Cardiogenesis processes in human and animals have differential dynamics, suggesting the existence of species-specific regulators during heart development. However, it remains a challenge to discover the human-specific cardiac regulatory genes, given that most coding genes are conserved. Here, researchers at the University of Pittsburgh School of Medicine report the identification of a human-specific long noncoding RNA, Heart Brake LncRNA 1 (HBL1), which regulates cardiomyocyte development from human induced pluripotent stem cells (hiPSCs). Overexpression of HBL1 repressed, whereas knockdown and knockout of HBL1 increased, cardiomyocyte differentiation from hiPSCs. HBL1 physically interacted with MIR1 in an AGO2 complex. Disruption of MIR1 binding sites in HBL1 showed an effect similar to that of HBL1 knockout. SOX2 bound to HBL1 promoter and activated its transcription. Knockdown of SOX2 in hiPSCs led to decreased HBL1 expression and increased cardiomyocyte differentiation efficiency. Thus, HBL1 plays a modulatory role in fine-tuning human-specific cardiomyocyte development by forming a regulatory network with SOX2 and MIR1.
Identification of Lineage-Specific lncRNAs during Cardiomyocyte Differentiation from hESCs
(A) Scheme of differentiation and enrichment of cardiovascular cells from human RUES2 ESCs. (B) Expression profiles of the lineage-specific marker genes (left) and lncRNA genes (right) quantitated by the normalized FPKM (fragments per kilobase of exon per million reads). (C) Scheme for the construction of pFEFW-E2-crimsom lentiviral vector for lncRNA knockdown (upper). Human S3 iPSC cells with knockdown of lncRNA TCONS_00028911 were cultured on feeders (lower). Scale bars, 200 μm. (D) Detection of lncRNA TCONS_00028911 expression by qRT-PCR. (E) Cardiomyocyte differentiation protocol using embryoid body (EB) method (upper) and images of EBs under differentiation from S34 hiPSCs (lower). Scale bars, 600 μm.