Distinct Sets of PIWI Proteins Produce Arbovirus and Transposon-Derived piRNAs in Aedes Aegypti Mosquito Cells

Nucleic Acids Res. 2015 Jul 27;43(13):6545-56. doi: 10.1093/nar/gkv590. Epub 2015 Jun 11.

Abstract

The PIWI-interacting RNA (piRNA) pathway is essential for transposon silencing in many model organisms. Its remarkable efficiency relies on a sophisticated amplification mechanism known as the ping-pong loop. In Alphavirus-infected Aedes mosquitoes, piRNAs with sequence features that suggest ping-pong-dependent biogenesis are produced from viral RNA. The PIWI family in Aedes mosquitoes is expanded when compared to other model organisms, raising the possibility that individual PIWI proteins have functionally diversified in these insects. Here, we show that Piwi5 and Ago3, but none of the other PIWI family members, are essential for piRNA biogenesis from Sindbis virus RNA in infected Aedes aegypti cells. In contrast, the production of piRNAs from transposons relies on a more versatile set of PIWI proteins, some of which do not contribute to viral piRNA biogenesis. These results indicate that functional specialization allows distinct mosquito PIWI proteins to process RNA from different endogenous and exogenous sources.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aedes / metabolism
  • Aedes / virology
  • Animals
  • Arboviruses / genetics*
  • Argonaute Proteins / antagonists & inhibitors
  • Argonaute Proteins / physiology*
  • Cell Line
  • DNA Transposable Elements*
  • Insect Proteins / antagonists & inhibitors
  • Insect Proteins / physiology*
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism*
  • RNA, Viral / genetics
  • RNA, Viral / metabolism*
  • Sindbis Virus / genetics*

Substances

  • Argonaute Proteins
  • DNA Transposable Elements
  • Insect Proteins
  • RNA, Small Interfering
  • RNA, Viral