Regulation of cardiac microRNAs by cardiac microRNAs

MiRNA-miRNA interaction network in peripheral blood of patients with myocardial infarction: a gene expression meta-analysis

In recent years, investigations have revealed that microRNAs (miRNAs) can bind together and form a miRNA-miRNA-mRNA regulatory network that alters the consequence of miRNA-mRNA interaction. If we consider the miRNA that binds to mRNA as the primary miRNA and the miRNA that binds to the primary miRNA as the secondary one, secondry miRNAs can act as master regulators upstream of primary miRNAs and their target mRNAs. One of the distinguishing characteristics of secondary miRNAs as master regulators within a diverse set of differentially expressed genes is the absence of direct target mRNA for them. Instead, these master regulators exclusively govern the regulation of miRNAs that target specific mRNAs. Through in silico analysis, we identified 18 miRNAs among 385 differentially expressed miRNAs (DEmiRNAs) with no direct target mRNAs among 58 differentially expressed mRNAs (DEmRNAs) in peripheral blood of patients with myocardial infarction (MI). Instead, these secondary miRNAs targeted 9 primary miRNAs that had 36 direct targets among 58 DEmRNAs. We found that one primary miRNA might be regulated by more than one secondary miRNAs and each secondary miRNA can target more than one primary miRNAs. Among identified miRNA-miRNA-mRNA networks miR-188-5p/miR-299-3p/natural killer cell granule protein (NKG7), miR-200a-3p/miR-199b-5p/granzyme B (GZMB), and miR-377-3p/miR-581/oviductal glycoprotein 1 (OVGP1) exhibited higher scors in terms of expression levels (>2-fold increase or decrease) and strengh of interactions (ΔG < -5). Given the extensive network of miRNA interactions, focusing on master regulators opens up avenues for identifying key regulatory nodes for more effective therapeutic strategies.

Role of miRNA in Cardiovascular Diseases in Children-Systematic Review

The number of children suffering from cardiovascular diseases (CVDs) is rising globally. Therefore, there is an urgent need to acquire a better understanding of the genetic factors and molecular mechanisms related to the pathogenesis of CVDs in order to develop new prevention and treatment strategies for the future. MicroRNAs (miRNAs) constitute a class of small non-coding RNA fragments that range from 17 to 25 nucleotides in length and play an essential role in regulating gene expression, controlling an abundance of biological aspects of cell life, such as proliferation, differentiation, and apoptosis, thus affecting immune response, stem cell growth, ageing and haematopoiesis. In recent years, the concept of miRNAs as diagnostic markers allowing discrimination between healthy individuals and those affected by CVDs entered the purview of academic debate. In this review, we aimed to systematise available information regarding miRNAs associated with arrhythmias, cardiomyopathies, myocarditis and congenital heart diseases in children. We focused on the targeted genes and metabolic pathways influenced by those particular miRNAs, and finally, tried to determine the future of miRNAs as novel biomarkers of CVD.

The roles of miRNAs in adult skeletal muscle satellite cells

Satellite cells are bona fide muscle stem cells that are indispensable for successful post-natal muscle growth and regeneration after severe injury. These cells also participate in adult muscle adaptation in several capacities. MicroRNAs (miRNAs) are post-transcriptional regulators of mRNA that are implicated in several aspects of stem cell function. There is evidence to suggest that miRNAs affect satellite cell behavior in vivo during development and myogenic progenitor behavior in vitro, but the role of miRNAs in adult skeletal muscle satellite cells is less studied. In this review, we provide evidence for how miRNAs control satellite cell function with emphasis on satellite cells of adult skeletal muscle in vivo. We first outline how miRNAs are indispensable for satellite cell viability and control the phases of myogenesis. Next, we discuss the interplay between miRNAs and myogenic cell redox status, senescence, and communication to other muscle-resident cells during muscle adaptation. Results from recent satellite cell miRNA profiling studies are also summarized. In vitro experiments in primary myogenic cells and cell lines have been invaluable for exploring the influence of miRNAs, but we identify a need for novel genetic tools to further interrogate how miRNAs control satellite cell behavior in adult skeletal muscle in vivo.

miR-147b is an oncomiR acting synergistically with HIPK2 to promote pancreatic carcinogenesis

MicroRNAs (miRs, miRNAs) are known players in the regulatory network of pancreatic tumorigenesis, but the downstream effectors remain poorly characterized. This study addressed this issue based on in silico prediction, in vitro experiments, and in vivo validation. The differentially expressed PCa-related miRNAs and bioinformatics tools predicted downstream regulators. The expression of miR-147b was examined in PCa cell lines. Putative targets of miR-147b were predicted by a publicly available database and confirmed by luciferase activity assay. Mimic/inhibitor, siRNA/overexpression plasmid, or pifithrin-α (p53 inhibitor) were delivered into PCa cells to assess the effect of miR-147b, HIPK2, and p53 on malignant phenotypes of PCa cells. AntagomiR-147b and shRNA targeting HIPK2 were introduced to xenograft-bearing nude mice for in vivo experiments. The expression of miR-147b was significantly increased in PCa cell lines. Ectopic expression of miR-147b promoted the malignant phenotypes of PCa cells and inhibited their apoptosis. HIPK2 was confirmed as a target gene of miR-147b. Inhibiting miR-147b could promote HIPK2 expression and potentially activate the p53 pathway, inhibiting PCa cell growth. In vivo experiments suggested that miR-147b inhibition suppressed the growth of xenograft tumors in nude mice, while HIPK2 knockdown counteracted its effect. Collectively, our work reveals a novel miR-147b-mediated carcinogenic regulatory network in PCa that may be a viable target for PCa treatment.

Detecting RNA-RNA interactome

The last decade has seen a robust increase in various types of novel RNA molecules and their complexity in gene regulation. RNA molecules play a critical role in cellular events by interacting with other biomolecules, including protein, DNA, and RNA. It has been established that RNA-RNA interactions play a critical role in several biological processes by regulating the biogenesis and function of RNA molecules. Interestingly, RNA-RNA interactions regulate the biogenesis of diverse RNA molecules, including mRNAs, microRNAs, tRNAs, and circRNAs, through splicing or backsplicing. Structured RNAs like rRNA, tRNA, and snRNAs achieve their functional conformation by intramolecular RNA-RNA interactions. In addition, functional consequences of many intermolecular RNA-RNA interactions have been extensively studied in the regulation of gene expression. Hence, it is essential to understand the mechanism and functions of RNA-RNA interactions in eukaryotes. Conventionally, RNA-RNA interactions have been identified through diverse biochemical methods for decades. The advent of high-throughput RNA-sequencing technologies has revolutionized the identification of global RNA-RNA interactome in cells and their importance in RNA structure and function in gene expression regulation. Although these technologies revealed tens of thousands of intramolecular and intermolecular RNA-RNA interactions, we further look forward to future unbiased and quantitative high-throughput technologies for detecting transcriptome-wide RNA-RNA interactions. With the ability to detect RNA-RNA interactome, we expect that future studies will reveal the higher-order structures of RNA molecules and multi-RNA hybrids impacting human health and diseases. This article is categorized under: RNA Methods > RNA Analyses In Vitro and In Silico RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems.

The Epigenetic Role of MiRNAs in Endocrine Crosstalk Between the Cardiovascular System and Adipose Tissue: A Bidirectional View

Overweight and obesity (OBT) is a serious health condition worldwide, and one of the major risk factors for cardiovascular disease (CVD), the main reason for morbidity and mortality worldwide. OBT is the proportional increase of Adipose Tissue (AT) compared with other tissue and fluids, associated with pathological changes in metabolism, hemodynamic overload, cytokine secretion, systemic inflammatory profile, and cardiac metabolism. In turn, AT is heterogeneous in location, and displays secretory capacity, lipolytic activation, insulin sensitivity, and metabolic status, performing anatomic, metabolic, and endocrine functions. Evidence has emerged on the bidirectional crosstalk exerted by miRNAs as regulators between the heart and AT on metabolism and health conditions. Here, we discuss the bidirectional endocrine role of miRNAs between heart and AT, rescuing extracellular vesicles’ (EVs) role in cell-to-cell communication, and the most recent results that show the potential of common therapeutic targets through the elucidation of parallel and ⁄or common epigenetic mechanisms.

Neurohormonal Connections with Mitochondria in Cardiomyopathy and Other Diseases

Neurohormonal signaling and mitochondrial dynamism are seemingly distinct processes that are almost ubiquitous among multicellular organisms. Both of these processes are regulated by GTPases, and disturbances in either can provoke disease. Here, inconspicuous pathophysiological connectivity between neurohormonal signaling and mitochondrial dynamism is reviewed in the context of cardiac and neurological syndromes. For both processes, greater understanding of basic mechanisms has evoked a reversal of conventional pathophysiological concepts. Thus, neurohormonal systems induced in, and previously thought to be critical for, cardiac functioning in heart failure are now pharmaceutically interrupted as modern standard of care. And, mitochondrial abnormalities in neuropathies that were originally attributed to an imbalance between mitochondrial fusion and fission are increasingly recognized as an interruption of axonal mitochondrial transport. The data are presented in a historical context to provided insight into how scientific thought has evolved and to foster an appreciation for how seemingly different areas of investigation can converge. Finally, some theoretical notions are presented to explain how different molecular and functional defects can evoke tissue-specific disease.

Spatially Resolved, Error-Robust Multiplexed MicroRNA Profiling in Single Living Cells

Simultaneous imaging of multiple microRNAs (miRNAs) in individual living cells is challenging due to the lack of spectrally distinct encoded fluorophores and non-cytotoxic methods. We describe a multiplexed error-robust combinatorial fluorescent label-encoding method, termed fluorophores encoded error-corrected labels (FluoELs), enabling multiplexed miRNA imaging in living cells with error-correcting capability. The FluoELs comprise proportional dual fluorophores for encoding and a constant quantitative single fluorophore for error-corrected quantification. Both are embedded in 260 nm core-shell silica nanoparticles modified with molecular beacon detection probes. The FluoELs are low cytotoxic and could accurately quantify and spatially resolve nine breast-cancer-related miRNAs and evaluate their coordination. The FluoELs enabled a single-cell analysis platform to evaluate miRNA expression profiles and the molecular mechanisms underlying miRNA-associated diseases.

MicroRNAs as T Lymphocyte Regulators in Multiple Sclerosis

MicroRNA (miRNA) is a class of endogenous non-coding small RNA with regulatory activities, which generally regulates the expression of target genes at the post-transcriptional level. Multiple Sclerosis (MS) is thought to be an autoimmune-mediated chronic inflammatory demyelinating disease of the central nervous system (CNS) that typically affect young adults. T lymphocytes play an important role in the pathogenesis of MS, and studies have suggested that miRNAs are involved in regulating the proliferation, differentiation, and functional maintenance of T lymphocytes in MS. Dysregulated expression of miRNAs may lead to the differentiation balance and dysfunction of T lymphocytes, and they are thus involved in the occurrence and development of MS. In addition, some specific miRNAs, such as miR-155 and miR-326, may have potential diagnostic values for MS or be useful for discriminating subtypes of MS. Moreover, miRNAs may be a promising therapeutic strategy for MS by regulating T lymphocyte function. By summarizing the recent literature, we reviewed the involvement of T lymphocytes in the pathogenesis of MS, the role of miRNAs in the pathogenesis and disease progression of MS by regulating T lymphocytes, the possibility of differentially expressed miRNAs to function as biomarkers for MS diagnosis, and the therapeutic potential of miRNAs in MS by regulating T lymphocytes.

Circulating microRNA profile in humans and mice with congenital GH deficiency

Reduced inflammation, increased insulin sensitivity, and protection against cancer are shared between humans and mice with GH/IGF1 deficiency. Beyond hormone levels, miRNAs are important regulators of metabolic changes associated with healthy aging. We hypothesized that GH deficiency in humans alters the abundance of circulating miRNAs and that a subset of those miRNAs may overlap with those found in GH-deficient mice. In this study, subjects with untreated congenital isolated GH deficiency (IGHD; n = 23) and control subjects matched by age and sex (n = 23) were recruited and serum was collected for miRNA sequencing. Serum miRNAs from young (6 month) and old (22 month) Ames dwarf (df/df) mice with GH deficiency and their WT littermates (n = 5/age/genotype group) were used for comparison. We observed 14 miRNAs regulated with a genotype by age effect and 19 miRNAs regulated with a genotype effect independent of age in serum of IGHD subjects. These regulated miRNAs are known for targeting pathways associated with longevity such as mTOR, insulin signaling, and FoxO. The aging function was overrepresented in IGHD individuals, mediated by hsa-miR-31, hsa-miR-146b, hsa-miR-30e, hsa-miR-100, hsa-miR-181b-2, hsa-miR-195, and hsa-miR-181b-1, which target the FoxO and mTOR pathways. Intriguingly, miR-181b-5p, miR-361-3p, miR-144-3p, and miR-155-5p were commonly regulated in the serum of humans and GH-deficient mice. In vitro assays confirmed target genes for the main up-regulated miRNAs, suggesting miRNAs regulated in IGHD individuals can regulate the expression of age-related genes. These findings indicate that systemic miRNAs regulated in IGHD individuals target pathways involved in aging in both humans and mice.

miRNA interplay: mechanisms and consequences in cancer

Canonically, microRNAs (miRNAs) control mRNA expression. However, studies have shown that miRNAs are also capable of targeting non-coding RNAs, including long non-coding RNAs and miRNAs. The latter, termed a miRNA:miRNA interaction, is a form of self-regulation. In this Review, we discuss the three main modes of miRNA:miRNA regulation: direct, indirect and global interactions, and their implications in cancer biology. We also discuss the cell-type-specific nature of miRNA:miRNA interactions, current experimental approaches and bioinformatic techniques, and how these strategies are not sufficient for the identification of novel miRNA:miRNA interactions. The self-regulation of miRNAs and their impact on gene regulation has yet to be fully understood. Investigating this hidden world of miRNA self-regulation will assist in discovering novel regulatory mechanisms associated with disease pathways.

Profiling of microRNAs in actinic keratosis and cutaneous squamous cell carcinoma patients

Actinic keratosis (AK) is a common skin lesion often defined as premalignant with more evidence indicating it as early stage of cutaneous squamous cell carcinoma (cSCC). The AK may remain stable, transform towards incisive cSCC or in some cases revert spontaneously. Several different underlying conditions can increase risk of cSCC, however, advanced age represents major risk of AK and its progression towards cSCC indicating increased risk during chronological aging. Importantly, AK and cSCC are characterized by similar genetic profile, which lead researchers to search for novel biomarkers allowing early detection. As skin sampling is often invasive and causes scaring, in the current study, we investigated a novel approach to establish potential blood circulating genetic markers in patients diagnosed with AK and cSCC. Based on clinical diagnosis and dermoscopy, we recruited 13 patients with AK (divided into two groups: the first included patients with no more than three lesions, the second group included patients with at least ten lesions) and two additional individuals diagnosed with cSCC. Deep sequencing analysis of serum circulating miRNAs detected a total of 68 expressed miRNAs. Further analysis indicated 2 regulated miRNAs for AK cohort and 12 miRNAs for cSCC patients, while there were 26 miRNAs differentially regulated between cSCC and AK patients. There was also one commonly regulated miRNA between AK and cSCC patients and ten miRNAs that were regulated in cSCC when compared with both control and AK patients. We did not observe any differences between the AK groups. In conclusion, our analysis detected in circulation some miRNA that were previously recognized as important in AK, cSCC, and other type of skin cancer supporting this approach as potential non-invasive diagnosis of AK and cSCC.

Cyclic stretching boosts microRNA-499 to regulate Bcl-2 via microRNA-208a in atrial fibroblasts

MicroRNAs that modulate transcription can regulate other microRNAs and are also up-regulated under pathological stress. MicroRNA-499 (miR-499), microRNA-208a (miR-208a) and B-cell lymphoma 2 (Bcl-2) play roles in cardiovascular diseases, such as direct reprogramming of cardiac fibroblast into cardiomyocyte and cardiomyocyte apoptosis. Whether miR208a, miR499 and Bcl-2 were critical regulators in cardiac fibroblast apoptosis under mechanical stretching conditions in human cardiac fibroblasts-adult atrial (HCF-aa) was investigated. Using negative pressure, HCF-aa grown on a flexible membrane base were cyclically stretched to 20% of their maximum elongation. In adult rats, an aortocaval shunt was used to create an in vivo model of volume overload. MiR208a was up-regulated early by stretching and returned to normal levels with longer stretching cycles, whereas the expression of miR499 and Bcl-2 was up-regulated by longer stretching times. Pre-treatment with antagomir-499 reversed the miR-208a down-regulation, whereas Bcl-2 expression could be suppressed by miR-208a overexpression. In the HCF-aa under stretching for 1 h, miR-499 overexpression decreased pri-miR-208a luciferase activity; this inhibition of pri-miR-208a luciferase activity with stretching was reversed when the miR-499-5p binding site in pri-miR-208a was mutated. The addition of antagomir-208a reversed the Bcl-2-3'UTR suppression from stretching for 1 h. Flow cytometric analysis revealed that pre-treatment with miR-499 or antagomir-208a inhibited cellular apoptosis in stretched HCF-aa. In hearts with volume overload, miR-499 overexpression inhibited myocardial miR-208a expression, whereas Bcl-2 expression could be suppressed by the addition of miR-208a. In conclusion, miR-208a mediated the regulation of miR-499 on Bcl-2 expression in stretched HCF-aa and hearts with volume overload.

MiR-330-3p and miR-485-5p as biomarkers for glioblastoma: An integrated bioinformatics and experimental study

Glioblastoma Multiforme (GBM) is the most common, invasive, and malignant primary brain tumor with a poor prognosis and a median survival of 12-15 months. This study tried to identify the most significant miRNA biomarkers in both tissue and serum samples of GBM. GSE25632 was employed from gene expression omnibus and using WGCNA package, association of miRNA networks and clinical data was explored and brown and green modules identified as the most relevant modules. Independently, Limma package was utilized to identify differentially expressed miRNAs (DEMs) in GSE25632 by cutoff logFC > 2 and P.value < 0.05. By merging the results of Limma and WGCNA, the miRNAs that were in brown and green modules and had mentioned cutoff were selected as hub miRNAs. Performing enrichment analysis, Pathways in cancer, Prostate cancer, Glioma, p53 signaling pathway, and Focal adhesion were identified as the most important signaling pathways. Based on miRNA- target genes, has-mir-330-3p and has-mir-485-5p were identified as core miRNAs. The expression level of core miRNAs was validated by GSE90604, GSE42657, and GSE93850. We evaluated the expression level of common target genes of two detected core genes based on GSE77043, GSE42656, GSE22891, GSE15824, and GSE122498. The ability of detected miRNAs to discriminate GBM from healthy controls was assessed by area under the curve (AUC) using the ROC curve analysis. Based on TCGA database, we tested the prognostic significance of miRNAs using overall survival analysis. We evaluated the expression level of the miRNAs in tissue of 83 GBM patients and also non-tumoral adjacent (as control) tissues. We used serum samples of 34 GBM patients to evaluate the expression levels of the hub miRNAs compare to the controls. Our results showed that has-mir-330-3p and has-mir-485-5p could be potential biomarkers in GBM.

Crosstalk between miR-203 and PKCθ regulates breast cancer stem cell markers

INTRODUCTION

Protein kinase C theta (PKCθ) is expressed in ER-negative breast cancer and promotes cancer stem cells (CSCs) phenotype. PKCθ gene (PRKCQ) is predicted to be a target for tumor suppressor miR-203. Herein, we aim to validate this prediction and evaluate the ability of miR-203 to inhibit migration of breast cancer cell line enriched with CSCs, MDA-MB-231, via PRKCQ targeting.

METHODS

Cells were transfected with miR-203 mimic, PRKCQ siRNA and negative control; then real-time PCR, migration assay, western blotting, reporter assay, and chromatin accessibility assay were performed.

RESULTS

Our findings displayed significant decrease in PRKCQ mRNA level and luciferase signals in cells with restored miR-203 expression, therefore, validated PRKCQ as a direct target of miR-203. Additionally, inhibiting PRKCQ by siRNA led to significant inhibition of miR-203 expression and significant decrease of chromatin accessibility at miR-203 promoter region 466-291 upstream TSS. Both of miR-203 re-expression and PRKCQ suppression resulted in altering migration ability of MDA-MB-231 through regulating AKT pathway and genes involved in breast cancer stem cells, CD44 and ALDH1A3. Expression of CDK5, GIV, and NANOG was significantly downregulated in miR-203 mimic-transfected cells, while PRKCQ siRNA-transfected cells displayed downregulation of OCT3/4, SOX2, and NANOG. Furthermore, we found that miR-224 expression was enhanced while miR-150 was downregulated after ectopic expression of miR-203.

CONCLUSION

The study highlighted the negative feedback loop between miR-203 and its target PRKCQ and the interplay between them in regulating genes involved in BCSCs. The study also concluded "microRNA-mediated microRNA regulation" as an event in breast cancer cells.

Endothelial dysfunction and inflammation in patients with non-obstructive coronary arteries

Aim To determine levels of markers for endothelial dysfunction and inflammation, endothelin-1, E-selectin, and tumor necrosis factor α (TNF-α) in patients with ischemic heart disease (IHD) and non-obstructive and obstructive coronary artery (CA) disease.Material and methods This study included 32 patients with verified IHD and non-obstructive (main group, n=19) and obstructive (comparison group, n=13) CA disease. Endothelial dysfunction was diagnosed by photoplethysmography and videocapillaroscopy. Serum concentrations of endothelin-1, E-selectin, and TNF- α were measured in all patients.Results Patients with non-obstructive CA disease showed a tendency towards more pronounced endothelial dysfunction (alternative stiffness index, 7.8 m /s [6.35; 9.08]; reflection index, 36.95 % [23.4; 52.65]; capillary density following reactive hyperemia, 54.33 cap /mm2 [48.92; 75.83]; capillary density following venous occlusion, 74.33 cap /mm2 [67.83; 93.00]) compared to the comparison group (alternative stiffness index, 9.05 m/s [7.08; 10.58]; reflection index, 28.25 % [23.35; 53.75]; capillary density following reactive hyperemia, 66.83 cap /mm2 [50.83; 78.67]; capillary density following venous occlusion, 87.0 cap /mm2 [77.58; 78.67]), although statistically significant differences were not found. Concentration of endothelin-1 was significantly higher in the IHD group with non-obstructive CA disease (0.45 ng/ml [0.28;0.65]) compared to patients with CA atherosclerotic stenosis (0.35 ng/ml [0.25; 0.38], p=0.035). Concentrations of E-selectin did not significantly differ between the groups (main group, 21.1 ng/ml [18.45; 35.03]; comparison group, 28.55 ng/ml [19.08; 35.01], p=0.29). In both groups, concentrations of TNF-α did not exceed the lower threshold of sensitivity (&lt;2.3 pg/ml).Conclusion Endothelial dysfunction and increased endothelin-1 in patients with non-obstructive CA disease along with inflammation may additionally contribute to the pathogenesis of IHD in the absence of hemodynamically significant CA stenoses. Too low level of TNFα in both groups prevented us from using it as a diagnostic marker. Further study is needed that would include a greater number of patients and a search for alternative markers.

Global miRNA to miRNA Interactions: Impacts for miR-21

miRNAs inherently alter the cellular environment by regulating target genes. miRNAs may also regulate other miRNAs, with far-reaching influence on miRNA and mRNA expression. We explore this realm of small RNA regulation with a focus on the role of the oncogenic miR-21 and its impact on other miRNA species.

Circulating non-coding RNAs in biomarker-guided cardiovascular therapy: a novel tool for personalized medicine?

Current clinical guidelines emphasize the unmet need for technological innovations to guide physician decision-making and to transit from conventional care to personalized cardiovascular medicine. Biomarker-guided cardiovascular therapy represents an interesting approach to inform tailored treatment selection and monitor ongoing efficacy. However, results from previous publications cast some doubts about the clinical applicability of biomarkers to direct individualized treatment. In recent years, the non-coding human transcriptome has emerged as a new opportunity for the development of novel therapeutic strategies and biomarker discovery. Non-coding RNA (ncRNA) signatures may provide an accurate molecular fingerprint of patient phenotypes and capture levels of information that could complement traditional markers and established clinical variables. Importantly, ncRNAs have been identified in body fluids and their concentrations change with physiology and pathology, thus representing promising non-invasive biomarkers. Previous publications highlight the translational applicability of circulating ncRNAs for diagnosis and prognostic stratification within cardiology. Numerous independent studies have also evaluated the potential of the circulating non-coding transcriptome to predict and monitor response to cardiovascular treatment. However, this field has not been reviewed in detail. Here, we discuss the state-of-the-art research into circulating ncRNAs, specifically microRNAs and long non-coding RNAs, to support clinical decision-making in cardiovascular therapy. Furthermore, we summarize current methodological and conceptual limitations and propose future steps for their incorporation into personalized cardiology. Despite the lack of robust population-based studies and technical barriers, circulating ncRNAs emerge as a promising tool for biomarker-guided therapy.

Forced expression of miR-143 and -145 in cardiomyocytes induces cardiomyopathy with a reductive redox shift

BACKGROUND

Animal model studies show that reductive stress is involved in cardiomyopathy and myopathy, but the exact physiological relevance remains unknown. In addition, the microRNAs miR-143 and miR-145 have been shown to be upregulated in cardiac diseases, but the underlying mechanisms associated with these regulators have yet to be explored.

METHODS

We developed transgenic mouse lines expressing exogenous miR-143 and miR-145 under the control of the alpha-myosin heavy chain (αMHC) promoter/enhancer.

RESULTS

The two transgenic lines showed dilated cardiomyopathy-like characteristics and early lethality with markedly increased expression of miR-143. The expression of hexokinase 2 (HK2), a cardioprotective gene that is a target of miR-143, was strongly suppressed in the transgenic hearts, but the in vitro HK activity and adenosine triphosphate (ATP) content were comparable to those observed in wild-type mice. In addition, transgenic complementation of HK2 expression did not reduce mortality rates. Although HK2 is crucial for the pentose phosphate pathway (PPP) and glycolysis, the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) was unexpectedly higher in the hearts of transgenic mice. The expression of gamma-glutamylcysteine synthetase heavy subunit (γ-GCSc) and the in vitro activity of glutathione reductase (GR) were also higher, suggesting that the recycling of GSH and its de novo biosynthesis were augmented in transgenic hearts. Furthermore, the expression levels of glucose-6-phosphate dehydrogenase (G6PD, a rate-limiting enzyme for the PPP) and p62/SQSTM1 (a potent inducer of glycolysis and glutathione production) were elevated, while p62/SQSTM1 was upregulated at the mRNA level rather than as a result of autophagy inhibition. Consistent with this observation, nuclear factor erythroid-2 related factor 2 (Nrf2), Jun N-terminal kinase (JNK) and inositol-requiring enzyme 1 alpha (IRE1α) were activated, all of which are known to induce p62/SQSTM1 expression.

CONCLUSIONS

Overexpression of miR-143 and miR-145 leads to a unique dilated cardiomyopathy phenotype with a reductive redox shift despite marked downregulation of HK2 expression. Reductive stress may be involved in a wider range of cardiomyopathies than previously thought.

Non-coding RNAs: emerging players in cardiomyocyte proliferation and cardiac regeneration

Soon after birth, the regenerative capacity of the mammalian heart is lost, cardiomyocytes withdraw from the cell cycle and demonstrate a minimal proliferation rate. Despite improved treatment and reperfusion strategies, the uncompensated cardiomyocyte loss during injury and disease results in cardiac remodeling and subsequent heart failure. The promising field of regenerative medicine aims to restore both the structure and function of damaged tissue through modulation of cellular processes and regulatory mechanisms involved in cardiac cell cycle arrest to boost cardiomyocyte proliferation. Non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) are functional RNA molecules with no protein-coding function that have been reported to engage in cardiac regeneration and repair. In this review, we summarize the current understanding of both the biological functions and molecular mechanisms of ncRNAs involved in cardiomyocyte proliferation. Furthermore, we discuss their impact on the structure and contractile function of the heart in health and disease and their application for therapeutic interventions.

Bioinformatics analysis of small RNAs in Helicobacter pylori and the role of NAT‑67 under tinidazole treatment

Helicobacter pylori (Hp) infection is a major cause of gastrointestinal disease. However, the pathogenesis of gastric mucosa injury by Hp has remained elusive. Small non-coding RNA (sRNA) is a type of widespread RNA in prokaryotic organisms and regulates bacterial growth, reproduction and virulence. In the present study, Hp sRNA profiles were generated to reveal the sequences and possible functions of sRNA by bioinformatics analysis. The role of sRNA in tinidazole (TNZ) treatment was also explored. Total sRNAs of HP26695 were sequenced using an Illumina HiSeq2000. Detected Tags were then compared with a known sRNA database to build an sRNA profile. Reverse transcription-quantitative (RT-q)PCR products were sequenced directly and agarose gel electrophoresis was used to identify NAT-67 and 5′ureB-sRNA in HP. Furthermore, HP was treated with TNZ for 6, 12 and 24 h. The bacterial concentration was measured, the expression of NAT-67, 5′ureB-sRNA and ceuE was determined by RT-qPCR and superoxide dismutase (SOD) activity and reactive oxygen species (ROS) production were detected. A total of 163 sRNA tags were predicted in Hp through bioinformatics analysis. Among them, 35 tags were evolutionarily aconserved in different Hp strains. By target prediction, it was indicated that certain candidate sRNAs were associated with bacterial oxidative stress, virulence and chemotaxis. It was also observed that NAT-67 and 5′ureB-sRNA were downregulated in TNZ-treated HP. TNZ treatment inhibited the growth of Hp, which was accompanied by downregulation of ceuE and SOD activity, as well as upregulation of ROS. RNA sequencing and bioinformatics are valuable in predicting the expression profile and function of sRNA in HP. sRNA-targeted genes may be associated with virulence, oxidative stress and chemokines. Downregulation of NAT-67 by TNZ may be involved in Hp oxidative stress regulation, which may comprise one of the mechanisms of the antibacterial effects of TNZ.

microRNA profiling in the Weddell seal suggests novel regulatory mechanisms contributing to diving adaptation

Background

The Weddell Seal (Leptonychotes weddelli) represents a remarkable example of adaptation to diving among marine mammals. This species is capable of diving > 900 m deep and remaining underwater for more than 60 min. A number of key physiological specializations have been identified, including the low levels of aerobic, lipid-based metabolism under hypoxia, significant increase in oxygen storage in blood and muscle; high blood volume and extreme cardiovascular control. These adaptations have been linked to increased abundance of key proteins, suggesting an important, yet still understudied role for gene reprogramming.

In this study, we investigate the possibility that post-transcriptional gene regulation by microRNAs (miRNAs) has contributed to the adaptive evolution of diving capacities in the Weddell Seal.

Results

Using small RNA data across 4 tissues (brain, heart, muscle and plasma), in 3 biological replicates, we generate the first miRNA annotation in this species, consisting of 559 high confidence, manually curated miRNA loci. Evolutionary analyses of miRNA gain and loss highlight a high number of Weddell seal specific miRNAs.

Four hundred sixteen miRNAs were differentially expressed (DE) among tissues, whereas 80 miRNAs were differentially expressed (DE) across all tissues between pups and adults and age differences for specific tissues were detected in 188 miRNAs. mRNA targets of these altered miRNAs identify possible protective mechanisms in individual tissues, particularly relevant to hypoxia tolerance, anti-apoptotic pathways, and nitric oxide signal transduction. Novel, lineage-specific miRNAs associated with developmental changes target genes with roles in angiogenesis and vasoregulatory signaling.

Conclusions

Altogether, we provide an overview of miRNA composition and evolution in the Weddell seal, and the first insights into their possible role in the specialization to diving.

Reviewing the Limitations of Adult Mammalian Cardiac Regeneration: Noncoding RNAs as Regulators of Cardiomyogenesis

The adult mammalian heart is incapable of regeneration following cardiac injury, leading to a decline in function and eventually heart failure. One of the most evident barriers limiting cardiac regeneration is the inability of cardiomyocytes to divide. It has recently become clear that the mammalian heart undergoes limited cardiomyocyte self-renewal throughout life and is even capable of modest regeneration early after birth. These exciting findings have awakened the goal to promote cardiomyogenesis of the human heart to repair cardiac injury or treat heart failure. We are still far from understanding why adult mammalian cardiomyocytes possess only a limited capacity to proliferate. Identifying the key regulators may help to progress towards such revolutionary therapy. Specific noncoding RNAs control cardiomyocyte division, including well explored microRNAs and more recently emerged long noncoding RNAs. Elucidating their function and molecular mechanisms during cardiomyogenesis is a prerequisite to advance towards therapeutic options for cardiac regeneration. In this review, we present an overview of the molecular basis of cardiac regeneration and describe current evidence implicating microRNAs and long noncoding RNAs in this process. Current limitations and future opportunities regarding how these regulatory mechanisms can be harnessed to study myocardial regeneration will be addressed.

Fibroblast growth factor 21 inhibited ischemic arrhythmias via targeting miR-143/EGR1 axis

Ventricular arrhythmia is the most common cause of sudden cardiac death in patients with myocardial infarction (MI). Fibroblast growth factor 21 (FGF21) has been shown to play an important role in cardiovascular and metabolic diseases. However, the effects of FGF21 on ventricular arrhythmias following MI have not been addressed yet. The present study was conducted to investigate the pharmacological action of FGF21 on ventricular arrhythmias after MI. Adult male mice were administrated with or without recombinant human basic FGF21 (rhbFGF21), and the susceptibility to arrhythmias was assessed by programmed electrical stimulation and optical mapping techniques. Here, we found that rhbFGF21 administration reduced the occurrence of ventricular tachycardia (VT), improved epicardial conduction velocity and shorted action potential duration at 90% (APD90) in infarcted mouse hearts. Mechanistically, FGF21 may improve cardiac electrophysiological remodeling as characterized by the decrease of INa and IK1 current density in border zone of infarcted mouse hearts. Consistently, in vitro study also demonstrated that FGF21 may rescue oxidant stress-induced dysfunction of INa and IK1 currents in cultured ventricular myocytes. We further found that oxidant stress-induced down-regulation of early growth response protein 1 (EGR1) contributed to INa and IK1 reduction in post-infarcted hearts, and FGF21 may recruit EGR1 into the SCN5A and KCNJ2 promoter regions to up-regulate NaV1.5 and Kir2.1 expression at transcriptional level. Moreover, miR-143 was identified as upstream of EGR1 and mediated FGF21-induced EGR1 up-regulation in cardiomyocytes. Collectively, rhbFGF21 administration effectively suppressed ventricular arrhythmias in post-infarcted hearts by regulating miR-143-EGR1-NaV1.5/Kir2.1 axis, which provides novel therapeutic strategies for ischemic arrhythmias in clinics.

Profiling of tRNA Halves and YRNA Fragments in Serum and Tissue From Oral Squamous Cell Carcinoma Patients Identify Key Role of 5' tRNA-Val-CAC-2-1 Half

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck cancer and, as indicated by The Oral Cancer Foundation, kills at an alarming rate of roughly one person per hour. With this study, we aimed at better understanding disease mechanisms and identifying minimally invasive disease biomarkers by profiling novel small non-coding RNAs (specifically, tRNA halves and YRNA fragments) in both serum and tumor tissue from humans. Small RNA-Sequencing identified multiple 5' tRNA halves and 5' YRNA fragments that displayed significant differential expression levels in circulation and/or tumor tissue, as compared to control counterparts. In addition, by implementing a modification of weighted gene coexpression network analysis, we identified an upregulated genetic module comprised of 5' tRNA halves and miRNAs (miRNAs were described in previous study using the same samples) with significant association with the cancer trait. By consequently implementing miRNA-overtargeting network analysis, the biological function of the module (and by "guilt by association," the function of the 5' tRNA-Val-CAC-2-1 half) was found to involve the transcriptional targeting of specific genes involved in the negative regulation of the G1/S transition of the mitotic cell cycle. These findings suggest that 5' tRNA-Val-CAC-2-1 half (reduced in serum of OSCC patients and elevated in the tumor tissue) could potentially serve as an OSCC circulating biomarker and/or target for novel anticancer therapies. To our knowledge, this is the first time that the specific molecular function of a 5'-tRNA half is specifically pinpointed in OSCC.

MicroRNA regulation in colorectal cancer tissue and serum

Colorectal cancer is recognized as the fourth leading cause of cancer-related deaths worldwide. Thus, there is ongoing search for potential new biomarkers allowing quicker and less invasive detection of the disease and prediction of the treatment outcome. Therefore, the aim of our study was to identify colorectal cancer specific miRNAs expressed in cancerous and healthy tissue from the same patient and to further correlate the presence of the same miRNAs in the circulation as potential biomarkers for diagnosis. In the current study we detected a set of 40 miRNAs differentially regulated in tumor tissue when comparing with healthy tissue. Additionally, we found 8 miRNAs differentially regulated in serum of colorectal cancer patients. Interestingly, there was no overlap in miRNAs regulated in tissue and serum, suggesting that serum regulated miRNAs may be not actively secreted from colorectal tumor cells. However, four of differentially expressed miRNAs, including miR-21, miR-17, miR-20a and miR-32 represent the miRNAs characteristic for different tumor types, including breast, colon, lung, pancreas, prostate and stomach cancer. This finding suggests important groups of miRNAs which can be further validated as markers for diagnosis of tumor tissue and regulation of carcinogenesis.

Inhibition of microRNA‑124‑3p protects against acute myocardial infarction by suppressing the apoptosis of cardiomyocytes

The aims of the present study were to investigate the roles and underlying mechanisms of microRNA‑124‑3p (miR‑124‑3p) in the progression of acute myocardial infarction (AMI). The expression of miR‑124‑3p was determined via reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). TargetScan analysis and a luciferase reporter assay were conducted to reveal the association between miR‑124‑3p and nuclear factor κ‑light‑chain‑enhancer of activated B cells (NF‑κB) repressing factor (NKRF). To investigate the role of miR‑124‑3p in AMI, a cell model of myocardial hypoxic/ischemic injury was established by subjecting H9c2 cardiac cells to hypoxia for 48 h. The viability of cells was determined using an MTT assay, and cell apoptosis was analyzed by flow cytometry. Additionally, the expression levels of inflammatory factors [tumor necrosis factor‑α (TNF‑α), interleukin (IL)‑1β and IL‑6] were measured via ELISA. Furthermore, gene and protein expression levels were determined by performing RT‑qPCR and western blot analyses, respectively. It was revealed that the expression of miR‑124‑3p was significantly increased in the blood of patients with AMI and hypoxia‑treated H9c2 cells. Additionally, it was demonstrated that NKRF was a direct target of miR‑124‑3p. The hypoxia‑induced decrease in the viability of H9c2 cells and increase in cell apoptosis were eliminated by the downregulation of miR‑124‑3p. Furthermore, hypoxia significantly increased the levels of TNF‑α, IL‑1β and IL‑6, whereas miR‑124‑3p downregulation eliminated these effects. Downregulated expression of B‑cell lymphoma 2, pro‑caspase 3 and pro‑caspase 9 protein, and upregulated expression of cleaved caspases 3 and 9 was observed in hypoxic H9c2 cells; the altered expression of these proteins was suppressed by miR‑124‑3p inhibitor. Additionally, miR‑124‑3p inhibitor suppressed the hypoxia‑induced activation of the NF‑κB signaling pathway in H9c2 cells. Furthermore, it was demonstrated that the various effects of miR‑124‑3p inhibitor on H9c2 cells were eliminated by the small interfering RNA‑mediated downregulation of NKRF. In conclusion, the results of the present study indicated that miR‑124‑3p downregulation protected against AMI via inhibition of inflammatory responses and the apoptosis of cardiomyocytes by regulating the NKRF/NF‑κB pathway.

Load-Dependent Changes in Left Ventricular Structure and Function in a Pathophysiologically Relevant Murine Model of Reversible Heart Failure

BACKGROUND

To better understand reverse left ventricular (LV) remodeling, we developed a murine model wherein mice develop LV remodeling after transverse aortic constriction (TAC) and a small apical myocardial infarct (MI) and undergo reverse LV remodeling after removal of the aortic band.

METHODS AND RESULTS

Mice studied were subjected to sham (n=6) surgery or TAC+MI (n=12). Two weeks post-TAC+MI, 1 group underwent debanding (referred to as heart failure debanding [HF-DB] mice; n=6), whereas the aortic band remained in a second group (heart failure [HF] group; n=6). LV remodeling was evaluated by 2D echocardiography at 1 day, 2 weeks and 6 weeks post-TAC+MI. The hearts were analyzed by transcriptional profiling at 4 and 6 weeks and histologically at 6 weeks. Debanding normalized LV volumes, LV mass, and cardiac myocyte hypertrophy at 6 weeks in HF-DB mice, with no difference in myofibrillar collagen in the HF and HF-DB mice. LV ejection fraction and radial strain improved after debanding; however, both remained decreased in the HF-DB mice relative to sham and were not different from HF mice at 6 weeks. Hemodynamic unloading in the HF-DB mice was accompanied by a 35% normalization of the HF genes at 2 weeks and 80% of the HF genes at 4 weeks.

CONCLUSIONS

Hemodynamic unloading of a pathophysiologically relevant mouse model of HF results in normalization of LV structure, incomplete recovery of LV function, and incomplete reversal of the HF transcriptional program. The HF-DB mouse model may provide novel insights into mechanisms of reverse LV remodeling.

Circulating microRNA-378 levels serve as a novel biomarker for assessing the severity of coronary stenosis in patients with coronary artery disease

Background: Circulating microRNAs (miRNA) are steady preserved in blood plasma. Multiple evidences have shown that miRNAs play a crucial role in cardiovascular disease including miRNA-378, which has been illustrated to participate in diverse physiological and pathological processes of cardiovascular disease. In the present study, we aim to explore the expression of plasma miRNA-378 and its clinical significance in patients with coronary artery disease (CAD).

Methods: MiRNA-378 expression in blood plasma was performed by quantitative real-time PCR (qRT-PCR) in 215 CAD patients and 52 matched controls of healthy populations. Medical information of all patients including the results of coronary angiography (CAG) was acquired through hospital information system (HIS). Spearman’s correlation, binary linear regression, and covariance analysis were used to examine the association between miRNA-378 and relative clinical risk factors. Receiver operating characteristic curve analysis was applied to evaluate the value of miRNA-378 in predicting the disease severity of coronary lesion.

Results: Plasma miR-378 expression was significantly down-regulated in CAD patients compared with healthy controls. Relative miR-378 level was shown conversely correlated with Gensini score, which present the severity of coronary artery lesions. Moreover, it is indicated that miR-378 expression can effectively distinguish patients with or without coronary artery stenosis.

Conclusions: Plasma miR-378 levels appear to be a promising non-invasive biomarker, but require to be further validated by a large cohort study in future.

Circulating microRNA in cardiovascular disease

Acute myocardial infarction (AMI) and heart failure (HF) are two major causes of cardiovascular mortality and morbidity. Early diagnosis of these conditions is essential to instigate immediate treatment that may result in improved outcomes. Traditional biomarkers of AMI include cardiac troponins and other proteins released from the injured myocardium but there are a number of limitations with these biomarkers especially with regard to specificity. In the past few years circulating nucleic acids, notably microRNA that are small non-coding RNAs that regulate various cellular processes, have been investigated as biomarkers of disease offering improved sensitivity and specificity in the diagnosis and prognostication of various conditions. In this review, the role of microRNAs as biomarkers used in the diagnosis of AMI and HF is discussed, their advantage over traditional biomarkers is outlined and the potential for their implementation in clinical practice is critically assessed.

Noncoding RNAs regulating cardiac muscle mass

Noncoding RNAs, including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs) play roles in the development and homeostasis of nearly every tissue of the body, including the regulation of processes underlying heart growth. Cardiac hypertrophy can be classified as either physiological (beneficial heart growth) or pathological (detrimental heart growth), the latter of which results in impaired cardiac function and heart failure and is predictive of a higher incidence of death due to cardiovascular disease. Several miRNAs have a functional role in exercise-induced cardiac hypertrophy, while both miRNAs and lncRNAs are heavily involved in pathological heart growth and heart failure. The latter have the potential to act as an endogenous sponge RNA and interact with specific miRNAs to control cardiac hypertrophy, adding another level of complexity to our understanding of the regulation of cardiac muscle mass. In addition to tissue-specific effects, ncRNA-mediated tissue cross talk occurs via exosomes. In particular, miRNAs can be internalized in exosomes and secreted from various cardiac and vascular cell types to promote angiogenesis, as well as protection and repair of ischemic tissues. ncRNAs hold promising therapeutic potential to protect the heart against ischemic injury and aid in regeneration. Numerous preclinical studies have demonstrated the therapeutic potential of ncRNAs, specifically miRNAs, for the treatment of cardiovascular disease. Most of these studies employ antisense oligonucleotides to inhibit miRNAs of interest; however, off-target effects often limit their potential to be translated to the clinic. In this context, approaches using viral and nonviral delivery tools are promising means to provide targeted delivery in vivo.

Circulating miR-23b as a Novel Biomarker for Early Risk Stratification After ST-Elevation Myocardial Infarction

Background

miR-23b overexpression can promote cardiomyocyte apoptosis and reduce cell growth under hypoxic conditions, suggesting that miR-23b acts as a biomarker for ST-elevation myocardial infarction (STEMI). The aim of this study was to investigate the effect of miR-23b on STEMI patients.

Material/Methods

We enrolled 80 eligible patients with STEMI and 60 control subjects. Blood samples were obtained at 6 h, 12 h, 24 h, 48 h, 3 days, and 7 days after the onset of symptoms. Another blood sample was collected before and after percutaneous coronary intervention (PCI). The samples were used for real-time quantitative PCR analysis. A Siemens Immulite2000 detector (Germany) was used for cTnI detection, and the serum CK-MB content was detected by electrochemical luminescence method.

Results

The expression level of miR-23b was increased in patients with STEMI (P<0.05). No significance difference was observed among risk factors, although the clinical data was comparable (P>0.05). The level of miR-23b in STEMI patients after PCI was lower (P<0.05). The ROC curve of plasma miR-23b showed a separation, with an AUC of 0.809 (95%CI, 0.737–0.936, P<0.05), compared to CK-MB with an AUC of 0.753 (95%CI, 0.707–0.896) and cTnI with an AUC of 0.783 (95%CI, 0.723–0.917).

Conclusions

The present study reveals that miR-23b is a useful biomarker of STEMI, providing a novel insight for the diagnosis for STEMI.

Tissue and serum microRNA profile of oral squamous cell carcinoma patients

Head and neck cancer is characterized by malignant tumors arising from the epithelium covering the upper aerodigestive tract, and the majority of these epithelial malignancies are squamous cell carcinomas (SCCs) of the oral cavity (OSCCs). The aim of the current work was to identify miRNAs regulated in OSCC cancerous tissue when compared to a healthy adjacent tissue and to verify the presence of the same miRNAs in the circulation of these patients. For that serum samples and biopsies of healthy and tumor tissues were collected from five patients diagnosed with OSCC of the oral cavity, RNA was extracted from these samples and microRNAs libraries were prepared and sequenced. A total 255 miRNAs were identified in tissue and 381 different miRNAs were identified in serum samples. When comparing the miRNA expression between tumor and healthy tissue we identified 48 miRNAs (25 down- and 23 up-regulated) that were differentially expressed (FDR < 0.05). From these 48 differentially expressed miRNAs in tissue, 30 miRNAs were also found in the serum of the same patients. hsa-miR-32-5p was up-regulated in tumor compared to healthy tissue in our study, and was previously shown to be up-regulated in the serum of OSCC patients. Therefore, this suggests that miRNAs can be used as potential non-invasive biomarkers of OSCC.

MicroRNA-1825 induces proliferation of adult cardiomyocytes and promotes cardiac regeneration post ischemic injury

In mammals, proliferative capacity of cardiomyocytes is lost soon after birth, while zebrafish and other lower organisms like newts are known to regenerate injured hearts even at an adult age. Here, we show that miR-1825 can induce robust proliferation of adult rat cardiomyocytes and can improve cardiac function in-vivo post myocardial infarction. Rat adult cardiomyocytes transfected with miR-1825 showed a significant increase in DNA synthesis, mitosis, cytokinesis, and an increase in cell number when compared to cel-miR-67 transfected control. We also observed a reduction in mitochondrial number and a decrease in ROS and DNA-damage. RNA-sequencing data identified NDUFA10, a key gene involved in the mitochondrial electron transport chain to be a direct target of miR-1825. SiRNA mediated silencing of NDUFA10 showed a significant increase in cardiomyocyte proliferation indicating its role downstream of miRNA-1825. In addition, microRNA microarray results identified miR-1825 to regulate expression of a known proliferation inducing miRNA, miR-199a. We also identified the direct targets of miR-199a, namely p16, Rb1, and Meis2 to be downregulated following miR-1825 transfection. However, miR-199a alone did not have similar proliferation inducing effects as miR-1825, indicating that miR-1825 works through multiple pathways and is a master regulator of cardiomyocyte proliferation. In addition, our in-vivo analysis in animal models of LAD ligation and intra-cardiac miRNA delivery showed proliferation of endogenous cardiomyocytes in the peri-infarcted region and an improvement in heart function. These findings establish miR-1825 as a potential therapeutic agent for induction of cardiomyocyte proliferation and cardiac regeneration, with a significant translational potential.

The roles of non-coding RNAs in cardiac regenerative medicine

The emergence of non-coding RNAs (ncRNAs) has challenged the central dogma of molecular biology that dictates that the decryption of genetic information starts from transcription of DNA to RNA, with subsequent translation into a protein. Large numbers of ncRNAs with biological significance have now been identified, suggesting that ncRNAs are important in their own right and their roles extend far beyond what was originally envisaged. ncRNAs do not only regulate gene expression, but are also involved in chromatin architecture and structural conformation. Several studies have pointed out that ncRNAs participate in heart disease; however, the functions of ncRNAs still remain unclear. ncRNAs are involved in cellular fate, differentiation, proliferation and tissue regeneration, hinting at their potential therapeutic applications. Here, we review the current understanding of both the biological functions and molecular mechanisms of ncRNAs in heart disease and describe some of the ncRNAs that have potential heart regeneration effects.

Circulating microRNA-150-5p as a novel biomarker for advanced heart failure: A genome-wide prospective study

BACKGROUND

Circulating microRNAs (miRs) are promising biomarkers for heart failure (HF). Previous studies have provided inconsistent miR "signatures." The phenotypic and pathophysiologic heterogeneity of HF may have contributed to this inconsistency. In this study we assessed whether advanced HF (AHF) patients present a distinct miR signature compared with healthy subjects (HS) and mild to moderate HF (MHF) patients.

METHODS

The study consisted of 2 phases: a screening phase and a validation phase. In the screening phase, 752 miRs were profiled in HS and MHF and AHF patients (N = 15), using the real-time quantitative polymerase chain reaction (RT-qPCR) technique and global mean normalization. In the validation phase, the miRs found to be significantly dysregulated in AHF patients compared with both HS and MHF patients were validated in 15 HS, 25 patients with MHF and 29 with AHF, using RT-qPCR, and normalizing to exogenous (cel-miR-39) and endogenous controls.

RESULTS

In the screening phase, 5 miRs were found to be significantly dysregulated: -26a-5p; -145-3p; -150-5p; -485-3p; and -487b-3p. In the validation phase, miR-150-5p was confirmed to be significantly downregulated in AHF patients when compared with both HS and MHF patients, irrespective of the normalization method used. miR-26a-5p was confirmed to be significantly dysregulated only when normalized to cell-miR-39. Dysregulation of the other miRs could not be confirmed. miR-150-5p was significantly associated with maladaptive remodeling, disease severity and outcome.

CONCLUSIONS

Our data suggest miR-150-5p as a novel circulating biomarker for AHF. The association of miR-150-5p with maladaptive remodeling, disease severity and outcome supports the pathophysiologic relevance of downregulated miR-150-5p expression to AHF.

Characterization of miRNA-regulated networks, hubs of signaling, and biomarkers in obstruction-induced bladder dysfunction

Bladder outlet obstruction (BOO) induces significant organ remodeling, leading to lower urinary tract symptoms accompanied by urodynamic changes in bladder function. Here, we report mRNA and miRNA transcriptome sequencing of bladder samples from human patients with different urodynamically defined states of BOO. Patients' miRNA and mRNA expression profiles correlated with urodynamic findings. Validation of RNA sequencing results in an independent patient cohort identified combinations of 3 mRNAs (NRXN3, BMP7, UPK1A) and 3 miRNAs (miR-103a-3p, miR-10a-5p, miR-199a-3p) sufficient to discriminate between bladder functional states. All BOO patients shared cytokine and immune response pathways, TGF-β and NO signaling pathways, and hypertrophic PI3K/AKT signaling pathways. AP-1 and NFkB were dominant transcription factors, and TNF-α was the top upstream regulator. Integrated miRNA-mRNA expression analysis identified pathways and molecules targeted by differentially expressed miRNAs. Molecular changes in BOO suggest an increasing involvement of miRNAs in the control of bladder function from the overactive to underactive/acontractile states.

Changes of Ovarian microRNA Profile in Long-Living Ames Dwarf Mice during Aging

The Ames dwarf (df/df) mice have extended longevity and can preserve the ovarian reserve longer than Normal (N) mice. Based on this, the aim of our study was to evaluate the ovarian microRNA (miRNA) profile in young and aged df/df and N mice. Ovarian tissue was collected at 5–6 months and at 21–22 months of age for miRNA sequencing. We detected a total of 404 miRNAs in the ovarian samples, from which the abundance of 22 and 33 miRNAs changed with age in N and df/df mice, respectively. Of these, only three miRNAs were commonly regulated with age between N and df/df mice, indicating a very divergent miRNA profile between genotypes. We also detected that 46 miRNAs were regulated between N and df/df mice, of which 23 were regulated exclusively in young mice, 12 exclusively in old mice and 12 commonly regulated at young and old ages. Many genes likely to be targeted by these miRNAs are involved in the FoxO, mTOR, PI3k/Akt and insulin signaling pathways. These results suggest that the aging process has a differential impact on the ovarian miRNA profile in df/df mice, and suggest that these miRNAs can be central players in the maintenance of a younger ovarian phenotype.

Exercise Training and Epigenetic Regulation: Multilevel Modification and Regulation of Gene Expression

Exercise training elicits acute and adaptive long term changes in human physiology that mediate the improvement of performance and health state. The responses are integrative and orchestrated by several mechanisms, as gene expression. Gene expression is essential to construct the adaptation of the biological system to exercise training, since there are molecular processes mediating oxidative and non-oxidative metabolism, angiogenesis, cardiac and skeletal myofiber hypertrophy, and other processes that leads to a greater physiological status. Epigenetic is the field that studies about gene expression changes heritable by meiosis and mitosis, by changes in chromatin and DNA conformation, but not in DNA sequence, that studies the regulation on gene expression that is independent of genotype. The field approaches mechanisms of DNA and chromatin conformational changes that inhibit or increase gene expression and determine tissue specific pattern. The three major studied epigenetic mechanisms are DNA methylation, Histone modification, and regulation of noncoding RNA-associated genes. This review elucidates these mechanisms, focusing on the relationship between them and their relationship with exercise training, physical performance and the enhancement of health status. On this chapter, we clarified the relationship of epigenetic modulations and their intimal relationship with acute and chronic effect of exercise training, concentrating our effort on skeletal muscle, heart and vascular responses, that are the most responsive systems against to exercise training and play crucial role on physical performance and improvement of health state.

Molecular inotropy mediated by cardiac miR-based PDE4D/PRKAR1α/phosphoprotein signaling

Molecular inotropy refers to cardiac contractility that can be modified to affect overall heart pump performance. Here we show evidence of a new molecular pathway for positive inotropy by a cardiac-restricted microRNA (miR). We report enhanced cardiac myocyte performance by acute titration of cardiac myosin-embedded miR-208a. The observed positive effect was independent of host gene myosin effects with evidence of negative regulation of cAMP-specific 3',5'-cyclic phosphodiesterase 4D (PDE4D) and the regulatory subunit of PKA (PRKAR1α) content culminating in PKA-site dependent phosphorylation of cardiac troponin I (cTnI) and phospholamban (PLN). Further, acute inhibition of miR-208a in adult myocytes in vitro increased PDE4D expression causing reduced isoproterenol-mediated phosphorylation of cTnI and PLN. Next, rAAV-mediated miR-208a gene delivery enhanced heart contractility and relaxation parameters in vivo. Finally, acute inducible increases in cardiac miR-208a in vivo reduced PDE4D and PRKAR1α, with evidence of increased content of several complementary miRs harboring the PDE4D recognition sequence. Physiologically, this resulted in significant cardiac cTnI and PLN phosphorylation and improved heart performance in vivo. As phosphorylation of cTnI and PLN is critical to myocyte function, titration of miR-208a represents a potential new mechanism to enhance myocardial performance via the PDE4D/PRKAR1α/PKA phosphoprotein signaling pathway.

Sex differences in response to miRNA-34a therapy in mouse models of cardiac disease: identification of sex-, disease- and treatment-regulated miRNAs

KEY POINTS

MicroRNA (miRNA)-based therapies are in development for numerous diseases, including heart disease. Currently, very limited basic information is available on the regulation of specific miRNAs in male and female hearts in settings of disease. The identification of sex-specific miRNA signatures has implications for translation into the clinic and suggests the need for customised therapy. In the present study, we found that a miRNA-based treatment inhibiting miRNA-34a (miR-34a) was more effective in females in a setting of moderate dilated cardiomyopathy than in males. Furthermore, the treatment showed little benefit for either sex in a setting of more severe dilated cardiomyopathy associated with atrial fibrillation. The results highlight the importance of understanding the effect of miRNA-based therapies in cardiac disease settings in males and females.

ABSTRACT

MicroRNA (miRNA)-34a (miR-34a) is elevated in the diseased heart in mice and humans. Previous studies have shown that inhibiting miR-34a in male mice in settings of pathological cardiac hypertrophy or ischaemia protects the heart against progression to heart failure. Whether inhibition of miR-34a protects the female heart is unknown. Furthermore, the therapeutic potential of silencing miR-34a in settings of dilated cardiomyopathy (DCM) and atrial fibrillation (AF) has not been assessed previously. In the present study, we examined the effect of silencing miR-34a in males and females in (1) a model of moderate DCM and (2) a model of severe DCM with AF. The cardiac disease models were administered with a locked nucleic acid-modified oligonucleotide (LNA-antimiR-34a) at 6-7 weeks of age when the models display cardiac dysfunction and conduction abnormalities. Cardiac function and morphology were measured 6 weeks after treatment. In the present study, we show that inhibition of miR-34a provides more protection in the DCM model in females than males. Disease prevention in LNA-antimiR-34a treated DCM female mice was characterized by attenuated heart enlargement and lung congestion, lower expression of cardiac stress genes (B-type natriuretic peptide, collagen gene expression), less cardiac fibrosis and better cardiac function. There was no evidence of significant protection in the severe DCM and AF model in either sex. Sex- and treatment-dependent regulation of miRNAs was also identified in the diseased heart, and may explain the differential response of males and females. These studies highlight the importance of examining the impact of miRNA-based drugs in both sexes and under different disease conditions.