Project description:Evi1 is essential for proliferation of hematopoietic stem cells and implicated in the development of myeloid disorders. Particularly, high Evi1 expression defines one of the largest clusters in acute myeloid leukemia and is significantly associated with extremely poor prognosis. Improvement of the therapeutic outcome of leukemia with activated Evi1 is one of the most challenging issues. However, mechanistic basis of Evi1-mediated leukemogenesis has not been fully elucidated. Here we show that Evi1 directly represses PTEN transcription in the murine bone marrow, which leads to activation of AKT/mTOR signaling. In a murine bone marrow transplantation model, Evi1 leukemia showed remarkable sensitivity to an mTOR inihibitor rapamycin. Furthermore, we found that Evi1 binds to several polycomb group proteins and recruits polycomb repressive complexes for PTEN downregulation, which reveals a novel epigenetic mechanism of AKT/mTOR activation in leukemia. Expression analyses and chromatin immunoprecipitation assays using human samples indicate that our findings in mice models are recapitulated in human leukemic cells. Dependence of Evi1-expressing leukemic cells on AKT/mTOR signaling provides the first example of targeted therapeutic modalities that suppress the leukemogenic activity of Evi1. The PTEN/AKT/mTOR signaling pathway and the Evi1-polycomb interaction can be promising therapeutic targets for leukemia with activated Evi1. Gene expression analysis for the purpose of identifying the target genes of Evi1 in primary bone marrow. 5-FU-primed mononuclear bone marrow cells harvested from C57/B6 mice were retrovirally transduced with Evi1-GFP or GFP. GFP positive cells were sorted and analyzed by Affymetrix® Mouse Genome 430 2.0 Array® for gene expression. Four independent experiments were performed.
Project description:ATAC-seq profiling of Nfat5 KO and wild type macrophages derived from bone marrow (primary cells), treated or not with Lipopolysaccharide (LPS).
Project description:To investigate the pathological effect of miR-126 on the progression of acute myeloid leukemia (AML) induced by AML1-ETO9a (AE9a), we conducted a series of mouse bone marrow transplantation (BMT) assays with the following groups: AE9a (primary donor cells were wild-type mouse bone marrow progenitor (i.e., lineage negative; Lin-) cells retrovirally transduced with MSCV-PIG-AE9a), AE9a+miR-126 (primary donor cells were wild-type mouse bone marrow progenitor (i.e., Lin-) cells retrovirally transduced with MSCV-PIG-AE9a-miR-126), and miR-126KO+AE9a (primary donor cells were miR-126 knockout mouse bone marrow progenitor (i.e., Lin-) cells retrovirally transduced with MSCV-PIG-AE9a), along with a control group (primary donor cells were wild-type mouse bone marrow progenitor (i.e., Lin-) cells retrovirally transduced with MSCV-PIG empty vector). The control group was only used in the primary and secondary BMT assays, whereas the three leukemic groups including AE9a, AE9a+miR-126 and miR-126KO+AE9a were used in four passages (i.e., primary, secondary, tertiary and quaternary) of BMT assays. Then, gene expression profiling was conducted with bone marrow samples collected from different groups to decipher the molecular mechanisms underlying miR-126 effects on leukemia initiation and progression and maintenance and self-renewal of leukemia stem/initiating cells.