Introduction of silencing-inducing transgenes does not affect expression of known transcripts

While the RNA interference (RNAi) mechanism has only been discovered a decade ago, RNAi is now often used to study gene function by sequence-specific knockdown of gene expression. However, it is still unknown whether introduction of silencing-inducing transgenes alters the transcriptome. To address this question, genome-wide transcriptional changes in silenced and non-silenced backgrounds were monitored through microarray analysis. No significant transcriptional changes were detected when compared to the non-silenced control. This result was confirmed by real-time polymerase chain reaction analysis of genes known to be involved in RNA silencing. In conclusion, introduction of silencing-inducing constructs does not affect expression of known transcripts in other genes than in those homologous to the targeted ones. Consequently, when gene function is studied by RNAi, the transcriptional changes detected will specifically be the result of knockout of the gene of interest, at least for the genes present on the array used in our study.