LncRNAs in the Domain Are Essential for Mid-Embryonic Heart Development.

The domain is important for normal embryonic growth and development. The heart is the earliest developing and functioning organ of the embryo. In this study, we constructed a transcriptional termination model by inserting termination sequences and clarified that the lack of long non-coding RNA (lncRNA) expression in the domain caused the death of maternal insertion mutant (MKI) and homozygous mutant (HOMO) mice starting from E13.5. Parental insertion mutants (PKI) can be born and grow normally. Macroscopically, dying MKI and HOMO embryos showed phenomena such as embryonic edema and reduced heart rate. Hematoxylin and eosin (H.E.) staining showed thinning of the myocardium in MKI and HOMO embryos. In situ hybridization (IHC) and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) showed downregulation of lnc, , and expression in MKI and HOMO hearts. The results of single-cell RNA sequencing (scRNA-Seq) analysis indicated that the lack of lncRNA expression in the domain led to reduced proliferation of epicardial cells and may be an important cause of cardiac dysplasia. In conclusion, this study demonstrates that domain lncRNAs play an integral role in ventricular development.