Abstract

Small non-coding RNAs have been shown to play critical roles in mediating epigenetic modifications in regulating chromatin structures, which is likely to be important during the specification of primordial germ cells (PGCs) in mice, and during genome-wide epigenetic reprogramming in early germ cells. Little is currently known about the role of small non-coding RNAs in early germ cells because of the limited numbers of available cells for analysis. First, the role of all non-coding RNAs in germ cells specification and in the establishment of the specific and critical chromatin signature in E8.5 PGCs will be studied in a mouse model in which Argonaute 2 (Ago2) is inactivated. Second, we will investigate gonadal germ cells at E10 .5-E12.5 when they exhibit extensive epigenetic reprogramming, including genome-wide DNA demethylation and chromatin remodelling. We will use RNA -Seq to obtain comprehensive information on all non-coding RNAs, which will help to identify particular types of small non-coding RNA that are likely involved in the regulation of chromatin structure. These data may also provide information on their putative target genes. To investigate the function of small non-coding RNAs at these particular stages, we will use mouse models in which Dicer or Ago2 are specifically deleted in early PGC and we will analyse the effect of the inactivation of the RNAi pathway on this global epigenetic reprogramming. Elucidating the function of small non-coding RNA in these major epigenetic events is important for our understanding of the mechanisms involved in the generation of the totipotent state.