Death Associated Protein 3 (DAP3) Coordinates Splicing Regulatory Networks to Modulate Global Alternative Splicing in Cancer

The dynamic regulation of transcriptome requires coordinated participation of multiple RNA binding proteins (RBPs) in RNA processing. Dysregulated RNA processing, such as aberrant alternative splicing, is implicated in many cancers. Therefore, it is critical to explore the cancer-related RNA processing regulation and the underlying mechanisms. Many RBPs lack classical RNA-binding domains and their functions in RNA processing regulation remain unclear. Through an unbiased transcriptome-wide analysis, we report DAP3 binds ubiquitously to endogenous RNAs in vivo and its depletion reshapes the alternative splicing landscape in cancer cells. Mechanistically, we show DAP3 coordinates splicing regulatory networks, not only via mediating the formation of ribonucleoprotein (RNP) complexes, but also via modulating splicing of numerous splicing factors. Specific DAP3-regulated splicing changes such as non-productive splicing of WSB1 and RBM6, play important roles in tumorigenesis. Together, these findings provide critical mechanistic insights into the molecular functions of DAP3 in cancer development as a master regulator of RNA processing. We constructed strand-specific cDNA libraries of 3 total RNA samples and sequenced the libraries using Illumina NovaSeq 6000 PE150 platform achieving 100 millions of mappable reads per sample. Then we examined alternative splicing in EC109 cells after RBM6 depletion.