Table 2 The circRNAs could sponge proteins and circRNAs capable of interacting with RBPs

circMbl

Protein reservoirs

Mbl

CircMbl could absorb MBL to terminate its promotion effect on the generation of circMbl, constructing a feedback loop regulating the balance of circMbl and its cognate linear mRNA

[60]

circRNP

Protein reservoirs

NF90/NF110

During the viral infection, NF90/NF110 was exported from nucleus by circRNPs and then released to bind to viral mRNAs for antiviral immune response

[59]

circAmotl1

Protein reservoirs

c-myc

Circ-Amotl1 induced nuclear translocation of c-myc, promoting c-myc stability and upregulating c-myc targets to accelerate tumorigenesis

[34]

circAmotl1

Protein reservoirs

Stat3

By binding to Stat3, circAmotl1 lead the nuclear translocation of Stat3, accelerating wound healing process via modulating Dnmt3a and miR-17 function

[105]

circPABPN1

Protein reservoirs

HuR

CircPABPN1 could suppress the translation of cognate mPABPN1 by binding to HuR, an RBP that could promote the translation of PABPN1 mRNA

[107]

circDNMT1

Protein reservoirs

p53 and AUF1

Both p53 and AUF1 undergo nuclear translocation through interacting with circ-Dnmt1. Nuclear translocated p53 promoted cellular autophagy while AUF1 nuclear translocation resulted in increased Dnmt1 translation

[106]

circFoxo3

Interact with RBPs

p21 and CDK2

CircFoxo3 repressed cell cycle in G1 phase by binding to the cell cycle proteins CDK2 and p21, forming a ternary complex as well as circFoxo3-CDK2 complex and circFoxo3-p21 complex

[110]

circFoxo3

Interact with RBPs

ID-1, E2F1, FAK, and HIF1a

CircFoxo3 was mainly located in the cytoplasm interacting with anti-senescent protein ID-1 and E2F1, the anti-stress proteins FAK and HIF1a retained in cytoplasm to abrogate their anti-senescent and anti-stress functions

[111]

circFoxo3

Interact with RBPs

p53 and MDM2

By binding to MDM2 and p53, circFoxo3 facilitated MDM2-induced p53 ubiquitination and subsequent degradation while freeing Foxo3 from being ubiquitinated, thus improved the level of PUMA which induced cell apoptosis

[112]

CircCcnb1

Interact with RBPs

H2AX and Bclaf1; H2AX and p53

In the conditions of p53 was mutant, circ-Ccnb1 could form a complex with H2AX and Bclaf1 to decrease the ability of proliferation and survival but increase the apoptosis; in the conditions of wild-type p53, circCcnb1 bind to H2AX and wild-type p53, avoiding induction of cell death

[113]