Janika Viereck

Non-coding RNAs in Development and Disease: Background, Mechanisms, and Therapeutic Approaches

Advances in RNA-sequencing techniques have led to the discovery of thousands of non-coding transcripts with unknown function. There are several types of non-coding linear RNAs such as microRNAs (miRNA) and long non-coding RNAs (lncRNA), as well as circular RNAs (circRNA) consisting of a closed continuous loop. This review guides the reader through important aspects of non-coding RNA biology. This includes their biogenesis, mode of actions, physiological function, as well as their role in the disease context (such as in cancer or the cardiovascular system). We specifically focus on non-coding RNAs as potential therapeutic targets and diagnostic biomarkers.

Circulating microRNAs as potential biomarkers of aerobic exercise capacity.

Purpose microRNAs (miRs) are crucial intracellular mediators of various biological processes, also affecting the cardiovascular system. Recently, it has been shown that miRs circulate extracellularly in the bloodstream and that such circulating miRs change in response to physical activity. Therefore, the purpose of the current study was to investigate heart/muscle specific and inflammation related miRs in plasma of individuals before, directly after, and 24 h after a marathon run and to analyze their relation to conventional biochemical, cardiovascular, and performance indexes. Male endurance athletes (n =14) were recruited for the study after performing a battery of cardiac functional tests. Blood samples were collected before, directly after, and 24 h after a public marathon run. miR-1, miR-133, miR-206, miR-499, miR-208b, miR-21, and miR-155 were measured using individual Taqman assays and normalized to Caenorhabditis elegans miR-39 (cel-39) spike-in control. Moreover, soluble cardiac, inflammatory, and muscle damage markers were determined. As a result, skeletal- and heart muscle-specific miRs showed a significant increase after the marathon. The strongest increase was observed for miR-206. Twenty-four hours after the run, only miR-499 and miR-208b were returned to preexercise levels, whereas the others were still enhanced. In contrast, miR-21 and -155 were not affected by exercise. miR-1, -133a, and -206 correlated to aerobic performance parameters such as maximum oxygen uptake (V̇o2max) and running speed at individual anaerobic lactate threshold (VIAS). miR-1 showed a moderate negative correlation with fractional shortening, whereas miR-133a was positively related to the thickness of intraventricular septum. None of the miRs correlated with cardiac injury markers such as troponin T, troponin I, and pro-brain natriuretic peptide. In conclusion, these findings suggest a potential role for muscle- and heart-specific miRs in cardiovascular adaptation processes after endurance exercise. Moreover, the specific correlation of miR-1, -133a, and -206 to performance parameters indicated their potential role as biomarkers of aerobic capacity.

Long noncoding RNA Chast promotes cardiac remodeling

Inhibition of the long noncoding RNA Chast prevents pressure overload–induced cardiac remodeling in mice. The missing lnc in cardiac hypertrophy RNA that does not code for a protein comprises a large portion of the human genome. These so-called noncoding RNAs are emerging as important players in disease pathogenesis, yet their functional roles are not always well known. Viereck et al. have discovered a new long noncoding RNA (lncRNA) that promotes cardiac remodeling and hypertrophy in mice, which could one day be targeted with therapeutics to treat human cardiovascular diseases. The identified lncRNA, which the authors named Chast (for “cardiac hypertrophy–associated transcript”), was discovered to be up-regulated in hypertrophic mouse hearts. When mouse and human heart cells expressed Chast, they tended to be larger than their normal counterparts. By silencing Chast with antisense oligonucleotides, mice either did not develop hypertrophy or were rescued from established disease. In a step toward translation, the authors discovered a human homolog, CHAST, that similarly caused cells in a dish to enlarge. Additional investigation in patients will confirm the relevance of this lncRNA in human disease and whether it is indeed a promising target for treating cardiac hypertrophy and heart failure. Recent studies highlighted long noncoding RNAs (lncRNAs) to play an important role in cardiac development. However, understanding of lncRNAs in cardiac diseases is still limited. Global lncRNA expression profiling indicated that several lncRNA transcripts are deregulated during pressure overload–induced cardiac hypertrophy in mice. Using stringent selection criteria, we identified Chast (cardiac hypertrophy–associated transcript) as a potential lncRNA candidate that influences cardiomyocyte hypertrophy. Cell fractionation experiments indicated that Chast is specifically up-regulated in cardiomyocytes in vivo in transverse aortic constriction (TAC)–operated mice. In accordance, CHAST homolog in humans was significantly up-regulated in hypertrophic heart tissue from aortic stenosis patients and in human embryonic stem cell–derived cardiomyocytes upon hypertrophic stimuli. Viral-based overexpression of Chast was sufficient to induce cardiomyocyte hypertrophy in vitro and in vivo. GapmeR-mediated silencing of Chast both prevented and attenuated TAC-induced pathological cardiac remodeling with no early signs on toxicological side effects. Mechanistically, Chast negatively regulated Pleckstrin homology domain–containing protein family M member 1 (opposite strand of Chast), impeding cardiomyocyte autophagy and driving hypertrophy. These results indicate that Chast can be a potential target to prevent cardiac remodeling and highlight a general role of lncRNAs in heart diseases.

Circulating Noncoding RNAs as Biomarkers of Cardiovascular Disease and Injury

The discovery of thousands of noncoding RNAs (ncRNAs) has expanded our view on mammalian genomes and transcriptomes, as well as their organization and regulation. Accumulating evidence on aberrantly regulated ncRNAs, including short microRNAs, long ncRNAs and circular RNAs, across various heart diseases indicates that ncRNAs are critical contributors to cardiovascular pathophysiology. In addition, ncRNAs are released into the circulation where they are present in concentration levels that differ between healthy subjects and diseased patients. Although little is known about the origin and function of such circulating ncRNAs, these molecules are increasingly recognized as noninvasive and readily accessible biomarker for risk stratification, diagnosis and prognosis of cardiac injury, and multiple forms of cardiovascular disease. In this review, we summarize recent findings on biological characteristics of circulating ncRNAs and highlight their value as potential biomarker in selected pathologies of cardiovascular disease.

Inhibition of the Cardiac Fibroblast-Enriched lncRNA Meg3 Prevents Cardiac Fibrosis and Diastolic Dysfunction

Rationale: Cardiac fibroblasts (CFs) drive extracellular matrix remodeling after pressure overload, leading to fibrosis and diastolic dysfunction. Recent studies described the role of long noncoding RNAs (lncRNAs) in cardiac pathologies. Nevertheless, detailed reports on lncRNAs regulating CF biology and describing their implication in cardiac remodeling are still missing. Objective: Here, we aimed at characterizing lncRNA expression in murine CFs after chronic pressure overload to identify CF-enriched lncRNAs and investigate their function and contribution to cardiac fibrosis and diastolic dysfunction. Methods and Results: Global lncRNA profiling identified several dysregulated transcripts. Among them, the lncRNA maternally expressed gene 3 (Meg3) was found to be mostly expressed by CFs and to undergo transcriptional downregulation during late cardiac remodeling. In vitro, Meg3 regulated the production of matrix metalloproteinase-2 (MMP-2). GapmeR-mediated silencing of Meg3 in CFs resulted in the downregulation of Mmp-2 transcription, which, in turn, was dependent on P53 activity both in the absence and in the presence of transforming growth factor-&bgr; I. Chromatin immunoprecipitation showed that further induction of Mmp-2 expression by transforming growth factor-&bgr; I was blocked by Meg3 silencing through the inhibition of P53 binding on the Mmp-2 promoter. Consistently, inhibition of Meg3 in vivo after transverse aortic constriction prevented cardiac MMP-2 induction, leading to decreased cardiac fibrosis and improved diastolic performance. Conclusions: Collectively, our findings uncover a critical role for Meg3 in the regulation of MMP-2 production by CFs in vitro and in vivo, identifying a new player in the development of cardiac fibrosis and potential new target for the prevention of cardiac remodeling.

Long Noncoding RNAs in Pathological Cardiac Remodeling

A novel long noncoding RNA Chaer acts as noncoding epigenetic regulator at the onset of cardiac hypertrophy and enables an improved understanding about the complex mechanisms in cardiovascular disease.

Impact of a Met(11)Thr single nucleotide polymorphism of surfactant protein D on allergic airway inflammation in a murine asthma model.

ABSTRACT The surfactant-associated proteins SP-A and D are pattern recognition molecules with collectin structure. A single nucleotide polymorphism (SNP) exchanging a methionine (Met) for a threonine (Thr) in the amino-terminal SP-D domain influences the oligomeric structure and function of the protein. In this study, we investigated the susceptibility of mice transgenic for the human SP-D Met(11)Thr SNP to allergic airway inflammation and consequences for microRNA (miRNA, miR) expression. Mice expressing either human Met or Thr SP-D were sensitized and challenged with ovalbumin (OVA) in an acute model of allergic asthma. The influence of the SP-D polymorphism on the allergic airway inflammation was evaluated by lung function measurement, pulmonary inflammation parameters, morphological analysis and miRNA expression. Airway hyperresponsiveness, allergic inflammation, and mucus metaplasia were not significantly different between mice expressing one or the other allelic variant of SP-D. OVA sensitization and challenge led to significant airway hyperresponsiveness in wildtype mice and significantly lower eosinophil numbers and interleukin 5 levels in Thr SP-D mice. OVA challenge induced an upregulation of miR-21 and 155 in Thr SP-D mice and a downregulation of miR-21 in Met SP-D mice. Our results show that murine expression of human polymorphic SP-D variants does not significantly influence the severity of allergic airway inflammation. MiR-21 and 155 are differentially regulated in transgenic mice in response to allergic inflammation. Further studies are required to elucidate the impact of this SNP on inflammatory conditions of the lung.

Long Noncoding RNAs as Inducers and Terminators of Vascular Development

Most of the human genome is transcribed.1 However, only 200 nt) noncoding RNAs (lncRNAs) are increasingly recognized as important modulators of gene expression in several physiological and pathological settings.4,5 Recent studies have emphasized the importance of lncRNAs as potential therapeutic targets or biomarkers for heart diseases.6,7 Article see p 1278 The heart is unique in its ability to contract and acutely respond to physiological changes. A completely developed heart is made up of different cell lineages that coordinately shape different regions of the organ with unique physiological characteristics. During embryonic development, as a result of gastrulation, the 3 germ layers, that is, the ectoderm, endoderm, and mesoderm, are formed.8 The cells that are destined to make up the heart are derived from the mesodermal layer. …

MicroRNA-Mediated Regulation of Cardiovascular Differentiation and Therapeutic Implications

Some stem cells—for example, embryonic, mesenchymal, and some progenitor cells—have the capacity to differentiate into cardiovascular cells lines such as cardiomyocytes, smooth-muscle cells, and endothelial cells. Mesenchymal stem cells serve a cardio-protective function by secreting large amounts of paracrine factors that regulate wound healing. miRNAs are important in cardiac wound healing and regeneration mediated by stem/progenitor cells, in that they modulate or precondition cardiac stem cells and thus optimize stem cell–based therapies. Stem/progenitor cell–based therapies are promising approaches to overcoming the limited capacity of the adult heart to recover after injury, using miRNAs as key regulators in cardiac wound healing and regeneration.