Project description:Methylation data from normal thymocytes, 24 day pre-tumor Dnmt3b-deficient thymocytes, Wild-Type Tumors, and Dnmt3b-deficient Tumors
Project description:The TAL1/SCL and LMO1 oncogenic transcription factors establish a pre-leukemic state by reprogramming thymocytes into self-renewing pre-leukemic stem cells (pre-LSCs). Pre-TCR signaling accelerates the progression to T-cell acute lymphoblastic leukemia (T-ALL). To directly address the importance of pre-TCR signaling in driving progression to T-ALL, we leverage on Cd3-deficient mice in which pre-TCR signaling and progression through β-selection is abrogated. In the absence of pre-TCR signaling in Cd3ε-deficient SCL-LMO1 transgenic mice, T-ALL onset is delayed by 150 days. Despite the absence of pre-TCR/CD3 signaling in these mice, we show that leukemic thymocytes exhibit the gene expression profiles of thymocytes that have undergone β-selection, i.e. exhibiting a re-activation of pre-TCR-driven proliferation signature, and a down regulation of HEB/TCF12 target genes. Lastly, monoallelic deletion of Heb is sufficient to accelerate T-ALL onset in Cd3ε-deficient SCL-LMO1 transgenic mice. Together, these results underscore the role of HEB/TCF12 as a tumor suppressor in T-ALL.
Project description:Aberrant DNA methylation is a hallmark of cancer but mechanisms contributing to the abnormality remain elusive. Here, we report that most of lung cancer cell lines tested expressed predominantly ∆DNMT3B-del whereas normal bronchial epithelial cells expressed equal quantities of ∆DNMT3B and ∆DNMT3B-del. We demonstrate biological impacts of ∆DNMT3B4-del, a ∆DNMT3B-del isoform, in a transgenic mouse model. Expression of ∆DNMT3B4-del in the mouse lungs resulted in an increased global DNA hypomethylation, focal DNA hypermethylation, epithelial hyperplastia and tumor formation when challenged with a tobacco carcinogen. In patients with non-small cell lung cancer, 83% of the primary tumors expressed predominantly ∆DNMT3B-del. Our results demonstrate ∆DNMT3B4-del as a critical factor in developing aberrant DNA methylation during lung tumorigenesis.
Project description:Dnmt3b is a tumor suppressor in oncogene-driven lymphoid and myeloid malignancies in mice. However, it is poorly understood whether reduced Dnmt3b activities can initiate malignant hematopoiesis. We modulated Dnmt3b activity in vivo by generating Dnmt3b+/− mice expressing one wild-type allele. Here, we analyzed methylation and gene expression in Dnmt3b+/- peripheral T-cell lymphomas (PTCLs).
Project description:Here we utilized a conditional knock-out mouse model to investigate the role of Smarca5, an ISWI subfamily chromatin remodeling ATPase, during thymocyte development using hCD2-iCre transgene. We did transcriptional profiling of FACS-sorted CD4/CD8 double-positive thymocytes as this thymic population was persistent yet strongly underrepresented in adult 6-week mutant thymi. Controls included age-matched CD4/CD8 double-positive thymocytes from wild-type and tumor suppressor protein Trp53-null mice. For comparison, the Smarca5/Trp53-double-deficient thymocytes included in the experiment were partially rescued upon loss of Trp53.
Project description:comparative genome hybridisation of Hdac1/2 cKO lymphomas and matched normal tissue Histone deacetylases (HDACs) are epigenetic erasers of lysine-acetyl marks. Inhibition of HDACs using small molecule inhibitors (HDACi) is a potential strategy in the treatment of various diseases and is approved for treating hematological malignancies. Harnessing the therapeutic potential of HDACi requires knowledge of HDAC-function in vivo. Here, we generated a thymocyte-specific gradient of HDAC-activity using compound conditional knockout mice for Hdac1 and Hdac2. Unexpectedly, gradual loss of HDAC-activity engendered a dosage dependent accumulation of immature thymocytes and correlated with the incidence and latency of monoclonal lymphoblastic thymic lymphomas. Strikingly, complete ablation of Hdac1 and Hdac2 abrogated lymphomagenesis due to a block in early thymic development. Genomic, biochemical and functional analyses of pre-leukemic thymocytes and tumors revealed a critical role for Hdac1/Hdac2-governed HDAC-activity in regulating a p53-dependent barrier to constrain Myc-overexpressing thymocytes from progressing into lymphomas by regulating Myc-collaborating genes. One Myc-collaborating and p53-suppressing gene, Jdp2, was derepressed in an Hdac1/2-dependent manner and critical for the survival of Jdp2-overexpressing lymphoma cells. Although reduced HDAC-activity facilitates oncogenic transformation in normal cells, resulting tumor cells remain highly dependent on HDAC-activity, indicating that a critical level of Hdac1 and Hdac2 governed HDAC-activity is required for tumor maintenance. genomic DNA from LckCre+;Hdac1/2 cKO lymphomas and matched normal genomic DNA was hybridized onto a Nimblegen whole genome array
Project description:Purpose: The goal of this study was to identify the gene expression profile of mouse retina which carries deletions in Dnmt1, Dnmt3a and Dnmt3b genes. Method: Retinal mRNA profiles of Postnatal day 15 wild type mice and Dnmt1, Dnmt3a and Dnmt3b mutant mice were generated by deep-sequencing
Project description:To assess the importance of the Wnt pathway during T cell develoment, we generated a mouse line (R26-M-NM-2cat) in which high levels of active M-NM-2-catenin are maintained throughout T cell development. Young R26-M-NM-2cat mice (6-week-old) show a differentiation block at the CD4+CD8+ DP stage. All R26-M-NM-2cat mice develop T cell leukemias with a DP phenotype at 5-6 months of age. To identify the molecular pathways involved in tumor development, we profiled the global gene expression of transformed and pre-transformed DP cells. Thymocytes from 6-week-old mice (with a normal sized thymus and a polyclonal thymocyte population) were used to define the pre-transformed transcriptome. RNA from control and pre-leukemic R26-M-NM-2cat DP thymocytes as well as R26-M-NM-2cat total tumor cells were extracted and used for transcriptome analysis.
