Abstract 12841: Overexpression of Scarna20 Promotes Small Nuclear RNA Pseudouridylation and Improves Cardiomyogenesis

Abstract

Introduction: Non-coding RNAs, particularly small Cajal body-associated RNAs (scaRNAs), play an important role in alternative splicing and maturation of mRNAs through pseudouridylatory modification. Our small non-coding RNA sequencing analysis has identified that scaRNA20 plays a major role in cardiomyocyte differentiation. In this study, we aim to elucidate the role of scaRNA20 during cardiac differentiation using in vitro induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iCMC) subjected to 3% hypoxic conditions. Hypothesis: Overexpression (OE) of scaRNA20 in iPSCs leads to enhanced cardiomyogenesis and increases the endurance properties of cardiomyocytes by maintaining contractility under hypoxic conditions. Methods and results: We have used OE and knockdown (KD) assays to delineate the role of scaRNA20 during the process of iPSC to iCMC differentiation. The video recordings of scaRNA20-OE-iCMCs and scaRNA20-KD-iCMC contractilities were measured by a novel Particle Image Velocimetry (PIV) method. Our results show that the contractility was impaired in control iCMCs whereas in scaRNA20-OE-iCMCs it was well-maintained under the hypoxic conditions. In contrast, scaRNA20-KD-iCMCs resulted in poor differentiation, they were non-functional and had an impaired contractility. Furthermore, we investigated the pseudouridylation levels of spliceosomal RNA U12 which is a direct target for scaRNA20. We found an increased level of Ψ 28 in scaRNA20-OE iCMCs (Figure A-D) . In addition, the scaRNA20 overexpression in iCMCs resulted in the upregulation of DKC1, NHP2, and NOP10 and downregulation of GAR1, COIL, and WRAP53 and these effects regulate the activation of pTP53 and STAT3 and thus activating cardiac genes. Conclusion: Taken together, our results show for the first time that modulation of iCMCs with scaRNA20 helps maintain the endurance properties of cardiomyocytes while under hypoxic conditions, and it also improves cardiomyogenesis.