Mislocalization of pathogenic RBM20 variants in dilated cardiomyopathy is caused by loss-of-interaction with Transportin-3

First, we compared gene expression and alternative splicing changes between differentially-localized P633L-RBM20, WT-RBM20, and R634Q-RBM20 in iPSC-CMs. Using ICS, we sorted iPSC-CMs with differentially-localized RBM20 based on correlation with nuclear staining. This was followed by RNA-sequencing of the sorted populations. Second, we analysed gene expression and splicing changes in iPSC-CMs overexpressing of WT-, R634Q-, or NLS-tagged R634Q-RBM20 in splice deficient cells carrying the homozygous frameshift mutation (S635FS). Third, we performed RNA sequencing of our HeLa Tet:Cas9 eGFP-RBM20-WT and -R634Q to compare their gene expression to iPSC-CMs. Lastly, we performed two genome-wide CRISPR ICS screens in HeLa cells stably expressing eGFP-RBM20-WT and -R634Q, and TetO-Cas9, to identify genes essential for RBM20 nuclear import. Gene expression and PSI analyses from RNA-seq data in iPSC-CMs; gene expression analysis from RNA-seq data in HeLa, gene statistics from ICS screens in eGFP-RBM20 HeLa reporter lines.