BMI-1 modulation and trafficking during M phase in diffuse intrinsic pontine glioma

BMI-1 (B-cell-specific Moloney murine leukemia virus integration site 1) has been implicated in both normal and cancer cell biology. While the canonical function of BMI-1 involves epigenetic repression, novel extranuclear functions have been recently reported. In the present study, we demonstrate that the phosphorylation of BMI-1 in diffuse intrinsic pontine glioma (DIPG) cells occurs in M phase and that it triggers simultaneous translocation of the phosphorylated BMI-1 to the cytoplasm. This translocation is mediated by the RanGTP-dependent transporter CRM1, also known as exportin. Furthermore, we uncovered a previously unidentified nuclear export signal (NES) in the BMI-1 protein, suggesting an active transport type of modified BMI-1 mediated by CRM1. These findings associate BMI-1 phosphorylation with its trafficking in M phase. Collectively, this study sheds light on the molecular mechanisms underlying BMI-1 functions in DIPG, thereby potentially paving the way for the development of targeted therapeutic strategies related to M phase progression.