Project description:The TEL-JAK2 fusion oncogene and the ICN1 activated allele of NOTCH1 are the result of specific chromosomal translocations in T cell acute lymphoblastic leukemia (T-ALL). Mouse models of these diseases (TEL-JAK2 transgenic mice; Carron C. et al. Blood (2000); a bone marrow transplantation model for ICN1-induced T-ALL) were used to compare the transcriptional program specific to each oncoprotein in mouse models of these leukemias. Tumor load was >50% leukemic cells in all selected organs.
Project description:The TEL-JAK2 fusion oncogene and the ICN1 activated allele of NOTCH1 are the result of specific chromosomal translocations in T cell acute lymphoblastic leukemia (T-ALL). Mouse models of these diseases (TEL-JAK2 transgenic mice; Carron C. et al. Blood (2000); a bone marrow transplantation model for ICN1-induced T-ALL) were used to compare the transcriptional program specific to each oncoprotein in mouse models of these leukemias. Tumor load was >50% leukemic cells in all selected organs. Leukemic cells were collected from the thymus of terminally-ill TEL-JAK2 leukemic mice and bone marrow of terminally-ill ICN1 leukemic mice. RNA was extracted from each sample and processed for hybridization to Affymetrix arrays.
Project description:To examine Ikaros tumor suppressor mechanisms, we have utilized inducible RNAi to dynamically restore endogenous Ikaros expression in T-ALL driven by its knockdown. This causes rapid transcriptional repression of Notch1 and associated targets including Myc, even in leukemias harboring spontaneous activating Notch1 mutations (producing aberrant ICN1) similar to those found in 60% of human T-ALL. Ikaros restoration results in sustained regression of Notch1-wild type leukemias while endogenous or engineered ICN1 expression promotes rapid disease relapse, indicating that ICN1 functionally antagonizes Ikaros in T-ALL.
Project description:To examine Ikaros tumor suppressor mechanisms, we have utilized inducible RNAi to dynamically restore endogenous Ikaros expression in T-ALL driven by its knockdown. This causes rapid transcriptional repression of Notch1 and associated targets including Myc, even in leukemias harboring spontaneous activating Notch1 mutations (producing aberrant ICN1) similar to those found in 60% of human T-ALL. Ikaros restoration results in sustained regression of Notch1-wild type leukemias while endogenous or engineered ICN1 expression promotes rapid disease relapse, indicating that ICN1 functionally antagonizes Ikaros in T-ALL.
Project description:To examine Ikaros tumor suppressor mechanisms, we have utilized inducible RNAi to dynamically restore endogenous Ikaros expression in T-ALL driven by its knockdown. This causes rapid transcriptional repression of Notch1 and associated targets including Myc, even in leukemias harboring spontaneous activating Notch1 mutations (producing aberrant ICN1) similar to those found in 60% of human T-ALL. Ikaros restoration results in sustained regression of Notch1-wild type leukemias while endogenous or engineered ICN1 expression promotes rapid disease relapse, indicating that ICN1 functionally antagonizes Ikaros in T-ALL.
Project description:TEL-JAK2 is a fusion oncogene resulting from a t(9;12) chromosomal translocation in T-ALL, translated as a constitutively activated TEL-JAK2 tyrosine kinase. Mice carrying a TEL-JAK2 transgene develop T-ALL. Gene deregulated in TEL-JAK2 T-ALL cells as compared to mouse thymocytes were identified
Project description:Around 20-25% of childhood acute lymphoblastic leukemias carry the TEL-AML1 (TA) fusion gene. It is a fusion of two central hematopoietic transcription factors, TEL (ETV6) and AML1 (RUNX1). Despite its prevalence, the exact genomic targets of TA have remained elusive. We evaluated gene loci and enhancers targeted by TA genome-wide in precursor B acute leukemia cells using global nuclear run-on sequencing (GRO-seq).
Project description:Cyclin C was cloned as a growth-promoting G1 cyclin, and several studies postulated a role for cyclin C in driving cell proliferation. Moreover, cyclin C, together with its kinase partner, the cyclin-dependent kinase CDK8, is believed to represent an essential component of basal transcriptional machinery where it globally represses gene expression. However, the function of cyclin C in vivo has never been addressed. Here we show that in the living organism cyclin C acts as a haploinsufficient tumor suppressor, through its function of controlling Notch1 oncogene levels. Cyclin C activates an M-bM-^@M-^\orphanM-bM-^@M-^] CDK19 kinase, as well as CDK8 and CDK3. These cyclin C-CDK complexes phosphorylate Notch1 intracellular domain (ICN1), which allows binding of ICN1 to Fbw7 and triggers ICN1 polyubiquitination. Genetic ablation of cyclin C blocks ICN1 phosphorylation, disrupts Fbw7 binding, and decreases ICN1 ubiquitination in vivo, thereby strongly elevating ICN1 levels in several compartments of cyclin C knockout mice. Ablation of cyclin C, or cyclin C heterozygosity collaborate with other oncogenic lesions and accelerate development of T-cell acute lymphoblastic leukemia (T-ALL) in cyclin Cdeficient mice. Furthermore, the locus encoding cyclin C is heterozygously deleted in a significant fraction of human T-ALL, and these tumors express reduced cyclin C levels. In addition, we describe point mutations in human T-ALL tumors that render cyclin C-CDK unable to phosphorylate ICN1. These studies reveal that in sharp contrast to all other cyclin proteins, cyclin C functions as a growth-suppressor in vivo, and suggest that human tumor cells develop different strategies to evade cyclin C inhibitory function. Comparison of wild-type mouse embryonic fibroblasts (n=3 biological replicates) versus cyclin C knockout MEFs (n=3), wild-type mouse embryonic stem cells (n=3) versus cyclin C knockout ESC (n=3), wild-type mouse embryonic brain (n=3) versus cyclin C knockout embryonic brain (n=3)
Project description:To examine Ikaros tumor suppressor mechanisms, we have utilized inducible RNAi to dynamically restore endogenous Ikaros expression in T-ALL driven by its knockdown. This causes rapid transcriptional repression of Notch1 and associated targets including Myc, even in leukemias harboring spontaneous activating Notch1 mutations (producing aberrant ICN1) similar to those found in 60% of human T-ALL. Ikaros restoration results in sustained regression of Notch1-wild type leukemias while endogenous or engineered ICN1 expression promotes rapid disease relapse, indicating that ICN1 functionally antagonizes Ikaros in T-ALL. RNA-seq was performed on T-ALL (Vav-tTA;TRE-GFP-shIkaros primary leukemia ALL211) cells isolated from two untreated and two 3-day Dox-treated mice.
Project description:To examine Ikaros tumor suppressor mechanisms, we have utilized inducible RNAi to dynamically restore endogenous Ikaros expression in T-ALL driven by its knockdown. This causes rapid transcriptional repression of Notch1 and associated targets including Myc, even in leukemias harboring spontaneous activating Notch1 mutations (producing aberrant ICN1) similar to those found in 60% of human T-ALL. Ikaros restoration results in sustained regression of Notch1-wild type leukemias while endogenous or engineered ICN1 expression promotes rapid disease relapse, indicating that ICN1 functionally antagonizes Ikaros in T-ALL. RNA-seq was performed on T-ALL (Vav-tTA;TRE-GFP-shIkaros primary leukemia ALL65) cells isolated from three untreated and three 3-day Dox-treated mice. There were two sequencing runs of each RNA sample.