During normal or pathological epithelial-to-mesenchymal transition, epithelium-specific gene expression is shut down, with the DNA-binding factor ZEB1 acting as a master suppressor of epithelial identity. Here, we show that ZEB1 occupies primate-specific tandem repeats (TRs) harboring dozens of copies of its DNA-binding motif and located within genomic loci relevant for epithelial identity. Deletion of one such repeat in a quasi-mesenchymal human cancer cell line induced the reacquisition of epithelial features and phenocopied the effects of ZEB1 gene deletion. Since ZEB1 binds clustered motifs in a non-cooperative manner, changes in its nuclear concentration enable graded adjustments of TR occupancy, thus fine-tuning repression level. In addition, high motif density in TRs allows ZEB1 binding (and shutdown of epithelial programs) despite differences in chromatin organization and accessibility among epithelial cell types. SOURCE: Chiara Balestrieri (balestrieri.c@gmail.com) -  European Institute of Oncology

Pluto Bioinformatics

GSE88735: Cooptation of tandem DNA repeats for the control of epithelial-to-mesenchymal transition [RNA-Seq]