PS-B02-9: HEART RELATED CIRCULAR RNA (HRCR) INFLUENCES POLYGENIC CARDIAC HYPERTROPHY BY ALTERING CARDIAC MICRORNAS

Abstract

Left ventricular hypertrophy (LVH) is the main risk factor for cardiovascular disease after age. Circular RNAs (circRNA), a novel and underexplored RNA type, are created by the back-splicing of pre-mRNA and have been proposed to regulate gene expression post-transcriptionally via targeting micro RNAs (miRNA). Heart related circRNA (Hrcr) has been proposed as an important regulator of LVH and has been shown to be downregulated in mice with cardiac hypertrophy induced by chronic infusion of isoproterenol. Our aim was to investigate the expression of Hrcr in the hypertrophic heart during development and at maturity. We used the hypertrophic heart rat (HHR), a unique normotensive polygenic model of LVH and heart failure, and its genetic control strain, the normal heart rat (NHR). We first measured the expression of Hrcr by quantitative real-time PCR in left ventricles of HHR and NHR at five ages (2 days old, 4-, 13-, 33- and 50-weeks old). Secondly, we silenced HRCR in human primary cardiomyocytes and performed small RNA sequencing to reveal its miRNA downstream targets. Lastly, we performed in silico investigations to predict miRNA-mRNA targets and explore enriched gene ontology terms in our dataset.We found that Hrcr is upregulated in the HHR at 13-, 33- and 50-weeks old (FC = 2.77-3.57; P < 0.05). The silencing of HRCR revealed novel downstream targets, including four miRNAs (miR-1-3p, miR-330, miR-27a-5p and miR-299-5p) and two noncoding RNAs (ribosomal RNA RNA5-8SP2 and piwi-interacting RNA piR-17153). The miRNA-mRNA interactions predicted a total of 359 mRNAs highly likely to be targeted by the differentially expressed miRNAs. Lastly, 206 gene ontology terms were enriched in our dataset, including terms related to heart development and cardiovascular disease.