PLoS Genet 2015 Aug 20;11(8):e1005444. Epub 2015 Aug 20.
Dulbecco Telethon Institute, Palermo, Italy; Università degli Studi di Palermo, Dipartimento STEBICEF-Sezione Biologia Cellulare, Palermo, Italy.
In order to study the role played by cellular RNA pools produced by homologous genomic loci in defining the transcriptional state of a silenced gene, we tested the effect of non-functional alleles of the white gene in the presence of a functional copy of white, silenced by heterochromatin. We found that non-functional alleles of white, unable to produce a coding transcript, could reactivate in trans the expression of a wild type copy of the same gene silenced by heterochromatin. This new epigenetic phenomenon of transcriptional trans-reactivation is heritable, relies on the presence of homologous RNA's and is affected by mutations in genes involved in post-transcriptional gene silencing. Our data suggest a general new unexpected level of gene expression control mediated by homologous RNA molecules in the context of heterochromatic genes.