Piwi Modulates Chromatin Accessibility by Regulating Multiple Factors Including Histone H1 to Repress Transposons

Yuka Iwasaki, Kensaku Murano, Hirotsugu Ishizu, Aoi Shibuya, Yumiko Iyoda, Mikiko C. Siomi, Haruhiko Siomi, Kuniaki Saito

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

PIWI-interacting RNAs (piRNAs) mediate transcriptional and post-transcriptional silencing of transposable element (TE) in animal gonads. In . Drosophila ovaries, Piwi-piRNA complexes (Piwi-piRISCs) repress TE transcription by modifying the chromatin state, such as by H3K9 trimethylation. Here, we demonstrate that Piwi physically interacts with linker histone H1. Depletion of Piwi decreases H1 density at a subset of TEs, leading to their derepression. Silencing at these loci separately requires H1 and H3K9me3 and heterochromatin protein 1a (HP1a). Loss of H1 increases target loci chromatin accessibility without affecting H3K9me3 density at these loci, while loss of HP1a does not impact H1 density. Thus, Piwi-piRISCs require both H1 and HP1a to repress TEs, and the silencing is correlated with the chromatin state rather than H3K9me3 marks. These findings suggest that Piwi-piRISCs regulate the interaction of chromatin components with target loci to maintain silencing of TEs through the modulation of chromatin accessibility. Piwi-piRNA complexes silence transposons in animal gonads. Iwasaki et al. identify linker histone H1 as a component of nuclear Piwi-piRNA complexes and show that Piwi-piRNA complexes require both H1 and HP1a to repress targets and that the transcriptional silencing is correlated with the chromatin state rather than H3K9me3 marks.

Original languageEnglish
JournalMolecular Cell
DOIs
Publication statusAccepted/In press - 2015 Dec 16

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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