GW-Bodies and P-Bodies Constitute Two Separate Pools of Sequestered Non-Translating RNAs

PLoS One. 2016 Mar 1;11(3):e0150291. doi: 10.1371/journal.pone.0150291. eCollection 2016.

Abstract

Non-translating RNAs that have undergone active translational repression are culled from the cytoplasm into P-bodies for decapping-dependent decay or for sequestration. Organisms that use microRNA-mediated RNA silencing have an additional pathway to remove RNAs from active translation. Consequently, proteins that govern microRNA-mediated silencing, such as GW182/Gw and AGO1, are often associated with the P-bodies of higher eukaryotic organisms. Due to the presence of Gw, these structures have been referred to as GW-bodies. However, several reports have indicated that GW-bodies have different dynamics to P-bodies. Here, we use live imaging to examine GW-body and P-body dynamics in the early Drosophila melanogaster embryo. While P-bodies are present throughout early embryonic development, cytoplasmic GW-bodies only form in significant numbers at the midblastula transition. Unlike P-bodies, which are predominantly cytoplasmic, GW-bodies are present in both nuclei and the cytoplasm. RNA decapping factors such as DCP1, Me31B, and Hpat are not associated with GW-bodies, indicating that P-bodies and GW-bodies are distinct structures. Furthermore, known Gw interactors such as AGO1 and the CCR4-NOT deadenylation complex, which have been shown to be important for Gw function, are also not present in GW-bodies. Use of translational inhibitors puromycin and cycloheximide, which respectively increase or decrease cellular pools of non-translating RNAs, alter GW-body size, underscoring that GW-bodies are composed of non-translating RNAs. Taken together, these data indicate that active translational silencing most likely does not occur in GW-bodies. Instead GW-bodies most likely function as repositories for translationally silenced RNAs. Finally, inhibition of zygotic gene transcription is unable to block the formation of either P-bodies or GW-bodies in the early embryo, suggesting that these structures are composed of maternal RNAs.

Publication types

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

MeSH terms

  • Animals
  • Argonaute Proteins / genetics
  • Cytoplasm / genetics
  • Drosophila Proteins / genetics
  • Drosophila melanogaster / genetics
  • MicroRNAs / genetics
  • Protein Biosynthesis / genetics*
  • RNA Interference / physiology
  • RNA, Long Noncoding / genetics*
  • Transcription, Genetic / genetics

Substances

  • AGO1 protein, Drosophila
  • Argonaute Proteins
  • Drosophila Proteins
  • Gw protein, Drosophila
  • MicroRNAs
  • RNA, Long Noncoding