Analysis of Gene Expression Changes upon Topobexin Treatment and TOP2B-knockout in hiPSC derived cardiomyocytes

The role of DNA topoisomerase II beta (TOP2B) in cardiomyocyte differentiation is poorly understood. To address this, Human induced pluripotent stem cells (hiPSC) were differentiated into cardiomyocytes (CM) that are wildtype or contain a genomic deletion of Topoisomerase 2B (BKO). Both WT and BKO hiPSC could be induced to differentiate into sheets of beating cardiomyocytes. BKO hiPSC take slightly longer to differentiate into sheets of beating CM than WT iPSC. RNA was prepared from both undifferentiated and differentiated WT and BKO hiPSC. RNA seq was used to examine gene expression changes when the WT and BKO hiPSC were differentiated into CM. Gene expression changes following differentiation of BKO cells were largely similar to those in WT cells. In addition, the differentiated WT CM were treated with dexrazoxane (ICRF-187), a TOP2 catalytic inhibitor that targets both TOP2A and TOP2B, or topobexin, a new TOP2B selective catalytic inhibitor. Topobexin inhibition partially phenocopied a TOP2B deletion and thus providing an alternative to TOP2B gene knockout in many cell lines. In future, hiPSC derived CM with and without TOP2B and inhibition by topobexin ex vivo CM could be used to study anthracycline-induced cardiotoxicity and to screen for cardioprotectants. HighlightsO_LIUsed CRISPR-Cas9 to delete TOP2B from hiPSC C_LIO_LIProduced beating cardiomyocytes from both WT and TOP2B null hiPSC C_LIO_LITranscriptome analysis of WT and TOP2B null hiPSC and derived cardiomyocytes C_LIO_LIRNA seq showed he specific TOP2B inhibitor topobexin largely phenocopies TOP2B gene inactivation in iPSC derived cardiomyocytes. C_LIO_LITopobexin inhibition could be used as an alternative to a TOP2B gene knockout in many different cell types, speeding up the analysis of the function of TOP2B. C_LI