SRSF3 promotes the generation of XBP1s to stabilize autophagy and enhance hypoxia adaptation in glioma

Hypoxia is a key driver of glioblastoma (GBM) progression. Serine/arginine-rich splicing factor 3 (SRSF3) is associated with the malignant progression of GBM, but its role in the hypoxic microenvironment of GBM remains unclear. This study aimed to explore the regulatory role and molecular mechanisms of SRSF3 in hypoxia adaptation in GBM. The expression of SRSF3 in normal astrocytes and GBM cells was detected. The effects of knockdown or overexpression of SRSF3 combined with hypoxia treatment on malignant phenotypes and hypoxia stress adaptation in GBM cells were evaluated. Cell viability, colony formation, migration, invasion, and cell death assays were performed to assess phenotypic changes. Mechanisms were investigated using mRFP-GFP-LC3, autophagy, and unfolded protein response (UPR)-related molecular detection. SRSF3 was highly expressed in GBM cells. Knockdown of SRSF3 inhibited cell viability, migration, invasion, and colony formation, whereas overexpression of SRSF3 promoted malignant behaviors. Further studies revealed that hypoxia induction significantly increased the expression levels of GRP78, CHOP, ATF4, LC3-II/I, and p62; upregulated the GFP/mRFP ratio; and increased cleaved-caspase3 expression, promoting cell death. Mechanistic studies revealed that SRSF3 overexpression promoted XBP1s formation, alleviated hypoxia-induced autophagic flux blockage, and reduced cell death. The IRE1 RNase inhibitor 4μ8C weakened the SRSF3-mediated promotion of XBP1s generation. SRSF3 enhances adaptive UPR output by promoting IRE1-dependent XBP1 splicing, thereby maintaining autophagic flux and promoting GBM cell survival under hypoxic conditions.