Genome-wide maps of chromatin state and KAP1 occupancy in KRAB zinc finger protein (KRAB-ZFP) gene cluster KO ES cells and testis

We have shown that many mouse KRAB-ZFPs target retrotransposons which are generally marked by H3K9me3 and KAP1 in ES cells. To test whether these KRAB-ZFPs are require to establish and maintain repressive chromatin marks at these elements, we performed ChIP-seq with antibodies against KAP1 (2 KRAB-ZFP cluster KOs) and H3K9me3 (5 KRAB-ZFP cluster KOs). We show that KRAB-ZFP targeted retrotransposons show reduced KAP1 binding and H3K9me3 in these KO ES cells. Furthermore, we performed ChIP-seq with antibodies against histone modifications typical for promoters and enhancers in Chr4-cl KO ES cells and testis. We show that, in ES cells, ETn retrotransposons gain signatures of active enhancers which acts on earby gene expression. In testis, a handful of different retrotransposons gain enhancer marks, although to a lesser degree. In conclusion, our data shows that KRAB-ZFPs are required to maintain H3K9me3 at retrotransposons in ES cells and to prevent some retrotransposons of becoming enhancers that affect gene expression patterns. Native or cross-linked chromatin was prepared from ES cells or testis and immunoprecipitated with antibodies against KAP1 or various histone modifications