Project description:Purpose: To characterize the genome-wide distribution of H3K79me2 in murine MN1 driven myeloid leukemia Methods: We performed Chip-seq for the H3K79me2 in leukemias isolated from moribund mice that had been injected with common myeloid progenitors (CMPs) transduced with MSCV-MN1-GFP Results: H3K79me2 is enriched at key loci that 1. are bound by MN1 in the data set of Heuser et al, (Cancer Cell. 2011 Jul 12;20(1):39-52.), 2. upregulated upon transduction with MN1, and lose expression upon deletion of the H3K79 methyltransferase Dot1l. Conclusions: A leukemogenic program in MN1 leukemias is marked by H3K79me2 and dependent on this mark ChIP-Seq for H3K79me2 using MN1 driven leukemias isolated from the bone marrow of moribund mice.
Project description:MN1 leukemia is a poor prognosis leukemia occuring as MN1 overexpression or fusion with TEL (MN1-TEL), MN1 and MN1-TEL show different biology in terms of dependence of known self-renewal associated genes in leukemia, c-kit positive murine primary bone marrow cells were retrovirally transduced with MN1, MN1-TEL or MN1-TEL mutant MN1-TELdelDBD showing biological similarity with MN1, after retroviral transformation of cells and 10 d culture RNA was extracted and gene expression profiling was assessed
Project description:We used Affymetrix microarrays to characterize gene expression profiles that were perturbed in common myeloid progenitor (CMP) cells due to enforced expression of full-length or truncated forms of MN1. Expression profiles of MN1-induced leukemias arising from whole bone marrow transduction were also compared with the profiles obtained from the CMP cells. Lineage negative mouse bone marrow cells were transduced with retroviral vectors expressing full-length or truncated MN1 proteins. After 2 days in culture, cells were FACS-sorted for GFP expression and cultured for a further 3 days in growth media. After 5 days total, RNA was isolated and processed for microarray analysis. RNA was also prepared for microarray analysis from leukemias arising in mice following whole bone marrow transduction with full-lenght MN1.
Project description:We evaluated the function of Meningioma 1 (MN1), a cofactor of HOXA9 and MEIS1, in murine MLL-r leukemia by CRISPR-Cas9 mediated deletion of MN1. MN1 was required for in vivo leukemogenicity of MLL-r murine and human AML cells. Loss of MN1 inhibited cell cycle and proliferation, promoted apoptosis and induced differentiation of MLL-r cells. Expression analysis and chromatin immunoprecipitation with sequencing demonstrated that MN1 primarily maintains active transcription of HOXA9 and HOXA10, which are critical downstream genes of MLL, and their target genes like BCL2, MCL1 and Survivin.
Project description:We used Affymetrix microarrays to characterize gene expression profiles that were perturbed in common myeloid progenitor (CMP) cells due to enforced expression of full-length or truncated forms of MN1. Expression profiles of MN1-induced leukemias arising from whole bone marrow transduction were also compared with the profiles obtained from the CMP cells.
Project description:Expression of meningioma 1 (MN1) has been proposed to be a negative prognostic molecular marker in adult AML with normal cytogenetics, however its role in pediatric leukemia is unknown. We found elevated MN1 expression in 53 of 88 pediatric leukemia cases: significant amounts of MN1 were found in immature B-cell ALL and most cases of infant leukemia but no MN1 expression was detected in T-cell acute lymphoblastic leukemia (T-ALL). Interestingly 17 of 19 cases harboring MLL-X fusions showed also elevated MN1 expression. Lentiviral siRNA mediated MN1 knock-down resulted in cell cycle arrest and impaired clonogenic growth of 3 MLL-X-positive human leukemia cell lines overexpressing MN1 (THP-1, RS4;11, MOLM13). In a mouse MLL/ENL-induced leukemia MN1 overexpression resulted from retroviral provirus insertion. Strikingly co-expression of MN1 with MLL/ENL resulted in significantly reduced latency for induction of an AML phenotype in mice suggesting functional cooperation. MN1 overexpression in MLL/ENL-carrying cells resulted in expansion of the L-GMP population and facilitated disease induction in secondary recipients. Gene expression profiling allowed to define a number of potential MN1 hematopoietic targets. Up-regulation of CD34, FLT3, HLF, or DLK1 was validated in bone marrow transiently overexpressing MN1, in MN1-induced mouse leukemias, as well as in some cases of pediatric leukemias overexpressing MN1. Taken together, our work suggests that MN1 overexpression is essential for growth of leukemic cells, and that MN1 can act as a cooperating oncogene with MLL-X fusion genes most probably through modification of a distinct gene expression program that leads to expansion of a leukemia initiating cell population. In three independent experiments bone marrow cells were transduced with MSCV-MN1-IRES/YFP or empty vector. 72h after transduction EYFP-positive cells were FACS-sorted and RNA isolated by ion-exchange chromatography with RNAmini (Qiagen) according to the manufacturerâs protocol
Project description:The molecular mechanism defining susceptibility of normal cells to oncogenic transformation may be a valuable therapeutic target. We characterized the cell of origin and its critical pathways in MN1 leukemias. Common myeloid (CMP), but not granulocyte-macrophage progenitors (CMP) could be transformed by constitutively overexpressed MN1. Complementation studies of CMP-signature genes in GMPs demonstrated that leukemogenicity of MN1 required the MEIS1/abdB-like HOX protein complex. Colocalization studies by ChIP-seq identified common chromatin targets of MN1 and MEIS1 that were associated with open chromatin and transcriptional activation. Transcriptional repression of MEIS1 target sites in established MN1 leukemias had antileukemic activity. As MN1 relies on but can not activate expression of MEIS1/abdB-like HOX proteins, transcriptional activity of these genes determines which cell is the cell of origin in MN1 leukemia. We have showed at the single cell level that CMPs, but not GMPs, are susceptible to MN1-induced transformation. To identify transcriptional differences between CMPs and GMPs that may explain this difference in susceptibilities to MN1 transformation we produced gene expression profiles (two biological replicates in each experimental arm) of bone marrow cells from MN1 leukemic mice and mature myeloid bone marrow cells (Gr1+/CD11b+) from healthy mice and compared those to already published gene expression profiles of CMPs and GMPs (Krivtsov, A.V., et al. (2006). Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9. Nature 442, 818-822).
Project description:Myeloid differentiation is blocked in acute myeloid leukemia (AML), but the molecular mechanisms are not well characterized. MN1 is overexpressed in some AML patients and confers resistance to all-trans retinoic acid (ATRA)-induced differentiation. To understand the role of MN1 as a transcriptional regulator in myeloid differentiation, we fused transcriptional activation (VP16) or repression (M33) domains with MN1 and characterized these cells in vivo. Transcriptional activation of MN1 target genes induced myeloproliferative disease with long latency and differentiation potential to mature neutrophils. A large proportion of differentially expressed genes between leukemic MN1 and differentiation-permissive MN1VP16 cells belonged to the immune response pathway like Irf8 and Ccl9. As MN1 is a co-factor of MEIS1 and RARA, we compared chromatin occupancy between MN1, MEIS1 and RARA. Immune response genes that were upregulated in MN1VP16 cells were co-targeted by MN1 and MEIS1, but not RARA, suggesting that myeloid differentiation is blocked through transcriptional repression of shared target genes of MN1 and MEIS1. Constitutive expression of Irf8 or its target gene Ccl9 identified these genes as potent inhibitors of MN1-induced leukemia. Our data show that MN1 prevents activation of the immune response pathway, and suggest that restoration of Irf8 signalling as a novel therapeutic target in AML. C57BL/6J bone marrow cells were harvested from mice treated for 4 days with 150 mg 5-fluorouracil/kg and stimulated for 48 hours in DMEM supplemented with 15% FBS, 10 ng/mL hIL6, 6ng/mL mIL3, and 20ng/mL mSCF. The cells were infected with MN1 or MN1VP16 retroviral constructs by cocultivation with irradiated E86 viral producer cells in the presence of 5μg/mL protamine sulfate (Sigma) for 48 hours and then transplanted into lethally irradiated syngeneic recipient mice. 4 weeks after transplantation MN1, MN1VP16 GFP+ cells and Gr1+/CD11b+ bone marrow cells were FACS-sorted and analyzed by Affymetrix GeneChip Mouse 430 2.0 (43.000 probes) microarrays