Declined presentation the novel C/EBPalpha target gene EVI2B regulates myeloid differentiation and hematopoietic progenitor cell function

C/EBPalpha and its target genes are known as important regulators of myeloid differentiation and maintenance of hematopoietic stem cells. Here, we identified a novel C/EBPalpha target gene, EVI2B, and demonstrated its abundant expression in the majority of hematopoietic populations, with remarkably high levels in myeloid lineage cells. We demonstrated that Evi2b depletion alters myeloid lineage development in vitro, both in murine and human models. Further, we observed that Evi2b-depleted hematopoietic stem and progenitor cells (HSPC) demonstrate impaired colony forming ability as well as decreased capacity to reconstitute the hematopoietic system of lethally irradiated mice. In addition, we demonstrated increased apoptosis and decreased proliferation in progenitor cells with reduced levels of EVI2B, which explains the affected functionality of these cells. To deepen our understanding of the mechanistic role of EVI2B in hematopoiesis, we aimed to identify Evi2b interacting proteins. Using immunoprecipitation followed my mass spectrometry analysis we identified a list of potential EVI2B binding partners. In within those, CD97, a G protein-coupled receptor involved in adhesion and migration, was present. The interaction between EVI2B and CD97 was verified by western blot analysis in murine and human cells. Both EVI2B and CD97 localize in the cellular membrane, and we hypothesize that EVI2B interacts with CD97 and possibly regulates its function. In addition, alterations in Evi2b-depleted HSPCs might be caused by impaired performance of the EVI2B /CD97 complex leading to changes in cell adhesion and/or migration. Altogether, our work provides an insight into the role of EVI2B in myeloid differentiation and functionality of hematopoietic progenitors, and suggests its involvement in cellular adhesion and/or migration.