How might flukes and tapeworms maintain genome integrity without a canonical piRNA pathway?

Trends Parasitol. 2014 Mar;30(3):123-9. doi: 10.1016/j.pt.2014.01.001. Epub 2014 Jan 28.

Abstract

Surveillance by RNA interference is central to controlling the mobilization of transposable elements (TEs). In stem cells, Piwi argonaute (Ago) proteins and associated proteins repress mobilization of TEs to maintain genome integrity. This defense mechanism targeting TEs is termed the Piwi-interacting RNA (piRNA) pathway. In this opinion article, we draw attention to the situation that the genomes of cestodes and trematodes have lost the piwi and vasa genes that are hallmark characters of the germline multipotency program. This absence of Piwi-like Agos and Vasa helicases prompts the question: how does the germline of these flatworms withstand mobilization of TEs? Here, we present an interpretation of mechanisms likely to defend the germline integrity of parasitic flatworms.

Keywords: Cestoda; Platyhelminthes; Trematoda; argonaute; germline; piRNA pathway; piwi; transposable elements; vasa.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Argonaute Proteins / genetics
  • Cestoda / genetics*
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / metabolism
  • Genomic Instability / genetics*
  • Phylogeny
  • Protein Processing, Post-Translational
  • RNA, Small Interfering / genetics*
  • Trematoda / genetics*

Substances

  • Argonaute Proteins
  • RNA, Small Interfering
  • DEAD-box RNA Helicases