Impact of nuclear Piwi elimination on chromatin state in Drosophila melanogaster ovaries.
The Piwi-interacting RNA (piRNA)-interacting Piwi protein is involved in transcriptional silencing of transposable elements in ovaries of Drosophila melanogaster. Here we characterized the genome-wide effect of nuclear Piwi elimination on the presence of the heterochromatic H3K9me3 mark and HP1a, as well as on the transcription-associated mark H3K4me2. Our results demonstrate that a significant increase in the H3K4me2 level upon nuclear Piwi loss is not accompanied by the alterations in H3K9me3 and HP1a levels for several germline-expressed transposons, suggesting that in this case Piwi prevents transcription by a mechanism distinct from H3K9 methylation. We found that the targets of Piwi-dependent chromatin repression are mainly related to the elements that display a higher level of H3K4me2 modification in the absence of silencing, i.e. most actively transcribed elements. We also show that Piwi-guided silencing does not significantly influence the chromatin state of dual-strand piRNA-producing clusters. In addition, host protein-coding gene expression is essentially not affected due to the nuclear Piwi elimination, but we noted an increase in small nuclear spliceosomal RNAs abundance and propose Piwi involvement in their post-transcriptional regulation. Our work reveals new aspects of transposon silencing in Drosophila, indicating that transcription of transposons can underpin their Piwi dependent silencing, while canonical heterochromatin marks are not obligatory for their repression.
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.
Mikhail S
MS
Klenov
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.
Sergey A
SA
Lavrov
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.
Alina P
AP
Korbut
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.
Anastasia D
AD
Stolyarenko
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.
Evgeny Y
EY
Yakushev
European Molecular Biology Laboratory, Grenoble Outstation, 71 avenue des Martyrs, 38042 France Unit for Virus Host-Cell Interactions, University of Grenoble Alpes-EMBL-CNRS, 71 avenue des Martyrs, 38042 France.
Michael
M
Reuter
European Molecular Biology Laboratory, Grenoble Outstation, 71 avenue des Martyrs, 38042 France Unit for Virus Host-Cell Interactions, University of Grenoble Alpes-EMBL-CNRS, 71 avenue des Martyrs, 38042 France.
Ramesh S
RS
Pillai
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia gvozdev@img.ras.ru.
Vladimir A
VA
Gvozdev
D000818:Animals; D060565:Argonaute Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics; D002843:Chromatin / Q000378:metabolism*; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D005260:Female; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism; D010053:Ovary / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000378:metabolism; D018626:Retroelements
D060565:Argonaute Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D029721:Drosophila Proteins; D006657:Histones; D012342:RNA, Small Nuclear; D018626:Retroelements; C116498:piwi protein, Drosophila; D000090266:Chromobox Protein Homolog 5