LONG NON CODING RNAS IN DEVELOPING HEART: A SINGLE CELL APPROACH

Abstract

Long noncoding RNAs (lncRNAs) regulate important early stages of cardiac differentiation, however their role in cardiomyocyte specification and maturation, is still unknown. Here, we performed single cell RNA-seq for hESC-CM in prolonged 2, 6 and 12 weeks. Weighted correlation network analysis (WGCNA) and co-expression analysis identified core cardiac specific genes to be significantly upregulated in maturing hESC-CMs. Among these we identified the lncRNA VENTHEART (VHRT), that is co-regulated with core cardiac contractile processes, including calcium regulatory genes. VHRT was highly expressed in MYL2+ ventricular-like CMs. VHRT knockdown (KD) in 6-weeks old hESC-CMs downregulated key cardiac genes and loss of the ventricular-like action potential. In agreement with this, deletion of VHRT locus led to impaired CM sarcomere formation, and lack of CM specification gene programs. VHRT replacement in VHRT-KO cells was however insufficient to rescue the phenotype. We established, by 3C assay, that the VHRT locus interacts with the MYL2 region, with histone marks characteristic of a super-enhancer. Thus, we conclude that both the VHRT lncRNA transcript and its genomic locus are important and required for proper CM specification and function.