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Hen1 is required for oocyte development and piRNA stability in zebrafish

Leonie M Kamminga, Maartje J Luteijn, Marjo J den Broeder, Stefan Redl, Lucas J T Kaaij, Elke F Roovers, Peter Ladurner, Eugene Berezikov, René F Ketting

Author Affiliations

  1. Leonie M Kamminga1,,
  2. Maartje J Luteijn1,,
  3. Marjo J den Broeder1,
  4. Stefan Redl2,
  5. Lucas J T Kaaij1,
  6. Elke F Roovers1,
  7. Peter Ladurner2,
  8. Eugene Berezikov1 and
  9. René F Ketting*,1
  1. 1 Hubrecht Institute‐KNAW, University Medical Centre Utrecht, Utrecht, The Netherlands
  2. 2 Institute of Zoology, Innsbruck, Austria
  1. *Corresponding author. Hubrecht Institute‐KNAW, University Medical Centre Utrecht, Uppsalalaan 8, Utrecht, 3584 CT, The Netherlands. Tel.: +31 30 212 1800; Fax: +31 30 251 6554; E‐mail: r.ketting{at}
  1. These authors contributed equally to this work

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Piwi‐interacting RNAs (piRNAs) are germ line‐specific small RNA molecules that have a function in genome defence and germ cell development. They associate with a specific class of Argonaute proteins, named Piwi, and function through an RNA interference‐like mechanism. piRNAs carry a 2′‐O‐methyl modification at their 3′ end, which is added by the Hen1 enzyme. We show that zebrafish hen1 is specifically expressed in germ cells and is essential for maintaining a female germ line, whereas it is dispensable in the testis. Hen1 protein localizes to nuage through its C‐terminal domain, but is not required for nuage formation. In hen1 mutant testes, piRNAs become uridylated and adenylated. Uridylation frequency is highest on retro‐transposon‐derived piRNAs and is accompanied by decreased piRNA levels and mild derepression of transposon transcripts. Altogether, our data suggest the existence of a uridylation‐mediated 3′–5′ exonuclease activity acting on piRNAs in zebrafish germ cells, which is counteracted by nuage‐bound Hen1 protein. This system discriminates between piRNA targets and is required for ovary development and fully efficient transposon silencing.

  • Received May 4, 2010.
  • Accepted August 27, 2010.
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