Abstract
In eukaryotes, trimethylation of lysine 9 on histone H3 (H3K9) is associated with transcriptional silencing of transposable elements (TEs). In drosophila ovaries, this heterochromatic repressive mark is thought to be deposited by SetDB1 on TE genomic loci after the initial recognition of nascent transcripts by PIWI-interacting RNAs (piRNAs) loaded on the Piwi protein. Here, we show that the nucleosome remodeler Mi-2, in complex with its partner MEP-1, forms a subunit that is transiently associated, in a MEP-1 C-terminus-dependent manner, with known Piwi interactors, including a recently reported SUMO ligase, Su(var)2-10. Together with the histone deacetylase Rpd3, this module is involved in the piRNA-dependent TE silencing, correlated with H3K9 deacetylation and trimethylation. Therefore, drosophila piRNA-mediated transcriptional silencing involves three epigenetic effectors, a remodeler, Mi-2, an eraser, Rpd3 and a writer, SetDB1, in addition to the Su(var)2-10 SUMO ligase.
Highlights
In eukaryotes, trimethylation of lysine 9 on histone H3 (H3K9) is associated with transcriptional silencing of transposable elements (TEs)
A physical link between these two modules might be provided by Su(var)[2,3,4,5,6,7,8,9,10] that we found to interact with MEP-1 in both S2 and ovarian somatic cells (OSCs), in addition to its previously reported Piwi and SetDB1 partners[24]
In Drosophila ovaries, the PIWI-interacting RNAs (piRNAs) loaded on the Piwi protein are involved in the targeting of TE nascent transcripts, by sequence complementarity, for the deposition of this heterochromatic repressive mark[19,20,49] by the SetDB1 methyltransferase[21,22,23]
Summary
Trimethylation of lysine 9 on histone H3 (H3K9) is associated with transcriptional silencing of transposable elements (TEs) In drosophila ovaries, this heterochromatic repressive mark is thought to be deposited by SetDB1 on TE genomic loci after the initial recognition of nascent transcripts by PIWI-interacting RNAs (piRNAs) loaded on the Piwi protein. Of note, when artificially tethered to DNA, MEP-1 is sufficient to repress the target, concomitantly with H3K9me[3] deposition and H3K9 deacetylation Together, these findings suggest that conserved mechanisms of RNA-mediated transcriptional silencing use nucleosome remodelers, chromatin erasers, and writers
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
