Genome-wide identification and functional analysis of circRNAs in Trichophyton rubrum conidial and mycelial stages

An updated database of virus circular RNAs provides new insights into the biogenesis mechanism of the molecule

Virus circular RNAs (circRNA) have been reported to be extensively expressed and play important roles in viral infections. Previously we build the first database of virus circRNAs named VirusCircBase which has been widely used in the field. This study significantly improved the database on both the data quantity and database functionality: the number of virus circRNAs, virus species, host organisms was increased from 46440, 23, 9 to 60859, 43, 22, respectively, and 1902 full-length virus circRNAs were newly added; new functions were added such as visualization of the expression level of virus circRNAs and visualization of virus circRNAs in the Genome Browser. Analysis of the expression of virus circRNAs showed that they had low expression levels in most cells or tissues and showed strong expression heterogeneity. Analysis of the splicing of virus circRNAs showed that they used a much higher proportion of non-canonical back-splicing signals compared to those in animals and plants, and mainly used the A5SS (alternative 5' splice site) in alternative-splicing. Most virus circRNAs have no more than two isoforms. Finally, human genes associated with the virus circRNA production were investigated and more than 1000 human genes exhibited moderate correlations with the expression of virus circRNAs. Most of them showed negative correlations including 42 genes encoding RNA-binding proteins. They were significantly enriched in biological processes related to cell cycle and RNA processing. Overall, the study provides a valuable resource for further studies of virus circRNAs and also provides new insights into the biogenesis mechanisms of virus circRNAs.

Role of circular RNAs in disease progression and diagnosis of cancers: An overview of recent advanced insights

Tumor microenvironment (TME) is a crucial regulator of tumor progression and cells in the TME release a number of molecules that are responsible for anaplasticity, invasion, metastasis of tumor, establishing stem cell niches, up-regulation and down-regulation of various pathways in cancer cells, interfering with immune surveillance and immune escape. Moreover, they can serve as diagnostic markers, and determine effective therapies. Among them, CircRNAs have gained special attention due to their involvement in mutated pathways in cancers. By functioning as a molecular sponge for miRNAs, binding with proteins, and directing selective splicing. CircRNAs modify the immunological environment of cancers to promote their growth. Besides of critical role in tumor growth, circRNAs are emerging as potential candidates as biomarkers for diagnosis cancer therapy. Also, circRNAs vaccination even offers a novel approach to tumor immunotherapy. Over the recent years, studies are advocating that circRNAs have tissue specific tumor specific expression patterns, which indicates their potential clinical utility. Especially, circRNAs have emerged as potential predictive and prognostic biomarkers. Although, there has been significant progress in deciphering the role of circRNA in cancers, literature lacks comprehensive overview on this topic. Keeping in view of these significant discoveries, this review systematically discusses circRNA and their role in the tumor in different dimensions.