Ectopic assembly of heterochromatin in Drosophila melanogaster triggered by transposable elements
A persistent question in biology is how cis -acting sequence elements influence trans -acting factors and the local chromatin environment to modulate gene expression. We reported previously that the DNA transposon 1360 can enhance silencing of a reporter in a heterochromatic domain of Drosophila mel...
Gespeichert in:
Veröffentlicht in: | Proceedings of the National Academy of Sciences - PNAS 2012-08, Vol.109 (35), p.14104-14109 |
---|---|
Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | A persistent question in biology is how cis -acting sequence elements influence trans -acting factors and the local chromatin environment to modulate gene expression. We reported previously that the DNA transposon 1360 can enhance silencing of a reporter in a heterochromatic domain of Drosophila melanogaster . We have now generated a collection of variegating phiC31 landing-pad insertion lines containing 1360 and a heat-shock protein 70 (hsp70)-driven white reporter to explore the mechanism of 1360 -sensitive silencing. Many 1360 -sensitive sites were identified, some in apparently euchromatic domains, although all are close to heterochromatic masses. One such site (line 1198; insertion near the base of chromosome arm 2L) has been investigated in detail. ChIP analysis shows 1360 -dependent Heterochromatin Protein 1a (HP1a) accumulation at this otherwise euchromatic site. The phiC31 landing pad system allows different 1360 constructs to be swapped with the full-length element at the same genomic site to identify the sequences that mediate 1360 -sensitive silencing. Short deletions over sites with homology to PIWI-interacting RNAs (piRNAs) are sufficient to compromise 1360 -sensitive silencing. Similar results were obtained on replacing 1360 with Invader4 (a retrotransposon), suggesting that this phenomenon likely applies to a broader set of transposable elements. Our results suggest a model in which piRNA sequence elements behave as cis -acting targets for heterochromatin assembly, likely in the early embryo, where piRNA pathway components are abundant, with the heterochromatic state subsequently propagated by chromatin modifiers present in somatic tissue. |
---|---|
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.1207036109 |