Armitage determines Piwi-piRISC processing from precursor formation and quality control to inter-organelle translocation.

Piwi and piRNA form the piRNA-induced silencing complex (piRISC) to repress transposons. In the current model, Armitage (Armi) brings the Piwi-piRISC precursor (pre-piRISC) to mitochondria, where Zucchini-dependent piRISC maturation occurs. Here, we show that Armi is necessary for Piwi-pre-piRISC formation at Yb bodies and that Armi triggers the exit of Piwi-pre-piRISC from Yb bodies and the translocation to mitochondria.

Piwi Nuclear Localization and Its Regulatory Mechanism in Drosophila Ovarian Somatic Cells.

In Drosophila ovarian somatic cells (OSCs), Piwi represses transposons transcriptionally to maintain genome integrity. Piwi nuclear localization requires the N terminus and PIWI-interacting RNA (piRNA) loading of Piwi. However, the underlying mechanism remains unknown.

PIWI-Interacting RNA in Drosophila: Biogenesis, Transposon Regulation, and Beyond.

PIWI-interacting RNAs (piRNAs) are germline-enriched small RNAs that control transposons to maintain genome integrity. To achieve this, upon being processed from piRNA precursors, most of which are transcripts of intergenic piRNA clusters, piRNAs bind PIWI proteins, germline-specific Argonaute proteins, to form effector complexes. The mechanism of this piRNA-mediated transposon silencing pathway is fundamentally similar to that of siRNA/miRNA-dependent gene silencing in that a small RNA guides its partner Argonaute protein to target gene transcripts for repression via RNA-RNA base pairing.