Circular RNAs in the Central Nervous System

Abstract

Circular RNAs (circRNAs) are endogenous single-stranded RNAs characterized by covalently closed loop structures with neither 5′ to 3′ polarity nor poly(A) tails. They are generated most commonly from back-splicing of protein-coding exons. CircRNAs have a tissue-specific distribution and are evolutionarily conserved, and many circRNAs play important biological functions by combining with microRNAs and proteins to regulate protein functions and their own translation. Numerous studies have shown that circRNAs are enriched in the central nervous system (CNS) and play an important role in the development and maintenance of homeostasis. Correspondingly, they also play an important role in the occurrence and progression of CNS diseases. In this review, we highlight the current state of circRNA biogenesis, properties, function and the crucial roles they play in the CNS.

Expression Profile and Potential Function of Circular RNAs in Peripheral Blood Mononuclear Cells in Male Patients With Primary Gout

“…Circular RNAs (circRNAs) are a new type of non-coding RNA molecule, which are composed of exons, introns, or fragments of the two, and are highly resistant to degradation because of their distinct circular structure ( Zhou et al, 2020 ). Emerging evidence suggests that circRNAs are potential candidates for diagnostic biomarkers and therapeutic targets for a variety of diseases, including tumors ( Wang J. et al, 2021 ), cardiovascular diseases ( Ward et al, 2021 ), and nervous system diseases ( Li M.-L. et al, 2021 ). However, at present, knowledge of circRNAs in gout remains limited.…”

Fission Impossible: Stabilized miRNA-Based Analogs in Neurodegenerative Disease

“…Augmentation therapy using specific miRNAs has emerged as a promising approach through the use of stabilized synthetic miRNA or anti-miRNA mimics. Interestingly, in these diseases concatenated linear sncRNAs containing miRNA sequences may take the form of a circular RNA (circRNA) that have been found in multiple eukaryotic organisms including humans and may be especially abundant within the human CNS (Lukiw, 2013 ; Lauretti et al, 2021 ; Li et al, 2021 ; Su et al, 2022 ). Unlike linear miRNA, miRNA-containing circRNA may form a covalently closed loop lacking free 3' and 5' ends resulting in circRNAs being up to 5 times more stable than their linear counterparts with extended half-lives due to lack of exposed ends normally targeted by 3' or 5' exoribonucleases (Enuka et al, 2016 ; Lauretti et al, 2021 ).…”

“…ciRS-7 thereby acts as a kind of endogenous, competing, anti-complementary miRNA “sponge” to adsorb and hence quench miRNA-7 activities (Zhao et al, 2016 ; Lauretti et al, 2021 ). Stabilized circRNAs may have high therapeutic value in acting as long-lived “sponges” for the inactivation or down-regulation of overly expressed miRNAs in pathological conditions such as AD (Enuka et al, 2016 ; Mumtaz et al, 2020 ; Li et al, 2021 ; Su et al, 2022 ).…”

Involvement of CircRNA Expression Profile in Diabetic Retinopathy and Its Potential Diagnostic Value

“…CircRNAs are universally expressed and conserved in human and vertebrate neural retina Meng-Lan Li et al, 2021). In mouse and rat retinas, circRNA population increases during development, with significant developmental stage specificity (Han et al, 2017;George et al, 2019;Mellough et al, 2019;Kaining Chen et al, 2021;Gang Chen et al, 2021).…”