GSE112516
Co-regulation of alternative splicing by hnRNPM and ESRP1 during EMT
The epithelial-mesenchymal transition (EMT) is a fundamental developmental process that is abnormally activated in cancer metastasis. Dynamic changes in alternative splicing occur during EMT. ESRP1 and hnRNPM are splicing regulators that promote an epithelial splicing program and a mesenchymal splicing program, respectively. The functional relationships between these splicing factors in the genome-scale remain elusive. Comparing alternative splicing targets of hnRNPM and ESRP1 revealed that they co-regulate a set of cassette exon events, with the majority showing discordant splicing regulation. hnRNPM discordantly regulated splicing events show a positive correlation with splicing during EMT while concordant splicing events do not, highlighting the antagonistic role of hnRNPM and ESRP1 during EMT. Motif enrichment analysis near co-regulated exons identifies guanine-uridine rich motifs downstream of hnRNPM-repressed and ESRP1-enhanced exons, supporting a model of competitive binding to these cis-elements to antagonize alternative splicing. The set of co-regulated exons are enriched in genes associated with cell-migration and cytoskeletal reorganization, which are pathways associated with EMT. Splicing levels of co-regulated exons are associated with breast cancer patient survival and correlate with gene sets involved in EMT and breast cancer subtypes. In conclusion, hnRNPM and ESRP1 co-regulate antagonistically a set of alternative splicing events that occur during EMT. This regulation is likely mediated through competition for the same intronic binding sites downstream of variable exons. hnRNPM and ESRP1 regulated splicing events are associated with breast cancer survival. Overall design: PolyA-RNA-sequencing of control and hnRNPM knockdown cell lines