Genetic approaches to evaluate lncRNA functional contributions. (A) Genetic ablation of a lncRNA gene or a lncRNA promoter is a powerful technique that can be used to confirm any regulatory activity arising from a particular locus. The optional incorporation of a reporter gene at the deleted locus can be used to visualize the biological contexts in which the lncRNA gene is expressed and evaluate any contribution of the local act of transcription to an observed phenotype. (B) An alternative strategy is to introduce a premature transcriptional terminator sequence, which will prevent transcription of the full-length lncRNA transcript. With this approach, however, it is not possible to assess the contribution of the act of transcription. (C) With either approach, the rescue of any observed phenotype by transgene expression is currently still considered the gold standard to confirm a functional lncRNA molecule; however, a rescue may not be possible if the RNA works exclusively in cis.
