GSE99959
Identification of two types of GGAA microsatellites and their roles in EWS/FLI binding and gene regulation in Ewing sarcoma
Ewing sarcoma is a bone malignancy of children and young adults, frequently harboring the EWS/FLI t(11;22)(q24;q12) chromosomal translocation. The resulting fusion protein is an aberrant transcription factor that uses highly repetitive GGAA-containing elements (microsatellites) to activate and repress thousands of target genes mediating oncogenesis. However, the mechanisms of EWS/FLI interaction with microsatellites and regulation of target genes expression is not clearly understood. Here, we profile genome-wide protein binding and gene expression. Using a combination of unbiased genome-wide computational and experimental analysis, we define GGAA-microsatellites in a Ewing sarcoma context. Our study identifies two distinct classes of GGAA-microsatellites and demonstrates that EWS/FLI responsiveness is dependent on microsatellite length. At close range (within 5 kb) “promoter-like” microsatellites, EWS/FLI binding and subsequent target genes activation is highly dependent on the number of GGAA-motifs. “Enhancer-like” microsatellites demonstrate a positive correlation with length-dependent EWS/FLI binding, but minimal correlation for activated and none for repressed target genes. Our data suggest that EWS/FLI binds to “promoter-like” and “enhancer-like” microsatellites to mediate activation and repression of target genes through different regulatory mechanisms. Such characterization contributes valuable insight to EWS/FLI transcription factor biology and clarifies the role of GGAA-microsatellites on a global genomic scale. This may provide a unique perspective on the role of non-coding DNA in cancer susceptibility and therapeutic development. Overall design: Examination of EWS/FLI binding in A673 cells.