Fig. 5

KPNA2 imports KIFC1 into the nucleus of BCa cells. A To identify the protein cargos of KPNA2 in BCa cells, 173 potential cargos from the BioGRID database and the top 99 potential cargos from mass spectrometry analysis data were integrated using Venn Diagrams. Seven common potential cargo proteins (KIFC1, HNRNPH1, EWSR1, LMNA, FUS, NUP50, and HNRNPC) were chosen for further investigation. B The TCGA visualization database GEPIA was utilized to analyze the mRNA levels of the seven genes in BCa tissues and normal bladder tissues. Among these genes, KIFC1 showed a significant up-regulation in BCa tissues compared with normal bladder tissues. C Pearson correlation analysis of TCGA data revealed a positive correlation between the expression of KIFC1 and KPNA2 in 426 BCa tissues (r = 0.7731, p < 0.001). Similarly, analysis of GSE13507 data showed a positive correlation between KIFC1 expression and KPNA2 in 188 BCa tissues (r = 0.3753, p < 0.001). In addition, correlation analysis of KIFC1 and KPNA2 mRNA levels in our 39 BCa tissues demonstrated a positive correlation between the two genes (r = 0.5627, p < 0.001). D The immunohistochemistry staining results revealed that KIFC1 expression was elevated in BCa tissues exhibiting intense KPNA2 immunostaining, whereas KIFC1 expression was reduced in BCa tissues with faint KPNA2 immunostaining. E The HDOCK database suggests that KPNA2 can bind to KIFC1. F The co-immunoprecipitation assay was performed for the interaction of KIFC1 and KPNA2 in BCa cells. G, H After knockdown of KPNA2 in BCa cells, changes in the cytoplasmic and nuclear fractions of KIFC1 were determined by Western blotting and immunofluorescence. I After synchronizing the cells, the protein levels of KIFC1 and KPNA2 in the mitotic cell lysates and inhibited mitotic cell lysates were determined using western blotting. The findings indicated that both KIFC1 and KPNA2 were overexpressed during the M phase of BCa cells. J, K Knockdown of KIFC1 and/or KPNA2 in BCa cells led to a notable reduction in the proportion of G2/M phase cells. Western blotting analysis revealed that the knockdown of KIFC1 and/or KPNA2 led to a decrease in the cell cycle protein B1. L Dot plots of PI (DNA) vs FITC (MPM-2) showing cells in G2 and M-phase specifically during the time of mitotic exit in 5637-NC and 5637 KIFC1-siRNA2 cells. M The western blot showed cyclin B1 protein levels in synchronized 5637-NC and 5637 KIFC1-siRNA2 cells following release from thymidine block at G1/S boundary