MicroRNAs in cardiac development

Circulating miR-133a-3p and miR-451a as potential biomarkers for diagnosis of coronary artery disease

BACKGROUND

Coronary artery disease (CAD) remains the leading cause of mortality and morbidity around the world. Despite significant progress in the diagnosis and treatment of cardiovascular diseases, still there is a clinical need to identify novel biomarkers for early diagnosis and treatment of CAD. The aim of the study is to investigate circulating miRNAs in CAD patients to identify potential biomarkers for early detection and therapeutic management of CAD.

METHODS

We assessed the expression of different candidate miRNAs (miR-21-5p, miR-133a-3p, miR-221-3p, miR-451a and miR-584-5p) in plasma from 50 CAD patients and 50 controls by qRT-PCR analysis.

RESULTS

The expression levels of miR-133a-3p (fold change (FC): 28.05, p < 0.0001), miR-451a (FC: 27.47, p < 0.0001), miR-584-5p (FC: 7.89, p < 0.0001), miR-21-5p (FC: 5.35, p < 0.0001) and miR-221-3p (FC: 5.03, p < 0.0001) were significantly up-regulated in CAD patients compared to controls. Receiver operating characteristic curve analysis showed that miR-133a-3p and miR-451a were powerful biomarkers for detecting CAD.

CONCLUSIONS

Our results suggested that miR-21-5p, miR-133a-3p, miR-221-3p, miR-451a and miR-584-5p may serve as independent biomarkers for CAD. Further, the combination of miR-133a-3p and miR-451a could be used as a specific signature in CAD diagnosis.

Regulatory Mechanisms That Guide the Fetal to Postnatal Transition of Cardiomyocytes

Heart disease remains a global leading cause of death and disability, necessitating a comprehensive understanding of the heart's development, repair, and dysfunction. This review surveys recent discoveries that explore the developmental transition of proliferative fetal cardiomyocytes into hypertrophic postnatal cardiomyocytes, a process yet to be well-defined. This transition is key to the heart's growth and has promising therapeutic potential, particularly for congenital or acquired heart damage, such as myocardial infarctions. Although significant progress has been made, much work is needed to unravel the complex interplay of signaling pathways that regulate cardiomyocyte proliferation and hypertrophy. This review provides a detailed perspective for future research directions aimed at the potential therapeutic harnessing of the perinatal heart transitions.

Inhibition of RhoA and Cdc42 by miR-133a Modulates Retinoic Acid Signalling during Early Development of Posterior Cardiac Tube Segment

It is well known that multiple microRNAs play crucial roles in cardiovascular development, including miR-133a. Additionally, retinoic acid regulates atrial marker expression. In order to analyse the role of miR-133a as a modulator of retinoic acid signalling during the posterior segment of heart tube formation, we performed functional experiments with miR-133a and retinoic acid by means of microinjections into the posterior cardiac precursors of both primitive endocardial tubes in chick embryos. Subsequently, we subjected embryos to whole mount in situ hybridisation, immunohistochemistry and qPCR analysis. Our results demonstrate that miR-133a represses RhoA and Cdc42, as well as Raldh2/Aldh1a2, and the specific atrial markers Tbx5 and AMHC1, which play a key role during differentiation. Furthermore, we observed that miR-133a upregulates p21 and downregulates cyclin A by repressing RhoA and Cdc42, respectively, thus functioning as a cell proliferation inhibitor. Additionally, retinoic acid represses miR-133a, while it increases Raldh2, Tbx5 and AMHC1. Given that RhoA and Cdc42 are involved in Raldh2 expression and that they are modulated by miR-133a, which is influenced by retinoic acid signalling, our results suggest the presence of a negative feedback mechanism between miR-133a and retinoic acid during early development of the posterior cardiac tube segment. Despite additional unexplored factors being possible contributors to this negative feedback mechanism, miR-133a might also be considered as a potential therapeutic tool for the diagnosis, therapy and prognosis of cardiac diseases.

A Review of Acute Coronary Syndrome and its Potential Impact on Cognitive Function

According to the World Health Organization (WHO) forecasts, in 2030, the number of people suffering from dementia will reach 82 million people worldwide, representing a huge burden on health and social care systems. Epidemiological data indicates a relationship between coronary heart disease (CHD) and the occurrence of cognitive impairment (CI) and dementia. It is known that both diseases have common risk factors. However, the impact of myocardial infarction (MI) on cognitive function remains controversial and largely unknown. The main goal of this study is to attempt to summarize and discuss selected scientific reports on the causes, mechanisms and effects of CI in patients after acute coronary syndrome (ACS), especially after MI. The risk of CI can increase in patients after ACS, and can therefore also adversely affect the further course of treatment. A late diagnosis of CI can lead to serious clinical implications, such as an increase in the number of hospitalizations and mortality.

Systematic review of microRNA biomarkers in acute coronary syndrome and stable coronary artery disease

The aim of this systematic review was to assess dysregulated miRNA biomarkers in coronary artery disease (CAD). Dysregulated microRNA (miRNAs) have been shown to be linked to cardiovascular pathologies including CAD and may have utility as diagnostic and prognostic biomarkers. We compared miRNAs identified in acute coronary syndrome (ACS) compared with stable CAD and control populations. We conducted a systematic search of controlled vocabulary and free text terms related to ACS, stable CAD and miRNA in Biosis Previews (OvidSP), The Cochrane Library (Wiley), Embase (OvidSP), Global Health (OvidSP), Medline (PubMed and OvidSP), Web of Science (Clarivate Analytics), and ClinicalTrials.gov which yielded 7370 articles. Of these, 140 original articles were appropriate for data extraction. The most frequently reported miRNAs in any CAD (miR-1, miR-133a, miR-208a/b, and miR-499) are expressed abundantly in the heart and play crucial roles in cardiac physiology. In studies comparing ACS cases with stable CAD patients, miR-21, miR-208a/b, miR-133a/b, miR-30 family, miR-19, and miR-20 were most frequently reported to be dysregulated in ACS. While a number of miRNAs feature consistently across studies in their expression in both ACS and stable CAD, when compared with controls, certain miRNAs were reported as biomarkers specifically in ACS (miR-499, miR-1, miR-133a/b, and miR-208a/b) and stable CAD (miR-215, miR-487a, and miR-502). Thus, miR-21, miR-133, and miR-499 appear to have the most potential as biomarkers to differentiate the diagnosis of ACS from stable CAD, especially miR-499 which showed a correlation between the level of their concentration gradient and myocardial damage. Although these miRNAs are potential diagnostic biomarkers, these findings should be interpreted with caution as the majority of studies conducted predefined candidate-driven assessments of a limited number of miRNAs (PROSPERO registration: CRD42017079744).

MicroRNA-375 overexpression disrupts cardiac development of Zebrafish (Danio rerio) by targeting notch2

MicroRNAs are small noncoding RNAs that are important for proper cardiac development. In our previous study of fetuses with ventricular septal defects, we discovered that microRNA-375 (miR-375) is obviously upregulated compared with that in healthy controls. Our study also confirmed that miR-375 is crucial for cardiomyocyte differentiation. This research mainly focused on the biological significance and mechanism of miR-375 using a zebrafish model. We injected zebrafish embryos with 1-2 nl of a miR-375 mimic at various concentrations (0/2/4/8 μM) or with negative control. The deformation and mortality rates were separately assessed. The different expression levels of miR-375 and related genes were examined by qRT-PCR, and luciferase assays and in situ hybridization were used to clarify the mechanism of miR-375 during embryonic development. Overexpression of miR-375 disrupted the cardiac development of zebrafish embryos. Disruption of miR-375 led to a decreased heart rate, pericardial edema, and abnormal cardiac looping. Various genes involved in cardiac development were downregulated due to the overexpression of miR-375. Moreover, the NOTCH signaling pathway was affected, and the luciferase reporter gene assays confirmed notch2, which was predicted by bioinformatics analysis, as the target gene of miR-375. Our findings demonstrated that the overexpression of miR-375 is detrimental to embryonic development, including cardiac development, and can partially simulate a multisystemic disorder. MiR-375 has an important role during cardiac morphogenesis of zebrafish embryos by targeting notch2, indicating its potential as a diagnostic marker.

Placental DNA methylation changes in detection of tetralogy of Fallot

OBJECTIVES

To determine whether the methylation level of cytosine nucleotides in placental DNA can be used to predict tetralogy of Fallot (TOF) and provide insights into the developmental mechanism of this condition.

METHODS

Tissue sections were obtained from formalin-fixed paraffin-embedded specimens of placental tissue obtained at birth from eight cases with non-chromosomal, non-syndromic TOF and 10 unaffected newborns. The Illumina Infinium HumanMethylation450 BeadChip assay was used to measure cytosine ('CpG' or 'cg') methylation levels at loci throughout the placental genome. Differential methylation was assessed by comparing the β-values (a measure of the extent of cytosine methylation) for individual CpG loci in fetuses with TOF vs in controls. The most discriminating CpG sites were determined based on a preset cut-off of ≥ 2.0-fold change in the methylation level. The predictive accuracy of CpG loci with significant methylation changes for TOF was determined by the area under the receiver-operating-characteristics curve (AUC). A false-discovery-rate (FDR) P-value < 0.05 was used to define a statistically significant difference in the methylation level. Ingenuity Pathway Analysis (IPA) (Qiagen) was used to identify gene pathways that were significantly overexpressed, and thus altered, in TOF cases compared with controls.

RESULTS

We found a total of 165 significantly differentially methylated CpG loci in TOF cases compared with controls, in 165 separate genes. These biomarkers demonstrated from fair to excellent individual predictive accuracy for TOF detection, with AUCs ≥ 0.75 (FDR P-value < 0.001 for all). The following CpG loci (gene) had the highest predictive accuracy: cg05273049 (ARHGAP22; AUC = 1.00; 95% CI, 1.00-1.00), cg02540011 (CDK5; AUC = 0.96; 95% CI, 0.87-1.00), cg08404201 (TRIM27; AUC = 0.95; 95% CI, 0.84-1.00) and cg00687252 (IER3; AUC = 0.95; 95% CI, 0.84-1.00). IPA revealed over-representation (dysregulation) of 14 gene pathways involved in normal cardiac development, including cardiomyocyte differentiation via bone morphogenetic protein receptors, cardiac hypertrophy signaling and role of nuclear factor of activated T cells in cardiac hypertrophy. Cardiac hypertrophy is an important feature of TOF.

CONCLUSIONS

Analysis of placental DNA cytosine methylation changes yielded accurate markers for TOF detection and provided mechanistic information on TOF development. Our work appears to confirm the central role of epigenetic changes and of the placenta in the development of TOF. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Circulatory miR-133b and miR-21 as Novel Biomarkers in Early Prediction and Diagnosis of Coronary Artery Disease

While coronary artery disease (CAD) has become a major threat worldwide, the timely biomarker-based early diagnosis of CAD remains a major unmet clinical challenge. We aimed towards assessing the level of circulatory microRNAs as candidates of novel biomarkers in patients with CAD. A total of 147 subjects were recruited which includes 78 subjects with angiographically proven CAD, 15 pre-atherosclerotic normal coronary artery (NCA) subjects and 54 healthy individuals. Quantitative real-time PCR assays were performed. MiR-133b was downregulated by 4.6 fold (p < 0.0001) whereas miR-21 was upregulated by ~2 fold (p < 0.0001) in plasma samples of CAD patients. Importantly, both the miRNAs showed association with disease severity as miR-133b was downregulated by 8.45 fold in acute coronary syndrome (ACS), 3.38 fold in Stable angina (SA) and 2.08 fold in NCA. MiR-21 was upregulated by 2.46 fold in ACS, 1.90 fold in SA and 1.12 fold in NCA. Moreover, miR-133b could significantly differentiate subjects with ST-elevation myocardial infarction (STEMI) from Non-STEMI. Area under the curve (AUC) for miR-133b was 0.80 with >75.6% sensitivity and specificity, AUC for miR-21 was 0.79 with >69.4% sensitivity and specificity. Our results suggest that miR-133b and miR-21 could be possible candidates of novel biomarkers in early prediction of CAD.

Direct Cardiac Reprogramming for Cardiovascular Regeneration and Differentiation

Cardiovascular disease is the leading cause of death worldwide. Cardiomyocytes have limited regenerative capacity; consequently, regenerative therapies are in high demand. There are currently several potential strategies for heart regeneration, with one approach involving in situ generation of new cardiomyocytes from endogenous cell sources. Direct cardiac reprogramming has emerged as a novel therapeutic approach to regenerating the damaged heart by directly converting endogenous cardiac fibroblasts into cardiomyocyte-like cells. Following our first report of direct cardiac reprogramming, significant advances have elucidated the molecular mechanisms associated with cardiac reprogramming. These advances have also improved cardiac-reprogramming efficiency by enabling direct in vivo cardiac reprogramming. Moreover, progress has been made in cardiac reprogramming of human fibroblasts. Although basic research has supported substantial progress in this field, numerous challenges remain in terms of clinical application. Here, we review the current state of cardiac reprogramming as a new technology for understanding and treating cardiovascular diseases.

Altered microRNA and target gene expression related to Tetralogy of Fallot

MicroRNAs (miRNAs) play an important role in guiding development and maintaining function of the human heart. Dysregulation of miRNAs has been linked to various congenital heart diseases including Tetralogy of Fallot (TOF), which represents the most common cyanotic heart malformation in humans. Several studies have identified dysregulated miRNAs in right ventricular (RV) tissues of TOF patients. In this study, we profiled genome-wide the whole transcriptome and analyzed the relationship of miRNAs and mRNAs of RV tissues of a homogeneous group of 22 non-syndromic TOF patients. Observed profiles were compared to profiles obtained from right and left ventricular tissue of normal hearts. To reduce the commonly observed large list of predicted target genes of dysregulated miRNAs, we applied a stringent target prediction pipeline integrating probabilities for miRNA-mRNA interaction. The final list of disease-related miRNA-mRNA pairs comprises novel as well as known miRNAs including miR-1 and miR-133, which are essential to cardiac development and function by regulating KCNJ2, FBN2, SLC38A3 and TNNI1. Overall, our study provides additional insights into post-transcriptional gene regulation of malformed hearts of TOF patients.

Direct Cardiac Reprogramming ― Converting Cardiac Fibroblasts to Cardiomyocytes ―

Cardiovascular disease is the leading cause of death and disability worldwide. Despite advances in cardiovascular therapy, mortality in heart disease still remains high. Direct cardiac reprogramming is a promising approach for cardiac tissue repair involving in situ generation of new cardiomyocytes from endogenous cardiac fibroblasts. Although, initially, the reprogramming efficiency was low, several developments in reprogramming methods have improved the in vitro cardiac reprogramming efficiency. Subsequently, in vivo cardiac reprogramming has demonstrated improvement in cardiac function and fibrosis after myocardial infarction. Here, we review recent progress in cardiac reprogramming as a new technology for cardiac regeneration.

Cardiac regeneration with pluripotent stem cell-derived cardiomyocytes and direct cardiac reprogramming

Cardiovascular disease is the leading cause of death globally. Cardiomyocytes (CMs) have poor regenerative capacity, and pharmacological therapies have limited efficacy in severe heart failure. Currently, there are several promising strategies for cardiac regeneration. The most promising approach to remuscularize failing hearts is cell transplantation therapy using newly generated CMs from exogenous sources, such as pluripotent stem cells. Alternatively, approaches to generate new CMs from endogenous cell sources in situ may also repair the injured heart and improve cardiac function. Direct cardiac reprogramming has emerged as a novel therapeutic approach to regenerate injured hearts by directly converting endogenous cardiac fibroblasts into CM-like cells. Through cell transplantation and direct cardiac reprogramming, new CMs can be generated and scar tissue reduced to improve cardiac function; therefore, cardiac regeneration may serve as a powerful strategy for treatment of severe heart failure. While substantial progress has been made in these two strategies for cardiac regeneration over the past several years, challenges remain for clinical translation. This review provide an overview of previous reports and current challenges in this field.

Concordant miRNA and mRNA expression profiles in humans and mice with bladder outlet obstruction

Bladder outlet obstruction (BOO) leads to lower urinary tract symptoms (LUTS) and urodynamic changes of the bladder function. Previously we identified microRNA (miRNA) and mRNA expression profiles associated with different states of BOO-induced LUTD in human patients. Bladder wall remodeling resulting from obstruction is widely studied in animal models of experimentally-induced partial BOO (pBOO). Here we determined the expression profiles of miRNAs and selected mRNAs in pBOO mice and compared the observed changes to human patients. Similar to results from human patients, we observed a down-regulation of smooth muscle-associated miRNAs mmu-miR-1, mmu-miR-143, mmu-miR-145, mmu-miR-486 and mmu-miR-133a in pBOO mouse bladders. Pro-fibrotic miRNAs mmu-miR-142-3p and mmu-miR-21 were up-regulated, and anti-fibrotic miRNA mmu-miR-29c was down-regulated. Pathway analysis in human BOO patients identified TNF-alpha as the top upstream regulator. Although there was evidence of hypertrophic changes in pBOO mice, contrary to human data, we observed no regulation of TNF-responsive genes in the mouse model. Experimentally-induced pBOO in mice led to significant gene expression changes, including alteration of pro-fibrotic mRNAs and miRNAs resembling human BOO patients. Gene expression changes were also validated in a mouse model of bladder inflammation. Lack of evidence of TNF-alpha-induced miRNA and mRNA regulation might indicate a different pathophysiological mechanism of organ remodeling in pBOO model compared to the human disease.

Identification of the miRNAome of early mesoderm progenitor cells and cardiomyocytes derived from human pluripotent stem cells

MicroRNAs are small non-coding RNAs involved in post-transcriptional regulation of gene expression related to many cellular functions. We performed a small-RNAseq analysis of cardiac differentiation from pluripotent stem cells. Our analyses identified some new aspects about microRNA expression in this differentiation process. First, we described a dynamic expression profile of microRNAs where some of them are clustered according to their expression level. Second, we described the extensive network of isomiRs and ADAR modifications. Third, we identified the microRNAs families and clusters involved in the establishment of cardiac lineage and define the mirRNAome based on these groups. Finally, we were able to determine a more accurate miRNAome associated with cardiomyocytes by comparing the expressed microRNAs with other mature cells. MicroRNAs exert their effect in a complex and interconnected way, making necessary a global analysis to better understand their role. Our data expands the knowledge of microRNAs and their implications in cardiomyogenesis.

HBL1 Is a Human Long Noncoding RNA that Modulates Cardiomyocyte Development from Pluripotent Stem Cells by Counteracting MIR1

Cardiogenesis processes in human and animals have differential dynamics, suggesting the existence of species-specific regulators during heart development. However, it remains a challenge to discover the human-specific cardiac regulatory genes, given that most coding genes are conserved. Here, we report the identification of a human-specific long noncoding RNA, Heart Brake LncRNA 1 (HBL1), which regulates cardiomyocyte development from human induced pluripotent stem cells (hiPSCs). Overexpression of HBL1 repressed, whereas knockdown and knockout of HBL1 increased, cardiomyocyte differentiation from hiPSCs. HBL1 physically interacted with MIR1 in an AGO2 complex. Disruption of MIR1 binding sites in HBL1 showed an effect similar to that of HBL1 knockout. SOX2 bound to HBL1 promoter and activated its transcription. Knockdown of SOX2 in hiPSCs led to decreased HBL1 expression and increased cardiomyocyte differentiation efficiency. Thus, HBL1 plays a modulatory role in fine-tuning human-specific cardiomyocyte development by forming a regulatory network with SOX2 and MIR1.

Genetic and Epigenetic Mechanisms Linking Air Pollution and Congenital Heart Disease

Epidemiological studies strongly suggest that parental air pollutants exposure during the periconceptional period may play a major role in causing fetal/newborn malformations, including a frequent heterogeneity in the methods applied and a difficulty in estimating the clear effect of environmental toxicants. Moreover, only some couples exposed to toxicants during the pre-conception period give birth to a child with congenital anomalies. The reasons for such phenomena remain elusive but they can be explained by the individual, innate ability to metabolize these contaminants that eventually defines the ultimate dose of a biological active toxicant. In this paper, we reviewed the major evidence regarding the role of parental air pollutant exposure on congenital heart disease (CHD) risk as well as the modulating effect on detoxification systems. Finally, major epigenetic alterations induced by adverse environment contaminants have been revised as possible mechanisms altering a correct heart morphogenesis.

MicroRNA: A new therapeutic strategy for cardiovascular diseases

Myocardial infarction, atherosclerosis, and hypertension are the most common heart-related diseases that affect both the heart and the blood vessels. Multiple independent risk factors have been shown to be responsible for cardiovascular diseases. The combination of a healthy diet, exercise, and smoking cessation keeps these risk factors in check and helps maintain homeostasis. The dynamic monolayer endothelial cell integrity and cell-cell communication are the fundamental mechanisms in maintaining homeostasis. Recently, it has been revealed that small noncoding RNAs (ncRNAs) play a critical role in regulation of genes involved in either posttranscriptional or pretranslational modifications. They also control diverse biological functions like development, differentiation, growth, and metabolism. Among ncRNAs, the short interfering RNAs (siRNAs), and microRNAs (miRNAs) have been extensively studied, but their specific functions remain largely unknown. In recent years, miRNAs are efficiently studied as one of the important candidates for involvement in most biological processes and have been implicated in many human diseases. Thus, the identification and the respective targets of miRNAs may provide novel molecular insight and new therapeutic strategies to treat diseases. This review summarizes the recent developments and insight on the role of miRNAs in cardiovascular disease prognosis, diagnostic and clinical applications.

Comparison of miRNA expression profiles in pituitary-adrenal axis between Beagle and Chinese Field dogs after chronic stress exposure

MicoRNAs (miRNAs), usually as gene regulators, participate in various biological processes, including stress responses. The hypothalamus–pituitary–adrenal axis (HPA axis) is an important pathway in regulating stress response. Although the mechanism that HPA axis regulates stress response has been basically revealed, the knowledge that miRNAs regulate stress response within HPA axis, still remains poor. The object of this study was to investigate the miRNAs in the pituitary and adrenal cortex that regulate chronic stress response with high-throughput sequencing. The pituitary and adrenal cortex of beagles and Chinese Field dogs (CFD) from a stress exposure group (including beagle pituitary 1 (BP1), CFD pituitary 1 (CFDP1), beagle adrenal cortex 1 (BAC1), CFD adrenal cortex 1 (CFDAC1)) and a control group (including beagle pituitary 2 (BP2), CFD pituitary 2 (CFDP2), beagle adrenal cortex 2 (BAC2), CFD adrenal cortex 2 (CFDAC2)), were selected for miRNA-seq comparisons. Comparisons, that were made in pituitary (including BP1 vs. BP2, CFDP1 vs. CFDP2, BP1 vs. CFDP1 and BP2 vs. CFDP2) and adrenal cortex (including BAC1 vs. BAC2, CFDAC1 vs. CFDAC2, BAC1 vs. CFDAC1 and BAC2 vs. CFDAC2), showed that a total of 39 and 18 common differentially expressed miRNAs (DE-miRNAs) (Total read counts > 1,000, Fold change > 2 & p-value < 0.001), that shared in at least two pituitary comparisons and at least two adrenal cortex comparisons, were detected separately. These identified DE-miRNAs were predicted for target genes, thus resulting in 3,959 and 4,010 target genes in pituitary and adrenal cortex, respectively. Further, 105 and 10 differentially expressed genes (DEGs) (Fold change > 2 & p-value < 0.05) from those target genes in pituitary and adrenal cortex were obtained separately, in combination with our previous corresponding transcriptome study. Meanwhile, in line with that miRNAs usually negatively regulated their target genes and the dual luciferase reporter assay, we finally identified cfa-miR-205 might play an important role by upregulating MMD in pituitary and hippocampus, thus enhancing the immune response, under chronic stress exposure. Our results shed light on the miRNA expression profiles in the pituitary and adrenal cortex with and without chronic stress exposure, and provide a new insight into miR-205 with its feasible role in regulating chronic stress in the pituitary and hippocampus through targeting MMD.

Reciprocal repression between Fgf8 and miR-133 regulates cardiac induction through Bmp2 signaling

This data article contains complementary figures and results related to the research article entitled “Negative Fgf8-Bmp2 feed-back is controlled by miR-130 during early cardiac specification” [15], which reveals what specific role miR-130 plays during the cardiac induction process. This study evidenced miR-130 a putative microRNA that targets Erk1/2 (Mapk1) 3′UTR- as a necessary linkage in the control of Fgf8 signaling, mediated by Bmp2. Thus, miR-130 regulates a negative Fgf8-Bmp2 feed-back loop responsible to achieve early cardiac specification. A significant aspect supporting our conclusions is given by the expression pattern of miR-130 during early cardiac specification, as well as by those results obtained after the designed experimental procedures. The data presented here reveal that miR-133 is also expressed within the precardiac areas during early cardiogenesis, pattern which is comparable to that of FGFR1, receptor involved in the Fgf8/ERK signaling pathway. Interestingly, our miR-133 overexpression experiments resulted in a decrease of Fgf8 expression, whereas we observed an increase of Bmp2 and subsequently of cardiac specific markers Nkx-2.5 and Gata4. Additionally, our loss-of-function experiments -through Fgf8 siRNA electroporation- showed an increase of miR-133 expression. Finally, after our Bmp2 experiments, we observed that miR-133 is upstream-regulated by Bmp2. All those results suggest that miR-133 also constitutes a crucial linkage in the crosstalk between Fgf8 and Bmp2 signaling by regulating the Fgf8/ERK pathway during cardiac induction.

Deep Sequencing Analysis of miRNA Expression in Breast Muscle of Fast-Growing and Slow-Growing Broilers

Growth performance is an important economic trait in chicken. MicroRNAs (miRNAs) have been shown to play important roles in various biological processes, but their functions in chicken growth are not yet clear. To investigate the function of miRNAs in chicken growth, breast muscle tissues of the two-tail samples (highest and lowest body weight) from Recessive White Rock (WRR) and Xinghua Chickens (XH) were performed on high throughput small RNA deep sequencing. In this study, a total of 921 miRNAs were identified, including 733 known mature miRNAs and 188 novel miRNAs. There were 200, 279, 257 and 297 differentially expressed miRNAs in the comparisons of WRRh vs. WRRl, WRRh vs. XHh, WRRl vs. XHl, and XHh vs. XHl group, respectively. A total of 22 highly differentially expressed miRNAs (fold change > 2 or < 0.5; p-value < 0.05; q-value < 0.01), which also have abundant expression (read counts > 1000) were found in our comparisons. As far as two analyses (WRRh vs. WRRl, and XHh vs. XHl) are concerned, we found 80 common differentially expressed miRNAs, while 110 miRNAs were found in WRRh vs. XHh and WRRl vs. XHl. Furthermore, 26 common miRNAs were identified among all four comparisons. Four differentially expressed miRNAs (miR-223, miR-16, miR-205a and miR-222b-5p) were validated by quantitative real-time RT-PCR (qRT-PCR). Regulatory networks of interactions among miRNAs and their targets were constructed using integrative miRNA target-prediction and network-analysis. Growth hormone receptor (GHR) was confirmed as a target of miR-146b-3p by dual-luciferase assay and qPCR, indicating that miR-34c, miR-223, miR-146b-3p, miR-21 and miR-205a are key growth-related target genes in the network. These miRNAs are proposed as candidate miRNAs for future studies concerning miRNA-target function on regulation of chicken growth.

Role of circulating miRNAs as biomarkers in idiopathic pulmonary arterial hypertension: possible relevance of miR-23a

Idiopathic pulmonary hypertension (IPAH) is a rare disease characterized by a progressive increase in pulmonary vascular resistance leading to heart failure. MicroRNAs (miRNAs) are small noncoding RNAs that control the expression of genes, including some involved in the progression of IPAH, as studied in animals and lung tissue. These molecules circulate freely in the blood and their expression is associated with the progression of different vascular pathologies. Here, we studied the expression profile of circulating miRNAs in 12 well-characterized IPAH patients using microarrays. We found significant changes in 61 miRNAs, of which the expression of miR23a was correlated with the patients' pulmonary function. We also studied the expression profile of circulating messenger RNA (mRNAs) and found that miR23a controlled 17% of the significantly changed mRNA, including PGC1α, which was recently associated with the progression of IPAH. Finally we found that silencing of miR23a resulted in an increase of the expression of PGC1α, as well as in its well-known regulated genes CYC, SOD, NRF2, and HO1. The results point to the utility of circulating miRNA expression as a biomarker of disease progression.

High association between human circulating microRNA-497 and acute myocardial infarction

Recent papers have reported the fundamental roles of miR-497 in infarction which acute myocardial infarction (AMI) belongs to. However, the expression levels of miR-497 in AMI patients were unclear, especially the circulating miR-497 that was detectable in the human plasma. In this study, we focused on the expression levels of circulating miR-497 in AMI and the roles of plasma miR-497 as a promising biomarker for AMI. The plasma miR-497 levels were detected from 27 AMI patients and 31 healthy volunteers by qRT-PCR. The cTnI concentrations of these samples were also analyzed by ELISA. Results showed circulating miR-497 levels were upregulated in AMI patients at 4 h, 8 h, 12 h, and 24 h, by contrast to those in control. Interestingly, time courses of circulating miR-497 levels displayed similar trends to that of cTnI concentrations in AMI patients; further study revealed the high correlation between circulating miR-497 and cTnI concentrations (r = 0.573, P < 0.001). At last, the receiver operating characteristic (ROC) curve was performed and declared that there was a faithworthy sensitivity and specificity to identify the AMI patients by using circulating miR-497. In conclusion, circulating miR-497 might be a promising biomarker for AMI identification and there was high association between human miR-497 and acute myocardial infarction.

The RNA-binding protein TDP-43 selectively disrupts microRNA-1/206 incorporation into the RNA-induced silencing complex

MicroRNA (miRNA) maturation is regulated by interaction of particular miRNA precursors with specific RNA-binding proteins. Following their biogenesis, mature miRNAs are incorporated into the RNA-induced silencing complex (RISC) where they interact with mRNAs to negatively regulate protein production. However, little is known about how mature miRNAs are regulated at the level of their activity. To address this, we screened for proteins differentially bound to the mature form of the miR-1 or miR-133 miRNA families. These muscle-enriched, co-transcribed miRNA pairs cooperate to suppress smooth muscle gene expression in the heart. However, they also have opposing roles, with the miR-1 family, composed of miR-1 and miR-206, promoting myogenic differentiation, whereas miR-133 maintains the progenitor state. Here, we describe a physical interaction between TDP-43, an RNA-binding protein that forms aggregates in the neuromuscular disease, amyotrophic lateral sclerosis, and the miR-1, but not miR-133, family. Deficiency of the TDP-43 Drosophila ortholog enhanced dmiR-1 activity in vivo. In mammalian cells, TDP-43 limited the activity of both miR-1 and miR-206, but not the miR-133 family, by disrupting their RISC association. Consistent with TDP-43 dampening miR-1/206 activity, protein levels of the miR-1/206 targets, IGF-1 and HDAC4, were elevated in TDP-43 transgenic mouse muscle. This occurred without corresponding Igf-1 or Hdac4 mRNA increases and despite higher miR-1 and miR-206 expression. Our findings reveal that TDP-43 negatively regulates the activity of the miR-1 family of miRNAs by limiting their bioavailability for RISC loading and suggest a processing-independent mechanism for differential regulation of miRNA activity.

Comparative expression profiles of microRNA in left and right atrial appendages from patients with rheumatic mitral valve disease exhibiting sinus rhythm or atrial fibrillation

BACKGROUND

The atrial fibrillation (AF) associated microRNAs (miRNAs) were found in the right atrium (RA) and left atrium (LA) from patients with rheumatic mitral valve disease (RMVD). However, most studies only focus on the RA; and the potential differences of AF-associated miRNAs between the RA and LA are still unknown. The aim of this study was to perform miRNA expression profiles analysis to compare the potential differences of AF-associated miRNAs in the right atrial appendages (RAA) and left atrial appendages (LAA) from RMVD patients.

METHODS

Samples tissues from the RAA and LAA were obtained from 18 RMVD patients (10 with AF) during mitral valve replacement surgery. From these tissues, miRNA expression profiles were created and analyzed using a human miRNA microarray. Then, the results were validated using qRT-PCR analysis for 12 selected miRNAs. Finally, potential targets of 10 validated miRNAs were predicted and their functions and potential pathways were analyzed using the miRFocus database.

RESULTS

In RAA, 65 AF-associated miRNAs were found and significantly dysregulated (i.e. 28 miRNAs were up-regulated and 37 were down-regulated). In LAA, 42 AF-associated miRNAs were found and significantly dysregulated (i.e. 22 miRNAs were up-regulated and 20 were down-regulated). Among these AF-associated miRNAs, 23 of them were found in both RAA and LAA, 45 of them were found only in RAA, and 19 of them were found only in LAA. Finally, 10 AF-associated miRNAs validated by qRT-PCR were similarly distributed in RAA and LAA; 3 were found in both RAA and LAA, 5 were found only in RAA, and 2 were found only in LAA. Potential miRNA targets and molecular pathways were identified.

CONCLUSIONS

We have found the different distributions of AF-associated miRNAs in the RAA and LAA from RMVD patients. This may reflect different miRNA mechanisms in AF between the RA and LA. These findings may provide new insights into the underlying mechanisms of AF in RMVD patients.

Atrial fibrillation alters the microRNA expression profiles of the left atria of patients with mitral stenosis

Background

Structural changes of the left and right atria associated with atrial fibrillation (AF) in mitral stenosis (MS) patients are well known, and alterations in microRNA (miRNA) expression profiles of the right atria have also been investigated. However, miRNA changes in the left atria still require delineation. This study evaluated alterations in miRNA expression profiles of left atrial tissues from MS patients with AF relative to those with normal sinus rhythm (NSR).

Methods

Sample tissues from left atrial appendages were obtained from 12 MS patients (6 with AF) during mitral valve replacement surgery. From these tissues, miRNA expression profiles were created and analyzed using a human miRNA microarray. Results were validated via reverse-transcription and quantitative PCR for 5 selected miRNAs. Potential miRNA targets were predicted and their functions and potential pathways analyzed via the miRFocus database.

Results

The expression levels of 22 miRNAs differed between the AF and NSR groups. Relative to NSR patients, in those with AF the expression levels of 45% (10/22) of these miRNAs were significantly higher, while those of the balance (55%, 12/22) were significantly lower. Potential miRNA targets and molecular pathways were identified.

Conclusions

AF alters the miRNA expression profiles of the left atria of MS patients. These findings may be useful for the biological understanding of AF in MS patients.

Let-7 in cardiovascular diseases, heart development and cardiovascular differentiation from stem cells

The let-7 family is the second microRNA found in C. elegans. Recent researches have found it is highly expressed in the cardiovascular system. Studies have revealed the aberrant expression of let-7 members in cardiovascular diseases, such as heart hypertrophy, cardiac fibrosis, dilated cardiomyopathy (DCM), myocardial infarction (MI), arrhythmia, angiogenesis, atherosclerosis, and hypertension. Let-7 also participates in cardiovascular differentiation of embryonic stem cells. TLR4, LOX-1, Bcl-xl and AGO1 are by now the identified target genes of let-7. The circulating let-7b is suspected to be the biomarker of acute MI and let-7i, the biomarker of DCM. Further studies are necessary for identifying the gene targets and signaling pathways of let-7 in cardiovascular diseases. Let-7 might be a potential therapeutic target for cardiovascular diseases. This review focuses on the research progresses regarding the roles of let-7 in cardiovascular development and diseases.

Circulating miR-30a, miR-195 and let-7b associated with acute myocardial infarction

Background

MicroRNAs (miRNAs) play key roles in diverse biological and pathological processes, including the regulation of proliferation, apoptosis, angiogenesis and cellular differentiation. Recently, circulating miRNAs have been reported as potential biomarkers for various pathologic conditions. This study investigated miR-30a, miR-195 and let-7b as potential of biomarker for acute myocardial infarction (AMI).

Methods and Results

Plasma samples from 18 patients with AMI and 30 healthy adults were collected. Total RNA was extracted from plasma with TRIzol LS Reagent. MiRNA levels and plasma cardiac troponin I (cTnI) concentrations were measured by quantitative real-time PCR and ELISA assay, respectively. Results showed that circulating miR-30a in AMI patients was highly expressed at 4 h, 8 h and 12 h after onset of AMI, and miR-195 was highly expressed at 8 h and 12 h. However, let-7b was lower in AMI patients than in controls throughout the whole time points. Interestingly, in these patients, circulating miR-30a, miR-195 and let-7b all reached their expression peak at 8 h. By the receiver operating characteristic (ROC) curve analyses, these plasma miRNAs were of significant diagnostic value for AMI. The combined ROC analysis revealed the an AUC value of 0.93 with 94% sensitivity and 90% specificity at 8 h after onset, and an AUC value of 0.92 with 90% sensitivity and 90% specificity at 12 h after onset, in discriminating the AMI patients from healthy controls.

Conclusions

Our results imply that the plasma concentration of miR-30a, miR-195 and let-7b can be potential indicators for AMI.

New Genetic Insights into Congenital Heart Disease

There has been remarkable progress in understanding the genetic basis of cardiovascular malformations. Chromosome microarray analysis has provided a new tool to understand the genetic basis of syndromic cardiovascular malformations resulting from microdeletion or microduplication of genetic material, allowing the delineation of new syndromes. Improvements in sequencing technology have led to increasingly comprehensive testing for aortopathy, cardiomyopathy, single gene syndromic disorders, and Mendelian-inherited congenital heart disease. Understanding the genetic etiology for these disorders has improved their clinical recognition and management and led to new guidelines for treatment and family-based diagnosis and surveillance. These new discoveries have also expanded our understanding of the contribution of genetic variation, susceptibility alleles, and epigenetics to isolated congenital heart disease. This review summarizes the current understanding of the genetic basis of syndromic and non-syndromic congenital heart disease and highlights new diagnostic and management recommendations.

A Novel YY1-miR-1 regulatory circuit in skeletal myogenesis revealed by genome-wide prediction of YY1-miRNA network

microRNAs (miRNAs) are non-coding RNAs that regulate gene expression post-transcriptionally, and mounting evidence supports the prevalence and functional significance of their interplay with transcription factors (TFs). Here we describe the identification of a regulatory circuit between muscle miRNAs (miR-1, miR-133 and miR-206) and Yin Yang 1 (YY1), an epigenetic repressor of skeletal myogenesis in mouse. Genome-wide identification of potential down-stream targets of YY1 by combining computational prediction with expression profiling data reveals a large number of putative miRNA targets of YY1 during skeletal myoblasts differentiation into myotubes with muscle miRs ranking on top of the list. The subsequent experimental results demonstrate that YY1 indeed represses muscle miRs expression in myoblasts and the repression is mediated through multiple enhancers and recruitment of Polycomb complex to several YY1 binding sites. YY1 regulating miR-1 is functionally important for both C2C12 myogenic differentiation and injury-induced muscle regeneration. Furthermore, we demonstrate that miR-1 in turn targets YY1, thus forming a negative feedback loop. Together, these results identify a novel regulatory circuit required for skeletal myogenesis and reinforce the idea that regulatory circuitries involving miRNAs and TFs are prevalent mechanisms.

MicroRNA profiling during cardiomyocyte-specific differentiation of murine embryonic stem cells based on two different miRNA array platforms

MicroRNA (miRNA) plays a critical role in a wide variety of biological processes. Profiling miRNA expression during differentiation of embryonic stem cells will help to understand the regulation pathway of differentiation, which in turn may elucidate disease mechanisms. The identified miRNAs could then serve as a new group of possible therapeutic targets. In the present paper, miRNA expression profiles were determined during cardiomyocyte-specific differentiation and maturation of murine embryonic stem (ES) cells. For this purpose a homogeneous cardiomyocyte population was generated from a transgenic murine ES cell line. Two high throughput array platforms (Affymetrix and Febit) were used for miRNA profiling in order to compare the effect of the platforms on miRNA profiling as well as to increase the validity of target miRNA identification. Four time points (i.e. day 0, day 12, day 19 and day 26) were chosen for the miRNA profiling study, which corresponded to different stages during cardiomyocyte-specific differentiation and maturation. Fifty platform and pre-processing method-independent miRNAs were identified as being regulated during the differentiation and maturation processes. The identification of these miRNAs is an important step for characterizing and understanding the events involved in cardiomyocyte-specific differentiation of ES cells and may also highlight candidate target molecules for therapeutic purposes.

Probing human cardiovascular congenital disease using transgenic mouse models

Congenital heart defects (CHDs) impact in utero embryonic viability, children, and surviving adults. Since the first transfer of genes into mice, transgenic mouse models have enabled researchers to experimentally study and genetically test the roles of genes in development, physiology, and disease progression. Transgenic mice have become a bona fide human CHD pathology model and their use has dramatically increased within the past two decades. Now that the entire mouse and human genomes are known, it is possible to knock out, mutate, misexpress, and/or replace every gene. Not only have transgenic mouse models changed our understanding of normal development, CHD processes, and the complex interactions of genes and pathways required during heart development, but they are also being used to identify new avenues for medical therapy.