Genome-wide identification of binding sites of Evi1 in human myeloid cell lines

The EVI1 gene codes for a transcription factor with important roles in development and leukemogenesis. Overexpression of EVI1 in acute myeloid leukemia (AML) is one of the worst prognostic factors in patients with and without 3q26 rearrangements. Evi1 acts in several pathways through the interaction with proteins with important functions in hematopoiesis; however, the role of Evi1 as a transcription factor is not well known, and only some Evi1 target genes have been identified in mice. Our aim was to investigate the pathways and direct target genes of EVI1. Differential expression profiles after EVI1 knockdown allowed us to identify 125 genes involved in cell growth, differentiation and signal transduction that could be related to EVI1. Moreover, we looked for potential EVI1 binding sites within the region 1000 bp upstream of the transcription start sites of all human genes. We selected a total of 70 genes from the bioinformatics search, genes related to EVI1 by literature, and genes differentially expressed in the expression array. ChIP in the TF1 and HEL cell lines with two EVI1 antibodies demonstrated that EVI1 binds to the proximal promoter regions of 18 of these genes, most of them involved in important differentiation and proliferation pathways, confirming the important role of EVI1. Interestingly, EVI1 binds to the proximal region of its promoter, suggesting that it could be regulating its own transcription. Further functional studies are in progress. These data provide a starting point for further studies aimed at uncovering the mechanism for EVI1-induced transformation leukemias.

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