Circ-GTF2I/miR-590-5p Axis Aggravates Myocardial Ischemia-Reperfusion Injury by Regulating Kelch Repeat and BTB Domain-Containing Protein 7

Critical analysis of descriptive microRNA data in the translational research on cardioprotection and cardiac repair: lost in the complexity of bioinformatics

The unsuccessful translation of cardiac regeneration and cardioprotection from animal experiments to clinical applications in humans has raised the question of whether microRNA bioinformatics can narrow the gap between animal and human research outputs. We reviewed the literature for the period between 2000 and 2024 and found 178 microRNAs involved in cardioprotection and cardiac regeneration. On analyzing the orthologs and annotations, as well as downstream regulation, we observed species-specific differences in the diverse regulation of the microRNAs and related genes and transcriptomes, the influence of the experimental setting on the microRNA-guided biological responses, and database-specific bioinformatics results. We concluded that, in addition to reducing the number of in vivo experiments, following the 3R animal experiment rules, the bioinformatics approach allows the prediction of several currently unknown interactions between pathways, coding and non-coding genes, proteins, and downstream regulatory elements. However, a comprehensive analysis of the miRNA-mRNA-protein networks needs a profound bioinformatics and mathematical education and training to appropriately design an experimental study, select the right bioinformatics tool with programming language skills and understand and display the bioinformatics output of the results to translate the research data into clinical practice. In addition, using in-silico approaches, a risk of deviating from the in vivo processes exists, with adverse consequences on the translational research.

Circular RNA regulatory role in pathological cardiac remodelling

Cardiac remodelling involves structural, cellular and molecular alterations in the heart after injury, resulting in progressive loss of heart function and ultimately leading to heart failure. Circular RNAs (circRNAs) are a recently rediscovered class of non-coding RNAs that play regulatory roles in the pathogenesis of cardiovascular diseases, including heart failure. Thus, a more comprehensive understanding of the role of circRNAs in the processes governing cardiac remodelling may set the ground for the development of circRNA-based diagnostic and therapeutic strategies. In this review, the current knowledge about circRNA origin, conservation, characteristics and function is summarized. Bioinformatics and wet-lab methods used in circRNA research are discussed. The regulatory function of circRNAs in cardiac remodelling mechanisms such as cell death, cardiomyocyte hypertrophy, inflammation, fibrosis and metabolism is highlighted. Finally, key challenges and opportunities in circRNA research are discussed, and orientations for future work to address the pharmacological potential of circRNAs in heart failure are proposed. LINKED ARTICLES: This article is part of a themed issue Non-coding RNA Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v182.2/issuetoc.

Investigation of the Circular Transcriptome in Alzheimer's Disease Brain

Circular RNAs (circRNAs) are a subclass of non-coding RNAs which have demonstrated potential as biomarkers for Alzheimer's disease (AD). In this study, we conducted a comprehensive exploration of the circRNA transcriptome within AD brain tissues. Specifically, we assessed circRNA expression patterns in the dorsolateral prefrontal cortex collected from nine AD-afflicted individuals and eight healthy controls. Utilising two circRNA detection tools, CIRI2 and CIRCexplorer2, we detected thousands of circRNAs and performed a differential expression analysis. CircRNAs which exhibited statistically significantly differential expression were identified as AD-specific differentially expressed circRNAs. Notably, our investigation revealed 120 circRNAs with significant upregulation and 1325 circRNAs displaying significant downregulation in AD brains when compared to healthy brain tissue. Additionally, we explored the expression profiles of the linear RNA counterparts corresponding to differentially expressed circRNAs in AD-afflicted brains and discovered that the linear RNA counterparts exhibited no significant changes in the levels of expression. We used CRAFT tool to predict that circUBE4B had potential to target miRNA named as hsa-miR-325-5p, ultimately regulated CD44 gene. This study provides a comprehensive overview of differentially expressed circRNAs in the context of AD brains, underscoring their potential as molecular biomarkers for AD. These findings significantly enhance our comprehension of AD's underlying pathophysiological mechanisms, offering promising avenues for future diagnostic and therapeutic developments.

Inhibition of circ_0073932 attenuates myocardial ischemia‒reperfusion injury via miR-493-3p/FAF1/JNK

Oxidative stress and apoptosis play crucial roles in myocardial ischemia‒reperfusion injury (MIRI). In this study, we investigated the role of circ_0073932 in MIRI as well as its molecular mechanism. A hypoxia/reoxygenation (H/R) cardiomyocyte model was established with H9C2 cardiomyocytes, and RT-qPCR was used to measure gene expression. We observed that circ_0073932 expression was abnormally increased in the H/R cardiomyocyte model and in blood samples from MIRI patients. Inhibition of circ_0073932 suppressed H/R-induced cell apoptosis, oxidative stress (ROS, LDH and MDA), and p-JNK expression. Dual luciferase reporter assays showed that circ_0073932 targeted the downregulation of miR-493-3p, and miR-493-3p targeted the downregulation of FAF1. Furthermore, si-circ_0073932, an miR-493-3p inhibitor, oe-FAF1, or si-FAF1 were transfected into H9C2 cardiomyocytes to investigate the roles of these factors in MIRI. Our results showed that compared with the H/R group, si-circ_0073932 inhibited H/R-induced cell apoptosis, oxidative stress (ROS, LDH and MDA), and p-JNK expression. These results were reversed by the miR-493-3p inhibitor or oe-FAF1. Finally, a rat model of MIRI was established, and si-circ_0073932 was administered. Inhibition of circ_0073932 reduced the area of myocardial infarction and decreased the levels of apoptosis and oxidative stress by inhibiting the JNK signaling pathway. Our study indicated that circ_0073932 mediates MIRI via miR-493-3p/FAF1/JNK in vivo and in vitro, revealing novel insights into the pathogenesis of MIRI and providing a new target for the clinical treatment of MIRI.

Retracted: Circ-GTF2I/miR-590-5p Axis Aggravates Myocardial Ischemia-Reperfusion Injury by Regulating Kelch Repeat and BTB Domain-Containing Protein 7

[This retracts the article DOI: 10.1155/2022/2327669.].

Knockdown of Mmu-circ-0001380 Attenuates Myocardial Ischemia/Reperfusion Injury via Modulating miR-106b-5p/Phlpp2 Axis

Myocardial ischemia/reperfusion (MI/R) injury induces myocardial damage and dysfunction. Increasing evidence has confirmed that circular RNAs (circRNAs) play crucial roles in regulating MI/R. Mmu-circ-0001380 has identified to be highly expressed in myocardium of MI/R mouse model. However, its biological function and molecular mechanism in MI/R injury are still unclear. Here, we demonstrated that knockdown of cric-0001380 attenuated myocardial injury of MI/R mice. In vitro, silence of circ-0001380 significantly enhanced viability, and inhibited apoptosis and oxidative stress in HL-1 cells under oxygen-glucose deprivation/reoxygenation (OGD/R). Mmu-miR-106b-5p interacted with circ-0001380, and suppressed the expression of pleckstrin homology domain and leucine rich repeat protein phosphatase 2 (Phlpp2). The miR-106b-5p/Phlpp2 axis mediated the effect of circ-0001380 on OGD/R-induced apoptosis through regulating the phosphorylation of p38, and further involved in regulating the viability and oxidative stress of HL-1 cells. In conclusion, circ-0001380 downregulation relieves MI/R injury via regulating the miR-106b-5p/Phlpp2 axis. The present study indicates that mmu-circ-0001380 exacerbates the myocardial ischemia/reperfusion injury through modulating the miR-106b-5p/Phlpp2 axis in vitro and in vivo.

Identification and Validation of an Aging-Associated circRNA-miRNA-mRNA Network in Neovascular Age-Related Macular Degeneration

INTRODUCTION

Neovascular age-related macular degeneration (NVAMD) is a leading cause of severe vision impairment in the elderly. Aging is one of the most pivotal underlying molecular mechanisms of NVAMD.

METHODS

In this study, we identified the potential aging-related genes involved in NVAMD. Considering that noncoding RNAs are vital regulators of NVAMD progression, we further explored and constructed an aging-originated circRNA-miRNA-mRNA network of NVAMD. Differential expression of 23 aging-associated genes was identified based on sequencing data and the Human Aging Genomic Resources tool at a threshold of p < 0.05, and log2|fold change| > 1.

RESULTS

We screened 12 microRNAs (miRNAs) using public datasets and miRNet database. A total of 13 circRNAs were subsequently mined using the starBase tool. Merging these 13 circRNAs, 12 miRNAs, and 15 genes together, we obtained 281 pairs of circRNA-miRNA and 30 pairs of miRNA-mRNA.

CONCLUSION

We created an aging-related circRNA-miRNA-mRNA network, which could be a promising target for future AMD treatments.