Repeat-associated siRNAs cause chromatin silencing of retrotransposons in the Drosophila melanogaster germline.
Silencing of genomic repeats, including transposable elements, in Drosophila melanogaster is mediated by repeat-associated short interfering RNAs (rasiRNAs) interacting with proteins of the Piwi subfamily. rasiRNA-based silencing is thought to be mechanistically distinct from both the RNA interference and microRNA pathways. We show that the amount of rasiRNAs of a wide range of retroelements is drastically reduced in ovaries and testes of flies carrying a mutation in the spn-E gene. To address the mechanism of rasiRNA-dependent silencing of retrotransposons, we monitored their chromatin state in ovaries and somatic tissues. This revealed that the spn-E mutation causes chromatin opening of retroelements in ovaries, resulting in an increase in histone H3 K4 dimethylation and a decrease in histone H3 K9 di/trimethylation. The strongest chromatin changes have been detected for telomeric HeT-A elements that correlates with the most dramatic increase of their transcript level, compared to other mobile elements. The spn-E mutation also causes depletion of HP1 content in the chromatin of transposable elements, especially along HeT-A arrays. We also show that mutations in the genes controlling the rasiRNA pathway cause no derepression of the same retrotransposons in somatic tissues. Our results provide evidence that germinal Piwi-associated short RNAs induce chromatin modifications of their targets.
Klenov
Mikhail S
MS
Department of Molecular Genetics of Cell, Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.
Lavrov
Sergey A
SA
Stolyarenko
Anastasia D
AD
Ryazansky
Sergey S
SS
Aravin
Alexei A
AA
Tuschl
Thomas
T
Gvozdev
Vladimir A
VA
D000251:Adenosine Triphosphatases / Q000235:genetics; D000818:Animals; D002843:Chromatin / Q000737:chemistry / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D005260:Female; D020868:Gene Silencing; D009154:Mutation; D010053:Ovary / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D018626:Retroelements
D002843:Chromatin; D029721:Drosophila Proteins; D034741:RNA, Small Interfering; D018626:Retroelements; D000251:Adenosine Triphosphatases; C096355:spn-E protein, Drosophila
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