Research Group

Translational Epigenetics

RNA-mediated gene regulation mainly involves gene inactivation processes, which are summarised under the term RNA interference (RNAi). In eukaryotes, RNAi is induced by double-stranded RNA (dsRNA). RNAi can induce gene silencing at the transcriptional, post-transcriptional and translational levels. Due to the diversity with which RNAi can intervene in the gene regulation of almost all eukaryotes, the elucidation of RNAi processes is still one of the most important working fields in biology and medicine today (see also Nobel Prize for Medicine, 2006).

RNA interference

In transcriptional gene inactivation, the regulatory elements of the genes are switched off by epigenetic changes. Post-transcriptional silencing results from the specific degradation of mRNA and mainly occurs when the mRNA has fully complementary sequences to the dsRNA. A termination of translation is usually observed when the mRNA has a high but not complete complementarity to the dsRNA. Although all RNAi mechanisms share common components, in most cases specific members of different enzyme families are essential for the individual gene inactivation processes. These enzyme classes mainly include variants of the ‘Dicer’ (DCR) or ‘Dicer-like’ (DCL), ‘Argonaute’ (AGO) and ‘RNA-directed RNA polymerase’ (RDR) proteins. Plants have a complete and the most diverse range of these enzymes. In addition, plants accumulate numerous types of small regulatory RNAs, which primarily include small interfering RNAs (siRNAs), micro RNAs (miRNAs), trans-acting siRNAs (ta-siRNAs) and natural antisense transcript siRNAs (nat-siRNAs). It is therefore obvious to use plants as a model system for the investigation of RNAi mechanisms.