The Role of ncRNAs in Cardiac Infarction and Regeneration

Mef2c- and Nkx2-5-Divergent Transcriptional Regulation of Chick WT1_76127 and Mouse Gm14014 lncRNAs and Their Implication in Epicardial Cell Migration

Cardiac development is a complex developmental process. The early cardiac straight tube is composed of an external myocardial layer and an internal endocardial lining. Soon after rightward looping, the embryonic heart becomes externally covered by a new epithelial lining, the embryonic epicardium. A subset of these embryonic epicardial cells migrate and colonize the embryonic myocardium, contributing to the formation of distinct cell types. In recent years, our understanding of the molecular mechanisms that govern proepicardium and embryonic epicardium formation has greatly increased. We have recently witnessed the discovery of a novel layer of complexity governing gene regulation with the discovery of non-coding RNAs. Our laboratory recently identified three distinct lncRNAs, adjacent to the Wt1, Bmp4 and Fgf8 chicken gene loci, with enhanced expression in the proepicardium that are distinctly regulated by Bmp, Fgf and thymosin β4, providing support for their plausible implication in epicardial formation. The expression of lncRNAs was analyzed in different chicken and mouse tissues as well as their subcellular distribution in chicken proepicardial, epicardial, ventricle explants and in different murine cardiac cell types. lncRNA transcriptional regulation was analyzed by using siRNAs and expression vectors of different transcription factors in chicken and mouse models, whereas antisense oligonucleotides were used to inhibit Gm14014 expression. Furthermore, RT-qPCR, immunocytochemistry, RNA pulldown, Western blot, viability and cell migration assays were conducted to investigate the biological functions of Wt1_76127 and Gm14014. We demonstrated that Wt1_76127 in chicken and its putative conserved homologue Gm14014 in mice are widely distributed in different embryonic and adult tissues and distinctly regulated by cardiac-enriched transcription factors, particularly Mef2c and Nkx2.5. Furthermore, silencing assays demonstrated that mouse Gm14014, but not chicken Wt1_76127, is essential for epicardial, but not endocardial or myocardial, cell migration. Such processes are governed by partnering with Myl9, promoting cytoskeletal remodeling. Our data show that Gm14014 plays a pivotal role in epicardial cell migration essential for heart regeneration under these experimental conditions.

The Macrophage-Fibroblast Dipole in the Context of Cardiac Repair and Fibrosis

Stromal and immune cells and their interactions have gained the attention of cardiology researchers and clinicians in recent years as their contribution in cardiac repair is increasingly recognized. The repair process in the heart is a particularly critical constellation of complex molecular and cellular events and interactions that characteristically fail to ensure adequate recovery following injury, insult, or exposure to stress conditions in this regeneration-hostile organ. The tremendous consequence of this pronounced inability to maintain homeostatic states is being translated in numerous ways promoting progress into heart failure, a deadly, irreversible condition requiring organ transplantation. Fibrosis is in fact a repair response eventually promoting cardiac dysfunction and cardiac fibroblasts are the major cellular players in this process, overproducing collagens and other extracellular matrix components when activated. On the other hand, macrophages may differentially affect fibroblasts and cardiac repair depending on their status and subsets. The opposite interaction is also probable. We discuss here the multifaceted aspects and crosstalk of this cell dipole and the opportunities it may offer for beneficial manipulation approaches that will hopefully lead to progress in heart disease interventions.

Research trends and hotspots of circular RNA in cardiovascular disease: A bibliometric analysis

From a global perspective, cardiovascular diseases (CVDs), the leading factor accounting for population mortality, and circRNAs, RNA molecules with stable closed-loop structures, have been proven to be closely related. The latent clinical value and the potential role of circRNAs in CVDs have been attracting increasing, active research interest, but bibliometric studies in this field are still lacking. Thus, in this study, we conducted a bibliometric analysis by using software such as VOSviewer, CiteSpace, Microsoft Excel, and the R package to determine the current research progress and hotspots and ultimately provide an overview of the development trends and future frontiers in this field. In our study, based on our search strategy, a total of 1206 publications published before July 31, 2023 were accessed from the WOSCC database. According to our findings, there is a notable increasing trend in global publications in the field of circRNA in CVDs. China was found to be the dominant country in terms of publication number, but a lack of high-quality articles was a significant fault. A cluster analysis on the co-cited references indicated that dilated cardiomyopathy, AMI, and cardiac hypertrophy are the greatest objects of concern. In contrast, a keywords analysis indicated that high importance has been ascribed to MI, abdominal aortic aneurysm, cell proliferation, and coronary artery diseases.

Sirtuin 1-activating derivatives belonging to the anilinopyridine class displaying in vivo cardioprotective activities

Sirtuin 1 (SIRT1) is an enzyme that relies on NAD+ cofactor and functions as a deacetylase. It has been associated with various biological and pathological processes, including cancer, diabetes, and cardiovascular diseases. Recent studies have shown that compounds that activate SIRT1 exhibit protective effects on the heart. Consequently, targeting SIRT1 has emerged as a viable approach to treat cardiovascular diseases, leading to the identification of several SIRT1 activators derived from natural or synthetic sources. In this study, we developed anilinopyridine-based SIRT1 activators that displayed significantly greater potency in activating SIRT1 compared to the reference compound resveratrol, as demonstrated in enzymatic assays. In particular, compounds 8 and 10, representative 6-aryl-2-anilinopyridine derivatives from this series, were further investigated pharmacologically and found to reduce myocardial damage caused by occlusion and subsequent reperfusion in vivo, confirming their cardioprotective properties. Notably, the cardioprotective effects of 8 and 10 were significantly superior to that of resveratrol. Significantly, compound 10 emerged as the most potent among the tested compounds, demonstrating the ability to substantially decrease the size of the ischemic area at a dosage one hundred times lower (0.1 mg kg-1) than that of resveratrol/compound 1. These promising findings open avenues for expanding and optimizing this chemical class of potent SIRT1 activators as potential agents for cardioprotection.

Exploring the Multifaceted Biologically Relevant Roles of circRNAs: From Regulation, Translation to Biomarkers

CircRNAs are a category of regulatory RNAs that have garnered significant attention in the field of regulatory RNA research due to their structural stability and tissue-specific expression. Their circular configuration, formed via back-splicing, results in a covalently closed structure that exhibits greater resistance to exonucleases compared to linear RNAs. The distinctive regulation of circRNAs is closely associated with several physiological processes, as well as the advancement of pathophysiological processes in several human diseases. Despite a good understanding of the biogenesis of circular RNA, details of their biological roles are still being explored. With the steady rise in the number of investigations being carried out regarding the involvement of circRNAs in various regulatory pathways, understanding the biological and clinical relevance of circRNA-mediated regulation has become challenging. Given the vast landscape of circRNA research in the development of the heart and vasculature, we evaluated cardiovascular system research as a model to critically review the state-of-the-art understanding of the biologically relevant functions of circRNAs. We conclude the review with a discussion of the limitations of current functional studies and provide potential solutions by which these limitations can be addressed to identify and validate the meaningful and impactful functions of circRNAs in different physiological processes and diseases.

Novel Insights into the Molecular Mechanisms Governing Embryonic Epicardium Formation

The embryonic epicardium originates from the proepicardium, an extracardiac primordium constituted by a cluster of mesothelial cells. In early embryos, the embryonic epicardium is characterized by a squamous cell epithelium resting on the myocardium surface. Subsequently, it invades the subepicardial space and thereafter the embryonic myocardium by means of an epithelial-mesenchymal transition. Within the myocardium, epicardial-derived cells present multilineage potential, later differentiating into smooth muscle cells and contributing both to coronary vasculature and cardiac fibroblasts in the mature heart. Over the last decades, we have progressively increased our understanding of those cellular and molecular mechanisms driving proepicardial/embryonic epicardium formation. This study provides a state-of-the-art review of the transcriptional and emerging post-transcriptional mechanisms involved in the formation and differentiation of the embryonic epicardium.

Propofol synergizes with circAPBB2 to protect against hypoxia/reoxygenation-induced oxidative stress, inflammation, and apoptosis of human cardiomyocytes

BACKGROUND

Myocardial injury is the main manifestation of cardiovascular diseases, and previous studies have shown that propofol (PPF) regulates myocardial injury. However, the mechanism of PPF in regulating myocardial injury remains to be further explored. This work aims to analyze the effects of PPF on human cardiomyocyte injury and the underlying mechanism.

METHODS

The regulatory and functional role of PPF and circAPBB2 in human cardiomyocyte injury were analyzed using an in vitro hypoxia/reoxygenation (H/R) cell model, which was established by treating human cardiomyocytes (AC16 cells) with H/R. The study evaluated AC16 cell injury by analyzing cytotoxicity, oxidative stress, inflammation and apoptosis of H/R-induced AC16 cells. Quantitative real-time polymerase chain reaction was performed to detect circAPBB2, miR-18a-5p and dual specificity phosphatase 14 (DUSP14) expression. Protein expression was analyzed by Western blot analysis assay. Dual-luciferase reporter assay, RNA pull-down assay and RNA immunoprecipitation assay were performed to identify the associations among circAPBB2, miR-18a-5p and DUSP14. Cytotoxicity was investigated by cell counting kit-8 assay and lactate dehydrogenase activity detection kit. Oxidative stress was evaluated by cellular reactive oxygen species assay kit and superoxide dismutase activity assay kit. The production of tumor necrosis factor-α and interleukin-1β was evaluated by enzyme-linked immunosorbent assays.

RESULTS

The expression of circAPBB2 and DUSP14 was significantly decreased, while miR-18a-5p was increased in H/R-induced AC16 cells when compared with controls. H/R treatment-induced cytotoxicity, oxidative stress, inflammation and cell apoptosis were attenuated after circAPBB2 overexpression or PPF treatment, whereas these effects were restored by increasing miR-18a-5p expression. PPF treatment improved the inhibitory effect of ectopic circAPBB2 expression on H/R-induced cell injury. MiR-18a-5p silencing ameliorated H/R-induced AC16 damage by interacting with DUSP14. Mechanically, circAPBB2 acted as a miR-18a-5p sponge, and miR-18a-5p targeted DUSP14 in AC16 cells.

CONCLUSION

PPF synergized with circAPBB2 to protect AC16 cells against H/R-induced oxidative stress, inflammation and apoptosis through the miR-18a-5p/DUSP14 pathway.