A functional link between nuclear RNA decay and transcritional control mediated by the Polycomb Repressive Complex 2

Pluripotent embryonic stem (ES) cells constitute an essential cellular niche in animal development. It is well documented that ES cells are sustained by epigenetic and transcriptional regulation, but the role of post-transcriptional processes remains less explored. Here, we identify a link between nuclear RNA levels, regulated by the ‘polyA RNA exosome targeting’ (PAXT) connection, and transcriptional control, regulated by the Polycomb Repressive Complex 2 (PRC2). Knockout of the PAXT component ZFC3H1 in mouse ES cells impairs their differentiation. In addition to the upregulation of bona fide PAXT substrates, Zfc3h1-/- cells abnormally express developmental genes usually subjected to PRC2-mediated repression. Such de-repression is paralleled by decreased PRC2 binding to chromatin at target genes, and low PRC2-directed H3K27 methylation. PRC2 complex stability is compromised in Zfc3h1-/- cells with elevated levels of unspecific RNA bound to PRC2 components. We propose that excess RNA hampers PRC2 function through its sequestration from DNA and complex destabilisation. Our results highlight the importance of balancing nuclear RNA levels and demonstrate the capacity of bulk RNA to regulate chromatin-associated proteins. Refer to invidual series