Pdsg1 and Pdsg2, novel proteins involved in developmental genome remodelling in Paramecium

PLoS One. 2014 Nov 14;9(11):e112899. doi: 10.1371/journal.pone.0112899. eCollection 2014.


The epigenetic influence of maternal cells on the development of their progeny has long been studied in various eukaryotes. Multicellular organisms usually provide their zygotes not only with nutrients but also with functional elements required for proper development, such as coding and non-coding RNAs. These maternally deposited RNAs exhibit a variety of functions, from regulating gene expression to assuring genome integrity. In ciliates, such as Paramecium these RNAs participate in the programming of large-scale genome reorganization during development, distinguishing germline-limited DNA, which is excised, from somatic-destined DNA. Only a handful of proteins playing roles in this process have been identified so far, including typical RNAi-derived factors such as Dicer-like and Piwi proteins. Here we report and characterize two novel proteins, Pdsg1 and Pdsg2 (Paramecium protein involved in Development of the Somatic Genome 1 and 2), involved in Paramecium genome reorganization. We show that these proteins are necessary for the excision of germline-limited DNA during development and the survival of sexual progeny. Knockdown of PDSG1 and PDSG2 genes affects the populations of small RNAs known to be involved in the programming of DNA elimination (scanRNAs and iesRNAs) and chromatin modification patterns during development. Our results suggest an association between RNA-mediated trans-generational epigenetic signal and chromatin modifications in the process of Paramecium genome reorganization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Nucleus / metabolism
  • Chromatin / metabolism
  • DNA, Protozoan / genetics
  • DNA, Protozoan / metabolism
  • Epigenesis, Genetic
  • Genome, Protozoan*
  • Histones / metabolism
  • Methylation
  • Microscopy, Confocal
  • Paramecium / genetics*
  • Paramecium / growth & development
  • Paramecium / metabolism
  • Protozoan Proteins / antagonists & inhibitors
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism


  • Chromatin
  • DNA, Protozoan
  • Histones
  • Protozoan Proteins
  • RNA, Small Interfering
  • Recombinant Fusion Proteins

Grants and funding

This work was supported by Swiss National Science Foundation grant 31003A_129957 (http://www.snf.ch/); European Research Council grant "EPIGENOME" GA 260358 (http://erc.europa.eu/); European Cooperation in Science and Technology Action BM1102 (http://www.cost.eu/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.