Circr, a Computational Tool to Identify miRNA:circRNA Associations

circ2LO: Identification of CircRNA Based on the LucaOne Large Model

Circular RNA is a type of noncoding RNA with a special covalent bond structure. As an endogenous RNA in animals and plants, it is formed through RNA splicing. The 5' and 3' ends of the exons form circular RNA at the back-splicing sites. Circular RNA plays an important regulatory role in diseases by interacting with the associated miRNAs. Accurate identification of circular RNA can enrich the data on circular RNA and provide new ideas for drug development. At present, mainstream circular RNA recognition algorithms are divided into two categories: those based on RNA sequence position information and those based on RNA sequence biometric information. Herein, we propose a method for the recognition of circular RNA, called circ2LO, which utilizes the LucaOne large model for feature embedding of the splicing sites of RNA sequences as well as their upstream and downstream sequences to prevent semantic information loss caused by the traditional one-hot encoding method. Subsequently, it employs a convolutional layer to extract features and a self-attention mechanism to extract interactive features to accurately capture the core features of the circular RNA at the splicing sites. Finally, it uses a fully connected layer to identify circular RNA. The accuracy of circ2LO on the human dataset reached 95.47%, which is higher than the values shown by existing methods. It also achieved accuracies of 97.04% and 72.04% on the Arabidopsis and mouse datasets, respectively, demonstrating good robustness. Through rigorous validation, the circ2LO model has proven its high-precision identification capability for circular RNAs, marking it as a potentially transformative analytical platform in the circRNA research field.

Resistance to Radiation Enhances Metastasis by Altering RNA Metabolism

The cellular programs that mediate therapy resistance are often important drivers of metastasis, a phenomenon that needs to be understood better to improve screening and treatment options for cancer patients. Although this issue has been studied extensively for chemotherapy, less is known about a causal link between resistance to radiation therapy and metastasis. We investigated this problem in triple-negative breast cancer (TNBC) and established that radiation resistant tumor cells have enhanced metastatic capacity, especially to bone. Resistance to radiation increases the expression of integrin β3 (ITGβ3), which promotes enhanced migration and invasion. Bioinformatic analysis and subsequent experimentation revealed an enrichment of RNA metabolism pathways that stabilize ITGβ3 transcripts. Specifically, the RNA binding protein heterogenous nuclear ribonucleoprotein L (HNRNPL), whose expression is regulated by Nrf2, mediates the formation of circular RNAs (circRNAs) that function as competing endogenous RNAs (ceRNAs) for the family of let-7 microRNAs that target ITGβ3. Collectively, our findings identify a novel mechanism of radiation-induced metastasis that is driven by alterations in RNA metabolism.

Validation and in silico function prediction of circtial1 as a novel marker of abnormal lung development in nitrofen-induced congenital diaphragmatic hernia (CDH)

PURPOSE

Circular RNAs (circRNAs) are stable, non-coding RNAs with tissue- and developmental-specific expression making them suitable biomarkers for congenital anomalies. Current circRNA discovery pipelines have focused on human and mouse. We aim to bridge this gap by combining bioinformatics resources and used circtial1 as a model candidate in the nitrofen rat model of congenital diaphragmatic hernia (CDH).

METHODS

Circtial1 backsplice junction sequences from a microarray were used to predict mature circRNA sequences and downstream pathways by miRNA interactions using CRAFT and circAtlas. We validated circtial1 expression using conventional PCR, amplicon sequencing, RT-Qpcr, and Basescope™ in situ hybridization.

RESULTS

Expression of parental gene tial1 was decreased in nitrofen-induced lungs at embryonic day (E)15 (p = 0.004) and E21 (p = 0.008), while at E18, there was no significant difference (p = 0.65). At E21, circtial1 expression did not differ between CDH and control lungs (p = 0.07); however, there was a decreased expression in male pups (p = 0.0167). In situ hybridization confirmed low circtial1 expression. CircRNA::miRNA::mRNA interactions revealed pathway enrichment for inflammation/infection and neuron function/development.

CONCLUSION

For the first time, we report circRNA profiling in nitrofen-induced CDH with a sex-specific expression of circtial1. Current bioinformatics tools have significant challenges, but can guide hypothesis formation on their biological role.

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.

CircNetVis: an interactive web application for visualizing interaction networks of circular RNAs

Analyzing the interactions of circular RNAs (circRNAs) is a crucial step in understanding their functional impacts. While there are numerous visualization tools available for investigating circRNA interaction networks, these tools are typically limited to known circRNAs from specific databases. Moreover, these existing tools usually require complex installation procedures which can be time-consuming and challenging for users. There is a lack of a user-friendly web application that facilitates interactive exploration and visualization of circRNA interaction networks. CircNetVis is an interactive online web application to enhance the analysis of human/mouse circRNA interactions. The tool allows three different input formats of circRNAs including circRNA IDs from CircBase, circRNA coordinates (chromosome, start position, end position), and circRNA sequences in the FASTA format. It integrates multiple interaction networks for visualization and investigation of the interplay between circRNA, microRNAs, mRNAs and RNA binding proteins. CircNetVis also enables users to interactively explore the interactions of unknown circRNAs which are not reported from previous databases. The tool can generate interactive plots and allows users to save results as output files for offline usage. CircNetVis is implemented as a web application using R-shiny and freely available for academic use at https://www.meb.ki.se/shiny/truvu/CircNetVis/ .

Adipose Tissue Exosome circ_sxc Mediates the Modulatory of Adiposomes on Brain Aging by Inhibiting Brain dme-miR-87-3p

Aging of the brain usually leads to the decline of neurological processes and is a major risk factor for various neurodegenerative diseases, including sleep disturbances and cognitive decline. Adipose tissue exosomes, as adipocyte-derived vesicles, may mediate the regulatory processes of adipose tissue on other organs, including the brain; however, the regulatory mechanisms remain unclear. We analyzed the sleep-wake behavior of young (10 days) and old (40 days) Drosophila and found that older Drosophila showed increased sleep fragmentation, which is similar to mammalian aging characteristics. To investigate the cross-tissue regulatory mechanisms of adiposity on brain aging, we extracted 10-day and 40-day Drosophila adipose tissue exosomes and identified circRNAs with age-dependent expression differences by RNA-seq and differential analysis. Furthermore, by combining data from 3 datasets of the GEO database (GSE130158, GSE24992, and GSE184559), circ_sxc that was significantly downregulated with age was finally screened out. Moreover, dme-miR-87-3p, a conserved target of circ_sxc, accumulates in the brain with age and exhibits inhibitory effects in predicted binding relationships with neuroreceptor ligand genes. In summary, the current study showed that the Drosophila brain could obtain circ_sxc by uptake of adipose tissue exosomes which crossed the blood-brain barrier. And circ_sxc suppressed brain miR-87-3p expression through sponge adsorption, which in turn regulated the expression of neurological receptor ligand proteins (5-HT1B, GABA-B-R1, Rdl, Rh7, qvr, NaCP60E) and ensured brain neuronal synaptic signaling normal function of synaptic signaling. However, with aging, this regulatory mechanism is dysregulated by the downregulation of the adipose exosome circ_sxc, which contributes to the brain exhibiting sleep disturbances and other "aging" features.