Proposed mechanism for the initiation of transposable element silencing by the RDR6-directed DNA methylation pathway

The activity of transposable elements is epigenetically suppressed by both transcriptional and post-transcriptional mechanisms. We recently identified a direct connection between the small RNA-mediated post-transcriptional mRNA degradation of actively transcribing transposable elements and the de novo methylation of transposable element DNA, providing a mechanistic link between these two established pathways of transposable element silencing. Here we provide a model for the initiation, establishment and epigenetic maintenance of transposable element silencing that incorporates recent data in this rapidly emerging field.