Identification of a putative promoter element in intron5 of the RUNX1 gene (565.2)

t(8:21) is one of the most frequent chromosomal translocation found in acute myeloid leukemia (AML) and involves RUNX1 and ETO genes. To date all the break points mapped are located in intron 5 of RUNX1 gene. Interestingly, this intron exhibits DNaseI hypersensitive sites, which has been associated to cis regulatory elements. Therefore, we hypothesize that regulatory elements are harbored in intron5 of the RUNX1 gene. In order to test this hypothesis, we performed bioinformatics analysis of ChIPseq data available from the server ENCODE to identify regions of intron 5 enriched in epigenetics marks associated with regulatory elements. We show that in hematopoietic cells one region is enrich in K4H3me, K4H3me3 and K27H3ac that co‐localizes with DNaseI hypersensitive sites. These marks have been associated with promoter modules. Indeed, when we cloned this region (PPR=putative promoter region) in a reporter vector, we found that it activates expression of the reporter gene in an orientation dependent manner. Moreover, when we analyzed putative transcription factors binding sites, we found one RUNX binding motif. Indeed when we transfected the promoter with RUNX1 expression vector we found that RUNX1 modulates the PPR expression. Using ETS database, we have assembly a putative messenger for this promoter, which is differentially expressed in several cell lines. Taken together, our results shown that a novel promoter is located in intron 5 of RUNX1 gene. Grant Funding Source : Supported by Fondecyt 1130697