Circular RNAs' cap-independent translation protein and its roles in carcinomas

Abstract

Circular RNAs a kind of covalently closed RNA and widely expressed in eukaryotes. CircRNAs are involved in a variety of physiological and pathological processes, but their regulatory mechanisms are not fully understood. Given the development of the RNA deep-sequencing technology and the improvement of algorithms, some CircRNAs are discovered to encode proteins through the cap-independent mechanism and participate in the important process of tumorigenesis and development. Based on an overview of CircRNAs, this paper summarizes its translation mechanism and research methods, and reviews the research progress of CircRNAs translation in the field of oncology in recent years. Moreover, this paper aims to provide new ideas for tumor diagnosis and treatment through CircRNAs translation.

Keywords: Carcinoma; CircRNA-derived protein; Circular RNA; Translation.

Fig. 1

The function of circular RNA. A CircRNAs act as a sponge of miRNAs and play the role of CeRNA, thereby regulating the expression of mRNA. B CircRNAs interact with proteins as follows: a. CircRNAs act as RBP sponges; b. CircRNAs bind to certain proteins to enhance their functions; c. CircRNAs act as protein scaffolds to promote the co-localization of enzymes and their substrates; C CircRNAs pass Combines with RNA pol II and U1 snRNP to promote the transcription of parental genes. D CircRNAs translate into proteins

Fig. 2

CircRNAs translation mechanism. A The non-classical eIF4G protein (eIF4G2) directly recognizes the IRES on CircRNAs to assemble the eIF4 complex to translate the downstream ORF. B YTHDF3 can recognize m6A in CircRNAs and recruit eIF4G2 to m6A to initiate translation. C CircRNA containing infinite open reading frame (iORF) undergoes rolling circle amplification to achieve translation