Leonie Ringrose and colleagues show that a switch between forward and reverse noncoding transcription at the Drosophila melanogaster vestigial Polycomb/Trithorax response element switches the status of the element between silencing and activation. They further show that strand switching of noncoding RNAs occurs at several hundred PcG-binding sites in flies and vertebrates, suggesting that this regulatory mechanism could be widespread.
- Veronika A Herzog
- Adelheid Lempradl
- Leonie Ringrose
