DREAM represses distinct targets by cooperating with different THAP domain proteins [CHIP-seq]

The DREAM (DP, Retinoblastoma [Rb]-like, E2F, and MuvB) complex controls cellular quiescence by repressing cell cycle and other genes, but its mechanism of action is unclear. Here we demonstrate that two C. elegans THAP domain proteins, LIN-15B and LIN-36, co-localize with DREAM and function by different mechanisms for repression of distinct sets of targets. LIN-36 represses classical cell cycle targets by promoting DREAM binding and gene body enrichment of H2A.Z. Furthermore, the function of DREAM subunit EFL-1/E2F is specific for LIN-36 targets. In contrast, LIN-15B represses a subset of germline targets by facilitating H3K9me2 promoter marking. In humans, THAP proteins have been implicated in cell cycle regulation by poorly understood mechanisms. We propose that THAP domain proteins are key mediators of Rb/DREAM function, facilitating repression of distinct sets of targets. 50 single-end ChIP-seq libraries were generated from EGS+formaldehyde fixed nuclei from starved L1 C. elegans strains (wt and mutants).