Mapping chromatin occupancy of GATA1 and RUNX1 isoforms in Down syndrome myeloid leukemia

Down syndrome myeloid leukemia (ML-DS) is characterized by exclusive expression of an N-terminus truncated GATA1 (GATA1s) and disequilibrium of RUNX1 isoform expression. ML-DS blasts are dependent on intact RUNX1, while GATA1s and RUNX1A synergize to induce leukemia in mice. Here, we studied differential chromatin occupancy of GATA1 and GATA1s as well as RUNX1 isoforms at target gene promoters and their effect on gene transcription.

To this end, GATA1 and GATA1s-mutant as well as RUNX1A and RUNX1C isoforms were lentivirally introduced into the ML-DS cell line CMK and in gene-edited primary murine fetal liver cells. After doxycycline induction of transgene expression, transcription factor binding to target genes was analyzed by CUT&RUN. RNA sequencing revealed differential target gene activation by the different transcription factor isoforms. This was accompanied by differential promoter occupancy of GATA1s compared to GATA1, which is mainly characterized by loss of DNA-binding. Furthermore, we found a dominant negative effect of RUNX1A over RUNX1B/C, but also RUNX1A specific functions. These data explain the synergistic effect of GATA1s and RUNX1A during the pathogenesis of ML-DS.

Publikationsverlauf

Artikel online veröffentlicht:
13. Mai 2020