Fig. 4: The MCM7 protein level is increased by circKIF18A in NPCs.

a Schematic illustration of the process for identifying RBPs binding to circKIF18A. b The ranking list of the top ten proteins captured by biotinylated antisense oligonucleotides (ASOs) complementary to circKIF18A. c The interaction of circKIF18A with MCM7 was verified using RIP with an anti-MCM7 antibody and IgG in NPCs (n = 3, three different donors for three individual experiments; NS, no significance; *P < 0.05; **P < 0.01). d CircKIF18A regulated the protein level of MCM7 in NPCs (n = 3, three different donors). e The mRNA expression of MCM7 in NPCs treated as described above was detected by qRT–PCR (n = 3, three different donors for three individual experiments; NS, no significance; *P < 0.05; **P < 0.01). f and g Western blot analysis of MCM7 in circKIF18A-silenced NPCs at 2 h intervals under CHX (20 μM)-mediated protein synthesis inhibition (n = 3, three different donors; *P < 0.05; **P < 0.01). h and i The effect of circKIF18A overexpression on the MCM7 level in NPCs treated with CHX at 2 h intervals (n = 3, three different donors; *P < 0.05; **P < 0.01). j Representative immunofluorescence images of NPCs transfected with sh-circKIF18A #1, sh-circKIF18A #2, circKIF18A, and empty vector lentiviruses (n = 5, five different donors; scale bar: 10 μm). k The proteasome inhibitor MG132 abolished the effect of sh-circKIF18A on reducing the MCM7 protein level in NPCs (n = 3, three different donors). l and m The ubiquitination level of MCM7 in circKIF18A-silenced or circKIF18A-overexpressing NPCs treated with MG132 (n = 3, three different donors). All data are presented as the mean ± SD values.