Functional Involvement of circRNAs in the Innate Immune Responses to Viral Infection

Abstract

Effective viral clearance requires fine-tuned immune responses to minimize undesirable inflammatory responses. Circular RNAs (circRNAs) are a class of non-coding RNAs that are abundant and highly stable, formed by backsplicing pre-mRNAs, and expressed ubiquitously in eukaryotic cells, emerging as critical regulators of a plethora of signaling pathways. Recent progress in high-throughput sequencing has enabled a better understanding of the physiological and pathophysiological functions of circRNAs, overcoming the obstacle of the sequence overlap between circRNAs and their linear cognate mRNAs. Some viruses also encode circRNAs implicated in viral replication or disease progression. There is increasing evidence that viral infections dysregulate circRNA expression and that the altered expression of circRNAs is critical in regulating viral infection and replication. circRNAs were shown to regulate gene expression via microRNA and protein sponging or via encoding small polypeptides. Recent studies have also highlighted the potential role of circRNAs as promising diagnostic and prognostic biomarkers, RNA vaccines and antiviral therapy candidates due to their higher stability and lower immunogenicity. This review presents an up-to-date summary of the mechanistic involvement of circRNAs in innate immunity against viral infections, the current understanding of their regulatory roles, and the suggested applications.

Hijacking and rewiring of host CircRNA/miRNA/mRNA competitive endogenous RNA (ceRNA) regulatory networks by oncoviruses during development of viral cancers

“…15 Strong evidence suggests that the interaction between cancer-causing viruses and circRNA-regulated ceRNA networks is a key mechanism in tumour development. 16 Furthermore, circRNAs have demonstrated their potential as innovative targets for the treatment, diagnosis, and prognosis of viral diseases and associated tumours. This review article delves into the intricate biological functions and biogenesis of host cell circRNAs, particularly emphasising their regulatory roles within ceRNA networks, such as the circRNA/miRNA/mRNA axis.…”

“…In virus‐related cancers, circRNAs have emerged as crucial molecular tools targeted by viruses to hijack host systems for viral replication and ensure viral survival within host cells by controlling signalling pathways associated with cancer 15 . Strong evidence suggests that the interaction between cancer‐causing viruses and circRNA‐regulated ceRNA networks is a key mechanism in tumour development 16 . Furthermore, circRNAs have demonstrated their potential as innovative targets for the treatment, diagnosis, and prognosis of viral diseases and associated tumours.…”