Deletion of a lncRNA-Containing Septum Transversum Enhancer Alters lncRNA Expression but Is Not Required for Expression.

We have previously identified a transcriptional enhancer that drives expression within the septum transversum, the origin of the cells that contribute to the epicardium. This enhancer directly overlaps a common exon of a predicted family of long non-coding RNAs (lncRNA) that are specific to mice. To interrogate the necessity of this enhancer, as well as the importance of these novel lncRNAs, we deleted the enhancer sequences, including the common exon shared by these lncRNAs, using genome editing. Resultant homozygous enhancer mutants () present with no observable phenotype. Assessment of lncRNA expression reveals that mutants effectively eliminate detectable lncRNA expression. Expression analysis within mutant hearts indicates higher levels of than in controls. The generation of compound heterozygous mutants with the null allele () also did not reveal any observable phenotypes. Together these data indicate that deletion of this enhancer and by consequence a family of murine-specific lncRNAs does not impact embryonic development in observable ways.