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Requirements for multivalent Yb body assembly in transposon silencing in Drosophila

ABSTRACT: 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.

SUBMITTER: Shigeki Hirakata

PROVIDER: S-SCDT-EMBOR-2019-47708V1 | biostudies-other |

REPOSITORIES: biostudies-other

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Requirements for multivalent Yb body assembly in transposon silencing in Drosophila.

Project description: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.

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Requirements for multivalent Yb body assembly in transposon silencing in Drosophila

Project description:Female sterile (1) Yb (Yb) is a primary component of Yb bodies, perinuclear foci known as the site of PIWI-interacting RNA (piRNA) biogenesis in Drosophila ovarian somatic cells. Yb consists of 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 investigated the functions of the two other domains and found that Hel-C and eTud are necessary for Yb to self-associate and to interact with RNAs and other Yb body components, respectively. Both domains were essential for Yb body formation and transposon silencing. Without eTud, piRNA production was completely impaired. Loss of Hel-C severely reduced the levels of transposon-targeting piRNAs, although genic piRNAs unrelated to transposon silencing were still produced. Similar phenotypes were observed when mutations in flamenco, the primary source of transposon-targeting piRNAs, led to the expression of attenuated RNAs. Yb bodies are liquid-like multivalent condensates whose assembly depends on Yb self-association and widespread Yb−flamenco RNA binding.

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Requirements for multivalent Yb body assembly in transposon silencing in Drosophila

Project description:Requirements for multivalent Yb body assembly in transposon silencing in Drosophila

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Export of piRNA precursors by EJC triggers assembly of cytoplasmic Yb-body in Drosophila.

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Yb body assembly on the flamenco piRNA precursor transcripts reduces genic piRNA production

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Yb body assembly on the flamenco piRNA precursor transcripts reduces genic piRNA production.

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