Splicing factor SRSF1 promotes gliomagenesis via oncogenic splice-switching of MYO1B.

Abnormal alternative splicing (AS) caused by alterations to splicing factors contributes to tumor progression. Serine/arginine splicing factor 1 (SRSF1) has emerged as a key oncodriver in numerous solid tumors, leaving its roles and mechanisms largely obscure in glioma. Here, we demonstrate that SRSF1 is increased in glioma tissues and cell lines. Moreover, its expression was correlated positively with tumor grade and Ki-67 index, but inversely with patient survival. Using RNA-Seq, we comprehensively screened and identified multiple SRSF1-affected AS events. Motif analysis revealed a position-dependent modulation of AS by SRSF1 in glioma. Functionally, we verified that SRSF1 promoted cell proliferation, survival, and invasion by specifically switching the AS of the myosin IB (MYO1B) gene and facilitating the expression of the oncogenic and membrane-localized isoform, MYO1B-fl. Strikingly, MYO1B splicing was dysregulated in parallel with SRSF1 expression in gliomas and predicted the poor prognosis of the patients. Further investigation revealed that SRSF1-guided AS of the MYO1B gene increased the tumorigenic potential of glioma cells through the PDK1/AKT and PAK/LIMK pathways. Taken together, we identify SRSF1 as an important oncodriver that integrates AS control of MYO1B into promotion of gliomagenesis and represents a potential prognostic biomarker and target for glioma therapy.