Abstract 15541: Novel Molecular Entity for Effective Cardiac Regeneration: 5’ppp Microrna Induces Reprogramming and Accelerates Cardiomyocyte Maturation

• DOI: 10.1161/circ.142.suppl_3.15541
• Publication Date: 2021-05-10T17:09:12Z
• Authors: Jiabiao Hu; Conrad Hodgkinson; Syeda S Baksh; Richard E Pratt; Victor J Dzau
• Keywords: 03 medical and health sciences; 0302 clinical medicine

We have shown that miR combo directly reprograms fibroblasts into cardiomyocytes. However, both in vitro and in vivo, the generated cardiomyocytes are immature. Recently, we discovered that cardiomyocyte maturation is enhanced by NFkB activation. While miR combo

initiates

reprogramming, the effect on NFkB activity is modest. Therefore, miR combo only has a modest effect on maturation. We have now made an important discovery that 5’triphosphorylation (5’ppp) of RNA molecules markedly enhance NFkB activation; leading to increased and accelerated maturation of reprogramed cardiomyocytes. The addition of 5’ppp-RNA increased the number of mature cardiomyocytes by 4-fold (N=5, P<0.05). Moreover, 5’ppp-RNA also accelerated the appearance of mature cardiomyocyte mRNAs (1 day after transfection vs 4 days for unmodified RNA). Importantly, these effects were lost when the 5’ppp moiety was removed. Knockdown studies suggest that 5’ppp-RNA binds to the Pattern Recognition Receptor Rig1. MNase-seq and ChIP-seq analysis suggests that 5’ppp-RNA activates YY1 (N=4, P<0.001). We next asked if 5’ppp modification of the miRNAs within miR combo would also enhance cardiomyocyte maturation; thus, providing a single molecular entity that can

initiate reprogramming and accelerate maturation

of cardiomyocytes. Indeed, 5’ppp modification of the miR combo miR-1 increased the expression of the mature cardiomyocyte markers Actn2 (4-fold, N=3, P<0.05) and Myh6 (4-fold, N=3, P<0.05). In conclusion, 5’ppp-miR combo is a novel approach that has the advantage of both initiating reprogramming and accelerating cardiomyocyte maturation and should lead to more effective cardiac regeneration and restore cardiac function.