Publication highlight in Nature Genetics

August 14, 2014

Leonie Ringrose's group has shown that an epigenetic regulatory DNA element switches its function reversibly between activation and silencing, by switching the strand of its non coding transcription. Remarkably, the two strands work by different molecular mechanisms, and genome wide analysis shows that this may be a general mechanism in flies and vertebrates, for epigenetic switching.

A molecular gearbox for epigenetic regulatory elements

Polycomb/Trithorax response elements (PRE/TREs) can switch their function reversibly between silencing and activation by mechanisms that are poorly understood. Here we show that a switch in forward and reverse noncoding transcription from the Drosophila melanogaster vestigial (vg) PRE/TRE switches the status of the element between silencing (induced by the forward strand) and activation (induced by the reverse strand). In vitro, both noncoding RNAs inhibit PRC2 histone methyltransferase activity, but, in vivo, only the reverse strand binds PRC2. Overexpression of the reverse strand evicts PRC2 from chromatin and inhibits its enzymatic activity. We propose that the interaction of RNAs with PRC2 is differentially regulated in vivo, allowing regulated inhibition of local PRC2 activity. Genome-wide analysis shows that strand switching of noncoding RNAs occurs at several hundred Polycomb-binding sites in fly and vertebrate genomes. This work identifies a previously unreported and potentially widespread class of PRE/TREs that switch function by switching the direction of noncoding RNA transcription.

The full article can be found in Nature Genetics.

Title: A strand-specific switch in noncoding transcription switches the function of a Polycomb/Trithorax response element. Veronika Herzog, Adelheid Lempradl et al.