miR-146a Suppresses SUMO1 Expression and Induces Cardiac Dysfunction in Maladaptive Hypertrophy

The YAP/SERCA2a signaling pathway protects cardiomyocytes against reperfusion-induced apoptosis

Mitochondria and the endoplasmic reticulum (ER) are known to promote cardiac ischemia/reperfusion (I/R) injury. Overexpression of yes-associated protein (YAP) and/or sarcoplasmic reticulum calcium ATPase 2a (SERCA2a) has been shown to protect cardiomyocytes against I/R-induced injury. Here, we show that activation of the YAP/SERCA2a pathway attenuated mitochondrial damage and ER stress (ERS) to maintain cardiomyocyte viability in the setting of I/R injury. Our results demonstrate that I/R treatment reduced the transcription and expression of YAP and SERCA2a, along with a decline in cardiomyocyte viability. The overexpression of YAP promoted SERCA2a transcription, whereas SERCA2a upregulation did not affect the YAP transcription, suggesting that YAP functions upstream of SERCA2a. Activation of the YAP/SERCA2a pathway suppressed mitochondrial damage by sustaining the mitochondrial redox balance and restoring mitochondrial bioenergetics. Additionally, its activation repressed ERS, reduced calcium overload, and eventually blocked caspase activation. The knockdown of SERCA2a suppressed the protective effects of YAP overexpression on mitochondrial damage and ERS. Overall, our findings reveal that the YAP/SERCA2a pathway attenuates the mitochondrial damage and ERS in response to cardiac I/R injury by regulating the mitochondria–ER communication.

Roles and Clinical Applications of Exosomes in Cardiovascular Disease

Despite substantial improvements in therapeutic strategies, cardiovascular disease (CVD) is still among the leading causes of mortality and morbidity worldwide. Exosomes, extracellular vesicles with a lipid bilayer membrane of endosomal origin, have been the focus of a large body of research in CVD. Exosomes not only serve as carriers for signal molecules responsible for intercellular and interorgan communication underlying CVD pathophysiology but also are bioactive agents which are partly responsible for the therapeutic effect of stem cell therapy of CVD. We here review recent insights gained into the role of exosomes in apoptosis, hypertrophy, angiogenesis, fibrosis, and inflammation in CVD pathophysiology and progression and the application and mechanisms of exosomes as therapeutic agents for CVD.

Analysis of extracellular vesicle miRNA profiles in heart failure

Extracellular vesicles (EVs) have recently emerged as an important carrier for various genetic materials including microRNAs (miRs). Growing evidences suggested that several miRs transported by EVs were particularly involved in modulating cardiac function. However, it has remained unclear what miRs are enriched in EVs and play an important role in the pathological condition. Therefore, we established the miR expression profiles in EVs from murine normal and failing hearts and consecutively identified substantially altered miRs. In addition, we have performed bioinformatics approach to predict potential cardiac outcomes through the identification of miR targets. Conclusively, we observed approximately 63% of predicted targets were validated with previous reports. Notably, the predicted targets by this approach were often involved in both beneficial and malicious signalling pathways, which may reflect heterogeneous cellular origins of EVs in tissues. Lastly, there has been an active debate on U6 whether it is a proper control. Through further analysis of EV miR profiles, miR‐676 was identified as a superior reference control due to its consistent and abundant expressions. In summary, our results contribute to identifying specific EV miRs for the potential therapeutic targets in heart failure and suggest that miR‐676 as a new reference control for the EV miR studies.

Post-translational Modification Regulates Formation and Cargo-Loading of Extracellular Vesicles

Accumulating evidence suggests that post-translational modifications (PTMs) regulate the selective encapsulation of non-coding RNA molecules into extracellular vesicles (EVs) and contribute to the downstream functions of EVs or EV-cargo non-coding RNAs. EVs are a newly studied mechanism of intercellular communication that involves the transfer of molecules, including but not limited to proteins, lipids, and non-coding RNAs, to induce functional changes in the recipient cells. In this present mini-review, we focus on the PTM-regulated protein and non-coding RNA selection into eukaryotic EVs.

MicroRNA-27 attenuates pressure overload-Induced cardiac hypertrophy and dysfunction by targeting galectin-3

Cardiac hypertrophy is an adaptive response to hemodynamic stress to compensate for cardiac dysfunction. MicroRNAs can regulate cardiac function and play a vital role in the regulation of cardiac hypertrophy. In the current study, in vivo and vitro hypertrophy models are established to explore the role of miR-27b and to elucidate the underlying mechanism in cardiac hypertrophy. Expression of miR-27b was down-regulated in mice with cardiac hypertrophy. The cardiac function of the mice with cardiac hypertrophy could be restored with the overexpression of miR-27b, this is observed in terms of decreasing LVEDd, LVESd, and increasing LVFS, LVEF. This study also predicted and confirmed that galectin-3 is a target gene of miR-27b. Depletion of galectin-3 significantly attenuated hypertrophy of hearts in both in vitro and in vivo tests. In conclusion, MiR-27b be used to exert a protective role against cardiac dysfunction and hypertrophy by decreasing the expression level of galectin-3. The methodology suggested in this study provides a novel therapeutic strategy against cardiac hypertrophy.

Identification of a lncRNA-miRNA-mRNA network based on competitive endogenous RNA theory reveals functional lncRNAs in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease that affects 1 in every 200 people in the general population, leading to cardiac ischemia, heart failure and increased risk of sudden death. Recently, accumulating evidence has suggested that long noncoding RNAs (lncRNAs) may serve specific roles in various biological processes and participate in the pathology of various diseases, including HCM. Although a large number of lncRNAs have been detected, the functions of lncRNAs in HCM are still unknown. In the present study, a global triple network based on competitive endogenous RNA (ceRNA) theory was constructed using data from the National Center for Biotechnology Information Gene Expression Omnibus. Furthermore, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses of mRNAs in the lncRNA-microRNA (miRNA)-mRNA network were performed using the Cytoscape plugins, BiNGO and Database. The lncRNA-miRNA-mRNA network was composed of 30 lncRNA nodes, 94 mRNA nodes and 8 miRNA nodes. Subsequently, hub nodes and the number of relationship pairs were analyzed and showed that 5 lncRNAs (ENST00000597346.1, ENST00000458178.1, ENST00000544461.1, ENST00000567093.1 and ENST00000571219.1) were closely related to HCM. Cluster module analysis and Random Walk with Restart of the ceRNA network further confirmed the potential role of two lncRNAs (ENST00000458178.1 and ENST00000567093.1) in HCM. The present study provides a new strategy for identifying potential pathways associated with HCM or other diseases. Furthermore, lncRNA-miRNA pairs may be regarded as candidate diagnostic biomarkers or potential therapeutic targets for HCM.

Correlation of miR-146a-5p plasma levels and rs2910164 polymorphism with left ventricle outflow tract obstruction in hypertrophic cardiomyopathy

OBJECTIVE

Hypertrophic cardiomyopathy (HCM) is a genetic disease of the myocardium that is characterized by phenotypic variability among patients. miR-146a is a small non-coding RNA that is well known for its role in inflammation and myocardial hypertrophy. The aim of this study is to evaluate the role of miR-146a as a candidate genetic factor influencing HCM phenotype.

METHODS

In this study, 140 HCM patients and 112 control individuals were genotyped for the rs2910164 single nucleotide polymorphism (SNP) in the MIR146A gene; using this data, the correlation between different genotypes and clinical features of the disease were determined. Additionally, plasma levels of miR-146a-5p were determined in 50 HCM patients and 30 control individuals by using qPCR.

RESULTS

The incidence of GC and CC genotypes were significantly lower in HCM patients (odds ratio (OR) = 0.5 [0.3-0.8], p = 0.007). The GC/CC genotypes in the dominant genetic model positively correlated with the presence of left ventricle outflow tract (LVOT) obstruction (OR = 2.3 [1.2-4.7] and p = 0.018), a higher left ventricle mass index (118 ± 47 g/m² vs 92 ± 42 g/m² and p = 0.02), and increased left ventricle end-diastolic diameter (4.66 ± 0.64cm vs 4.39 ± 0.7cm and p = 0.026). Atrial fibrillation was significantly higher in patients homozygous for the C allele (OR = 10.6 [2-55], p = 0.003). Interestingly, the plasma levels of miR-146a-5p were significantly increased in HCM patients with LVOT obstruction.

CONCLUSION

Our findings indicate that the C allele of the rs2910164 SNP might be under negative selection in HCM patients. Additionally, plasma levels of miR-146a-5p and GC/CC genotypes are indicative of the obstructive phenotype in HCM patients.

Extracellular vesicular microRNAs as potential biomarker for early detection of doxorubicin-induced cardiotoxicity

Background

Long‐term use of doxorubicin (DOX) is limited by cumulative dose‐dependent cardiotoxicity.

Objectives

Identify plasma extracellular vesicle (EV)‐associated microRNAs (miRNAs) as a biomarker for cardiotoxicity in dogs by correlating changes with cardiac troponin I (cTnI) concentrations and, echocardiographic and histologic findings.

Animals

Prospective study of 9 client‐owned dogs diagnosed with sarcoma and receiving DOX single‐agent chemotherapy (total of 5 DOX treatments). Dogs with clinically relevant metastatic disease, preexisting heart disease, or breeds predisposed to cardiomyopathy were excluded.

Methods

Serum concentration of cTnI was monitored before each treatment and 1 month after the treatment completion. Echocardiography was performed before treatments 1, 3, 5, and 1 month after completion. The EV‐miRNA was isolated and sequenced before treatments 1 and 3, and 1 month after completion.

Results

Linear mixed model analysis for repeated measurements was used to evaluate the effect of DOX. The miR‐107 (P = .03) and miR‐146a (P = .02) were significantly downregulated whereas miR‐502 (P = .02) was upregulated. Changes in miR‐502 were significant before administration of the third chemotherapeutic dose. When stratifying miRNA expression for change in left ventricular ejection fraction, upregulation of miR‐181d was noted (P = .01). Serum concentration of cTnI changed significantly but only 1 month after treatment completion, and concentrations correlated with left ventricular ejection fraction and left ventricular internal dimension in diastole.

Conclusion and Clinical Significance

Downregulation of miR‐502 was detected before significant changes in cTnI concentrations or echocardiographic parameters. Further validation using a larger sample size will be required.

Role of SIRT1 in Modulating Acetylation of the Sarco-Endoplasmic Reticulum Ca2+-ATPase in Heart Failure

RATIONALE

SERCA2a, sarco-endoplasmic reticulum Ca²⁺-ATPase, is a critical determinant of cardiac function. Reduced level and activity of SERCA2a are major features of heart failure. Accordingly, intensive efforts have been made to develop efficient modalities for SERCA2a activation. We showed that the activity of SERCA2a is enhanced by post-translational modification with SUMO1 (small ubiquitin-like modifier 1). However, the roles of other post-translational modifications on SERCA2a are still unknown.

OBJECTIVE

In this study, we aim to assess the role of lysine acetylation on SERCA2a function and determine whether inhibition of lysine acetylation can improve cardiac function in the setting of heart failure.

METHODS AND RESULTS

The acetylation of SERCA2a was significantly increased in failing hearts of humans, mice, and pigs, which is associated with the reduced level of SIRT1 (sirtuin 1), a class III histone deacetylase. Downregulation of SIRT1 increased the SERCA2a acetylation, which in turn led to SERCA2a dysfunction and cardiac defects at baseline. In contrast, pharmacological activation of SIRT1 reduced the SERCA2a acetylation, which was accompanied by recovery of SERCA2a function and cardiac defects in failing hearts. Lysine 492 (K492) was of critical importance for the regulation of SERCA2a activity via acetylation. Acetylation at K492 significantly reduced the SERCA2a activity, presumably through interfering with the binding of ATP to SERCA2a. In failing hearts, acetylation at K492 appeared to be mediated by p300 (histone acetyltransferase p300), a histone acetyltransferase.

CONCLUSIONS

These results indicate that acetylation/deacetylation at K492, which is regulated by SIRT1 and p300, is critical for the regulation of SERCA2a activity in hearts. Pharmacological activation of SIRT1 can restore SERCA2a activity through deacetylation at K492. These findings might provide a novel strategy for the treatment of heart failure.

Regulatory RNAs in Heart Failure

Cardiovascular disease is an enormous socioeconomic burden worldwide and remains a leading cause of mortality and disability despite significant efforts to improve treatments and personalize healthcare. Heart failure is the main manifestation of cardiovascular disease and has reached epidemic proportions. Heart failure follows a loss of cardiac homeostasis, which relies on a tight regulation of gene expression. This regulation is under the control of multiple types of RNA molecules, some encoding proteins (the so-called messenger RNAs) and others lacking protein-coding potential, named noncoding RNAs. In this review article, we aim to revisit the notion of regulatory RNA, which has been thus far mainly confined to noncoding RNA. Regulatory RNA, which we propose to abbreviate as regRNA, can include both protein-coding RNAs and noncoding RNAs, as long as they contribute, directly or indirectly, to the regulation of gene expression. We will address the regulation and functional role of messenger RNAs, microRNAs, long noncoding RNAs, and circular RNAs (ie, regRNAs) in heart failure. We will debate the utility of regRNAs to diagnose, prognosticate, and treat heart failure, and we will provide directions for future work.

Targeting exosome-associated human antigen R attenuates fibrosis and inflammation in diabetic heart

RNA-binding proteins like human antigen R (HuR) are key regulators in post-transcriptional control of gene expression in several pathophysiological conditions. Diabetes adversely affects monocyte/macrophage biology and function. It is not known whether diabetic milieu affects cellular/exosome-HuR and its implications on cardiac inflammation and fibrosis. Here, we evaluate in vitro and in vivo effects of diabetic milieu on macrophage cellular/exosome-HuR, alterations in intercellular cross talk with fibroblasts, and its impact on cardiac remodeling. Human failing hearts show higher HuR levels. Diabetic milieu activates HuR expression in cardiac- and cultured bone marrow-derived macrophages (BMMØ) and stimulates HuR nuclear-to-cytoplasmic translocation and exosome transfer. Exosomes from macrophages exposed to diabetic milieu (high glucose or db/db mice) significantly increase inflammatory and profibrogenic responses in fibroblast (in vitro) and cardiac fibrosis in mice. Intriguingly, Exo-HuR deficiency (HuR knockdown in macrophage) abrogates the above effects. In diabetic mice, macrophage depletion followed by reconstitution with BMMØ-derived HuR-deficient exosomes inhibits angiotensin II-induced cardiac fibrosis response and preserves left ventricle function as compared to control-exosome administration. To the best of our knowledge, this is the first study to demonstrate that diabetes activates BMMØ HuR expression and its transfer into exosome. The data suggest that HuR might be targeted to alleviate macrophage dysfunction and pathological fibrosis in diabetes.

MicroRNA‑146a as a potential regulator involved in the pathogenesis of atopic dermatitis

Previous studies have demonstrated that microRNA (miR)‑146a is involved in the inflammatory response of atopic dermatitis (AD). The aim of the present study was to investigate the expression of miR‑146a in the serum of patients with AD and in skin lesions of AD animal models. In addition, we aimed to predict and verify the target genes of miR‑146a. miR‑146a expression was measured in AD patient serum via reverse transcription‑quantitative PCR. T‑helper (Th)1 [CD4+; interferon (IFN)‑γ+] and Th2 [CD4+; interleukin (IL)‑4+] expression in peripheral blood mononuclear cells was evaluated using flow cytometry. Following the establishment of a 2,4‑dinitrofluorobenzene‑induced C57BL/6 mouse AD model, Th1 (CD4+IFN‑γ+) and Th2 (CD4+IL‑4+) expression was analyzed in murine spleen cells via flow cytometry. Plasmids were transfected into 293T cells and at 48 h post‑transfection, cells were analyzed using a luciferase assay system. The results revealed that the AD group had a significantly lower Th1/Th2 ratio and a significantly higher miR‑146a expression compared with the control group (P<0.05). Furthermore, a decreased Th1/Th2 ratio and a significantly increased miR‑146a expression were observed in the model group compared with the control group (P<0.01). We also conducted a dual‑luciferase assay to determine whether small ubiquitin‑related modifier 1 (SUMO1) if the target gene of miR‑146a. We observed a ~30% decrease in the relative luciferase activity in cells containing the 3'‑untranslated region of SUMO1 + miR‑146a). The results of the luciferase assay indicated that may be a direct mRNA target of miR‑146a; however, the quantification of band density of SUMO1 expression following western blotting did not significantly differ. The development of animal models in AD research is of vital importance. The results revealed that miR‑146a may be a potential regulator involved in the pathogenesis of AD. Furthermore, the current study determined that miR‑146a could be a valuable marker of AD and thus, may be applied in the development of therapeutic strategies for treating AD.

Downregulation of miR-146a Contributes to Cardiac Dysfunction Induced by the Tyrosine Kinase Inhibitor Sunitinib

The main adverse effect of tyrosine kinase inhibitors, such as sunitinib, is cardiac contractile dysfunction; however, the molecular mechanisms of this effect remain largely obscure. MicroRNAs (miRNAs) are key regulatory factors in both cardiovascular diseases and the tyrosine kinase pathway. Therefore, we analyzed the differential expression of miRNAs in the myocardium in mice after exposure to sunitinib using miRNA microarray. A significant downregulation of miR-146a was observed in the myocardium of sunitinib-treated mice, along with a 20% decrease in left ventricle ejection fraction (LVEF). The downregulation of miR-146a was further validated by RT-qPCR. Among the potential targets of miR-146a, we focused on Pln and Ank2, which are closely related to cardiac contractile dysfunction. Results of luciferase reporter assay confirmed that miR-146a directly targeted the 3′ untranslated region of Pln and Ank2. Significant upregulation of PLN and ANK2 at the mRNA and protein levels was observed in the myocardium of sunitinib-treated mice. Cardiac-specific overexpression of miR-146a prevented the deteriorate effect of SNT on calcium transients, thereby alleviating the decreased contractility of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). SiRNA knockdown of PLN or ANK2 prevented sunitinib-induced suppression of contractility in hiPSC-CMs. Therefore, our in vivo and in vitro results showed that sunitinib downregulated miR-146a, which contributes to cardiac contractile dysfunction by regulating the downstream targets PLN and ANK2, and that upregulation of miR-146a alleviated the inhibitory effect of SNT on cardiac contractility. Thus, miR-146a could be a useful protective agent against sunitinib-induced cardiac dysfunction.

Post-translational and transcriptional dynamics - regulating extracellular vesicle biology

Introduction: Extracellular vesicles (EVs) are secreted into their extracellular environment, contain a specific repertoire of cellular cargo, and represent a novel vehicle for cell-cell communication. Protein post-translational modifications (PTMs) are emerging as major effectors of EV biology and function, and in turn, regulate cellular signaling. Areas covered: Discovery and investigation of PTMs such as methylation, glycosylation, acetylation, phosphorylation, sumoylation, and many others has established fundamental roles for PTMs within EVs and associated EV function. The application of enrichment strategies for modifications, high-resolution quantitative mass spectrometry-based proteomics, and improved technological approaches have provided key insights into identification and characterization of EV-based PTMs. Recently, an overwhelming appreciation for the diversity of modifications, including post-transcriptional modifications, dynamic roles of these modifications, and their emerging interplay, including protein-protein, protein-lipid, protein-RNA, and variable RNA modifications, is emerging. At a cellular level, such interplay is essential for gene expression/genome organization, protein function and localization, RNA metabolism, cell division, and cell signaling. Expert commentary: The understanding of these modifications and interactions will provide strategies toward how distinct cargo is localized, sorted, and delivered through EVs to mediate intercellular function, with further understanding of such modifications and intermolecular interactions will provide advances in EV-based therapeutic strategies.

The Non-Coding RNA Journal Club: Highlights on Recent Papers-6

We are delighted to share with you our sixth Journal Club and highlight some of the most interesting papers published recently [...].