Cistrome analysis of SKI and RUNX1 in HL60. Cistrome analysis of SKI and RUNX1 in HL60

SKI is a transcriptional co-regulator and overexpressed in various human tumors, for example in acute myeloid leukemia (AML). SKI contributes to the origin and maintenance of the leukemic phenotype. Here we use ChIP-seq and RNA-seq to identify the epigenetic alterations induced by SKI overexpression in AML cells. We show that approximately two thirds of differentially expressed genes are up-regulated upon SKI deletion, of which nearly 50% harbour SKI binding sites in their proximity, primarily in enhancer regions. Gene ontology analysis reveals that many of the differentially expressed genes are annotated to hematopoietic cell differentiation and inflammatory response, corroborating our finding that SKI deletion causes a release of the myeloid differentiation block in HL60 cells. We find that SKI peaks are enriched for RUNX1 consensus motifs, particularly in up-regulated SKI targets. RUNX1 ChIP-seq demonstrates that nearly 70% of RUNX1 binding sites overlap with SKI peaks, mainly at enhancer regions. SKI and RUNX1 co-occupy the same genomic sites and cooperate in gene silencing. Our work demonstrates for the first time on a genome-wide scale the predominant co-repressive function of SKI in AML cells and uncovers the transcription factor RUNX1 as an important mediator of SKI-dependent transcriptional repression. Overall design: Examining of SKI genome-wide binding and its comparison with other transcription factors and histone modifications.