Figure 6. Translational regulation of Bim.

A. Various Bim isoforms can be formed by alternative splicing, where upregulation of Bim_S is especially efficient in inducing apoptosis, while formation of BH3-deficient Bimγ lacks pro-apoptotic activity. The splicing factor SRSF1 promotes Bimγ formation, while activation of SRp55 by the B-Raf inhibitor PLX4720 or Zn²⁺ favors Bim_S. PTBP1, Brm and hnRNP2 favor the inclusion of the BH3-containing E4 exon over the E3 exon. B. Various RNA-binding proteins such as Hsp27 and Hsc70 prevent Bim translation. C. A range of microRNAs can target Bim, among them miR-17∼92, miR-106∼25, miR-181, miR-148 and miR-221/222 are considered as oncomiRs that can promote tumor progression.