-21, miR-29b, miR-30, miR-125b, miR-181b, miR-195 and miR-499-5p. We found five of these miRNAs (miR-18, miR-21, miR-125b, miR-195 and miR-499-5p) to be upregulated in both PE pregnancy and cardiac remodeling and two (miR-1 and miR-30) to be downregulated in both; the remaining two miRNAs (miR-29b and miR-181b) showed upregulation during PE but downregulation in cardiac remodeling. This innovative approach may be a step towards finding relevant biomarkers for complicated pregnancy and elucidating their relationship with remote cardiovascular disease. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

The MicroRNA-326: Autoimmune diseases, diagnostic biomarker, and therapeutic target

MicroRNAs (miRNAs) are uniquely regulated in healthy, inflamed, activated, cancerous, or other cells and tissues of a pathological state. Many studies confirm that immune dysregulation and autoimmune diseases with inflammation are correlated with various miRNA expression changes in targeted tissues and cells in innate or adaptive immunity. In this review, we will explain the history and classification of epigenetic changes. Next, we will describe the role of miRNAs changes, especially mir-326 in autoimmunity, autoinflammatory, and other pathological conditions. A systematic search of MEDLINE, Embase, and Cochrane Library was presented for all related studies from 1899 to 2017 with restrictions in the English language. In recent years, researchers have concentrated on mostly those roles of miRNA that are correlated with the inflammatory and anti-inflammatory process. Latest studies have proposed a fundamental pathogenic role in cancers and autoinflammatory diseases. Studies have described the role of microRNAs in autoimmunity and autoinflammatory diseases, cancers, and so on. The miRNA-326 expression plays a significant role in autoimmune and other types of diseases.

Exploring miRNA-mRNA regulatory network in cardiac pathology in Na+/H+ exchanger isoform 1 transgenic mice

Numerous studies have demonstrated that Na⁺/H⁺ exchanger isoform 1 (NHE1) is elevated in myocardial diseases and its effect is detrimental. To better understand the involvement of NHE1, we have previously studied cardiac-specific NHE1 transgenic mice and shown that these mice develop cardiac hypertrophy, interstitial fibrosis, and cardiac dysfunction. The purpose of current study was to identify microRNAs and their mRNA targets involved in NHE1-mediated cardiac injury. An unbiased high-throughput sequencing study was performed on both microRNAs and mRNAs. RNA sequencing showed that differentially expressed genes were enriched in hypertrophic cardiomyopathy pathway by Kyoto Encyclopedia of Genes and Genomes annotation in NHE1 transgenic hearts. These genes were classified as contraction defects (e.g., Myl2, Myh6, Mybpc3, and Actb), impaired intracellular Ca²⁺ homeostasis (e.g., SERCA2a, Ryr2, Rcan1, and CaMKII delta), and signaling molecules for hypertrophic cardiomyopathy (e.g., Itga/b, IGF-1, Tgfb2/3, and Prkaa1/2). microRNA sequencing revealed that 15 microRNAs were differentially expressed (2-fold, P < 0.05). Six of them (miR-1, miR-208a-3p, miR-199a-5p, miR-21-5p, miR-146a-5p, and miR-30c-5p) were reported to be related to cardiac pathological functions. The integrative analysis of microRNA and RNA sequencing data identified several crucial microRNAs including miR-30c-5p, miR-199a-5p, miR-21-5p, and miR-34a-5p as well as 10 of their mRNA targets that may affect the heart via NFAT hypertrophy and cardiac hypertrophy signaling. Furthermore, important microRNAs and mRNA targets were validated by quantitative PCR. Our study comprehensively characterizes the expression patterns of microRNAs and mRNAs, establishes functional microRNA-mRNA pairs, elucidates the potential signaling pathways, and provides novel insights on the mechanisms underlying NHE1-medicated cardiac injury.

microRNA-21 and hypertension

Hypertension, a multifactorial disease, is a major risk factor for the development of stroke, coronary artery disease, heart failure, and chronic renal failure. However, its underlying cellular and molecular mechanisms remain largely elusive. Numerous studies have shown that microRNAs (miRNAs) are involved in a variety of cellular processes, including cellular proliferation, apoptosis, differentiation, and the development of diseases. microRNA-21 (miR-21), a conserved single-stranded non-coding RNA that is composed of approximately 22 nucleotides, is one of the most intensively studied miRNAs in recent years, and it can regulate gene expression at the post-transcriptional level. miR-21 is expressed in many kinds of tumors and in the cardiovascular system, and it plays an important role in the occurrence and development of cardiovascular diseases. In recent years, more and more evidence indicates that miR-21 plays an important role in hypertension. This article reviews the source, function, and altered levels of miR-21 in hypertension and the role of miR-21 in the pathogenesis of hypertension and target organ damage (TOD). The potential role of miR-21 as a new target for predicting and treating hypertension is also explored.

β-arrestin-biased agonism of β-adrenergic receptor regulates Dicer-mediated microRNA maturation to promote cardioprotective signaling

RATIONALE

MicroRNAs (miRs) are small, non-coding RNAs that function to post-transcriptionally regulate target genes. First transcribed as primary miR transcripts (pri-miRs), they are enzymatically processed by Drosha into premature miRs (pre-miRs) and further cleaved by Dicer into mature miRs. Initially discovered to desensitize β-adrenergic receptor (βAR) signaling, β-arrestins are now well-appreciated to modulate multiple pathways independent of G protein signaling, a concept known as biased signaling. Using the β-arrestin-biased βAR ligand carvedilol, we previously showed that β-arrestin1 (not β-arrestin2)-biased β1AR (not β2AR) cardioprotective signaling stimulates Drosha-mediated processing of six miRs by forming a multi-protein nuclear complex, which includes β-arrestin1, the Drosha microprocessor complex and a single-stranded RNA binding protein hnRNPA1.

OBJECTIVE

Here, we investigate whether β-arrestin-mediated βAR signaling induced by carvedilol could regulate Dicer-mediated miR maturation in the cytoplasm and whether this novel mechanism promotes cardioprotective signaling.

METHODS AND RESULTS

In mouse hearts, carvedilol indeed upregulates three mature miRs, but not their pre-miRs and pri-miRs, in a β-arrestin 1- or 2-dependent manner. Interestingly, carvedilol-mediated activation of miR-466g or miR-532-5p, and miR-674 is dependent on β2ARs and β1ARs, respectively. Mechanistically, β-arrestin 1 or 2 regulates maturation of three newly identified βAR/β-arrestin-responsive miRs (β-miRs) by associating with the Dicer maturation RNase III enzyme on three pre-miRs of β-miRs. Myocardial cell approaches uncover that despite their distinct roles in different cell types, β-miRs act as gatekeepers of cardiac cell functions by repressing deleterious targets.

CONCLUSIONS

Our findings indicate a novel role for βAR-mediated β-arrestin signaling activated by carvedilol in Dicer-mediated miR maturation, which may be linked to its protective mechanisms.

MicroRNA-320 involves in the cardioprotective effect of insulin against myocardial ischemia by targeting survivin

It is generally accepted that insulin exerts an antiapoptotic effect against ischemia/reperfusion through the activation of PI3K/Akt/mTOR pathway. MicroRNAs involve in multiple cardiac pathophysiological processes, including ischemia/reperfusion-induced cardiac injury. However, the regulation of microRNAs in the cardioprotective effect of insulin is rarely discussed. In this study, using a cell model of ischemia through culturing H9C2 cardiac myocytes in serum-free medium with hypoxia, we demonstrated that pretreatment with insulin significantly inhibited cell apoptosis and downregulated microRNA-320 (miR-320) expression. Interestingly, miR-320 mimic impaired the cardioprotective effect of insulin against myocardial ischemia injury by targeting survivin, which is a member of the family of inhibitor of apoptosis proteins. Suppression miR-320 expression by miR-320 inhibitor in H9C2 cells with myocardial ischemia mimics the cardioprotective effect of insulin by maintaining survivin expression. Taken together, miR-320-mediated survivin expression involves in cardioprotective effect of insulin against myocardial ischemia injury.

SIGNIFICANCE OF THIS STUDY

Myocardial ischemia/reperfusion (I/R) injury remains an important clinical problem with extremely deficient clinical therapies. Insulin exerts an antiapoptotic effect against I/R through the activation of PI3K/Akt/mTOR pathway. Here, we provided evidences to show that microRNA-320 involves in the cardioprotective effect of insulin by targeting survivin, which is an inhibitor of apoptosis protein and functions as a key regulator in cell apoptosis and involves in the tumour genesis and progression. Our findings may provide a new potential therapeutic strategy for I/R injury and ischemic heart disease.

The lncRNA Plscr4 Controls Cardiac Hypertrophy by Regulating miR-214

Cardiac hypertrophy accompanied by maladaptive cardiac remodeling is the uppermost risk factor for the development of heart failure. Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have various biological functions, and their vital role in the regulation of cardiac hypertrophy still needs to be explored. In this study, we demonstrated that lncRNA Plscr4 was upregulated in hypertrophic mice hearts and in angiotensin II (Ang II)–treated cardiomyocytes. Next, we observed that overexpression of Plscr4 attenuated Ang II-induced cardiomyocyte hypertrophy. Conversely, the inhibition of Plscr4 gave rise to cardiomyocyte hypertrophy. Furthermore, overexpression of Plscr4 attenuated TAC (transverse aortic constriction)-induced cardiac hypertrophy. Finally, we demonstrated that Plscr4 acted as an endogenous sponge of miR-214 and forced expression of Plscr4 downregulated miR-214 expression to promote Mfn2 and attenuate hypertrophy. In contrast, knockdown of Plscr4 upregulated miR-214 to induce cardiomyocyte hypertrophy. Additionally, luciferase assay showed that miR-214 was the direct target of Plscr4, and overexpression of miR-214 counteracted the anti-hypertrophy effect of Plscr4. Collectively, these findings identify Plscr4 as a negative regulator of cardiac hypertrophy in vivo and in vitro due to its regulation of the miR-214-Mfn2 axis, suggesting that Plscr4 might act as a therapeutic target for the treatment of cardiac hypertrophy and heart failure.

Serum MicroRNA-27b as a Screening Biomarker for Left Ventricular Hypertrophy

MicroRNA-27b (miR-27b) is frequently upregulated in pressure-overloaded hypertrophic hearts. The clinical implications of aberrant circulating miR-27b in the diagnosis and management of left ventricular hypertrophy warrant study. We investigated whether serum miR-27b is a biomarker for left ventricular hypertrophy (LVH). We used stem-loop reverse-transcription quantitative polymerase chain reaction techniques to analyze serum miR-27b levels in 200 hypertensive patients with LVH, 100 hypertensive patients without LVH, and 100 healthy volunteers. We found that serum miR-27b levels were significantly higher in the hypertensive patients with LVH than in the hypertensive patients without LVH and in the healthy volunteers. Upon receiver operating characteristic curve analysis, serum miR-27b had an area under the curve of 0.885 with 91% sensitivity and 73% specificity in distinguishing hypertensive patients with LVH from healthy volunteers (P=0.021), and an area under the curve of 0.818 with 79.1% sensitivity and 70.3% specificity in distinguishing hypertensive patients with LVH from those without LVH (P=0.036). We conclude that circulating miR-27b might serve as a specific, noninvasive biomarker in screening for LVH.

Overexpression of microRNA-146 protects against oxygen-glucose deprivation/recovery-induced cardiomyocyte apoptosis by inhibiting the NF-κB/TNF-α signaling pathway

MicroRNA (miR) has been reported to be associated with ischemia and reperfusion (I/R) and cell apoptosis. Suppression of cell apoptosis may reduce the irreversible damage induced by reperfusion. The aims of the current study were to explore the cytoprotective effects of miR-146 against oxygen-glucose deprivation/recovery (OGD/R)-induced injury in H9c2 rat myocardial cells, as well as the underlying mechanisms. Following stimulation with OGD/R, the cells were transfected with miR-146 mimics or negative controls. The levels of miR-146 were analyzed by reverse transcription-quantitative polymerase chain reaction. Thereafter, cell viability and cell apoptosis were analyzed by MTT assay and terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling assay, respectively. In addition, the levels of tumor necrosis factor (TNF)-α were determined by ELISA and the levels of B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax), Bcl-2 and phosphorylated (p)-nuclear factor (NF)-κB were measured by western blotting. The results demonstrated that overexpression of miR-146 significantly increased cell viability and decreased apoptosis (P<0.05). It was observed that overexpression of miR-146 statistically reduced the levels of Bax, TNF-α and p-NF-κB but markedly upregulated the levels of Bcl-2 (P<0.05). These results indicate that overexpression of miR-146 may protect against OGD/R-induced cardiomyocyte apoptosis. Overexpression of miR-146 may alleviate the irreversible injury associated with reperfusion and the effects may be achieved by inhibiting the NF-κB/TNF-α signaling pathway.

Rescuing infusion of miRNA-1 prevents cardiac remodeling in a heart-selective miRNA deficient mouse

OBJECTIVE

The decreased expression of muscle-specific microRNA-1 (miR-1) has been found in many cardiovascular diseases and is considered to contribute to heart failure (HF). Here we investigated the role of miR-1 in myocardium protection by infusion of miR-1 in a cardiac global miRNA-deficient mouse.

METHODS

We generated a cardiac-selective miRNA-deficient mouse by crossing Dicer^flox/flox mice with mice expressing tamoxifen-inducible Cre recombinase under the control of a mouse αMHC promoter. When Dicer gene was removed following tamoxifen injection, the mice were treated with micrONTM mmu-miR-1a-3p agomir (agomir-1). The mice were subjected to echocardiography measurement, and the heart tissue specimens were stained with hematoxylin and eosin (H&E) and Sirius red. Terminal deoxynucleotidyl transferase-mediated dUTP nickend labeling assay and Ki67 immunofluorescence were used to determine apoptosis and proliferation.

RESULTS

Dicer deletion resulted in extensive decrease in cardiac miRNAs in the mice. In echocardiography, the mice developed rapid and dramatic left ventricular enlargement. In histology, apparent cardiomyocyte hypertrophy, myofiber disarray, ventricular fibrosis, inflammatory infiltration, and severe ventricular remodeling were exhibited. When the mice were treated with agomir-1, they did not show any significant abnormalities in heart structure and histology in response to Dicer ablation.

CONCLUSION

The proper expression of miRNAs plays vital roles in the maintenance of heart histology and function. Among these miRNAs, miR-1 is critical to inhibit myocyte hypertrophy and extracellular matrix deposition, thereby preventing cardiac remodeling in cardiac-selective Dicer deficient mice.

Mitochondria Associated MicroRNA Expression Profiling of Heart Failure

Heart failure (HF) is associated with mitochondrial dysfunction and energy metabolism impairment. MicroRNAs are implicated in the development of heart failure. However, the mitochondria enriched microRNA during heart failure remains elusive. Here, we generated a pressure overload-induced early and late stage heart failure model at 4 weeks and 8 weeks following transverse aortic constriction (TAC) in mice. We found that expression of mitochondrion protein COX4 was highly enriched in isolated mitochondria from cardiac tissues while GAPDH could hardly be detected. Furthermore, small RNA sequencing for mitochondria RNAs from failing hearts was performed. It was found that 69 microRNAs were upregulated and 2 were downregulated in early heart failure, while 16 microRNAs were upregulated and 6 were downregulated in late heart failure. 15 microRNA candidates were measured in both mitochondria and total cardiac tissues of heart failure by real-time PCR. MiR-696, miR-532, miR-690, and miR-345-3p were enriched in mitochondria from the failing heart at early stage. Bioinformatics analysis showed that mitochondria enriched microRNAs in HF were associated with energy metabolism and oxidative stress pathway. For the first time, we demonstrated microRNAs were enriched in mitochondria during heart failure, which established a link between microRNA and mitochondrion in heart failure.

MicroRNA-124 alleviates chronic skin inflammation in atopic eczema via suppressing innate immune responses in keratinocytes

Chronic skin inflammation in atopic eczema is associated with elevated expression of proinflammatory genes and activation of innate immune responses in keratinocytes. MicroRNAs (miRNAs) are short, single-stranded RNA molecules that silence genes via the degradation of target mRNAs or inhibition of translation. Recent studies have demonstrated that miR-124 is associated with regulation of inflammation factors in several diseases. The aim of this study was to investigate the role of miR-124 in skin inflammation of atopic eczema. We showed that miR-124 expression is decreased in chronic lesional skin of patients with atopic eczema, and could be strongly inhibited by IFN-γ and TNF-α. Through Western blot, real-time PCR and luciferase assays, we revealed that miR-124 inhibited the expression of p65, a member of NF-κB family which can regulate many factors involved in the immune response and inflammatory reactions, through direct targeting. Further, upon IFN-γ or TNF-α stimulation, IL8, CCL5 and CCL8 showed to be significantly upregulated by IFN-γ or TNF-α, downregulated by miR-124; the promotive effect of IFN-γ and TNF-α could be partially reversed by miR-124. The levels of IL8, CCL5 and CCL8 could be significantly downregulated by p65 knockdown, upregulated by miR-124 inhibition; the suppressive effect of p65 knockdown could be partially reversed by miR-124. Moreover, contrary to miR-124, p65, IL8, CCL5 and CCL8 mRNA expression was upregulated in chronic lesional skin of patients with atopic eczema, and all inversely correlated with miR-124. Taken together, our data demonstrate that miR-124 controls NF-κB-dependent inflammatory responses in keratinocytes and chronic skin inflammation in atopic eczema; rescuing miR-124 expression presents a promising strategy for atopic eczema treatment.

microRNA-133a attenuates cardiomyocyte hypertrophy by targeting PKCδ and Gq

During the past decade, microRNAs have continuously been suggested as a promising therapeutic tool due to their beneficial effects, such as their multi-targets and multi-functions in pathologic conditions. As a pathologic phenotype is generally regulated by multiple signaling pathways, in this study we identified a microRNA regulating multiple target genes within cardiac hypertrophic signaling pathways. microRNA-133a is known to play a crucial role in cardiac hypertrophy. However, the role of microRNA-133a, which may regulate several signaling pathways in norepinephrine-induced cardiac hypertrophy via multi-targeting, has not been investigated. In the current study, we showed that microRNA-133a can protect cardiomyocyte hypertrophy against norepinephrine stimulation in neonatal rat ventricular cardiomyocytes via new targets, PKCδ and Gq, all of which are related to downstream signaling pathways of the α₁-adrenergic receptor. Taken together, these results suggest the advantages of the therapeutic use of microRNAs as an effective potential drug regulating multiple signaling pathways under pathologic conditions.

Epigenetics, inflammation and metabolism in right heart failure associated with pulmonary hypertension

Right ventricular failure (RVF) is the most important prognostic factor for both morbidity and mortality in pulmonary arterial hypertension (PAH), but also occurs in numerous other common diseases and conditions, including left ventricle dysfunction. RVF remains understudied compared with left ventricular failure (LVF). However, right and left ventricles have many differences at the morphological level or the embryologic origin, and respond differently to pressure overload. Therefore, knowledge from the left ventricle cannot be extrapolated to the right ventricle. Few studies have focused on the right ventricle and have permitted to increase our knowledge on the right ventricular-specific mechanisms driving decompensation. Here we review basic principles such as mechanisms accounting for right ventricle hypertrophy, dysfunction, and transition toward failure, with a focus on epigenetics, inflammatory, and metabolic processes.

Dysregulation of microRNA-214 and PTEN contributes to the pathogenesis of hypoxic pulmonary hypertension

Hypoxia-induced pulmonary hypertension, which is characterized by vascular remodeling of blood vessels, is an important complication in COPD. In this study, we found that the expression of miR-214 was differentially expressed by screening 13 candidate miRNAs in pulmonary artery smooth muscle cells (PASMCs). Additionally, using luciferase assay in PASMCs, we found that phosphatase-and-tensin homolog (PTEN) was a target of miR-214. Furthermore, the expression of PTEN was found to be substantially downregulated in PASMCs from COPD patients with pulmonary hypertension (PH) compared with normal controls by using real-time polymerase chain reaction (PCR), immunohistochemistry, and Western blot. In addition, we transfected PASMCs with miR-214 mimics, using real-time PCR and Western blotting, to confirm the miRNA/mRNA relationship. Furthermore, the introduction of miR-214 significantly promoted the proliferation of PASMCs by suppressing apoptosis of the cells, which was mediated by the downregulation of PTEN. Exposure to hypoxia significantly increased the expression of miR-214 and decreased the expression of PTEN in PASMCs, and its proliferation was significantly promoted. Such effects could be significantly attenuated by the introduction of miR-214 inhibitors, which significantly downregulated miR-214 expression and upregulated the expression of PTEN. In conclusion, hypoxia-induced upregulation of miR-214 was found to promote PH development by targeting PTEN in PASMCs, and miR-214 could be a promising diagnostic tool and novel therapeutic target in the management of hypoxia-induced PH in COPD.

Role and Regulation of MicroRNAs in Aldosterone-Mediated Cardiac Injury and Dysfunction in Male Rats

Primary aldosteronism is characterized by excess aldosterone (ALDO) secretion independent of the renin-angiotensin system and accounts for approximately 10% of hypertension cases. Excess ALDO that is inappropriate for salt intake status causes cardiac hypertrophy, inflammation, fibrosis, and hypertension. The molecular mechanisms that trigger the onset and progression of ALDO-mediated cardiac injury are poorly understood. MicroRNAs (miRNAs) are endogenous, small, noncoding RNAs that have been implicated in diverse cardiac abnormalities, yet very little is known about their regulation and role in ALDO-mediated cardiac injury. To elucidate the regulation of miRNAs in ALDO-mediated cardiac injury, we performed a time-series analysis of left ventricle (LV) miRNA expression. Uninephrectomized male Sprague-Dawley rats were treated with ALDO (0.75 µg/h) infusion and SALT (1.0% NaCl/0.3% KCl) in the drinking water for up to 8 weeks. ALDO/SALT time dependently modulated the expression of multiple miRNAs in the LV. miR-21 was the most upregulated miRNA after 2 weeks of treatment and remained elevated until the end of the study. To elucidate the role of miR-21 in ALDO/SALT-mediated cardiac injury, miR-21 was downregulated by using antagomirs in ALDO/SALT-treated rats. miR-21 downregulation exacerbated ALDO/SALT-mediated cardiac hypertrophy, expression of fibrosis marker genes, interstitial and perivascular fibrosis, OH-proline content, and cardiac dysfunction. These results suggest that ALDO/SALT-mediated cardiac miR-21 upregulation may be a compensatory mechanism that mitigates ALDO/SALT-mediated cardiac deleterious effects. We speculate that miR-21 supplementation would have beneficial effects in reverting or mitigating cardiac injury and dysfunction in patients with primary aldosteronism.

MicroRNA-133 mediates cardiac diseases: Mechanisms and clinical implications

MicroRNAs (miRNAs) belong to the family of small non-coding RNAs that mediate gene expression by post-transcriptional regulation. Increasing evidence have demonstrated that miR-133 is enriched in muscle tissues and myogenic cells, and its aberrant expression could induce the occurrence and development of cardiac disorders, such as cardiac hypertrophy, heart failure, etc. In this review, we summarized the regulatory roles of miR-133 in cardiac disorders and the underlying mechanisms, which suggest that miR-133 may be a potential diagnostic and therapeutic tool for cardiac disorders.

Mechanistic Pathways of Sex Differences in Cardiovascular Disease

Major differences between men and women exist in epidemiology, manifestation, pathophysiology, treatment, and outcome of cardiovascular diseases (CVD), such as coronary artery disease, pressure overload, hypertension, cardiomyopathy, and heart failure. Corresponding sex differences have been studied in a number of animal models, and mechanistic investigations have been undertaken to analyze the observed sex differences. We summarize the biological mechanisms of sex differences in CVD focusing on three main areas, i.e., genetic mechanisms, epigenetic mechanisms, as well as sex hormones and their receptors. We discuss relevant subtypes of sex hormone receptors, as well as genomic and nongenomic, activational and organizational effects of sex hormones. We describe the interaction of sex hormones with intracellular signaling relevant for cardiovascular cells and the cardiovascular system. Sex, sex hormones, and their receptors may affect a number of cellular processes by their synergistic action on multiple targets. We discuss in detail sex differences in organelle function and in biological processes. We conclude that there is a need for a more detailed understanding of sex differences and their underlying mechanisms, which holds the potential to design new drugs that target sex-specific cardiovascular mechanisms and affect phenotypes. The comparison of both sexes may lead to the identification of protective or maladaptive mechanisms in one sex that could serve as a novel therapeutic target in one sex or in both.

Quaking Is a Key Regulator of Endothelial Cell Differentiation, Neovascularization, and Angiogenesis

The capability to derive endothelial cell (ECs) from induced pluripotent stem cells (iPSCs) holds huge therapeutic potential for cardiovascular disease. This study elucidates the precise role of the RNA‐binding protein Quaking isoform 5 (QKI‐5) during EC differentiation from both mouse and human iPSCs (hiPSCs) and dissects how RNA‐binding proteins can improve differentiation efficiency toward cell therapy for important vascular diseases. iPSCs represent an attractive cellular approach for regenerative medicine today as they can be used to generate patient‐specific therapeutic cells toward autologous cell therapy. In this study, using the model of iPSCs differentiation toward ECs, the QKI‐5 was found to be an important regulator of STAT3 stabilization and vascular endothelial growth factor receptor 2 (VEGFR2) activation during the EC differentiation process. QKI‐5 was induced during EC differentiation, resulting in stabilization of STAT3 expression and modulation of VEGFR2 transcriptional activation as well as VEGF secretion through direct binding to the 3′ UTR of STAT3. Importantly, mouse iPS‐ECs overexpressing QKI‐5 significantly improved angiogenesis and neovascularization and blood flow recovery in experimental hind limb ischemia. Notably, hiPSCs overexpressing QKI‐5, induced angiogenesis on Matrigel plug assays in vivo only 7 days after subcutaneous injection in SCID mice. These results highlight a clear functional benefit of QKI‐5 in neovascularization, blood flow recovery, and angiogenesis. Thus, they provide support to the growing consensus that elucidation of the molecular mechanisms underlying EC differentiation will ultimately advance stem cell regenerative therapy and eventually make the treatment of cardiovascular disease a reality. The RNA binding protein QKI‐5 is induced during EC differentiation from iPSCs. RNA binding protein QKI‐5 was induced during EC differentiation in parallel with the EC marker CD144. Immunofluorescence staining showing that QKI‐5 is localized in the nucleus and stained in parallel with CD144 in differentiated ECs (scale bar = 50 µm). stemcells2017 Stem Cells2017;35:952–966

Placental Stem Villus Arterial Remodeling Associated with Reduced Hydrogen Sulfide Synthesis Contributes to Human Fetal Growth Restriction

Intrauterine fetal growth restriction (IUGR) is often associated with compromised umbilical arterial flow, indicating increased placental vascular resistance. Oxidative stress is causatively implicated. Hydrogen sulfide maintains differentiated smooth muscle in vascular beds, and its synthetic enzyme cystathionine-γ-lyase (CSE) is down-regulated in growth-restricted placentas. We hypothesized that remodeling of resistance arteries in stem villi contributes to IUGR by compromising umbilical blood flow via oxidative stress, reducing hydrogen sulfide signaling. Stem villus arteries in human IUGR placentas displaying absent or reversed end-diastolic flow contained reduced myosin heavy chain, smooth muscle actin, and desmin, and increased markers of dedifferentiation, cellular retinol-binding protein 1, and matrix metalloproteinase 2, compared to term and preterm controls. Wall thickness/lumen ratio was increased, lumen diameter decreased, but wall thickness remained unchanged in IUGR placentas. CSE correlated positively with myosin heavy chain, smooth muscle actin, and desmin. Birth weight correlated positively with CSE, myosin heavy chain, smooth muscle actin, and desmin, and negatively with cellular retinol-binding protein 1 and matrix metalloproteinase 2. These findings could be recapitulated in vitro by subjecting stem villus artery explants to hypoxia-reoxygenation, or inhibiting CSE. Treatment with a hydrogen sulfide donor, diallyl trisulfide, prevented these changes. IUGR is associated with vascular remodeling of the stem villus arteries. Oxidative stress results in reduction of placental CSE activity, decreased hydrogen sulfide production, and smooth muscle cell dedifferentiation in vitro. This vascular remodeling is reversible, and hydrogen sulfide donors are likely to improve pregnancy outcomes.

Photocrosslinkable, biodegradable hydrogels with controlled cell adhesivity for prolonged siRNA delivery to hMSCs to enhance their osteogenic differentiation

Photocrosslinked, biodegradable hydrogels have been extensively investigated for biomedical applications, including drug delivery and tissue engineering. Here, dextran (DEX) was chemically modified with mono(2-acryloyloxyethyl) succinate (MAES) via an esterification reaction, resulting in macromers that could be photocrosslinked to form hydrolytically degradable hydrogels. Hydrogel swelling ratio and degradation rate were controlled by varying the degree of MAES modification. Thiolated cell adhesion peptides (GRGDSPC) were conjugated to acrylated dextran via thiol-acrylate reaction to regulate the interactions of human mesenchymal stem cells (hMSCs) with the photocrosslinkable hydrogels. The hydrogels permitted sustained release of short interfering RNA (siRNA) over 7 weeks and were cytocompatible with hMSCs. Sustained presentation of siRNA from these photocrosslinked DEX hydrogels enhanced the osteogenic differentiation of encapsulated hMSCs. These DEX hydrogels with tunable siRNA delivery and cell adhesive properties may provide an excellent platform for bioactive molecule delivery and tissue regeneration applications.

Diabetic Cardiomyopathy: Does the Type of Diabetes Matter?

In recent years, type 2 diabetes mellitus has evolved as a rapidly increasing epidemic that parallels the increased prevalence of obesity and which markedly increases the risk of cardiovascular disease across the globe. While ischemic heart disease represents the major cause of death in diabetic subjects, diabetic cardiomyopathy (DC) summarizes adverse effects of diabetes mellitus on the heart that are independent of coronary artery disease (CAD) and hypertension. DC increases the risk of heart failure (HF) and may lead to both heart failure with preserved ejection fraction (HFpEF) and reduced ejection fraction (HFrEF). Numerous molecular mechanisms have been proposed to underlie DC that partially overlap with mechanisms believed to contribute to heart failure. Nevertheless, the existence of DC remains a topic of controversy, although the clinical relevance of DC is increasingly recognized by scientists and clinicians. In addition, relatively little attention has been attributed to the fact that both underlying mechanisms and clinical features of DC may be partially distinct in type 1 versus type 2 diabetes. In the following review, we will discuss clinical and preclinical literature on the existence of human DC in the context of the two different types of diabetes mellitus.

Analysis of microRNA Microarrays in Cardiogenesis

microRNAs are a subclass of noncoding RNAs which have been demonstrated to play pivotal roles in multiple cellular mechanisms. microRNAs are small RNA molecules of 22-24 nt in length capable of modulating protein translation and/or RNA stability by base-priming with complementary sequences of the mRNAs, normally at the 3'untranslated region. To date, over 2,000 microRNAs have been already identified in humans, and orthologous microRNAs have been also identified in distinct animals and plants ranging a wide vast of species. High-throughput analyses by microarrays have become a gold standard to analyze the changes on microRNA expression in normal and pathological cellular or tissue conditions. In this chapter, we provide insights into the usage of this uprising technology in the context of cardiac development and disease.

Liver microRNA-21 is overexpressed in non-alcoholic steatohepatitis and contributes to the disease in experimental models by inhibiting PPARα expression

OBJECTIVE

Previous studies suggested that microRNA-21 may be upregulated in the liver in non-alcoholic steatohepatitis (NASH), but its role in the development of this disease remains unknown. This study aimed to determine the role of microRNA-21 in NASH.

DESIGN

We inhibited or suppressed microRNA-21 in different mouse models of NASH: (a) low-density lipoprotein receptor-deficient (Ldlr^-/-) mice fed a high-fat diet and treated with antagomir-21 or antagomir control; (b) microRNA-21-deficient and wild-type mice fed a methionine-choline-deficient (MCD) diet; (c) peroxisome proliferation-activator receptor α (PPARα)-deficient mice fed an MCD diet and treated with antagomir-21 or antagomir control. We assessed features of NASH and determined liver microRNA-21 levels and cell localisation. MicroRNA-21 levels were also quantified in the liver of patients with NASH, bland steatosis or normal liver and localisation was determined.

RESULTS

Inhibiting or suppressing liver microRNA-21 expression reduced liver cell injury, inflammation and fibrogenesis without affecting liver lipid accumulation in Ldlr^-/- fed a high-fat diet and in wild-type mice fed an MCD diet. Liver microRNA-21 was overexpressed, primarily in biliary and inflammatory cells, in mouse models as well as in patients with NASH, but not in patients with bland steatosis. PPARα, a known microRNA-21 target, implicated in NASH, was decreased in the liver of mice with NASH and restored following microRNA-21 inhibition or suppression. The effect of antagomir-21 was lost in PPARα-deficient mice.

CONCLUSIONS

MicroRNA-21 inhibition or suppression decreases liver injury, inflammation and fibrosis, by restoring PPARα expression. Antagomir-21 might be a future therapeutic strategy for NASH.

Role of miR-199b-5p in regulating angiogenesis in mouse myocardial microvascular endothelial cells through HSF1/VEGF pathway

Our study explored effects of miR-199b-5p on angiogenesis in mouse myocardial microvascular endothelial cells (MMVECs) and the involved working mechanisms. We applied explant culture to incubate C57/BL6 mouse MMVECs. Lipofection was used to transfect miR-199b-5p mimic, miR-199b-5p inhibitor and miR-199b-5p scramble respectively. MMVECs were divided into miR-199b-5p up-regulation, miR-199b-5p down-regulation and control groups based on above sequence. Expressions of miR-199b-5p, heat shock factor protein 1 (HSF1) mRNA were assessed by real-time quantitative polymerase chain reaction (RT-QPCR). Expressions of HSF1 and vascular endothelial growth factor (VEGF) were assessed by Western Blotting. Cell proliferation was assessed by CCK8. Tubule formation assay was conducted to assess formation of blood vessels. Results showed that miR-199b-5p up/down-regulation groups exhibited no obvious differences in the expressions of HSF1 mRNA compared to control group. However, miR-199b-5p up-regulation group recorded lower expressions of HSF1 and VEGF in the level of protein, and reduced cell proliferation and tubule formation. Whereas, miR-199b-5p down-regulation group presented the contrary results. The experiment indicated that miR-199b-5p can regulate proliferation and angiogenesis in mouse MMVECs through the pathway of HSF1/VEGF.

Polychlorinated biphenyl exposure alters the expression profile of microRNAs associated with vascular diseases

Exposure to persistent organic pollutants, including polychlorinated biphenyls (PCBs) is correlated with multiple vascular complications including endothelial cell dysfunction and atherosclerosis. PCB-induced activation of the vasculature subsequently leads to oxidative stress and induction of pro-inflammatory cytokines and adhesion proteins. Gene expression of these cytokines/proteins is known to be regulated by small, endogenous oligonucleotides known as microRNAs that interact with messenger RNA. MicroRNAs are an acknowledged component of the epigenome, but the role of environmentally-driven epigenetic changes such as toxicant-induced changes in microRNA profiles is currently understudied. The objective of this study was to determine the effects of PCB exposure on microRNA expression profile in primary human endothelial cells using the commercial PCB mixture Aroclor 1260. Samples were analyzed using Affymetrix GeneChip® miRNA 4.0 arrays for high throughput detection and selected microRNA gene expression was validated (RT-PCR). Microarray analysis identified 557 out of 6658 microRNAs that were changed with PCB exposure (p<0.05). In-silico analysis using MetaCore database identified 21 of these microRNAs to be associated with vascular diseases. Further validation showed that Aroclor 1260 increased miR-21, miR-31, miR-126, miR-221 and miR-222 expression levels. Upregulated miR-21 has been reported in cardiac injury while miR-126 and miR-31 modulate inflammation. Our results demonstrated evidence of altered microRNA expression with PCB exposure, thus providing novel insights into mechanisms of PCB toxicity.

Reversal of Phospholamban Inhibition of the Sarco(endo)plasmic Reticulum Ca2+-ATPase (SERCA) Using Short, Protein-interacting RNAs and Oligonucleotide Analogs

The sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA) and phospholamban (PLN) complex regulates heart relaxation through its removal of cytosolic Ca²⁺ during diastole. Dysfunction of this complex has been related to many heart disorders and is therefore a key pharmacological target. There are currently no therapeutics that directly target either SERCA or PLN. It has been previously reported that single-stranded DNA binds PLN with strong affinity and relieves inhibition of SERCA in a length-dependent manner. In the current article, we demonstrate that RNAs and single-stranded oligonucleotide analogs, or xeno nucleic acids (XNAs), also bind PLN strongly (K_d <10 nm) and relieve inhibition of SERCA. Affinity for PLN is sequence-independent. Relief of PLN inhibition is length-dependent, allowing SERCA activity to be restored incrementally. The improved in vivo stability of XNAs offers more realistic pharmacological potential than DNA or RNA. We also found that microRNAs (miRNAs) 1 and 21 bind PLN strongly and relieve PLN inhibition of SERCA to a greater extent than a similar length random sequence RNA mixture. This may suggest that miR-1 and miR-21 have evolved to contain distinct sequence elements that are more effective at relieving PLN inhibition than random sequences.

Calcific Aortic Valve Disease: Part 2-Morphomechanical Abnormalities, Gene Reexpression, and Gender Effects on Ventricular Hypertrophy and Its Reversibility

In part 1, we considered cytomolecular mechanisms underlying calcific aortic valve disease (CAVD), hemodynamics, and adaptive feedbacks controlling pathological left ventricular hypertrophy provoked by ensuing aortic valvular stenosis (AVS). In part 2, we survey diverse signal transduction pathways that precede cellular/molecular mechanisms controlling hypertrophic gene expression by activation of specific transcription factors that induce sarcomere replication in-parallel. Such signaling pathways represent potential targets for therapeutic intervention and prevention of decompensation/failure. Hypertrophy provoking signals, in the form of dynamic stresses and ligand/effector molecules that bind to specific receptors to initiate the hypertrophy, are transcribed across the sarcolemma by several second messengers. They comprise intricate feedback mechanisms involving gene network cascades, specific signaling molecules encompassing G protein-coupled receptors and mechanotransducers, and myocardial stresses. Future multidisciplinary studies will characterize the adaptive/maladaptive nature of the AVS-induced hypertrophy, its gender- and individual patient-dependent peculiarities, and its response to surgical/medical interventions. They will herald more effective, precision medicine treatments.

MicroRNA-26a protects against cardiac hypertrophy via inhibiting GATA4 in rat model and cultured cardiomyocytes

Pathological cardiac hypertrophy is characterized by deleterious changes developed in cardiovascular diseases, whereas microRNAs (miRNAs) are involved in the mediation of cardiac hypertrophy. To investigate the role of microRNA-26a (miR-26a) in regulating cardiac hypertrophy and its functioning mechanisms, overexpression and suppression of miR‑26a via its mimic and inhibitor in a transverse abdominal aortic constriction (TAAC)-induced rat model and in angiotensin II (Ang II)-induced cardiomyocytes (CMs) was performed. In the rat model, the heart weight (HW) compared with the body weight (BW), the CM area, and expression of the hypertrophy‑associated factors, atrial natriuretic factor (ANF) and β‑myosin heavy chain (β‑MHC), were assessed. In CMs, the protein synthesis rate was determined using a leucine incorporation assay. Mutation of the GATA‑binding protein 4 (GATA4) 3'‑untranslated region (UTR) and overexpression of GATA4 were performed to confirm whether GATA4 is the target of miR‑26a. The results indicated that miR-26a was significantly downregulated in the heart tissue of the rat model, as well as in Ang II‑induced CMs (P<0.05). The TAAC-induced rat model exhibited a higher HW/BW ratio, a larger CM area, and higher expression levels of ANF and β‑MHC. CMs, upon Ang II treatment, also demonstrated a larger CM area, higher levels of ANF and β‑MHC, as well as accelerated protein synthesis. miR‑26a was not able to regulate GATA4 with mutations in the 3'‑UTR, indicating that GATA4 was the direct target of miR‑26a. Overexpression of GATA4 abrogated the inhibitory functions of miR‑26a in cardiac hypertrophy. Taken together, the present study suggested an anti‑hypertrophic role of miR‑26a in cardiac hypertrophy, possibly via inhibition of GATA4. These findings may be useful in terms of facilitating cardiac treatment, with potential therapeutic targets and strategies.

Circulating MicroRNA-146a and MicroRNA-21 Predict Left Ventricular Remodeling after ST-Elevation Myocardial Infarction

OBJECTIVES

MicroRNA (miR)-146a and miR-21 have been reported to participate in inflammatory reactions and fibrosis.Excessive inflammation and cardiac fibrosis may play important roles in the development of left ventricular remodeling(LVR). This study assessed whether miR-146a, miR-21 and other biomarkers could predict LVR after myocardial infarction(MI).

METHODS

Circulating miR-146a, miR-21 and other biomarker levels were measured in 198 patients with acute MI 5 days after primary percutaneous coronary intervention(PCI). All patients were assessed by transthoracic echocardiography on day 5 and 1 year after primary PCI.

RESULTS

Concentrations of circulating miR-146a, miR-21, C-reactive protein, creatine kinase MB type and troponin I, as well as estimated glomerular filtration rate (eGFR) and left ventricular ejection fraction (LVEF), were significantly higher in patients with than in those without LVR (p < 0.05). Multivariate logistic regression analysis showed that circulating miR-146a (odds ratio, OR = 2.127, p < 0.0001), miR-21 (OR = 1.119,p < 0.0001), eGFR (OR = 0.939, p = 0.0137) and LVEF (OR =0.802, p = 0.0048) were independent predictors of LVR development. The area under the curve for the combination of miR-146a and miR-21 was significantly higher than for either alone.

CONCLUSION

Circulating miR-146a and miR-21 may be novel biomarkers predictive of LVR after acute MI. Their combination may better predict LVR than either alone.