Fig. 4

CircRNAs modulate splicing factor functions. CircRNAs exert their molecular functions to regulate splicing factor functions and alternative splicing. The binding between circRNA and splicing factors can either facilitate the assembly of protein complexes (A) or sequester their function by competing with target RNAs (B). In addition, such binding may also influence the stability of splicing factors by altering their accessibility to protein degradation machineries (C). As miRNA sponges (D), circRNAs also regulate the expression of splicing factors. As some splicing factors also participates in other RBP functions such as nonsense-mediated decay and nuclear export (E), the interaction between splicing factors and circRNAs carries even greater significance. CircRNA, circular RNA; HNRNP, heterogeneous nuclear ribonucleoprotein particle; mRNA, miRNA, microRNA; messenger RNA; RBP, RNA binding protein; SRSF1, serine/arginine-rich splicing factor 1, Ub, Ubiquitin