PRC2 inactivation cooperates with JAK3 mutant signaling in the development of T-cell acute lymphoblastic leukemia
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PROVIDER: PRJNA505355 | ENA |
REPOSITORIES: ENA
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Project description:T-ALL is characterized by deregulation of transcriptional control and impairment of epigenetic homeostasis. We observed that T-ALL cases with mutations in the IL7R-JAK-STAT pathway frequently harbor inactivating mutations in the PRC2 complex, in particular SUZ12 mutations. PRC2 is an epigenetic complex responsible for writing the H3K27me3 mark associated with gene repression. To assess whether loss of SUZ12 cooperates with mutant JAK3 signaling during T-ALL development, we expressed the JAK3(M511I) mutant in mouse bone marrow cells in vivo and tested the effect of Cas9-mediated inactivation of Suz12 on leukemia development. The mice developed a T-cell leukemia that infiltrated most hematological organs (bone marrow, thymus, spleen, lymph nodes, blood). At time of sacrifice the majority of cells in the blood and hematopoietic organs was JAK3(M511I) positive and Suz12 negative. Reduced Suz12 protein and H3K27me3 levels were confirmed with flow cytometry. Moreover, JAK3(M511I) also cooperates with Suz12 gRNA-mediated inactivation in vitro. Pro-T cells carrying both JAK3(M511I) and Suz12 gRNA were able to transform to IL7 independent growth, whereas single mutant (JAK3(M511I) only or Suz12 gRNA only) pro-T cells could not. In order to get insight in the mechanism of cooperation between JAK3 mutant signaling and Suz12 inactivation, we performed and integrated RNA- and ChIP-sequencing (Suz12, H3K27me3, H3K27Ac, H3K4me1, H3K4me3) on leukemic cells from the mice. This showed a global upregulation of many genes, including known PRC2 target genes upon loss of Suz12. Moreover, Suz12 was bound to promoters of Wnt signaling genes (Fzd7, Lrp4) and Wnt target genes (Axin2, Jag2, Mmp9), concomitant with high H3K27me3 levels. Loss of Suz12 led to drastic reduction of H3K27me3 at these loci and upregulation of these Wnt genes. As Wnt signaling is ectopically activated, we wanted to test whether JAK3(M511I) + Suz12 gRNA cells are more sensitive to Wnt inhibitor. JAK3(M511I) + Suz12 pro-T cells and leukemic spleen cells exhibited increased sensitivity to Wnt inhibitor compared to JAK3 mutant control cells, indicating that Wnt signaling contributes to the cooperation between Suz12 loss and JAK3 mutant signaling. In conclusion, our data show that Suz12 inactivation cooperates with mutant JAK3 signaling to drive leukemia development in vivo and demonstrates the use of Cas9 transgenic mice to study the role of tumor suppressor genes in T-ALL mouse models. Moreover, Suz12 loss leads to ectopic activation of Wnt signaling, a pathway contributing to the cooperation of Suz12 loss and JAK3 mutant signaling that can also be targeted with inhibitors.
2019-03-01 | GSE122496 | GEO
Project description:Mutations in the interleukin-7 receptor (IL7R) or the JAK3 kinase occur frequently in T-cell acute lymphoblastic leukemia (T-ALL) and both are able to drive cellular transformation and the development of T-ALL in mouse models. However, the signal transduction pathways downstream of JAK3 mutations remain poorly characterized. Here, we describe the phosphoproteome downstream of the JAK3(L857Q)/(M511I) activating mutations in transformed Ba/F3 lymphocyte cells and human JAK3 mutated T-ALL samples. Novel peptides shown to be downstream of mutant JAK3 regulating RNA metabolism as well as epigenetic and apoptotic processes were validated using targeted PRM proteomics.
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Project description:The tendency of mitochondria to undergo or resist BCL2-controlled apoptosis (so-called mitochondrial priming) is a powerful predictor of response to cytotoxic chemotherapy. To fully exploit this finding, it will be important to understand the molecular genetic contexts responsible for the relative mitochondrial priming of chemotherapy-sensitive versus resistant cell populations. Here, we report that mitochondrial apoptosis resistance in T-cell acute lymphoblastic leukemia (T-ALL) is mediated by inactivation of polycomb repressive complex 2 (PRC2). In T-ALL clinical samples from children with T-ALL treated on recent Dana-Farber Cancer Institute or Children’s Oncology Group clinical trials, we found that loss-of-function mutations in any of three core components of PRC2 (EZH2, EED or SUZ12) were associated with resistance to mitochondrial apoptosis. In human T-ALL cells, PRC2 depletion induced resistance to apoptosis induction by multiple chemotherapeutics with distinct mechanisms of action, including dexamethasone, doxorubicin and vincristine. PRC2 loss induced apoptosis resistance via transcriptional upregulation of the LIM domain transcription factor CRIP2, and subsequent downstream upregulation of the mitochondrial chaperone TRAP1. Importantly, TRAP1 overexpression was necessary to induce resistance to chemotherapy-induced apoptosis downstream of PRC2 inactivation, and pharmacologic inhibition of TRAP1 synergized with dexamethasone and doxorubicin. These findings demonstrate the importance of relative mitochondrial apoptotic priming as a prognostic factor in T-ALL, and implicate mitochondrial chaperone function as a molecular determinant of response to cancer chemotherapy, suggesting a rationale for targeted therapeutic intervention.
2018-10-18 | GSE112147 | GEO
Project description:Imprinted X-inactivation is a paradigm of transgenerational epigenetic inheritance in mammals and silences genes exclusively on the paternally-inherited X-chromosome. Here, we test the hypothesis that oocyte-derived maternal Polycomb repressive complex 2 (PRC2) protein EED orchestrates the selective inactivation of the paternal-X in mouse embryos. In maternal Eed null (Eedm-/-) but not zygotic Eed null female and male embryos, the maternal X-chromosome ectopically induced Xist lncRNA, which silences X-linked genes. Subsequently, Xist was silenced from one of the two X-chromosomes in females and from the sole maternal-X in males. As a result, later-stage female Eedm-/- embryos displayed random X-inactivation. The kinetics of Xist RNA induction in Eedm-/- embryos resemble that of early human embryos, which lack oocyte-derived PRC2 and only undergo random X-inactivation. Thus, expression of PRC2 genes in the oocyte and transmission of the gene products to the embryo may dictate the occurrence of imprinted X-inactivation in mammals.
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Project description:Jak3 is the only non-promiscuous member of the Jak family of secondary messengers. Jak3–/– mice display defective T and NK cell development, which results in a SCID phenotype. As a result, studies to date have focused on understanding and targeting the cell-autonomous role of Jak3 in immunity, while functional Jak3 expression outside the hematopoietic system remains largely unreported. We show that Jak3 is expressed in endothelial cells across hematopoietic and non-hematopoietic organs, with heightened expression in the bone marrow. The bone marrow niche is understood as a network of different cell types that regulate hematopoietic function. We show that the Jak3–/– bone marrow niche is deleterious for the maintenance of long-term repopulating hematopoietic stem cells (LT-HSCs) and that JAK3-overexpressing endothelial cells have increased potential to expand LT-HSCs in vitro. Increased arterial zonation in the bone marrow of Jak3–/– mice further situates Jak3 as a marker of sinusoidal endothelium. This work may serve to identify a novel function for a highly specific tyrosine kinase in the bone marrow vascular niche and to further characterize the LT-HSC function of sinusoidal endothelium.
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Project description:Leukemia is caused by the accumulation of multiple genomic lesions in hematopoietic precursor cells. However, how these events cooperate during oncogenic transformation remains poorly understood. We studied the cooperation between activated JAK3/STAT5 signaling and HOXA9 overexpression, two events identified as significantly co-occuring in T-cell acute lymphoblastic leukemia. Expression of mutant JAK3 and HOXA9 led to a rapid development of leukemia originating from multipotent or lymphoid-committed progenitors, with a significant decrease in disease latency compared to JAK3 or HOXA9 alone. Integrated RNA-seq, ChIP-seq and ATAC-seq revealed that STAT5 and HOXA9 have co-occupancy across the genome resulting in enhanced STAT5 transcriptional activity and ectopic activation of Fos/Jun (AP-1). Our data suggest that oncogenic transcription factors such as HOXA9 provide a fertile ground for specific signaling pathways to thrive, explaining why JAK/STAT pathway mutations accumulate in HOXA9 expressing cells.
2018-01-26 | GSE109653 | GEO