Sensitivity of splicing factor mutant hematopoietic cells to GSK-3 inhibition
Recurrent mutations in the splicing factors SRSF2 and SF3B1 are common in myelodysplasia (MDS) and acute myeloid leukemia (AML). These mutations are invariably heterozygous, as cells with splicing factor mutations nevertheless depend on wild-type splicing activity. Disrupting splicing further is lethal, suggesting a therapeutic vulnerability for splicing factor mutant hematopoietic neoplasms. Glycogen synthase kinase-3 (GSK-3) phosphorylates multiple splicing factors, including SRSF2 and SF3B1, and regulates the splicing of a broad range of mRNAs in human cells. Inhibition of GSK-3 disrupts splicing and promotes cell death in hematopoietic cells with heterozygous mutations in SRSF2 or SF3B1 and not in cells with wild-type splicing factors. To characterize how GSK-3 inhibition alters splicing and leads to cell death in SRSF2P95H/+ and SF3B1K700E/+ cells, we have performed deep RNA sequencing on K562 cells with SRSF2P95H/+ or SF3B1K700E/+ knocked into the endogenous locus (provided by Omar Abdel-Wahab (Wang et al; PMID 30799057) and treated with the GSK-3 inhibitor CHIR99021. Parental cells with wild-type splicing factors were included as controls. RNA-Seq data were further analyzed through the rMATS pipeline to assess changes in mRNA splicing (Liu et al, 2023). Overall design: To investigate the functional consequences of GSK-3 inhibition on gene expression and splicing, we performed deep RNA-sequencing (RNA-seq) of parental K562 and isogenic SRSF2P95H/+ and SF3B1K700E/+ lines treated with DMSO or GSK-3 inhibitor Chir99021.