Survival in quiescence requires the euchromatic deployment of Clr4/SUV39H by Argonaute-associated small RNAs [ChIP-Seq]

Cellular quiescence (G0) is a ubiquitous stress response through which cells enter a state of reversible dormancy, acquiring distinct properties including reduced metabolism, resistance to stress and long life. G0 entry involves dramatic changes to the chromatin landscape and transcriptional program of cells, but the mechanisms coordinating these processes remain poorly understood. Using the fission yeast, here we track the G0-associated chromatin and transcriptional changes temporally. We show that as cells enter G0, their survival and global gene expression programs become increasingly dependent on Clr4/SUV39H, the sole histone H3 lysine 9 (H3K9) methyltransferase, and RNA interference (RNAi) proteins. Notably, G0 entry results in RNAi-dependent H3K9 methylation of several euchromatic regions, prior to which Argonaute 1-associated small RNAs from these regions emerge. Overall our data reveal a new function for constitutive heterochromatin proteins in establishing the global G0 transcriptional program and suggest that stress-induced alterations in Argonaute-associated sRNAs can specify the deployment of transcriptional regulatory proteins to unique sites in eukaryotic genomes. Comparision of H3K9me2 peaks in wt/clr4D/ago1D