Circular RNA and its mechanisms in diabetic retinopathy: a systematic review

Circular RNAs (CircRNAs) are endogenous long non-coding RNAs. Unlike linear RNAs, they are structurally continuous and covalently closed, without 59 caps or 39 polyadenylation tails. High-throughput RNA sequencing has enabled people to find several endogenous circRNAs in different species and tissues. circRNA mainly acts as a sponge for microRNAs in cytoplasm to regulates protein translation, or interacts with RNA-binding proteins to generate RNA protein complexes that control transcription. circRNAs are closely associated with diseases such as diabetes, neurological disorders, cardiovascular diseases and cancer, which indicates that circRNAs are closely related to and also play an important functional role in the occurrence and development of human diseases. Recent studies have shown that they are differentially expressed in healthy and diseased eye tissues. There lacks of biomarkers for early detection of diabetic retinopathy, and the newly discovered circRNAs seem to be an ideal candidate of novel molecular markers and therapeutic targets. However, the molecular mechanism of circRNAs activity in the occurrence and development of diabetic retinopathy are not clear yet. This systematic review aims to summarize the research status on function and mechanism of circRNAs in regulating the occurrence of diabetic retinopathy.