Requirements for multivalent Yb body assembly in transposon silencing in Drosophila

Shigeki Hirakata, Hirotsugu Ishizu, Aoi Fujita, Yumiko Tomoe, Mikiko C. Siomi

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


Female sterile (1) Yb (Yb) is a primary component of Yb bodies, perinuclear foci considered to be the site of PIWI-interacting RNA (piRNA) biogenesis in Drosophila ovarian somatic cells (OSCs). Yb consists of three domains: Helicase C-terminal (Hel-C), RNA helicase, and extended Tudor (eTud) domains. We previously showed that the RNA helicase domain is necessary for Yb–RNA interaction, Yb body formation, and piRNA biogenesis. Here, we investigate the functions of Hel-C and eTud and reveal that Hel-C is dedicated to Yb–Yb homotypic interaction, while eTud is necessary for Yb–RNA association, as is the RNA helicase domain. All of these domains are indispensable for Yb body formation and transposon-repressing piRNA production. Strikingly, however, genic piRNAs unrelated to transposon silencing are produced in OSCs where Yb bodies are disassembled. We also reveal that Yb bodies are liquid-like multivalent condensates whose assembly depends on Yb–Yb homotypic interaction and Yb binding particularly with flamenco RNA transcripts, the source of transposon-repressing piRNAs. New insights into Yb body assembly and biological relevance of Yb bodies in transposon silencing have emerged.

Original languageEnglish
Article numbere47708
JournalEMBO Reports
Issue number7
Publication statusPublished - 2019 Jul


  • Yb body
  • female sterile (1) Yb
  • liquid–liquid phase separation
  • piRNA
  • transposon

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Genetics


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