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Collapse of germline piRNAs in the absence of Argonaute3 reveals somatic piRNAs in flies

  • 0Department of Biochemistry and Molecular Pharmacology and Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, 01605, USA.
Cell +

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April 28, 2009

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April 28, 2009

View abstract on PubMed

Summary

This summary is machine-generated.

Argonaute3 (Ago3) amplifies piRNA pools and enforces antisense bias to silence transposons. A second Piwi-centered pathway targets flamenco locus transposons, suggesting piRNA roles beyond germ cells.

Area Of Science

  • Molecular Biology
  • Genetics
  • Epigenetics

Background

  • Piwi-interacting RNAs (piRNAs) are crucial for silencing transposons in animal germ cells.
  • piRNAs are believed to originate from long transcripts at transposon-rich loci, forming an autoamplification loop.
  • This loop involves antisense piRNAs triggering sense piRNA production, which then generates more antisense piRNAs.

Purpose Of The Study

  • To genetically test the proposed piRNA autoamplification model.
  • To investigate the function of Argonaute3 (Ago3) in piRNA biogenesis and transposon silencing.
  • To identify alternative piRNA pathways and their roles.

Main Methods

  • Generation and analysis of strong loss-of-function mutations in the ago3 gene.
  • Direct genetic testing of the piRNA autoamplification model.
  • Detection and characterization of Ago3-independent piRNA pathways.

Main Results

  • Ago3 loss-of-function mutations confirmed its role in amplifying piRNA pools.
  • Ago3 was found to enforce an antisense bias in piRNAs, enhancing transposon silencing.
  • A second, Ago3-independent piRNA pathway involving Piwi was identified.
  • This second pathway targets transposons in the flamenco locus, active in somatic follicle cells.

Conclusions

  • Argonaute3 is essential for amplifying piRNA pools and maintaining their antisense bias for effective transposon control.
  • A distinct piRNA pathway, independent of Ago3 and centered on Piwi, targets specific transposons.
  • The findings suggest piRNAs have functional roles extending beyond the germline, including in somatic ovarian follicle cells.

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