Long non-coding RNAs link extracellular matrix gene expression to ischemic cardiomyopathy

Long non-coding RNAs in cardiac hypertrophy and heart failure: functions, mechanisms and clinical prospects

The surge in reports describing non-coding RNAs (ncRNAs) has focused attention on their possible biological roles and effects on development and disease. ncRNAs have been touted as previously uncharacterized regulators of gene expression and cellular processes, possibly working to fine-tune these functions. The sheer number of ncRNAs identified has outpaced the capacity to characterize each molecule thoroughly and to reliably establish its clinical relevance; it has, nonetheless, created excitement about their potential as molecular targets for novel therapeutic approaches to treat human disease. In this Review, we focus on one category of ncRNAs - long non-coding RNAs - and their expression, functions and molecular mechanisms in cardiac hypertrophy and heart failure. We further discuss the prospects for this specific class of ncRNAs as novel targets for the diagnosis and treatment of these conditions.

Role of long noncoding RNAs in pathological cardiac remodeling after myocardial infarction: An emerging insight into molecular mechanisms and therapeutic potential

Myocardial infarction (MI) is the leading cause of heart failure (HF), accounting for high mortality and morbidity worldwide. As a consequence of ischemia/reperfusion injury during MI, multiple cellular processes such as oxidative stress-induced damage, cardiomyocyte death, and inflammatory responses occur. In the next stage, the proliferation and activation of cardiac fibroblasts results in myocardial fibrosis and HF progression. Therefore, developing a novel therapeutic strategy is urgently warranted to restrict the progression of pathological cardiac remodeling. Recently, targeting long non-coding RNAs (lncRNAs) provided a novel insight into treating several disorders. In this regard, numerous investigations have indicated that several lncRNAs could participate in the pathogenesis of MI-induced cardiac remodeling, suggesting their potential therapeutic applications. In this review, we summarized lncRNAs displayed in the pathophysiology of cardiac remodeling after MI, emphasizing molecular mechanisms. Also, we highlighted the possible translational role of lncRNAs as therapeutic targets for this condition and discussed the potential role of exosomes in delivering the lncRNAs involved in post-MI cardiac remodeling.

Transcriptome and methylome sequencing reveals altered long non-coding RNA genes expression and their aberrant DNA methylation in equine sarcoids

Recent publications confirmed that long non-coding RNAs (lncRNAs) perform an essential function in gene-specific transcription regulation. Nevertheless, despite its important role, lncRNA has not yet been described in equine sarcoids, the skin neoplasia of horses. Therefore, the aim of this study is to deepen the knowledge about lncRNA expression in the pathogenesis of equine sarcoids and provide new insight into the regulatory function of lncRNA in the bovine papillomavirus-dependent neoplasia of horse dermal tissues. RNA sequencing (RNA-seq) data from 12 equine sarcoid samples and the corresponding controls were reanalyzed in this study. A total of 3396 differentially expressed (DE) lncRNAs and 128 DElncRNA-DE genes (DEGs) pairs were identified. Differentially expressed lncRNAs predicted target genes were enriched in pathways associated with inter alia the extracellular matrix disassembly and cancer pathways. Furthermore, methylation data from the same samples were integrated into the analysis, and 12 DElncRNAs were described as potentially disturbed by aberrant methylation. In conclusion, this study presents novel data about lncRNA's role in the pathogenesis of equine sarcoids.

The Function and Therapeutic Potential of lncRNAs in Cardiac Fibrosis

Cardiac fibrosis remains an unresolved problem in cardiovascular diseases. Fibrosis of the myocardium plays a key role in the clinical outcomes of patients with heart injuries. Moderate fibrosis is favorable for cardiac structure maintaining and contractile force transmission, whereas adverse fibrosis generally progresses to ventricular remodeling and cardiac systolic or diastolic dysfunction. The molecular mechanisms involved in these processes are multifactorial and complex. Several molecular mechanisms, such as TGF-β signaling pathway, extracellular matrix (ECM) synthesis and degradation, and non-coding RNAs, positively or negatively regulate myocardial fibrosis. Long noncoding RNAs (lncRNAs) have emerged as significant mediators in gene regulation in cardiovascular diseases. Recent studies have demonstrated that lncRNAs are crucial in genetic programming and gene expression during myocardial fibrosis. We summarize the function of lncRNAs in cardiac fibrosis and their contributions to miRNA expression, TGF-β signaling, and ECMs synthesis, with a particular attention on the exosome-derived lncRNAs in the regulation of adverse fibrosis as well as the mode of action of lncRNAs secreted into exosomes. We also discuss how the current knowledge on lncRNAs can be applied to develop novel therapeutic strategies to prevent or reverse cardiac fibrosis.

Extracellular Non-Coding RNAs in Cardiovascular Diseases

Cardiovascular diseases (CVDs) remain the world's leading cause of death despite the best available healthcare and therapy. Emerging as a key mediator of intercellular and inter-organ communication in CVD pathogenesis, extracellular vesicles (EVs) are a heterogeneous group of membrane-enclosed nano-sized vesicles released by virtually all cells, of which their RNA cargo, especially non-coding RNAs (ncRNA), has been increasingly recognized as a promising diagnostic and therapeutic target. Recent evidence shows that ncRNAs, such as small ncRNAs, circular RNAs, and long ncRNAs, can be selectively sorted into EVs or other non-vesicular carriers and modulate various biological processes in recipient cells. In this review, we summarize recent advances in the literature regarding the origin, extracellular carrier, and functional mechanisms of extracellular ncRNAs with a focus on small ncRNAs, circular RNAs, and long ncRNAs. The pathophysiological roles of extracellular ncRNAs in various CVDs, including atherosclerosis, ischemic heart diseases, hypertension, cardiac hypertrophy, and heart failure, are extensively discussed. We also provide an update on recent developments and challenges in using extracellular ncRNAs as biomarkers or therapeutical targets in these CVDs.

Non-Coding RNAs in Regulating Plaque Progression and Remodeling of Extracellular Matrix in Atherosclerosis

Non-coding RNAs (ncRNAs) regulate cell proliferation, migration, differentiation, inflammation, metabolism of clinically important biomolecules, and other cellular processes. They do not encode proteins but are involved in the regulatory network of various proteins that are directly related to the pathogenesis of diseases. Little is known about the ncRNA-associated mechanisms of atherosclerosis and related cardiovascular disorders. Remodeling of the extracellular matrix (ECM) is critical in the pathogenesis of atherosclerosis and related disorders; however, its regulatory proteins are the potential subjects to explore with special emphasis on epigenetic regulatory components. The activity of regulatory proteins involved in ECM remodeling is regulated by various ncRNA molecules, as evident from recent research. Thus, it is important to critically evaluate the existing literature to enhance the understanding of nc-RNAs-regulated molecular mechanisms regulating ECM components, remodeling, and progression of atherosclerosis. This is crucial since deregulated ECM remodeling contributes to atherosclerosis. Thus, an in-depth understanding of ncRNA-associated ECM remodeling may identify novel targets for the treatment of atherosclerosis and other cardiovascular diseases.

Targeting Ferroptosis as a Promising Therapeutic Strategy for Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury is a major challenge in perioperative medicine that contributes to pathological damage in various conditions, including ischemic stroke, myocardial infarction, acute lung injury, liver transplantation, acute kidney injury and hemorrhagic shock. I/R damage is often irreversible, and current treatments for I/R injury are limited. Ferroptosis, a type of regulated cell death characterized by the iron-dependent accumulation of lipid hydroperoxides, has been implicated in multiple diseases, including I/R injury. Emerging evidence suggests that ferroptosis can serve as a therapeutic target to alleviate I/R injury, and pharmacological strategies targeting ferroptosis have been developed in I/R models. Here, we systematically summarize recent advances in research on ferroptosis in I/R injury and provide a comprehensive analysis of ferroptosis-regulated genes investigated in the context of I/R, as well as the therapeutic applications of ferroptosis regulators, to provide insights into developing therapeutic strategies for this devastating disease.

Non-coding RNAs: Important participants in cardiac fibrosis

Cardiac remodeling is a pathophysiological process activated by diverse cardiac stress, which impairs cardiac function and leads to adverse clinical outcome. This remodeling partly attributes to cardiac fibrosis, which is a result of differentiation of cardiac fibroblasts to myofibroblasts and the production of excessive extracellular matrix within the myocardium. Non-coding RNAs mainly include microRNAs and long non-coding RNAs. These non-coding RNAs have been proved to have a profound impact on biological behaviors of various cardiac cell types and play a pivotal role in the development of cardiac fibrosis. This review aims to summarize the role of microRNAs and long non-coding RNAs in cardiac fibrosis associated with pressure overload, ischemia, diabetes mellitus, aging, atrial fibrillation and heart transplantation, meanwhile shed light on the diagnostic and therapeutic potential of non-coding RNAs for cardiac fibrosis.

LKB1: An emerging therapeutic target for cardiovascular diseases

Cardiovascular diseases (CVDs) are currently the most common cause of morbidity and mortality worldwide. Experimental studies suggest that liver kinase B1 (LKB1) plays an important role in the heart. Several studies have shown that cardiomyocyte-specific LKB1 deletion leads to hypertrophic cardiomyopathy, left ventricular contractile dysfunction, and an increased risk of atrial fibrillation. In addition, the cardioprotective effects of several medicines and natural compounds, including metformin, empagliflozin, bexarotene, and resveratrol, have been reported to be associated with LKB1 activity. LKB1 limits the size of the damaged myocardial area by modifying cellular metabolism, enhancing the antioxidant system, suppressing hypertrophic signals, and inducing mild autophagy, which are all primarily mediated by the AMP-activated protein kinase (AMPK) energy sensor. LKB1 also improves myocardial efficiency by modulating the function of contractile proteins, regulating the expression of electrical channels, and increasing vascular dilatation. Considering these properties, stimulation of LKB1 signaling offers a promising approach in the prevention and treatment of heart diseases.

LncAABR07025387.1 Enhances Myocardial Ischemia/Reperfusion Injury Via miR-205/ACSL4-Mediated Ferroptosis

Ferroptosis is associated with the pathology of myocardial ischemia/reperfusion (MI/R) injury following myocardial infarction, which is a leading cause of death worldwide. Although long noncoding RNAs (lncRNAs) are known to regulate gene expression, their roles in MI/R-induced ferroptosis remain unclear. In this study, we explored the lncRNA expression profiles in a rat model of MI/R injury and found that the novel lncRNA, lncAABR07025387.1, was highly expressed in MI/R-injured myocardial tissues and hypoxia/reoxygenation (H/R)-challenged myocardial cells. Silencing lncAABR07025387.1 improved MI/R injury in vivo and inhibited myocardial cell ferroptosis under H/R conditions. Bioinformatics analyses and luciferase, pull-down, and RNA-binding immunoprecipitation assays further revealed that lncAABR07025387.1 interacted with miR-205, which directly targeted ACSL4, a known contributor to ferroptosis. Furthermore, downregulating miR-205 reversed the ACSL4 inhibition induced by silencing lncAABR07025387.1. These findings suggest that, mechanistically, lncAABR07025387.1 negatively regulates miR-205 expression and subsequently upregulates ACSL4-mediated ferroptosis. In conclusion, this study demonstrates that lncAABR07025387.1 acts as a competing endogenous RNA during MI/R injury and highlights the therapeutic potential of lncRNAs for treating myocardial injury.

Long Non-Coding RNAs in Oral Submucous Fibrosis: Their Functional Mechanisms and Recent Research Progress

Many studies have shown that most genomes are transcribed into non-coding RNAs (ncRNAs), including microRNAs (miRs) and long non-coding RNAs (lncRNAs), which can affect different cell characteristics. LncRNAs are long heterologous RNAs that regulate gene expression and various signaling pathways during homeostasis and development. Studies have shown that a lncRNA is an important regulatory molecule that can be targeted to change the physiology and function of cells. Expression or dysfunction of lncRNAs is closely related to various genetic, autoimmune, and metabolic diseases. The importance of ncRNAs in oral submucosal fibrosis (OSF) has garnered much attention in recent years. However, most research has focused on miRs. The role of these molecules in OSF is incompletely understood. This review focuses on the emerging role and function of lncRNAs in OSF as novel regulators. Finally, the potential functional role of lncRNAs as biomarkers for OSF diagnosis is also described. LncRNAs are expected to become a new therapeutic target, but more research is needed to understand their biological functions more deeply.

A comprehensive method protocol for annotation and integrated functional understanding of lncRNAs

Long non-coding RNAs (lncRNAs) are of fundamental biological importance; however, their functional role is often unclear or loosely defined as experimental characterization is challenging and bioinformatic methods are limited. We developed a novel integrated method protocol for the annotation and detailed functional characterization of lncRNAs within the genome. It combines annotation, normalization and gene expression with sequence-structure conservation, functional interactome and promoter analysis. Our protocol allows an analysis based on the tissue and biological context, and is powerful in functional characterization of experimental and clinical RNA-Seq datasets including existing lncRNAs. This is demonstrated on the uncharacterized lncRNA GATA6-AS1 in dilated cardiomyopathy.

Transcriptome landscape of the late-stage alcohol-induced osteonecrosis of the human femoral head

Osteonecrosis resulting from heavy ethanol consumption is one of the major causes of nontraumatic osteonecrosis of the femoral head (ONFH). The underlying pathological and molecular mechanisms remain elusive. In this study, we performed deep RNA sequencing from femoral heads of patients diagnosed with late-stage alcohol-induced ONFH (AIONFH), other types of ONFH and traumatic injury (bone fracture). Genome-wide gene expression analyses identified 690 differentially expressed mRNAs in AIONFH. Gene annotation and pathway analyses revealed significant dysregulated genes involved in hemostasis, angiogenesis and bone remodeling processes from the late-stage AIONFH. Notably, ADH1B, which codes for one of the major alcohol dehydrogenases, is significantly upregulated in AIONFH samples. Further, we found that the ADH1B protein was primarily expressed in smooth muscle cells of the blood vessels, stromal cells and adipocytes of the femoral heads of AIONFH patients; but was absent in other ONFH samples. Our analyses also revealed unique long non-coding RNA (lncRNA) expression profiles and identified novel lncRNAs in AIONFH. In addition, we observed a close co-expression correlation between lncRNAs and mRNAs in AIONFH suggesting that cis-gene regulation represents a major mechanism of action of human femoral lncRNAs. Further, the expression signature of lncRNAs, but not mRNAs, distinguishes AIONFH from other types of ONFH. Taken together, our studies uncovered novel molecular signatures associated with late-stage AIONFH in which the dysregulation of several key signaling pathways within the femoral head may be involved in AIONFH. Subsequently, lncRNAs may serve as potential biomarkers for diagnosis and therapeutic treatment of AIONFH. Further studies are needed to confirm that ADH1B is specifically upregulated in AIONFH and not generally upregulated in patients who consume alcohol excessively.

LncRNA LncHrt preserves cardiac metabolic homeostasis and heart function by modulating the LKB1-AMPK signaling pathway

Metabolic modulation is a promising therapeutic approach to prevent adverse remodeling of the ischemic heart. Because little is known about the involvement of long non-coding RNAs (lncRNAs) in regulating cardiac metabolism, we used unbiased transcriptome profiling in a mouse model of myocardial infarction (MI). We identified a novel cardiomyocyte-enriched lncRNA, called LncHrt, which regulates metabolism and the pathophysiological processes that lead to heart failure. AAV-based LncHrt overexpression protects the heart from MI as demonstrated by improved contractile function, preserved metabolic homeostasis, and attenuated maladaptive remodeling responses. RNA-pull down followed by mass spectrometry and RNA immunoprecipitation (RIP) identified SIRT2 as a LncHrt-interacting protein involved in cardiac metabolic regulation. Mechanistically, we established that LncHrt interacts with SIRT2 to preserve SIRT2 deacetylase activity by interfering with the CDK5 and SIRT2 interaction. This increases downstream LKB1-AMPK kinase signaling, which ameliorates functional and metabolic deficits. Importantly, we found the expression of the human homolog of mouse LncHrt was decreased in patients with dilated cardiomyopathy. Together, these studies identify LncHrt as a cardiac metabolic regulator that plays an essential role in preserving heart function by regulating downstream metabolic signaling pathways. Consequently, LncHrt is a potentially novel RNA-based therapeutic target for ischemic heart disease.

Long non-coding RNA MFAT1 promotes skeletal muscle fibrosis by modulating the miR-135a-5p-Tgfbr2/Smad4 axis as a ceRNA

Fibrosis after skeletal muscle injury is common in sports and can cause irreversible damage to the biomechanical properties of skeletal muscle. Long non-coding RNAs (lncRNAs) have been validated to act as important modulators in the fibrosis of various organs. Here, we reported a novel lncRNA (the skeletal muscle fibrosis-associated transcript 1, lnc-MFAT1), which was highly expressed in skeletal muscle fibrosis. We demonstrate that lnc-MFAT1 knockdown can reduce TGFβ-induced fibrosis in vitro and attenuate skeletal muscle fibrosis after acute contusion in mice. Further study showed that lnc-MFAT1 acted as a competitive endogenous RNA of miR-135a-5p. Besides, the miR-135a-5p inhibition obviously promoted TGFβ-induced fibrosis in vitro via enhancing its target genes Tgfbr2/Smad4. Moreover, we discovered that lnc-MFAT1 regulates Tgfbr2/Smad4 expression by sponging miR-135a-5p to exert competing endogenous RNA function, resulting in TGFβ pathway activation. In conclusion, our study identified a crucial role of lnc-MFAT1-miR-135a-Tgfbr2/Smad4 axis in skeletal muscle fibrosis, providing a promising treatment option against skeletal muscle fibrosis.

The cardiac translational landscape reveals that micropeptides are new players involved in cardiomyocyte hypertrophy

Hypertrophic growth of cardiomyocytes is one of the major compensatory responses in the heart after physiological or pathological stimulation. Protein synthesis enhancement, which is mediated by the translation of messenger RNAs, is one of the main features of cardiomyocyte hypertrophy. Although the transcriptome shift caused by cardiac hypertrophy induced by different stimuli has been extensively investigated, translatome dynamics in this cellular process has been less studied. Here, we generated a nucleotide-resolution translatome as well as transcriptome data from isolated primary cardiomyocytes undergoing hypertrophy. More than 10,000 open reading frames (ORFs) were detected from the deep sequencing of ribosome-protected fragments (Ribo-seq), which orchestrated the shift of the translatome in hypertrophied cardiomyocytes. Our data suggest that rather than increase the translational rate of ribosomes, the increased efficiency of protein synthesis in cardiomyocyte hypertrophy was attributable to an increased quantity of ribosomes. In addition, more than 100 uncharacterized short ORFs (sORFs) were detected in long noncoding RNA genes from Ribo-seq with potential of micropeptide coding. In a random test of 15 candidates, the coding potential of 11 sORFs was experimentally supported. Three micropeptides were identified to regulate cardiomyocyte hypertrophy by modulating the activities of oxidative phosphorylation, the calcium signaling pathway, and the mitogen-activated protein kinase (MAPK) pathway. Our study provides a genome-wide overview of the translational controls behind cardiomyocyte hypertrophy and demonstrates an unrecognized role of micropeptides in cardiomyocyte biology.

Epigenetics-based therapeutics for myocardial fibrosis

Myocardial fibrosis (MF) is a reactive remodeling process in response to myocardial injury. It is mainly manifested by the proliferation of cardiac muscle fibroblasts and secreting extracellular matrix (ECM) proteins to replace damaged tissue. However, the excessive production and deposition of extracellular matrix, and the rising proportion of type I and type III collagen lead to pathological fibrotic remodeling, thereby facilitating the development of cardiac dysfunction and eventually causing heart failure with heightened mortality. Currently, the molecular mechanisms of MF are still not fully understood. With the development of epigenetics, it is found that epigenetics controls the transcription of pro-fibrotic genes in MF by DNA methylation, histone modification and noncoding RNAs. In this review, we summarize and discuss the research progress of the mechanisms underlying MF from the perspective of epigenetics, including the newest m6A modification and crosstalk between different epigenetics in MF. We also offer a succinct overview of promising molecules targeting epigenetic regulators, which may provide novel therapeutic strategies against MF.

Pivotal Role of TGF-β/Smad Signaling in Cardiac Fibrosis: Non-coding RNAs as Effectual Players

Unintended cardiac fibroblast proliferation in many pathophysiological heart conditions, known as cardiac fibrosis, results in pooling of extracellular matrix (ECM) proteins in the heart muscle. Transforming growth factor β (TGF-β) as a pivotal cytokine/growth factor stimulates fibroblasts and hastens ECM production in injured tissues. The TGF-β receptor is a heterodimeric receptor complex on the plasma membrane, made up from TGF-β type I, as well as type II receptors, giving rise to Smad2 and Smad3 transcription factors phosphorylation upon canonical signaling. Phosphorylated Smad2, Smad3, and cytoplasmic Smad4 intercommunicate to transfer the signal to the nucleus, culminating in provoked gene transcription. Additionally, TGF-β receptor complex activation starts up non-canonical signaling that lead to the mitogen-stimulated protein kinase cascade activation, inducing p38, JNK1/2 (c-Jun NH2-terminal kinase 1/2), and ERK1/2 (extracellular signal–regulated kinase 1/2) signaling. TGF-β not only activates fibroblasts and stimulates them to differentiate into myofibroblasts, which produce ECM proteins, but also promotes fibroblast proliferation. Non-coding RNAs (ncRNAs) are important regulators of numerous pathways along with cellular procedures. MicroRNAs and circular long ncRNAs, combined with long ncRNAs, are capable of affecting TGF-β/Smad signaling, leading to cardiac fibrosis. More comprehensive knowledge based on these processes may bring about new diagnostic and therapeutic approaches for different cardiac disorders.

Non-coding RNAs modulate function of extracellular matrix proteins

The extracellular matrix (ECM) creates a multifaceted system for the interaction of diverse structural proteins, matricellular molecules, proteoglycans, hyaluronan, and various glycoproteins that collaborate and bind with each other to produce a bioactive polymer. Alterations in the composition and configuration of ECM elements influence the cellular phenotype, thus participating in the pathogenesis of several human disorders. Recent studies indicate the crucial roles of non-coding RNAs in the modulation of ECM. Several miRNAs such as miR-21, miR-26, miR-19, miR-140, miR-29, miR-30, miR-133 have been dysregulated in disorders that are associated with disruption or breakdown of the ECM. Moreover, expression of MALAT1, PVT1, SRA1, n379519, RMRP, PFL, TUG1, TM1P3, FAS-AS1, PART1, XIST, and expression of other lncRNAs is altered in disorders associated with the modification of ECM components. In the current review, we discuss the role of lncRNAs and miRNAs in the modification of ECM and their relevance with the pathophysiology of human disorders such as cardiac/ lung fibrosis, cardiomyopathy, heart failure, asthma, osteoarthritis, and cancers.

Long noncoding RNA Cfast regulates cardiac fibrosis

Cardiac fibrosis occurs in most cardiac diseases, which reduces cardiac muscle compliance, impairs both systolic and diastolic heart function and, ultimately, leads to heart failure. Long noncoding RNAs (lncRNAs) have recently emerged as important regulators of a variety of biological processes; however, little is known about the expression and function of lncRNAs in cardiac fibrosis. Using unbiased transcriptome profiling in a mouse model of myocardial infarction (MI), we identified a cardiac fibroblast-enriched lncRNA (AK048087) named cardiac fibroblast-associated transcript (Cfast), which is significantly elevated after MI. Silencing Cfast expression by small interfering RNAs (siRNAs) or lentiviral short hairpin RNAs (shRNAs) resulted in suppression of fibrosis-related gene expression and transdifferentiation of myofibroblasts into cardiac fibroblasts. Depletion of Cfast by lentiviral shRNAs in mouse hearts significantly attenuated cardiac fibrosis induced by MI or isoproterenol-infusion. Importantly, inhibition of Cfast ameliorated cardiac function following cardiac injury. RNA pull-down followed by mass spectrometry analyses identified COTL1 (coactosin-like 1) as one of the Cfast interacting proteins. Mechanistically, Cfast competitively inhibits the COTL1 interaction with TRAP1 (transforming growth factor-β receptor-associated protein 1), which enhances TGF-β signaling by augmenting SMAD2/SMAD4 complex formation. Therefore, our study identifies Cfast as a novel cardiac fibroblast-enriched lncRNA that regulates cardiac fibroblast activation in response to pathophysiological stress. Cfast could serve as a potential therapeutic target for the prevention of cardiac fibrosis and cardiac diseases.

Cardiac ECM: Its Epigenetic Regulation and Role in Heart Development and Repair

The extracellular matrix (ECM) is the non-cellular component in the cardiac microenvironment, and serves essential structural and regulatory roles in establishing and maintaining tissue architecture and cellular function. The patterns of molecular and biochemical ECM alterations in developing and adult hearts depend on the underlying injury type. In addition to exploring how the ECM regulates heart structure and function in heart development and repair, this review conducts an inclusive discussion of recent developments in the role, function, and epigenetic guidelines of the ECM. Moreover, it contributes to the development of new therapeutics for cardiovascular disease.

Genomics of Human Fibrotic Diseases: Disordered Wound Healing Response

Fibrotic disease, which is implicated in almost half of all deaths worldwide, is the result of an uncontrolled wound healing response to injury in which tissue is replaced by deposition of excess extracellular matrix, leading to fibrosis and loss of organ function. A plethora of genome-wide association studies, microarrays, exome sequencing studies, DNA methylation arrays, next-generation sequencing, and profiling of noncoding RNAs have been performed in patient-derived fibrotic tissue, with the shared goal of utilizing genomics to identify the transcriptional networks and biological pathways underlying the development of fibrotic diseases. In this review, we discuss fibrosing disorders of the skin, liver, kidney, lung, and heart, systematically (1) characterizing the initial acute injury that drives unresolved inflammation, (2) identifying genomic studies that have defined the pathologic gene changes leading to excess matrix deposition and fibrogenesis, and (3) summarizing therapies targeting pro-fibrotic genes and networks identified in the genomic studies. Ultimately, successful bench-to-bedside translation of observations from genomic studies will result in the development of novel anti-fibrotic therapeutics that improve functional quality of life for patients and decrease mortality from fibrotic diseases.

Cardiac fibrosis

Myocardial fibrosis, the expansion of the cardiac interstitium through deposition of extracellular matrix proteins, is a common pathophysiologic companion of many different myocardial conditions. Fibrosis may reflect activation of reparative or maladaptive processes. Activated fibroblasts and myofibroblasts are the central cellular effectors in cardiac fibrosis, serving as the main source of matrix proteins. Immune cells, vascular cells and cardiomyocytes may also acquire a fibrogenic phenotype under conditions of stress, activating fibroblast populations. Fibrogenic growth factors (such as transforming growth factor-β and platelet-derived growth factors), cytokines [including tumour necrosis factor-α, interleukin (IL)-1, IL-6, IL-10, and IL-4], and neurohumoral pathways trigger fibrogenic signalling cascades through binding to surface receptors, and activation of downstream signalling cascades. In addition, matricellular macromolecules are deposited in the remodelling myocardium and regulate matrix assembly, while modulating signal transduction cascades and protease or growth factor activity. Cardiac fibroblasts can also sense mechanical stress through mechanosensitive receptors, ion channels and integrins, activating intracellular fibrogenic cascades that contribute to fibrosis in response to pressure overload. Although subpopulations of fibroblast-like cells may exert important protective actions in both reparative and interstitial/perivascular fibrosis, ultimately fibrotic changes perturb systolic and diastolic function, and may play an important role in the pathogenesis of arrhythmias. This review article discusses the molecular mechanisms involved in the pathogenesis of cardiac fibrosis in various myocardial diseases, including myocardial infarction, heart failure with reduced or preserved ejection fraction, genetic cardiomyopathies, and diabetic heart disease. Development of fibrosis-targeting therapies for patients with myocardial diseases will require not only understanding of the functional pluralism of cardiac fibroblasts and dissection of the molecular basis for fibrotic remodelling, but also appreciation of the pathophysiologic heterogeneity of fibrosis-associated myocardial disease.

Noncoding RNAs implication in cardiovascular diseases in the COVID-19 era

COronaVIrus Disease 19 (COVID-19) is caused by the infection of the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2). Although the main clinical manifestations of COVID-19 are respiratory, many patients also display acute myocardial injury and chronic damage to the cardiovascular system. Understanding both direct and indirect damage caused to the heart and the vascular system by SARS-CoV-2 infection is necessary to identify optimal clinical care strategies. The homeostasis of the cardiovascular system requires a tight regulation of the gene expression, which is controlled by multiple types of RNA molecules, including RNA encoding proteins (messenger RNAs) (mRNAs) and those lacking protein-coding potential, the noncoding-RNAs. In the last few years, dysregulation of noncoding-RNAs has emerged as a crucial component in the pathophysiology of virtually all cardiovascular diseases. Here we will discuss the potential role of noncoding RNAs in COVID-19 disease mechanisms and their possible use as biomarkers of clinical use.

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.

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.

LncRNA XIST promotes myocardial infarction by regulating FOS through targeting miR-101a-3p

The purpose of this study was to reveal the hypothesis that lncRNA X inactive specific transcript (XIST) can participate in the regulation of cardiomyocyte apoptosis in neonatal mice cardiomyocytes (NMCMs) and myocardial infarction (MI) through targeting miR-101a-3p. NMCMs were isolated from neonatal C57BL/6 mice and anoxia was induced in hypoxic chamber. MTT assay and flow cytometry were used to determine proliferation and apoptosis respectively. The target relationship among XIST, miR-101a-3p and FOS was revealed by bioinformatic analysis, luciferase reporter assay, pull-down assay and RNA immunoprecipitation assay. The expression of XIST, miR-101a-3p, FOS and apoptosis-related proteins was determined by qRT-PCR or western blot. MI model was constructed to reveal the role of XIST. We found that XIST was up-regulated in NMCMs under anoxia condition. Moreover, XIST increased FOS expression by sponging miR-101a-3p in anoxia cells. Silencing XIST expression improved cell viability and suppressed apoptosis in vitro and inhibited myocardial infarction by reducing the level of c-FOS and apoptosis-related proteins in vivo. Our findings suggest that XIST is involved in MI, modulation of its level can be used as a new strategy or potential target in the treatment of myocardial infarction.

Perspectives on Directions and Priorities for Future Preclinical Studies in Regenerative Medicine

The myocardium consists of numerous cell types embedded in organized layers of ECM (extracellular matrix) and requires an intricate network of blood and lymphatic vessels and nerves to provide nutrients and electrical coupling to the cells. Although much of the focus has been on cardiomyocytes, these cells make up <40% of cells within a healthy adult heart. Therefore, repairing or regenerating cardiac tissue by merely reconstituting cardiomyocytes is a simplistic and ineffective approach. In fact, when an injury occurs, cardiac tissue organization is disrupted at the level of the cells, the tissue architecture, and the coordinated interaction among the cells. Thus, reconstitution of a functional tissue must reestablish electrical and mechanical communication between cardiomyocytes and restore their surrounding environment. It is also essential to restore distinctive myocardial features, such as vascular patency and pump function. In this article, we review the current status, challenges, and future priorities in cardiac regenerative or reparative medicine. In the first part, we provide an overview of our current understanding of heart repair and comment on the main contributors and mechanisms involved in innate regeneration. A brief section is dedicated to the novel concept of rejuvenation or regeneration, which we think may impact future development in the field. The last section describes regenerative therapies, where the most advanced and disruptive strategies used for myocardial repair are discussed. Our recommendations for priority areas in studies of cardiac regeneration or repair are summarized in Tables 1 and 2 .

Role of the long noncoding RNA H19 in TGF-β1-induced Tenon's capsule fibroblast proliferation and extracellular matrix deposition

Glaucoma filtration surgery (GFS) is a classic surgical method used to treat glaucoma, the second leading cause of blindness. Scar formation caused by excessive Tenon's capsule fibroblast activation leads to surgical failure. However, the mechanism underlying this activation is largely unknown. In this study, we first isolated primary human Tenon's capsule fibroblasts (HTFs) and found that TGF-β promoted the viability, proliferation and extracellular matrix (ECM) deposition of HTFs. Then, we showed that TGF-β promoted the expression of H19 in HTFs and that suppression of H19 inhibited the effect of TGF-β on HTFs. Furthermore, we revealed that H19 exerted its effects by interacting with miR-200a in TGF-β-treated HTFs. Additionally, we showed that β-catenin was a target of miR-200a in TGF-β-treated HTFs. We also demonstrated that H19 acted by modulating the H19/miR-200a/β-catenin regulatory axis in TGF-β-treated HTFs. Ultimately, we found that the components of the H19/miR-200a/β-catenin regulatory axis were aberrantly expressed in a rat model of GFS. Our results show that H19 indeed acts by modulating β-catenin expression via miR-200a in TGF-β-treated HTFs, thus providing a novel rationale for the development of H19-based strategies to attenuate scar formation after GFS.

Collaborative Regulation of LRG1 by TGF-β1 and PPAR-β/δ Modulates Chronic Pressure Overload-Induced Cardiac Fibrosis

BACKGROUND

Despite its established significance in fibrotic cardiac remodeling, clinical benefits of global inhibition of TGF (transforming growth factor)-β1 signaling remain controversial. LRG1 (leucine-rich-α2 glycoprotein 1) is known to regulate endothelial TGFβ signaling. This study evaluated the role of LRG1 in cardiac fibrosis and its transcriptional regulatory network in cardiac fibroblasts.

METHODS

Pressure overload-induced heart failure was established by transverse aortic constriction. Western blot, quantitative reverse transcription polymerase chain reaction, immunofluorescence, and immunohistochemistry were used to evaluate the expression level and pattern of interested targets or pathology during fibrotic cardiac remodeling. Cardiac function was assessed by pressure-volume loop analysis.

RESULTS

LRG1 expression was significantly suppressed in left ventricle of mice with transverse aortic constriction-induced fibrotic cardiac remodeling (mean difference, -0.00085 [95% CI, -0.0013 to -0.00043]; P=0.005) and of patients with end-stage ischemic-dilated cardiomyopathy (mean difference, 0.13 [95% CI, 0.012-0.25]; P=0.032). More profound cardiac fibrosis (mean difference, -0.014% [95% CI, -0.029% to -0.00012%]; P=0.048 for interstitial fibrosis; mean difference, -1.3 [95% CI, -2.5 to -0.2]; P=0.016 for perivascular fibrosis), worse cardiac dysfunction (mean difference, -2.5 ms [95% CI, -4.5 to -0.4 ms]; P=0.016 for Tau-g; mean difference, 13% [95% CI, 2%-24%]; P=0.016 for ejection fraction), and hyperactive TGFβ signaling in transverse aortic constriction-operated Lrg1-deficient mice (mean difference, -0.27 [95% CI, -0.47 to -0.07]; P<0.001), which could be reversed by cardiac-specific Lrg1 delivery mediated by adeno-associated virus 9. Mechanistically, LRG1 inhibits cardiac fibroblast activation by competing with TGFβ1 for receptor binding, while PPAR (peroxisome proliferator-activated receptor)-β/δ and TGFβ1 collaboratively regulate LRG1 expression via SMRT (silencing mediator for retinoid and thyroid hormone receptor). We further demonstrated functional interactions between LRG1 and PPARβ/δ in cardiac fibroblast activation.

CONCLUSIONS

Our results established a highly complex molecular network involving LRG1, TGFβ1, PPARβ/δ, and SMRT in regulating cardiac fibroblast activation and cardiac fibrosis. Targeting LRG1 or PPARβ/δ represents a promising strategy to control pathological cardiac remodeling in response to chronic pressure overload.

Curcumin Management of Myocardial Fibrosis and its Mechanisms of Action: A Review

Myocardial fibrosis is implicated as a leading risk factor for heart failure, arrhythmia, and sudden death after cardiac injury, as the excessive interstitial extracellular matrix impedes heart contraction and electrical conduction. Complicated mechanisms involving oxidative stress, pro-inflammatory cytokines, chemokine families, NLRP3 inflammasomes, growth factors, and non-coding RNAs participate in cardiac fibrogenesis and make it difficult to designate specific and effective therapies. Oriental herbs have been popular for thousands of years in the health care of Asian residents, due to their multi-targeted, multi-faceted approaches and their multi-functional effects in fighting difficult and complicated diseases, including cardiovascular disorders such as myocardial fibrosis. Curcumin, a natural polyphenol and yellow pigment obtained from the spice turmeric, was found to have strong anti-oxidant and anti-inflammatory properties. Increasing evidence has shown that curcumin can be used to prevent and treat myocardial fibrosis, when the myocardium suffers pathological pro-fibrotic changes in vivo and in vitro. The present review focuses on recent studies elucidating the mechanisms of curcumin in treating different pathologic conditions, including ischemia, hypoxia/reoxygenation, pressure or volume overload, and hyperglycemia or high-fat-induced cardiac fibrosis. Novel analogs such as C66, B2BrBC, Y20, and J17 have been designed to maximize the therapeutic potentials of curcumin. These optimized curcumin analogs with improved bioavailability and pharmacokinetic profiles need to be clinically verified before curcumin could be recommended for the treatment of myocardial fibrosis.

LncRNA CAIF was downregulated in end-stage cardiomyopathy and is a promising diagnostic and prognostic marker for this disease

Cardiac autophagy inhibitory factor (CAIF) is a novel lncRNA with protective effects on myocardial infarction. We explored the involvement of CAIF in end-stage cardiomyopathy. Patients with end-stage cardiomyopathy and healthy volunteers were included in this study. Myocardial tissues and serum were collected. CAIF was detected by RT-qPCR. ROC curve was used for diagnostic analysis. Prognostic value of CAIF expression for end-stage cardiomyopathy was evaluated by survival curve analysis. Correlations between CAIF expression and clinicopathological data of patients with end-stage cardiomyopathy were analysed by chi-square test. Downregulated CAIF was observed in end-stage cardiomyopathy patients than in healthy controls. CAIF expression distinguished end-stage cardiomyopathy patients from healthy controls and predict the survival of patients. LncRNA CAIF was downregulated in end-stage cardiomyopathy and may serve as a promising prognostic and diagnostic marker for this disease.

LncRNA 2810403D21Rik/Mirf promotes ischemic myocardial injury by regulating autophagy through targeting Mir26a

More evidence is emerging of the roles long non-coding RNAs (lncRNAs) play as regulatory factors in a variety of biological processes, but the mechanisms underlying the function of lncRNAs in acute myocardial infarction (AMI) have not been explicitly delineated. The present study identified the lncRNA 2810403D21Rik/AK007586/Mirf (myocardial infarction-regulatory factor), that inhibited macroautophagy/autophagy by modulating Mir26a (microRNA 26a). Inhibition of Mir26a led to cardiac injury both in vitro and in vivo, whereas overexpression of Mir26a attenuated ischemic stress-induced cell death by activating autophagy through targeting Usp15 (ubiquitin specific peptidase 15). More importantly, 2810403D21Rik/Mirf acted as a competitive endogenous RNA (ceRNA) of Mir26a; forced expression of 2810403D21Rik/Mirf downregulated Mir26a to inhibit autophagy. In contrast, loss of 2810403D21Rik/Mirf resulted in upregulation of Mir26a to promote autophagy and alleviate cardiac injury, which in turn improved cardiac function in MI mice. This study identified a lncRNA 2810403D21Rik/Mirf that functions as an anti-autophagic molecule via ceRNA activity toward Mir26a. Our findings suggest that knockdown of 2810403D21Rik/Mirf might be a novel therapeutic approach for cardiac diseases associated with autophagy.

ABBREVIATIONS

3-MA: 3-methyladenine; AAV-9: adenovirus associated virus-9; agoMir26a: cholesterol-conjugated Mir26a mimic; AMI: acute myocardial infarction; AMO-26a: Mir26a inhibitor; ATG: autophagy related; BECN1: beclin 1; ceRNA: competitive endogenous RNAs; EF: ejection fraction; f-2810403D21Rik/Mirf: fragment encompassing the Mir26a binding site; FS: fraction shortening; GFP-mRFP: a plasmid expressing green fluorescent protein-monomeric red fluorescent protein; lncRNA: long non-coding RNA; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; Mirf: myocardial infarction-regulatory factor; miRNAs: microRNAs; NC: negative control; NMCMs: neonatal mice cardiomyocytes; shRNA: short hairpin RNA; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; Usp15: ubiquitin specific peptidase 15.

Protein Quality Control Activation and Microtubule Remodeling in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disorder. It is mainly caused by mutations in genes encoding sarcomere proteins. Mutant forms of these highly abundant proteins likely stress the protein quality control (PQC) system of cardiomyocytes. The PQC system, together with a functional microtubule network, maintains proteostasis. We compared left ventricular (LV) tissue of nine donors (controls) with 38 sarcomere mutation-positive (HCMSMP) and 14 sarcomere mutation-negative (HCMSMN) patients to define HCM and mutation-specific changes in PQC. Mutations in HCMSMP result in poison polypeptides or reduced protein levels (haploinsufficiency, HI). The main findings were 1) several key PQC players were more abundant in HCM compared to controls, 2) after correction for sex and age, stabilizing heat shock protein (HSP)B1, and refolding, HSPD1 and HSPA2 were increased in HCMSMP compared to controls, 3) α-tubulin and acetylated α-tubulin levels were higher in HCM compared to controls, especially in HCMHI, 4) myosin-binding protein-C (cMyBP-C) levels were inversely correlated with α-tubulin, and 5) α-tubulin levels correlated with acetylated α-tubulin and HSPs. Overall, carrying a mutation affects PQC and α-tubulin acetylation. The haploinsufficiency of cMyBP-C may trigger HSPs and α-tubulin acetylation. Our study indicates that proliferation of the microtubular network may represent a novel pathomechanism in cMyBP-C haploinsufficiency-mediated HCM.

Inhibition of prostaglandin E2 receptor 4 by lnc000908 to promote the endothelial-mesenchymal transition participation in cardiac remodelling

Long non‐coding RNAs (lncRNAs) have emerged as potent regulators of cardiac disease; however, the role of lncRNA in cardiac fibrosis remains partially understood. In this study, we identified a cardiac endothelial‐enriched lncRNA‐lnc000908, which was markedly up‐regulated in rats with cardiac fibrosis. In addition, the expression of prostaglandin E2 receptor 4 (EP4) was decreased in cardiac fibrosis. In vivo lnc000908 silencing by lentivirus increased the EP4 level, decreased endothelial‐mesenchymal transition (EndMT) and improved cardiac fibrosis and cardiac function. Consistently, the lnc000908 knockdown also up‐regulated EP4 and suppressed transforming growth factor‐beta (TGF‐β)‐induced EndMT in cardiac microvascular endothelial cells. In contrast, the lnc000908 overexpression by lentivirus decreased the EP4 level and induced EndMT. Of note, these pro‐ or anti‐EndMT effects were reversed by the EP4 overexpression or the EP4 antagonist AH‐23848, respectively. This study demonstrates that lnc000908 is a novel regulator of cardiac fibrosis by modulating the EP4 expression and EndMT.

Long Noncoding RNAs in Pathological Cardiac Remodeling: A Review of the Update Literature

Cardiac remodeling is a self-regulatory response of the myocardium and vasculature under the stressful condition. Cardiomyocytes (CMs), vascular smooth muscle cells (VSMCs), endothelial cells (ECs), and cardiac fibroblasts (CFs) are all involved in this process, characterized by change of morphological structures and mechanical/chemical activities as well as metabolic patterns. Despite current development of consciousness, the control of cardiac remodeling remains unsatisfactory, and to further explore the underlying mechanism and seek the optimal therapeutic targets is still the urgent need in clinical practice. It is now emerging that long noncoding RNAs (lncRNAs) play key regulatory roles in these adverse responses: lncRNA TUG1, AK098656, TRPV1, GAS5, Giver, and Lnc-Ang362 have been indicated in hypertension-related vascular remodeling, H19, TUG1, UCA1, MEG3, APPAT, and lincRNA-p21 in atherosclerosis (AS), and HIF1A-AS1 and Lnc-HLTF-5 in aortic aneurysm (AA). In addition, Neat1, AK139328, APF, CAIF, AK088388, CARL, MALAT1, HOTAIR, XIST, and NRF are involved in postischemia myocardial remodeling, while Mhrt, Chast, CHRF, ROR, H19, Plscr4, and MIAT are involved in myocardial hypertrophy, and MALAT1, wisper, MEG3, and H19 are involved in extracellular matrix (ECM) reconstitution. Signaling to specific miRNAs by acting as endogenous sponge (ceRNA) was the main form that regulates the target gene expression during cardiac remodeling. This review will underline the updates of lncRNAs and lncRNA-miRNA interactions in maladaptive remodeling and also cast light on their potential roles as therapeutic targets, hoping to provide supportive background for following research.

LncRNA: Shedding light on mechanisms and opportunities in fibrosis and aging

Fibrosis is universally observed in multiple aging-related diseases and progressions and is characterized by excess accumulation of the extracellular matrix. Fibrosis occurs in various human organs and eventually results in organ failure. Noncoding RNAs (ncRNAs) have emerged as essential regulators of cellular signaling and relevant human diseases. In particular, the enigmatic class of long noncoding RNAs (lncRNAs) is a kind of noncoding RNA that is longer than 200 nucleotides and does not possess protein coding ability. LncRNAs have been identified to exert both promotive and inhibitory effects on the multifaceted processes of fibrosis. A growing body of studies has revealed that lncRNAs are involved in fibrosis in various organs, including the liver, heart, lung, and kidney. As lncRNAs have been increasingly identified, they have become promising targets for anti-fibrosis therapies. This review systematically highlights the recent advances regarding the roles of lncRNAs in fibrosis and sheds light on the use of lncRNAs as a potential treatment for fibrosis.

LncRNA TUG1 sponges miR-204-5p to promote osteoblast differentiation through upregulating Runx2 in aortic valve calcification

Aims

Emerging evidence indicates that long non-coding RNAs (lncRNAs) play a vital role in cardiovascular physiology and pathology. Although the lncRNA TUG1 is implicated in atherosclerosis, its function in calcific aortic valve disease (CAVD) remains unknown.

Methods and results

In this study, we found that TUG1 was highly expressed in human aortic valves and primary valve interstitial cells (VICs). Moreover, TUG1 knockdown induced inhibition of osteoblast differentiation in CAVD both in vitro and in vivo. Mechanistically, silencing of TUG1 increased the expression of miR-204-5p and subsequently inhibited Runx2 expression at the post-transcriptional level. Importantly, TUG1 directly interacted with miR-204-5p and downregulation of miR-204-5p efficiently reversed the suppression of Runx2 induced by TUG1 short hairpin RNA (shRNA). Thus, TUG1 positively regulated the expression of Runx2, through sponging miR-204-5p, and promoted osteogenic differentiation in CAVD.

Conclusion

All together, the evidence generated by our study elucidates the role of lncRNA TUG1 as a miRNA sponge in CAVD, and sheds new light on lncRNA-directed diagnostics and therapeutics in CAVD.

Therapeutic role of miR-19a/19b in cardiac regeneration and protection from myocardial infarction

The primary cause of heart failure is the loss of cardiomyocytes in the diseased adult heart. Previously, we reported that the miR-17-92 cluster plays a key role in cardiomyocyte proliferation. Here, we report that expression of miR-19a/19b, members of the miR-17-92 cluster, is induced in heart failure patients. We show that intra-cardiac injection of miR-19a/19b mimics enhances cardiomyocyte proliferation and stimulates cardiac regeneration in response to myocardial infarction (MI) injury. miR-19a/19b protected the adult heart in two distinctive phases: an early phase immediately after MI and long-term protection. Genome-wide transcriptome analysis demonstrates that genes related to the immune response are repressed by miR-19a/19b. Using an adeno-associated virus approach, we validate that miR-19a/19b reduces MI-induced cardiac damage and protects cardiac function. Finally, we confirm the therapeutic potential of miR-19a/19b in protecting cardiac function by systemically delivering miR-19a/19b into mice post-MI. Our study establishes miR-19a/19b as potential therapeutic targets to treat heart failure.

RNA sequencing discloses the genome‑wide profile of long noncoding RNAs in dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a common type of non‑ischemic cardiomyopathy, of which the underlying mechanisms have not yet been fully elucidated. Long noncoding RNAs (lncRNAs) have been reported to serve crucial physiological roles in various cardiac diseases. However, the genome‑wide expression profile of lncRNAs remains to be elucidated in DCM. In the present study, a case‑control study was performed to identify expression deviations in circulating lncRNAs between patients with DCM and controls by RNA sequencing. Partial dysregulated lncRNAs were validated by reverse transcription‑polymerase chain reaction. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes pathway, and lncRNA‑messenger RNA (mRNA) co‑expression network analyses were employed to probe potential functions of these dysregulated lncRNAs in DCM. Comparison between 8 DCM and 8 control samples demonstrated that there were alterations in the expression levels of 988 lncRNAs and 1,418 mRNAs in total. The dysregulated lncRNAs were found to be mainly associated with system development, organ morphogenesis and metabolic regulation in terms of 'biological processes'. Furthermore, the analysis revealed that the gap junction pathway, phagosome, and dilated and hypertrophic cardiomyopathy pathways may serve crucial roles in the development of DCM. The lncRNA‑mRNA co‑expression network also suggested that the target genes of the lncRNAs were different in patients with DCM as compared with those in the controls. In conclusion, the present study revealed the genome‑wide profile of circulating lncRNAs in DCM by RNA sequencing, and explored the potential functions of these lncRNAs in DCM using bioinformatics analysis. These findings provide a theoretical foundation for future studies of lncRNAs in DCM.

The novel regulatory role of lncRNA-miRNA-mRNA axis in cardiovascular diseases

Long noncoding RNAs (lncRNAs) are RNAs longer than 200 nt in length that are characterized by low levels of sequence conservation and expression; lncRNAs modulate various biological functions at epigenetic, transcriptional and post-transcriptional levels, or directly regulate protein activity. As a family of small and evolutionarily conserved noncoding RNAs, microRNAs (miRNAs) are capable of regulating physiological and pathological processes via inhibiting target mRNA translation or promoting mRNA degradation. A number of studies have confirmed that both lncRNAs and miRNAs are closely associated with the development of cardiovascular diseases (CVDs), such as cardiac remodelling, heart failure, myocardial injury and arrhythmia, and that they act as biomarkers, potential therapeutic targets or strong indicators of prognosis; however, the underlying molecular mechanism has not been elucidated. Recently, emerging evidence showed that the novel regulatory mechanism underlying the crosstalk among lncRNAs, miRNAs and mRNAs plays a pivotal role in the pathophysiological processes of CVDs in response to stress stimuli. In this review, I comprehensively summarized the regulatory relationship of lncRNAs, miRNAs and mRNAs and highlighted the important role of the lncRNA-miRNA-mRNA axis in CVDs.

LncRNAs in TGF-β-Driven Tissue Fibrosis

Transforming growth factor-β (TGF-β) is a crucial mediator in tissue fibrosis that promotes accumulation of extracellular matrix (ECM), myofibroblasts to epithelial–mesenchymal transition (EMT), endothelial-mesenchymal transition (EndoMT), and apoptosis via canonical and noncanonical signaling pathways. In the past decades, a number of microRNAs have been reported to participate in TGF-β-mediated tissue scarring; however, the roles of long noncoding RNAs (lncRNAs) in fibrogenesis remain largely unknown. Recently, emerging evidence has shown that lncRNAs are involved in the development of different diseases, including cancer, autoimmune diseases, cardiovascular diseases, and fibrotic diseases. In this review, we summarize the current updates of lncRNAs in TGF-β1-driven tissue fibrosis and discuss their therapeutic potential for the treatment of chronic fibrotic diseases.

Long noncoding RNA Meg3 regulates cardiomyocyte apoptosis in myocardial infarction

Myocardial infarction (MI), with a major process of cardiomyocyte death, remains a leading cause of morbidity and mortality worldwide. To date, it has been shown that lncRNAs play important roles in cardiovascular pathology. However, the detailed studies on lncRNAs regulating cardiomyocyte death in myocardial infarction are still limited. In this study, we found a progressively upregulated expression of Meg3 in mouse injured heart after MI. Gain-of-function and loss-of-function approaches further revealed pro-apoptotic functions of Meg3 in rodent cardiomyocytes. Moreover, Meg3 was directly upregulated by p53 in hypoxic condition, and involved in apoptotic regulation via its direct binding with RNA-binding protein FUS (fused in sarcoma). Afterwards, adult MI mice that underwent intramyocardial injection with adeno-associated virus serotype 9 (AAV9) system carrying Meg3 shRNA showed a significant improvement of cardiac function. Moreover, we also found that MEG3 was increased in clinical heart failure samples, and had conservatively pro-apoptotic function in human cardiomyocytes that were differentiated from the human embryonic stem cells. Together, these results indicate that p53-induced Meg3-FUS complex plays an important role in cardiomyocyte apoptosis post-MI, and its specific knockdown in cardiomyocytes with AAV9 system represents a promising method to treat MI for preclinical investigation.