RETRACTED: LncRNA myocardial infarction-associated transcript (MIAT) contributed to cardiac hypertrophy by regulating TLR4 via miR-93

MIAT LncRNA: A multifunctional key player in non-oncological pathological conditions

The discovery of non-coding RNAs (ncRNAs) has unveiled a wide range of transcripts that do not encode proteins but play key roles in several cellular and molecular processes. Long noncoding RNAs (lncRNAs) are specific class of ncRNAs that are longer than 200 nucleotides and have gained significant attention due to their diverse mechanisms of action and potential involvement in various pathological conditions. In the current review, the authors focus on the role of lncRNAs, specifically highlighting the Myocardial Infarction Associated Transcript (MIAT), in non-oncological context. MIAT is a nuclear lncRNA that has been directly linked to myocardial infarction and is reported to control post-transcriptional processes as a competitive endogenous RNA (ceRNA) molecule. It interacts with microRNAs (miRNAs), thereby limiting the translation and expression of their respective target messenger RNA (mRNA) and regulating protein expression. Yet, MIAT has been implicated in other numerous pathological conditions such as other cardiovascular diseases, autoimmune disease, neurodegenerative diseases, metabolic diseases, and many others. In this review, the authors emphasize that MIAT exhibits distinct expression patterns and functions across different pathological conditions and is emerging as potential diagnostic, prognostic, and therapeutic agent. Additionally, the authors highlight the regulatory role of MIAT and shed light on the involvement of lncRNAs and specifically MIAT in various non-oncological pathological conditions.

LncRNA Zfas1 boosts cell apoptosis and autophagy in myocardial injury induced by hypoxia via miR-383-5p/ATG10 axis

Background

Myocardial injury has been regarded as a major cause of several heart diseases. Long non-coding RNA (lncRNA) has emerged as a key regulator in a wide array of diseases.

Aim of the study

This study aims to explore the role of Zfas1 in myocardial injury.

Methods

3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was adopted to evaluate the proliferative capability of H9c2 cells. Terminal deoxynucleotidyltransferase dUTP nick end labeling (TUNEL) and flow cytometry assays were employed to measure cell apoptosis. The expression of proteins related to apoptosis and autophagy was examined by Western blot. Immunofluorescence (IF) assay was performed to monitor the process of autophagy. Real-time reverse-transcription polymerase chain reaction (RT-qPCR) was employed to determine the expressions of autophagy-related gene 10 (ATG10), miR-383-5p and Zfas1. The interacting relationship between miR-383-5p and ATG10 (or Zfas1) was assessed by luciferase reporter and RNA-binding protein immunoprecipitation (RIP) assays.

Results

The treatment of hypoxia hindered cell proliferation but accelerated cell apoptosis and autophagy. ATG10 exhibited higher mRNA and protein expression in H9c2 cells induced by hypoxia. MiR-383-5p was revealed to be the upstream gene of ATG10 and could interact with ATG10. Zfas1 was validated to sponge miR-383-5p and positively regulated ATG10 expression. Zfas1 knockdown-mediated cellular proliferation, apoptosis and autophagy phenotypes were counteracted by ATG10 abundance.

Conclusions

LncRNA Zfas1 boosts cell apoptosis and autophagy in myocardial injury induced by hypoxia via miR-383-5p/ATG10 axis, indicating that Zfas1 may be utilized as a therapeutic target for myocardial injury.

A review on regulation of DNA methylation during post-myocardial infarction

Myocardial infarction (MI) imposes a huge medical and economic burden on society, and cardiac repair after MI involves a complex series of processes. Understanding the key mechanisms (such as apoptosis, autophagy, inflammation, and fibrosis) will facilitate further drug development and patient treatment. Presently, a substantial body of evidence suggests that the regulation of epigenetic processes contributes to cardiac repair following MI, with DNA methylation being among the notable epigenetic factors involved. This article will review the research on the mechanism of DNA methylation regulation after MI to provide some insights for future research and development of related drugs.

Synaptotagmin-7 mediates cardiac hypertrophy by targeting autophagy

Sustained cardiac hypertrophy damages the heart and weakens cardiac function, often leading to heart failure and even death. Pathological cardiac hypertrophy has become a central therapeutic target for many heart diseases including heart failure. However, the underlying mechanisms of cardiac hypertrophy, especially the involvement of autophagy program, are still ill-understood. Synaptotagmin-7 (Syt7), a multifunctional and high-affinity calcium sensor, plays a pivotal role in asynchronous neurotransmitter release, synaptic facilitation, and vesicle pool regulation during synaptic transmission. However, little is known about whether Syt7 is expressed in the myocardium and involved in the pathogenesis of heart diseases. Here we showed that Syt7 was significantly upregulated in Ang II-treated hearts and cardiomyocytes. Homozygous syt7 knockout (syt7-/-) mice exhibited significantly attenuated cardiac hypertrophy and fibrosis and improved cardiac function. We further found that Syt7 exerted a pro-hypertrophic effect by suppressing the autophagy process. In exploring the upstream mechanisms, microRNA (miR)-93 was identified to participate in the regulation of Syt7 expression. miR-93 protected hearts against Ang II-induced hypertrophy through targeting Syt7-autophagy pathway. In summary, our data reveal a new cardiac hypertrophy regulator and a novel hypertrophy regulating model composed of miR-93, Syt7 and autophagy program. These molecules may serve as potential therapeutic targets in the treatment of cardiac hypertrophy and heart failure.

Posttranscriptional Regulation by Proteins and Noncoding RNAs

Posttranscriptional regulation comprises those mechanisms occurring after the initial copy of the DNA sequence is transcribed into an intermediate RNA molecule (i.e., messenger RNA) until such a molecule is used as a template to generate a protein. A subset of these posttranscriptional regulatory mechanisms essentially are destined to process the immature mRNA toward its mature form, conferring the adequate mRNA stability, providing the means for pertinent introns excision, and controlling mRNA turnover rate and quality control check. An additional layer of complexity is added in certain cases, since discrete nucleotide modifications in the mature RNA molecule are added by RNA editing, a process that provides large mature mRNA diversity. Moreover, a number of posttranscriptional regulatory mechanisms occur in a cell- and tissue-specific manner, such as alternative splicing and noncoding RNA-mediated regulation. In this chapter, we will briefly summarize current state-of-the-art knowledge of general posttranscriptional mechanisms, while major emphases will be devoted to those tissue-specific posttranscriptional modifications that impact on cardiac development and congenital heart disease.

The role and medical prospects of long non-coding RNAs in cardiovascular disease

Cardiovascular disease (CVD) has reached epidemic proportions and is a leading cause of death worldwide. One of the long-standing goals of scientists is to repair heart tissue damaged by various forms of CVD such as cardiac hypertrophy, dilated cardiomyopathy, myocardial infarction, heart fibrosis, and genetic and developmental heart defects such as heart valve deformities. Damaged or defective heart tissue has limited regenerative capacity and results in a loss of functioning myocardium. Advances in transcriptomic profiling technology have revealed that long noncoding RNA (lncRNA) is transcribed from what was once considered "junk DNA." It has since been discovered that lncRNAs play a critical role in the pathogenesis of various CVDs and in myocardial regeneration. This review will explore how lncRNAs impact various forms of CVD as well as those involved in cardiomyocyte regeneration. Further, we discuss the potential of lncRNAs as a therapeutic modality for treating CVD.

The Role of Long Non-Coding RNAs in Cardiovascular Diseases

Long non-coding RNAs (lncRNAs) are non-coding RNA molecules longer than 200 nucleotides that regulate gene expression at the transcriptional, post-transcriptional, and translational levels. Abnormal expression of lncRNAs has been identified in many human diseases. Future improvements in diagnostic, prognostic, and therapeutic techniques will be facilitated by a deeper understanding of disease etiology. Cardiovascular diseases (CVDs) are the main cause of death globally. Cardiac development involves lncRNAs, and their abnormalities are linked to many CVDs. This review examines the relationship and function of lncRNA in a variety of CVDs, including atherosclerosis, myocardial infarction, myocardial hypertrophy, and heart failure. Therein, the potential utilization of lncRNAs in clinical diagnostic, prognostic, and therapeutic applications will also be discussed.

Cardiac-specific Trim44 knockout in rat attenuates isoproterenol-induced cardiac remodeling via inhibition of AKT/mTOR pathway

When pathological hypertrophy progresses to heart failure (HF), the prognosis is often very poor. Therefore, it is crucial to find new and effective intervention targets. Here, myocardium-specific Trim44 knockout rats were generated using CRISPR-Cas9 technology. Cardiac phenotypic observations revealed that Trim44 knockout affected cardiac morphology at baseline. Rats with Trim44 deficiency exhibited resistance to cardiac pathological changes in response to stimulation via isoproterenol (ISO) treatment, including improvement of cardiac remodeling and dysfunction by morphological and functional observations, reduced myocardial fibrosis and reduced expression of molecular markers of cardiac stress. Furthermore, signal transduction validation associated with growth and hypertrophy development in vivo and in vitro demonstrated that Trim44 deficiency inhibited the activation of signaling pathways involved in myocardial hypertrophy, especially response to pathological stress. In conclusion, the present study indicates that Trim44 knockout attenuates ISO-induced pathological cardiac remodeling through blocking the AKT/mTOR/GSK3β/P70S6K signaling pathway. This is the first study to demonstrate the function and importance of Trim44 in the heart at baseline and under pathological stress. Trim44 could be a novel therapeutic target for prevention of cardiac hypertrophy and HF.

Summary: This is the first study to demonstrate the function of Trim44 in the heart at baseline and under pathological stress. Trim44 could be a novel therapeutic target for prevention of cardiac hypertrophy.

SLC26A4-AS1 Aggravates AngII-induced Cardiac Hypertrophy by Enhancing SLC26A4 Expression

BACKGROUND

It has been reported that solute carrier family 26 members 4 antisense RNA 1 (SLC26A4-AS1) is highly related to cardiac hypertrophy.

OBJECTIVE

This research aims to investigate the role and specific mechanism of SLC26A4-AS1 in cardiac hypertrophy, providing a novel marker for cardiac hypertrophy treatment.

METHODS

Angiotensin II (AngII) was infused into neonatal mouse ventricular cardiomyocytes (NMVCs) to induce cardiac hypertrophy. Gene expression was detected by quantitative real-time PCR (RT-qPCR). Protein levels were evaluated via western blot. Functional assays analyzed the role of SLC26A4-AS1. The mechanism of SLC26A4-AS1 was assessed by RNA-binding protein immunoprecipitation (RIP), RNA pull-down, and luciferase reporter assays. The P value <0.05 was identified as statistical significance. Student's t-test evaluated the two-group comparison. The difference between different groups was analyzed by one-way analysis of variance (ANOVA).

RESULTS

SLC26A4-AS1 is upregulated in AngII-treated NMVCs and promotes AngII-induced cardiac hypertrophy. SLC26A4-AS1 regulates its nearby gene solute carrier family 26 members 4 (SLC26A4) via functioning as a competing endogenous RNA (ceRNA) to modulate the microRNA (miR)-301a-3p and miR-301b-3p in NMVCs. SLC26A4-AS1 promotes AngII-induced cardiac hypertrophy via upregulating SLC26A4 or sponging miR-301a-3p/miR-301b-3p.

CONCLUSION

SLC26A4-AS1 aggravates AngII-induced cardiac hypertrophy via sponging miR-301a-3p or miR-301b-3p to enhance SLC26A4 expression.

Potential roles of microRNAs and long noncoding RNAs as diagnostic, prognostic and therapeutic biomarkers in coronary artery disease

Coronary artery disease (CAD), which is mainly caused by atherosclerotic processes in coronary arteries, became a significant health issue. MicroRNAs (miRNAs), and long noncoding RNAs (lncRNAs), have been shown to be stable in plasma and could thereby be adopted as biomarkers for CAD diagnosis and treatment. MiRNAs can regulate CAD development through different pathways and mechanisms, including modulation of vascular smooth muscle cell (VSMC) activity, inflammatory responses, myocardial injury, angiogenesis, and leukocyte adhesion. Similarly, previously studies have indicated that the causal effects of lncRNAs in CAD pathogenesis and their utility in CAD diagnosis and treatment, has been found to lead to cell cycle transition, proliferation dysregulation, and migration in favour of CAD development. Differential expression of miRNAs and lncRNAs in CAD patients has been identified and served as diagnostic, prognostic and therapeutic biomarkers for the assessment of CAD patients. Thus, in the current review, we summarize the functions of miRNAs and lncRNAs, which aimed to identify novel targets for the CAD diagnosis, prognosis, and treatment.

Toll-like receptors in cardiac hypertrophy

Toll-like receptors (TLRs) are a family of pattern recognition receptors (PRRs) that can identify pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). TLRs play an important role in the innate immune response, leading to acute and chronic inflammation. Cardiac hypertrophy, an important cardiac remodeling phenotype during cardiovascular disease, contributes to the development of heart failure. In previous decades, many studies have reported that TLR-mediated inflammation was involved in the induction of myocardium hypertrophic remodeling, suggesting that targeting TLR signaling might be an effective strategy against pathological cardiac hypertrophy. Thus, it is necessary to study the mechanisms underlying TLR functions in cardiac hypertrophy. In this review, we summarized key findings of TLR signaling in cardiac hypertrophy.

Construction and function analysis of the LncRNA-miRNA-mRNA competing endogenous RNA network in autoimmune hepatitis

AIMS

To construct the lncRNA-miRNA-mRNA competing endogenous RNA (ceRNA) network based on our microarray chip data for providing new insights into the pathogenesis of autoimmune hepatitis.

METHODS

The ceRNA pairs were obtained by calculating the co-expression relationships among the differentially expressed lncRNAs (DELs), differentially expressed microRNAs (DEMis), and differentially expressed mRNAs (DEMs) with Pearson correlation analysis and hypergeometric distribution. The data of the differentially expressed genes were obtained from our previous studies in the concanavalin A-induced AIH mouse model. The biological functions of the ceRNA network were revealed by carrying out the GO and KEGG enrichment analysis. The expression of some differentially expressed genes constructed in the ceRNA pair was validated, and the correlation to liver injury was analyzed.

RESULTS

The mRNAs constructed in the ceRNA network were most significantly annotated in the GO terms of "inflammatory response" and enriched in "Cytokine-cytokine receptor interaction" and "MAPK signaling pathway". The differences in the expression of Gm38975, mmu-miR-125a-3p, and Map3k13 between the model group and control group were significant, and the expression of these genes at a transcriptional level was positively or negatively correlated to the activity of ALT and AST as well as the amount of MDA and NO.

CONCLUSION

Our work is the first in its kind to predict and illustrate the comprehensive lncRNA-miRNA-mRNA ceRNA network associated with the etiopathogenesis of AIH. This study indicates to lay the foundation for revealing the potential roles of ceRNAs in the occurrence of AIH and provide novel treatment targets for this disease.

Illuminating the Molecular Intricacies of Exosomes and ncRNAs in Cardiovascular Diseases: Prospective Therapeutic and Biomarker Potential

Cardiovascular diseases (CVDs) are one of the leading causes of death worldwide. Accumulating evidences have highlighted the importance of exosomes and non-coding RNAs (ncRNAs) in cardiac physiology and pathology. It is in general consensus that exosomes and ncRNAs play a crucial role in the maintenance of normal cellular function; and interestingly it is envisaged that their potential as prospective therapeutic candidates and biomarkers are increasing rapidly. Considering all these aspects, this review provides a comprehensive overview of the recent understanding of exosomes and ncRNAs in CVDs. We provide a great deal of discussion regarding their role in the cardiovascular system, together with providing a glimpse of ideas regarding strategies exploited to harness their potential as a therapeutic intervention and prospective biomarker against CVDs. Thus, it could be envisaged that a thorough understanding of the intricacies related to exosomes and ncRNA would seemingly allow their full exploration and may lead clinical settings to become a reality in near future.

LncRNA Gm43843 Promotes Cardiac Hypertrophy via miR-153-3p/Cacna1c Axis

Long noncoding RNAs (lncRNAs) have been reported to engage in many human diseases, including cardiac hypertrophy. Cardiac hypertrophy was mainly caused by excessive pressure load, which can eventually lead to a decline in myocardial contractility. Gm43843, a novel lncRNA, has not been well explored in cardiac hypertrophy so far. Herein, we are going to search the function and the underlying molecular mechanism of Gm43843 in cardiac hypertrophy. Gm43843 levels were measured via qRT-PCR in mouse myocardial cells when they are treated with angiogenin II (Ang II) or transfected with different plasmids. Western blot assay was implemented to detect the cardiac hypertrophy-related protein markers, while the cell was analyzed via immunofluorescence (IF) assay to evaluate the hypertrophy. Meanwhile, the binding of Gm43843 and the putative targets was examined based on mechanistic assay results. We found that Gm43843 expression was increased with the elevated concentration of Ang II. Inhibited Gm43843 was detected to reduce the hypertrophy of mouse myocardial cells. Meanwhile, Gm43843/miR-153-3p/Cacna1c axis was found to modulate cardiac hypertrophy. In short, Gm43843 promotes cardiac hypertrophy via miR-153-3p/Cacna1c axis.

Circ-TLR4 promotes cardiac hypertrophy through recruiting FUS to stabilize TLR4 mRNA

BACKGROUND

Cardiac hypertrophy is an adaptive and compensatory mechanism preserving cardiac output during detrimental stimuli. Circular RNAs (circRNAs) have been illustrated to exert important implications in the pathogenesis of multiple cardiovascular diseases (CVD) including demonstrated cardiac hypertrophy. Toll-like receptor 4 (TLR4) has been previously reported to be a crucial regulator in inflammatory response and cardiac hypertrophy. However, the role of circular isoforms derived from TLR4 in cardiac hypertrophy remains unclear.

METHODS

Expression of circ-TLR4 and TLR4 in cardiomyocytes was detected by RT-qPCR. The indicators of cardiac hypertrophy responses, including cell surface area, atrial natriuretic factor (ANF), B-type natriuretic peptide (BNP) and β-myosin heavy chain (β-MHC) were measured by immunofluorescence staining and western blot. RIP assay was used to validate the interaction between circ-TLR4 and TLR4.

RESULTS

Circ-TLR4 and TLR4 was up-regulated in cellular models of cardiac hypertrophy. Circ-TLR4 knockdown attenuated angiotensin II (Ang II)-induced hypertrophy responses in cardiomyocytes. Moreover, circ-TLR4 positively regulated TLR4 expression through recruiting FUS to stabilize TLR4 mRNA. Furthermore, TLR4 overexpression rescued the cardiac responses mediated by circ-TLR4 silencing.

CONCLUSION

Circ-TLR4 promotes cardiac hypertrophy through recruiting FUS to stabilize TLR4 mRNA.

MiR-150 Attenuates Maladaptive Cardiac Remodeling Mediated by Long Noncoding RNA MIAT and Directly Represses Profibrotic Hoxa4

BACKGROUND

MicroRNA-150 (miR-150) plays a protective role in heart failure (HF). Long noncoding RNA, myocardial infarction-associated transcript (MIAT) regulates miR-150 function in vitro by direct interaction. Concurrent with miR-150 downregulation, MIAT is upregulated in failing hearts, and gain-of-function single-nucleotide polymorphisms in MIAT are associated with increased risk of myocardial infarction (MI) in humans. Despite the correlative relationship between MIAT and miR-150 in HF, their in vivo functional relationship has never been established, and molecular mechanisms by which these 2 noncoding RNAs regulate cardiac protection remain elusive.

METHODS

We use MIAT KO (knockout), Hoxa4 (homeobox a4) KO, MIAT TG (transgenic), and miR-150 TG mice. We also develop DTG (double TG) mice overexpressing MIAT and miR-150. We then use a mouse model of MI followed by cardiac functional, structural, and mechanistic studies by echocardiography, immunohistochemistry, transcriptome profiling, Western blotting, and quantitative real-time reverse transcription-polymerase chain reaction. Moreover, we perform expression analyses in hearts from patients with HF. Lastly, we investigate cardiac fibroblast activation using primary adult human cardiac fibroblasts and in vitro assays to define the conserved MIAT/miR-150/HOXA4 axis.

RESULTS

Using novel mouse models, we demonstrate that genetic overexpression of MIAT worsens cardiac remodeling, while genetic deletion of MIAT protects hearts against MI. Importantly, miR-150 overexpression attenuates the detrimental post-MI effects caused by MIAT. Genome-wide transcriptomic analysis of MIAT null mouse hearts identifies Hoxa4 as a novel downstream target of the MIAT/miR-150 axis. Hoxa4 is upregulated in cardiac fibroblasts isolated from ischemic myocardium and subjected to hypoxia/reoxygenation. HOXA4 is also upregulated in patients with HF. Moreover, Hoxa4 deficiency in mice protects the heart from MI. Lastly, protective actions of cardiac fibroblast miR-150 are partially attributed to the direct and functional repression of profibrotic Hoxa4.

CONCLUSIONS

Our findings delineate a pivotal functional interaction among MIAT, miR-150, and Hoxa4 as a novel regulatory mechanism pertinent to ischemic HF.

Non-Coding RNAs: Prevention, Diagnosis, and Treatment in Myocardial Ischemia-Reperfusion Injury

Recent knowledge concerning the role of non-coding RNAs (ncRNAs) in myocardial ischemia/reperfusion (I/R) injury provides new insight into their possible roles as specific biomarkers for early diagnosis, prognosis, and treatment. MicroRNAs (miRNAs) have fewer than 200 nucleotides, while long ncRNAs (lncRNAs) have more than 200 nucleotides. The three types of ncRNAs (miRNAs, lncRNAs, and circRNAs) act as signaling molecules strongly involved in cardiovascular disorders (CVD). I/R injury of the heart is the main CVD correlated with acute myocardial infarction (AMI), cardiac surgery, and transplantation. The expression levels of many ncRNAs and miRNAs are highly modified in the plasma of MI patients, and thus they have the potential to diagnose and treat MI. Cardiomyocyte and endothelial cell death is the major trigger for myocardial ischemia–reperfusion syndrome (MIRS). The cardioprotective effect of inflammasome activation in MIRS and the therapeutics targeting the reparative response could prevent progressive post-infarction heart failure. Moreover, the pharmacological and genetic modulation of these ncRNAs has the therapeutic potential to improve clinical outcomes in AMI patients.

Molecular Mechanisms and Epigenetic Regulation in Diabetic Cardiomyopathy

Diabetes mellitus (DM) is an important lifestyle disease. Type 2 diabetes is one of the prime contributors to cardiovascular diseases (CVD) and diabetic cardiomyopathy (DbCM) and leads to increased morbidity and mortality in patients with DM. DbCM is a typical cardiac disease, characterized by cardiac remodeling in the presence of DM and in the absence of other comorbidities such as hypertension, valvular diseases, and coronary artery disease. DbCM is associated with defective cardiac metabolism, altered mitochondrial structure and function, and other physiological and pathophysiological signaling mechanisms such as oxidative stress, inflammation, myocardial apoptosis, and autophagy. Epigenetic modifiers are crucial players in the pathogenesis of DbCM. Thus, it is important to explore the role of epigenetic modifiers or modifications in regulating molecular pathways associated with DbCM. In this review, we have discussed the role of various epigenetic mechanisms such as histone modifications (acetylation and methylation), DNA methylation and non-coding RNAs in modulating molecular pathways involved in the pathophysiology of the DbCM.

MIAT, a potent CVD-promoting lncRNA

The initial identification of long non-coding RNA myocardial infarction associated transcript (MIAT) as a genetic risk factor of myocardial infarction has made this lncRNA (designated as lncR-MIAT here) a focus of intensive studies worldwide. Emerging evidence supports that lncR-MIAT is susceptible in its expression to multiple deleterious factors like angiotensin II, isoproterenol, hypoxia, and infection and is anomaly overexpressed in serum, plasma, blood cells and myocardial tissues under a variety of cardiovascular conditions including myocardial infarction, cardiac hypertrophy, diabetic cardiomyopathy, dilated cardiomyopathy, sepsis cardiomyopathy, atrial fibrillation and microvascular dysfunction. Experimental results consistently demonstrated that upregulation of lncR-MIAT plays active roles in the pathological processes of the cardiovascular system and knockdown of this lncRNA effectively ameliorates the adverse conditions. The available data revealed that lncR-MIAT acts through multiple mechanisms such as competitive endogenous RNA, natural antisense RNA and RNA/protein interactions. Moreover, the functional domains of lncR-MIAT accounting for certain specific cellular functions of the full-length transcript have been identified and characterized. These insights will not only tremendously advance our understanding of lncRNA biology and pathophysiology, but also offer good opportunities for more innovative and precise design of agents that have the potential to be developed into new drugs for better therapy of cardiovascular diseases (CVDs) in the future. Herein, we provide an overview of lncR-MIAT, focusing on its roles in cardiovascular diseases, underline the unique cellular/molecular mechanisms for its actions, and speculate the perspectives about the translational studies on the potential diagnostic and therapeutic applications of lncR-MIAT.

LncRNA MIAT Services as a Noninvasive Biomarker for Diagnosis and Correlated with Immune Infiltrates in Breast Cancer

Background

Myocardial infarction associated transcript (MIAT) is identified as a long chain non-coding RNA (lncRNA), which was associated with myocardial infarction susceptibility. While intense efforts have been made to elucidate the relationship between MIAT and carcinogenesis, the tumor immunoreaction of MIAT remains elusive. Thus, this study aimed to investigate the role of MIAT in the immunoregulation of breast cancer (BC) and further explore the better clinical significance.

Methods

The differential expression of MIAT between BC and normal/adjacent tissues was compared using Wilcoxon rank sum test. The diagnostic and prognostic values of elevated MIAT expression in BC tissues were unveiled via receiver operating characteristic (ROC) analysis and KM-plotter analysis. Limma and edgeR package were used to identify differentially expressed genes (DEGs) and microRNAs (DEMs) from TCGA database respectively. A co-expression dataset was constructed to comprehensively understand the relationship between MIAT and DEGs based on the Pearson correlation coefficient. Furthermore, GO and KEGG analyses were conducted to predict the potential functions of MIAT. We next intersected immune-related genes (IRGs) from ImmPort database with MIAT-co-expressed genes to obtain MIAT-co-expressed IRGs, in order to construct MIAT-microRNA (miRNA)-mRNA network. And the correlation between MIAT and tumor-infiltrating immune cells (TICs) and immunophenoscore (IPS) analysis was analyzed by TIMER and CIBERSORT. Finally, the reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was used to detect the expression profiles of MIAT in serum samples.

Results

The expression levels of MIAT were notably higher in BC than in normal or adjacent tissues. And MIAT expression could be used as a prognostic indicator of mortality risk in patients with BC in different aspects. Moreover, the enrichment analyses suggested that MIAT was strongly involved in BC immune response. In addition, TIMER database and CIBERSORT analyses indicated that MIAT was significantly correlated with 13 types of TICs (B cells, dendritic cells, neutrophils, CD8 T cells, CD4 memory resting T cells, CD4 memory activated T cells, gamma delta T cells, M1 macrophages, plasma cells, activated NK cells, monocytes, M2 macrophages, activated mast cells). Simultaneously, the IPS analysis implied that the higher the MIAT expression, the better the immunotherapy effect. The ROC curve analysis showed that the area under the curve (AUC) value of MIAT was 0.86 (sensitivity = 87.80%, specificity = 75.61%). And the high MIAT expression in serum was positive related to TNM stage (P = 0.032) and lymph node metastasis (P = 0.028).

Conclusion

MIAT may be a valuable noninvasive diagnostic biomarker for BC and is associated with tumor-infiltrating immune cells in tumor microenvironment, suggesting MIAT as a potential target for future treatment of BC.

Long Non-Coding RNAs in Cardiovascular Diseases: Potential Function as Biomarkers and Therapeutic Targets of Exercise Training

Despite advances in treatments and therapies, cardiovascular diseases (CVDs) remain one of the leading causes of death worldwide. The discovery that most of the human genome, although transcribed, does not encode proteins was crucial for focusing on the potential of long non-coding RNAs (lncRNAs) as essential regulators of cell function at the epigenetic, transcriptional, and post-transcriptional levels. This class of non-coding RNAs is related to the pathophysiology of the cardiovascular system. The different expression profiles of lncRNAs, in different contexts of CVDs, change a great potential in their use as a biomarker and targets of therapeutic intervention. Furthermore, regular physical exercise plays a protective role against CVDs; on the other hand, little is known about its underlying molecular mechanisms. In this review, we look at the accumulated knowledge on lncRNAs and their functions in the cardiovascular system, focusing on the cardiovascular pathology of arterial hypertension, coronary heart disease, acute myocardial infarction, and heart failure. We discuss the potential of these molecules as biomarkers for clinical use, their limitations, and how the manipulation of the expression profile of these transcripts through physical exercise can begin to be suggested as a strategy for the treatment of CVDs.

LncRNA Miat knockdown alleviates endothelial cell injury through regulation of miR-214-3p/Caspase-1 signalling during atherogenesis

Atherosclerosis is a common problem in healthy people around the world. Long noncoding RNAs (lncRNAs) play important roles in atherosclerosis. Myocardial infarction-associated transcript (Miat) is a cardiovascular disease-associated lncRNA. Its role and mechanism in atherosclerosis is still not fully clarified. Our study aims to explore the role and mechanism of lncRNA Miat in atherosclerosis. The atherosclerosis models were established both in vitro and in vivo. Real-time PCR was used to measure the expression of lncRNA Miat, miR-214, Caspase-1 and IL-1β. Western blot was performed to detect the protein expression of Caspase-1. CCK-8 assay, Tunel staining, and flow cytometry analysis were conducted to detect proliferation and apoptosis of human aortic endothelial cells (HAECs), respectively. Oil red O staining and HE staining were used to evaluated the histological changes of the aorta. The results found that lncRNA Miat was upregulated in ox-LDL-induced atherosclerosis model in vitro. The inhibition of lncRNA Miat protects against ox-LDL-induced HAEC injury, presented as increased cell viability and decreased apoptosis. LncRNA Miat and miR-214 has binding site, and CASP1, which encodes Caspase-1, is a target of miR-214. The downregulation of lncRNA Miat increased the expression of miR-214-3p and decreased the expression of Caspase-1, as well as its downstream molecule IL-1β in HAECs. However, the inhibition of miR-214-3p attenuated the effect of lncRNA Miat downregulation on HAECs. Furthermore, the downregulation of lncRNA Miat alleviated atherosclerosis in ApoE-deficient mice. Correspondingly, the expression of miR-214-3p was upregulated and Caspase-1 was downregulated after knockdown of lncRNA Miat. In conclusion, downregulation of lncRNA Miat exerts a protective effect against atherosclerosis through the regulation miR-214-3p/Caspase-1 signalling pathway. Therefore, the inhibition of lncRNA Miat expression may be an effective strategy in the treatment of atherosclerosis.

Reconnoitering the Role of Long-Noncoding RNAs in Hypertrophic Cardiomyopathy: A Descriptive Review

Hypertrophic cardiomyopathy (HCM) is the most common form of hereditary cardiomyopathy. It is characterized by an unexplained non-dilated hypertrophy of the left ventricle with a conserved or elevated ejection fraction. It is a genetically heterogeneous disease largely caused by variants of genes encoding for cardiac sarcomere proteins, including MYH7, MYBPC3, ACTC1, TPM1, MYL2, MYL3, TNNI3, and TNNT23. Preclinical evidence indicates that the enhanced calcium sensitivity of the myofilaments plays a key role in the pathophysiology of HCM. Notably, this is not always a direct consequence of sarcomeric variations but may also result from secondary mutation-driven alterations. Long non-coding RNAs (lncRNAs) are a large class of transcripts ≥200 nucleotides in length that do not encode proteins. Compared to coding mRNAs, most lncRNAs are not as well-annotated and their functions are greatly unexplored. Nevertheless, increasing evidence shows that lncRNAs are involved in a variety of biological processes and diseases including HCM. Accumulating evidence has indicated that lncRNAs are dysregulated in HCM, and closely related to sarcomere construction, calcium channeling and homeostasis of mitochondria. In this review, we have summarized the known regulatory and functional roles of lncRNAs in HCM.

Ablation of lncRNA Miat attenuates pathological hypertrophy and heart failure

Rationale: The conserved long non-coding RNA (lncRNA) myocardial infarction associate transcript (Miat) was identified for its multiple single-nucleotide polymorphisms that are strongly associated with susceptibility to MI, but its role in cardiovascular biology remains elusive. Here we investigated whether Miat regulates cardiac response to pathological hypertrophic stimuli. Methods: Both an angiotensin II (Ang II) infusion model and a transverse aortic constriction (TAC) model were used in adult WT and Miat-null knockout (Miat-KO) mice to induce pathological cardiac hypertrophy. Heart structure and function were evaluated by echocardiography and histological assessments. Gene expression in the heart was evaluated by RNA sequencing (RNA-seq), quantitative real-time RT-PCR (qRT-PCR), and Western blotting. Primary WT and Miat-KO mouse cardiomyocytes were isolated and used in Ca²⁺ transient and contractility measurements. Results: Continuous Ang II infusion for 4 weeks induced concentric hypertrophy in WT mice, but to a lesser extent in Miat-KO mice. Surgical TAC for 6 weeks resulted in decreased systolic function and heart failure in WT mice but not in Miat-KO mice. In both models, Miat-KO mice displayed reduced heart-weight to tibia-length ratio, cardiomyocyte cross-sectional area, cardiomyocyte apoptosis, and cardiac interstitial fibrosis and a better-preserved capillary density, as compared to WT mice. In addition, Ang II treatment led to significantly reduced mRNA and protein expression of the Ca²⁺ cycling genes Sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase 2a (SERCA2a) and ryanodine receptor 2 (RyR2) and a dramatic increase in global RNA splicing events in the left ventricle (LV) of WT mice, and these changes were largely blunted in Miat-KO mice. Consistently, cardiomyocytes isolated from Miat-KO mice demonstrated more efficient Ca²⁺ cycling and greater contractility. Conclusions: Ablation of Miat attenuates pathological hypertrophy and heart failure, in part, by enhancing cardiomyocyte contractility.

Long non-coding RNAs in cardiac hypertrophy

Cardiac hypertrophy (CH) is generally considered adaptive responses that may occur after myocardial infarction, pressure overload, volume overload, inflammatory heart muscle disease, or idiopathic dilated cardiomyopathy, whereas long-term stimulation eventually leads to heart failure (HF). However, the current molecular mechanisms involved in CH are unclear. Recently, increasing evidences reveal that long non-coding RNAs (lncRNAs) play vital roles in CH. Different lncRNAs can promote or inhibit the pathological process of CH by different mechanisms, while the regulation of lncRNAs expression can improve CH. Thus, CH-related lncRNAs may become a novel field of research on CH.

Identifying ceRNA Networks Associated With the Susceptibility and Persistence of Atrial Fibrillation Through Weighted Gene Co-Expression Network Analysis

Background: Atrial fibrillation (AF) is the most common arrhythmia. We aimed to construct competing endogenous RNA (ceRNA) networks associated with the susceptibility and persistence of AF by applying the weighted gene co-expression network analysis (WGCNA) and prioritize key genes using the random walk with restart on multiplex networks (RWR-M) algorithm.

Methods: RNA sequencing results from 235 left atrial appendage samples were downloaded from the GEO database. The top 5,000 lncRNAs/mRNAs with the highest variance were used to construct a gene co-expression network using the WGCNA method. AF susceptibility- or persistence-associated modules were identified by correlating the module eigengene with the atrial rhythm phenotype. Using a module-specific manner, ceRNA pairs of lncRNA–mRNA were predicted. The RWR-M algorithm was applied to calculate the proximity between lncRNAs and known AF protein-coding genes. Random forest classifiers, based on the expression value of key lncRNA-associated ceRNA pairs, were constructed and validated against an independent data set.

Results: From the 21 identified modules, magenta and tan modules were associated with AF susceptibility, whereas turquoise and yellow modules were associated with AF persistence. ceRNA networks in magenta and tan modules were primarily involved in the inflammatory process, whereas ceRNA networks in turquoise and yellow modules were primarily associated with electrical remodeling. A total of 106 previously identified AF-associated protein-coding genes were found in the ceRNA networks, including 16 that were previously implicated in the genome-wide association study. Myocardial infarction–associated transcript (MIAT) and LINC00964 were prioritized as key lncRNAs through RWR-M. The classifiers based on their associated ceRNA pairs were able to distinguish AF from sinus rhythm with respective AUC values of 0.810 and 0.940 in the training set and 0.870 and 0.922 in the independent test set. The AF-related single-nucleotide polymorphism rs35006907 was found in the intronic region of LINC00964 and negatively regulated the LINC00964 expression.

Conclusion: Our study constructed AF susceptibility- and persistence-associated ceRNA networks, linked genetics with epigenetics, identified MIAT and LINC00964 as key lncRNAs, and constructed random forest classifiers based on their associated ceRNA pairs. These results will help us to better understand the mechanisms underlying AF from the ceRNA perspective and provide candidate therapeutic and diagnostic tools.

Interaction between non-coding RNAs and Toll-like receptors

Toll-like receptors (TLRs) are a large group of pattern recognition receptors which are involved in the regulation of innate immune responses. Based on the interplay between TLRs and adapter molecules, two distinctive signaling cascades, namely the MyD88-dependent and TRIF-dependent pathways have been recognized. TLRs are involved in the development of a wide variety of diseases including cancer and autoimmune disorders. A large body of evidence has shown interaction between two classes of non-coding RNAs, namely microRNAs (miRNAs) and long noncoding RNAs (lncRNAs). These interactions have prominent roles in the pathogenesis of several disorders including infectious disorders, autoimmune conditions and neoplastic disorders. This review aims at description of the interaction between these non-coding RNAs and TLRs.

Silencing long non-coding RNA MIAT ameliorates myocardial dysfunction induced by myocardial infarction via MIAT/miR-10a-5p/EGR2 axis

Long non-coding RNA (lncRNA) myocardial infarction-associated transcript (MIAT) has been widely-demonstrated to function as diagnostic markers for acute myocardial infarction (MI). This study was designed to explore the modulatory role of MIAT and its underlying molecular mechanism in MI. Firstly, MI mouse model was developed via ligation of the descending branch of the left coronary artery, and cell model was established through exposure to hypoxic conditions. Online prediction indicated that MIAT could bind to microRNA-10a-5p (miR-10a-5p), while miR-10a-5p was highlighted to bind to early growth response gene-2 (EGR2). MIAT and EGR2 were subsequently determined to be highly-expressed, whereas miR-10a-5p was found to be poorly-expressed in cardiomyocytes exposed to hypoxia as well as in MI mice using RT-qPCR and Western blot assay. The binding relationships between MIAT and miR-10a-5p, and between miR-10a-5p and EGR2 were further confirmed by dual-luciferase reporter and RNA immunoprecipitation assays. The results of in vitro and in vivo experimentation also suggested that overexpression of miR-10a-5p or silencing of MIAT and EGR2 reduced cardiomyocyte apoptosis and increased ATP content, thus alleviating the impairment of cardiac function following MI. In a word, inhibition of MIAT protects against cardiac dysfunction induced by MI through the crosstalk with miR-10a-5p/EGR2.

MiR-93/HMGB3 regulatory axis exerts tumor suppressive effects in colorectal carcinoma cells

OBJECTIVE

MicroRNA (miR)-93 has been proven to mediate the initiation and progression of colorectal carcinoma (CRC); however, the mechanisms by which miR-93 mediates CRC development need deeper elucidation. The present study is designed to investigate the association between miR-93 and high mobility group box 3 (HMGB3), as well as the functions of miR-93, in CRC.

METHODS

miR-93 expression was quantified by RT-qPCR. CRC cells were transfected or cotransfected with miR-93 mimic, miR-93 inhibitor, pcDNA3.1-HMGB3 and sh-HMGB3, and then the proliferative, migratory and invasive capacities were detected in addition to the apoptotic rate. Western blotting assessed the expression levels of HMGB3, PI3K, p-PI3K, AKT and p-AKT. The interaction between miR-93 and HMGB3 was identified.

RESULTS

In CRC tissues, miR-93 was downregulated and HMGB3 was upregulated. LOVO and SW480 cells transfected with miR-93 mimic exhibited reduced proliferation, invasion and migration as well as increased apoptosis. The ratios of p-PI3K/PI3K and p-AKT/AKT were declined after miR-93 mimic was introduced into the CRC cell lines. miR-93 negatively downregulated HMGB3, and introduction of pcDNA3,1-HMGB3 could counteract, in part, the inhibitory effects of miR-93 on the malignant properties of CRC cells as well as the ratios of p-PI3K/PI3K and p-AKT/AKT.

CONCLUSION

miR-93 targeted HMGB3 to block the activation of the PI3K/AKT pathway and thus enhance CRC cell apoptosis.

Promoter polymorphisms in the lncRNA-MIAT gene associated with acute myocardial infarction in Chinese Han population: a case-control study

BACKGROUND

Coronary atherosclerotic disease (CAD) is one of the greatest causes of death and disability around the world, and has emerged as a major public health problem. Acute myocardial infarction (AMI) is the most serious type of CAD. Myocardial infarction (MI) association transcript (MIAT) has demonstrated that it plays an important role in AMI.

PURPOSE

To investigate the association between MIAT promoter polymorphisms and AMI in Chinese Han population.

METHODS

A total of 212 AMI patients and 218 healthy controls were recruited. The long non-coding RNA (lncRNA)-MIAT promoter polymorphisms (single nucleotide polymorphisms (SNPs)) were obtained using polymerase chain reaction (PCR) and sequencing techniques. Chi-square test was used to analyze the allele and genotype frequencies of each SNP in two groups. Logistic regression analysis was used to analyze the association of each SNP with AMI. Linkage disequilibrium (LD) and haplotype analysis were performed using SHEsis software. A JASPAR database search predicts transcription factors transition of linked polymorphism in MIAT promoter.

RESULTS

Ten SNPs were found, including rs56371714, rs55892869, rs151057042, rs2157598, rs150465374, rs5761664, rs8142890, rs5752375, rs9608515 and rs1055293700, whereas rs1055293700 was found only in the control group. Single and logistic regression analysis showed that there was a significant correlation between rs5752375 and rs9608515 polymorphisms and AMI, while other sites had no relationship with AMI. These MI association polymorphisms may change the binding sites with transcription factor.

CONCLUSIONS

The polymorphisms of lncRNA-MIAT promoter rs5752375 and rs9608515 were significantly associated with AMI in Chinese Han population. This result would be of clinical importance for the early diagnosis of AMI.

Research on Effect and Mechanism of Xuefu Zhuyu Decoction on CHD Based on Meta-Analysis and Network Pharmacology

Xuefu Zhuyu Decoction (XFZY) is an ancient compound widely used in the treatment of coronary heart disease. However, its efficacy evaluation is not complete and its mechanism of action is not clear enough. In an attempt to address these problems, the efficacy was evaluated by meta-analysis and the mechanism was elucidated by the network pharmacology method. We systematically searched relevant studies in PubMed, Chinese National Knowledge Infrastructure Database (CNKI), Cochrane Library, Wanfang Data, and other databases from 2007 to 2019. The association between XFZY treatment and CHD was estimated by risk ratio (RR) and corresponding 95% confidence intervals (95% CIs). The compounds and the potential protein targets of XFZY were obtained from TCMSP, and active compounds were selected according to their oral bioavailability and drug similarity. The potential genes of coronary heart disease were obtained from TTD, OMIM, and GeneCards. The potential pathways related to genes were determined by GO and KEGG pathway enrichment analyses. The compound-target and compound-target-pathway networks were constructed. Molecular docking validates the component and the target. A total of 21 studies including 1844 patients were enrolled in the present meta-analysis, indicating that XFZY has a greater beneficial on total effect (fixed effect RR = 1.30; 95% Cl: 1.24-1.36; P=0.82; I ² = 0.0%) and electrocardiogram efficacy (fixed effect RR = 1.40; 95% Cl: 1.26-1.56; P=0.96; I ² = 0.0%) compared with the control group. A total of 1342 components in XFZY were obtained, among which, 241 were chosen as bioactive components. GO and KEGG analyses got top 10 significantly enriched terms and 10 enriched pathways. The C-T network included 192 compounds and 3085 targets, whereas the C-T-P network included 10 compounds, 109 targets, and 5 pathways. There was a good binding activity between the components and the targets. XFZY has the curative effect on coronary heart disease, and its mechanism is related to 10 compounds, 10 core targets, and 5 pathways.

Epigenetic mechanisms underlying the benefits of flavonoids in cardiovascular health and diseases: are long non-coding RNAs rising stars?

Cardiovascular diseases (CVDs) rank as the first leading cause of death globally. High dietary polyphenol (especially flavonoids) intake has strongly been associated with low incidence of the primary outcome, overall mortality, blood pressure, inflammatory biomarkers, onset of new-onset type 2 diabetes mellitus (T2DM), and obesity. Phytogenic flavonoids affect the physiological and pathological processes of CVDs by modulating various biochemical signaling pathways. Non-coding RNAs (ncRNAs) have attracted increasing attention as fundamental regulator of gene expression involved in CVDs. Among the different ncRNA subgroups, long ncRNAs (lncRNAs) have recently emerged as regulatory eukaryotic transcripts and therapeutic targets with important and diverse functions in health and diseases. lncRNAs may be associated with the initiation, development and progression of CVDs by modulating acute and chronic inflammation, adipogenesis and lipid metabolism, and cellular physiology. This review summarizes this research on the modulatory effects of lncRNAs and their roles in mediating cellular processes. The mechanisms of action of flavonoids underlying their therapeutic effects on CVDs are also discussed. Based on our review, flavonoids might facilitate a significant epigenetic modification as part (if not full) of their tissue-/cell-related biological effects. This finding may be attributed to their interaction with cellular signaling pathways involved in chronic diseases. Certain lncRNAs might be the target of specific flavonoids, and some critical signaling processes involved in the intervention of CVDs might mediate the therapeutic roles of flavonoids.

Key Player in Cardiac Hypertrophy, Emphasizing the Role of Toll-Like Receptor 4

Toll-like receptor 4 (TLR4), a key pattern recognition receptor, initiates the innate immune response and leads to chronic and acute inflammation. In the past decades, accumulating evidence has implicated TLR4-mediated inflammatory response in regulation of myocardium hypertrophic remodeling, indicating that regulation of the TLR4 signaling pathway may be an effective strategy for managing cardiac hypertrophy's pathophysiology. Given TLR4's significance, it is imperative to review the molecular mechanisms and roles underlying TLR4 signaling in cardiac hypertrophy. Here, we comprehensively review the current knowledge of TLR4-mediated inflammatory response and its interaction ligands and co-receptors, as well as activation of various intracellular signaling. We also describe the associated roles in promoting immune cell infiltration and inflammatory mediator secretion, that ultimately cause cardiac hypertrophy. Finally, we provide examples of some of the most promising drugs and new technologies that have the potential to attenuate TLR4-mediated inflammatory response and prevent or reverse the ominous cardiac hypertrophy outcomes.

Knockdown of KCNQ1OT1 attenuates cardiac hypertrophy through modulation of the miR-2054/AKT3 axis

Background

Persistent cardiac hypertrophy threatens health worldwide. Long non-coding RNAs (lncRNAs) attracted lots of attention in cardiac diseases such as cardiac hypertrophy. In this study, we aimed to study the function of KCNQ1OT1 in cardiac hypertrophy.

Methods

We first used qRT-PCR to detect the expression of KCNQ1OT1 in Ang-II-induced cardiomyocytes and mouse cardiac hypertrophy models. The function of KCNQ1OT1 was investigated by a loss-of-function test. Analysis of the luciferase reporter gene and RNA pulldown confirmed the interaction between KCNQ1OT1 and miR-2054. The target gene of miR-2054 was predicted by bioinformatics analysis and confirmed by luciferase reporter gene detection. Rescue experiments were performed to evaluate the role of miR-2054/AKT3 in the function of KCNQ1OT1.

Results

Our results suggested that KCNQ1OT1 was up-regulated in Ang-II-induced cardiomyocytes and transverse aortic constriction (TAC) mice. Knocking down of KCNQ1OT1 can reduce cell size and downregulate the expression of ANF, BNP and α-MHC in response to Ang-II. KCNQ1OT1 has been shown to compete competitively with miR-2054 and has a negative correlation with its expression. The combination of miR-2054 can reverse the effect of the KCNQ1OT1 combination in Ang-II-induced cardiomyocytes. In addition, AKT3 is a target of miR-2054 and mediates its effect on Ang-II-induced cardiomyocytes.

Conclusions

Knockdown of KCNQ1OT1 could attenuate cardiac hypertrophy through modulation of the miR-2054/AKT3 axis.

The biological function and potential mechanism of long non-coding RNAs in cardiovascular disease

Long non-coding RNAs (lncRNAs), as part of the family of non-protein-coding transcripts, are implicated in the occurrence and progression of several cardiovascular diseases (CVDs). With recent advances in lncRNA research, these molecules are purported to regulate gene expression at multiple levels, thereby producing beneficial or detrimental biological effects during CVD pathogenesis. At the transcriptional level, lncRNAs affect gene expression by interacting with DNA and proteins, for example, components of chromatin-modifying complexes, or transcription factors affecting chromatin status. These potential mechanisms suggest that lncRNAs guide proteins to specific gene loci (eg promoter regions), or forestall proteins to specific genomic sites via DNA binding. Additionally, some lncRNAs are required for correct chromatin conformation, which occurs via chromatin looping in enhancer-like models. At the post-transcriptional level, lncRNAs interact with RNA molecules, mainly microRNAs (miRNAs) and mRNAs, potentially regulating CVD pathophysiological processes. Moreover, lncRNAs appear to post-transcriptionally modulate gene expression by participating in mRNA splicing, stability, degradation and translation. Thus, the purpose of this review is to provide a comprehensive summary of lncRNAs implicated in CVD biological processes, with an emphasis on potential mechanisms of action.

The roles of long noncoding RNAs in myocardial pathophysiology

Long noncoding RNAs (lncRNAs), more than 200 nt in length, are functional molecules found in various species. These lncRNAs play a vital role in cell proliferation, differentiation, and degeneration and are also involved in pathophysiological processes of cancer and neurodegenerative, autoimmune, and cardiovascular diseases (CVDs). In recent years, emerging challenges for intervention studies on ischemic heart diseases have received much attention. LncRNAs have a key function in the alleviation of myocardial infarction (MI) injury and myocardial ischemia–reperfusion injury. During cardiac hypertrophy (CH) and fibrosis, cardiac cells undergo structural changes and become dysfunctional due to the effects of neurohormonal factors. LncRNAs may serve as important therapeutic targets that promote cardiac remodeling and then retard the development of heart failure (HF). In addition, studies on the roles and mechanisms of action of lncRNAs participating in cardiac pathophysiology via other factors have become the focus of research worldwide. Here, we review the current knowledge on various lncRNAs and their functions in cardiac biology, particularly concentrating on ischemic heart disease, CH, and cardiac fibrosis. We next discuss the predictive value of lncRNAs as diagnostic biomarkers of CVDs.

Functional characterization of long noncoding RNAs

PURPOSE OF REVIEW

Mounting evidence suggests that long noncoding RNAs (lncRNAs) are essential regulators of gene expression. Although few lncRNAs have been the subject of detailed molecular and functional characterization, it is believed that lncRNAs play an important role in tissue homeostasis and development. In fact, gene expression profiling studies reveal lncRNAs are developmentally regulated in a tissue-type and cell-type specific manner. Such findings have brought significant attention to their potential contribution to disease cause. The current review summarizes recent studies of lncRNAs in the heart.

RECENT FINDINGS

lncRNA discovery has largely been driven by the implementation of next generation sequencing technologies. To date, such technologies have contributed to the identification of tens of thousands of distinct lncRNAs in humans -- accounting for a large majority of all RNA sequences transcribed across the human genome. Although the functions of these lncRNAs remain largely unknown, gain-of-function and loss-of-function studies (in vivo and in vitro) have uncovered a number of mechanisms by which lncRNAs regulate gene expression and protein function. Such mechanisms have been stratified according to three major functional categories: RNA sponges (RNA-mediated sequestration of free miRNAs; e.g. H19, MEG3, and MALAT1); transcription-modulating lncRNAs (RNA influences regulatory factor recruitment by binding to histone modifiers or transcription factors; e.g. CAIF, MANTIS, and NEAT1); and translation-modulating lncRNAs (RNA modifies protein function via directly interacting with a protein itself or binding partners; e.g. Airn, CCRR, and ZFAS1).

SUMMARY

Recent studies strongly suggest that lncRNAs function via binding to macromolecules (e.g. genomic DNA, miRNAs, or proteins). Thus, lncRNAs constitute an additional mode by which cells regulate gene expression.

Mechanism underlying increased cardiac extracellular matrix deposition in perinatal nicotine-exposed offspring

Although increased predisposition to cardiac fibrosis and cardiac dysfunction has been demonstrated in the perinatally nicotine-exposed heart, the underlying mechanisms remain unclear. With the use of a well-established rat model and cultured primary neonatal rat cardiac fibroblasts, the effect of perinatal nicotine exposure on offspring heart extracellular matrix deposition and the likely underlying mechanisms were investigated. Perinatal nicotine exposure resulted in increased collagen type I (COL1A1) and III (COL3A1) deposition along with a decrease in miR-29 family and an increase in long noncoding RNA myocardial infarction-associated transcript (MIAT) levels in offspring heart. Nicotine treatment of isolated primary neonatal rat cardiac fibroblasts suggested that these effects were mediated via nicotinic acetylcholine receptors including α7 and the induced collagens accumulation was reversed by a gain-of function of miR-29 family. Knockdown of MIAT resulted in increased miR-29 family and decreased COL1A1 and COL3A1 levels, suggesting nicotine-mediated MIAT induction as the underlying mechanism for nicotine-induced collagen deposition. Luciferase reporter assay and RNA immunoprecipitation studies showed an intense physical interaction between MIAT, miR-29 family, and argonaute 2, corroborating the mechanistic link between perinatal nicotine exposure and increased extracellular matrix deposition. Overall, perinatal nicotine exposure resulted in lower miR-29 family levels in offspring heart, while it elevated cardiac MIAT and collagen type I and III levels. These findings provide mechanistic basis for cardiac dysfunction in perinatal nicotine-exposed offspring and offer multiple novel potential therapeutic targets.NEW & NOTEWORTHY Using an established rat model and cultured primary neonatal cardiac fibroblasts, we show that nicotine mediated MIAT induction as the underlying mechanism for the excessive cardiac collagen deposition. These observations provide mechanistic basis for the increased predisposition to cardiac dysfunction following perinatal cigarette/nicotine exposure and offer novel potential therapeutic targets.

Regulation of Long Non-coding RNAs and MicroRNAs in Heart Disease: Insight Into Mechanisms and Therapeutic Approaches

Cardiovascular disease is the leading cause of mortality worldwide and there is an increasing need to identify new therapeutic targets that could be used to prevent or treat these diseases. Due to recent scientific advances, non-coding RNAs are widely accepted as important regulators of cellular processes, and the identification of an axis of interaction between long non-coding RNAs (lncRNAs) and micro RNAs (miRNAs) has provided another platform through which cardiovascular disease could be targeted therapeutically. Increasing evidence has detailed the importance of these non-coding RNAs, both individually and in an axis of regulation, in the processes and diseases involving the heart. However, further investigation into the consequences of targeting this mechanism, as well as refinement of how the system is targeted, are required before a treatment can be provided in clinic. This level of genomic regulation provides an exciting potential novel therapeutic strategy for the treatment of cardiovascular disease.

Differential expression of miR-142-3p protects cardiomyocytes from myocardial ischemia-reperfusion via TLR4/NFkB axis

Our research aims to explore the impact of miR-142 on myocardial apoptosis in the mouse ischemia and reperfusion (IR) model and investigate the underlying mechanisms at the molecular level. A considerable downregulation of miR-142 was observed in the cardiac area of mice post IR modeling. To understand the regulatory function of IR-induced miR-142 downregulation, the animals were categorized into four groups: IR model group; IR + agomir-142 group (IR mice treated with agomir-142); IR + antagomir-142 group (IR mice treated with antagomir-142); IR + agomir-142 + negative control (NC) group (IR mice processed with agomir-NC). The results indicated that agomir-142 upregulation was capable of shrinking IR damage-triggered infarction of the ventriculus sinister, strengthening myocardial function, and guarding against cardiomyocyte apoptosis, whereas further decreased miR-142 with antagomir-142 infection displayed negative influence of miR-142 against mice IR damage. In the cellular assay, miR-142 overexpression significantly improved proliferation and inhibited the apoptosis of neonatal rat cardiomyocytes (NRCs). Moreover, we found that miR-142 reduced the Bcl-2/Bax ratio and upregulated hydrogen peroxide (H₂ O₂ )-induced caspase-3 expression. Furthermore, transfection with an miR-142 mimic prevented the upregulation of TLR4/NFkB expression and activation in H₂ O₂ -treated NRCs. Our findings also revealed that miR-142 is linked to the 3'-untranslated area of the TLR4 gene. In addition, TLR4 overexpression considerably ablated the protective effects of miR-142 in terms of the cell viability of H₂ O₂ -treated NRCs. Taken together, miR-142 agomir injection in mice and miR-142 mimic transfection in NRCs plays a role in protecting the heart from IR damage and malfunction via the TLR4/NFkB axis both in vivo and in vitro.

Long Non-Coding RNAs in Atrial Fibrillation: Pluripotent Stem Cell-Derived Cardiomyocytes as a Model System

Atrial fibrillation (AF) is a type of sustained arrhythmia in humans often characterized by devastating alterations to the cardiac conduction system as well as the structure of the atria. AF can lead to decreased cardiac function, heart failure, and other complications. Long non-coding RNAs (lncRNAs) have been shown to play important roles in the cardiovascular system, including AF; however, a large group of lncRNAs is not conserved between mouse and human. Furthermore, AF has complex networks showing variations in mechanisms in different species, making it challenging to utilize conventional animal models to investigate the functional roles and potential therapeutic benefits of lncRNAs for AF. Fortunately, pluripotent stem cell (PSC)-derived cardiomyocytes (CMs) offer a reliable platform to study lncRNA functions in AF because of certain electrophysiological and molecular similarities with native human CMs. In this review, we first summarize the broad aspects of lncRNAs in various heart disease settings, then focus on their potential roles in AF development and pathophysiology. We also discuss current uses of PSCs in AF research and describe how these studies could be developed into novel therapeutics for AF and other cardiovascular diseases.

Competing Endogenous RNAs, Non-Coding RNAs and Diseases: An Intertwined Story

MicroRNAs (miRNAs), a class of small non-coding RNA molecules, are responsible for RNA silencing and post-transcriptional regulation of gene expression. They can mediate a fine-tuned crosstalk among coding and non-coding RNA molecules sharing miRNA response elements (MREs). In a suitable environment, both coding and non-coding RNA molecules can be targeted by the same miRNAs and can indirectly regulate each other by competing for them. These RNAs, otherwise known as competing endogenous RNAs (ceRNAs), lead to an additional post-transcriptional regulatory layer, where non-coding RNAs can find new significance. The miRNA-mediated interplay among different types of RNA molecules has been observed in many different contexts. The analyses of ceRNA networks in cancer and other pathologies, as well as in other physiological conditions, provide new opportunities for interpreting omics data for the field of personalized medicine. The development of novel computational tools, providing putative predictions of ceRNA interactions, is a rapidly growing field of interest. In this review, I discuss and present the current knowledge of the ceRNA mechanism and its implications in a broad spectrum of different pathologies, such as cardiovascular or autoimmune diseases, cancers and neurodegenerative disorders.

MiR-30e-5p is sponged by Kcnq1ot1 and represses Angiotensin II-induced hypertrophic phenotypes in cardiomyocytes by targeting ADAM9

Prolonged cardiac hypertrophy, a pathological compensatory response of the heart, finally leads to heart failure. Numerous studies have illustrated the vital roles of non-coding RNAs (ncRNAs) in cardiac hypertrophy. Here, we probed into the role and probable mechanism of microRNA-30e-5p (miR-30e-5p) in Angiotensin II (Ang-II)-stimulated hypertrophic cardiomyocytes. Intriguingly, the expression of hypertrophic markers, cell surface area and protein/DNA ratio were all reduced in Ang-II-induced hypertrophic cardiomyocytes when miR-30e-5p expression was augmented. Then, ADAM9 was screened out as the target of miR-30e-5p and ADAM9 overexpression rescued the effect of miR-30e-5p upregulation in Ang-II-treated cardiomyocytes. Moreover, we identified Kcnq1ot1 as the upstream of miR-30e-5p/ADAM9 axis and verified that Kcnq1ot1 aggrandized ADAM9 expression in Ang-II-treated cardiomyocytes through absorbing miR-30e-5p. Furthermore, rescue assays confirmed that ADAM9 up-regulation abrogated the repressive effect of Kcnq1ot1 depletion on Ang-II-induced cardiac hypertrophy. In conclusion, Kcnq1ot1 sequestered miR-30e-5p to release ADAM9 to facilitate cardiac hypertrophy, indicating that Kcnq1ot1 might be used as a potentially therapeutic target for cardiac hypertrophy.

A Guide to the Short, Long and Circular RNAs in Hypertension and Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in adults in developed countries. CVD encompasses many diseased states, including hypertension, coronary artery disease and atherosclerosis. Studies in animal models and human studies have elucidated the contribution of many genetic factors, including non-coding RNAs. Non-coding RNAs are RNAs not translated into protein, involved in gene expression regulation post-transcriptionally and implicated in CVD. Of these, circular RNAs (circRNAs) and microRNAs are relevant. CircRNAs are created by the back-splicing of pre-messenger RNA and have been underexplored as contributors to CVD. These circRNAs may also act as biomarkers of human disease, as they can be extracted from whole blood, plasma, saliva and seminal fluid. CircRNAs have recently been implicated in various disease processes, including hypertension and other cardiovascular disease. This review article will explore the promising and emerging roles of circRNAs as potential biomarkers and therapeutic targets in CVD, in particular hypertension.

The Expression of microRNA in Adult Rat Heart with Isoproterenol-Induced Cardiac Hypertrophy

Cardiac hypertrophy is a common pathological condition and an independent risk factor that triggers cardiovascular morbidity. As an important epigenetic regulator, miRNA is widely involved in many biological processes. In this study, miRNAs expressed in rat hearts that underwent isoprenaline-induced cardiac hypertrophy were identified using high-throughput sequencing, and functional verification of typical miRNAs was performed using rat primary cardiomyocytes. A total of 623 miRNAs were identified, of which 33 were specifically expressed in cardiac hypertrophy rats. The enriched pathways of target genes of differentially expressed miRNAs included the FoxO signaling pathway, dopaminergic synapse, Wnt signaling pathway, MAPK (mitogen-activated protein kinase) signaling pathway, and Hippo signaling pathway. Subsequently, miR-144 was the most differentially expressed miRNA and was subsequently selected for in vitro validation. Inhibition of miR-144 expression in primary myocardial cells caused up-regulation of cardiac hypertrophy markers atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). The dual luciferase reporter system showed that ANP may be a target gene of miR-144. Long non-coding RNA myocardial infarction associated transcript (LncMIAT) is closely related to heart disease, and here, we were the first to discover that LncMIAT may act as an miR-144 sponge in isoproterenol-induced cardiac hypertrophy. Taken together, these results enriched the understanding of miRNA in regulating cardiac hypertrophy and provided a reference for preventing and treating cardiac hypertrophy.

Up-regulation of SNHG16 induced by CTCF accelerates cardiac hypertrophy by targeting miR-182-5p/IGF1 axis

Long non-coding RNA (lncRNA) SNHG16 has been reported to be significant regulators in multiple cancers. However, never has the relationship between it and cardiac hypertrophy been studied until now. In this study, angiotensin II (Ang II)-treated cardiomyocytes isolated from neonatal mice were used as a model of cardiac hypertrophy in vitro. Real-time quantitative polymerase chain reaction was performed to measure the expression of SNHG16, miR-182-5p, and insulin-like growth factor 1 (IGF1). The relationship between SNHG16 and its downstream genes were corroborated by RNA pull-down and luciferase reporter experiments. Western blot was conducted to detect the expression of markers of hypertrophy. The results disclosed that SNHG16 expression was in a high level in the cardiac hypertrophic model. Down-regulation of SNHG16 could decline the expression of hypertrophic markers and reduce cell surface area induced by Ang II. Moreover, SNHG16 was discovered to be activated by transcription factor CCCTC-binding factor. In addition, SNHG16 could enlarge cell surface area and increase the expression of hypertrophic markers by inhibiting miR-182-5p expression in Ang II-treated cardiomyocytes. Finally, overexpression of IGF1 could rescue the effects of silenced SNHG16 on cardiac hypertrophy cells. In brief, our study illustrated that silenced SNHG16 repressed Ang II-imposed cardiac hypertrophy via targeting miR-182-5p/IGF1 axis.

Gene therapy for cardiovascular diseases in China: basic research

Cardiovascular disease has become a major disease affecting health in the whole world. Gene therapy, delivering foreign normal genes into target cells to repair damages caused by defects and abnormal genes, shows broad prospects in treating different kinds of cardiovascular diseases. China has achieved great progress of basic gene therapy researches and pathogenesis of cardiovascular diseases in recent years. This review will summarize the latest research about gene therapy of proteins, epigenetics, including noncoding RNAs and genome-editing technology in myocardial infarction, cardiac ischemia-reperfusion injury, atherosclerosis, muscle atrophy, and so on in China. We wish to highlight some important findings about the essential roles of basic gene therapy in this field, which might be helpful for searching potential therapeutic targets for cardiovascular disease.