ABSTRACT: Activation of b-catenin has been causatively linked to the etiology of colon cancer. Conditional stabilization of this molecule in pro-T-cells promotes thymocyte development without the requirement for preTCR signaling. We show here that activated b-catenin stalls the developmental transition from the double-positive (DP) to the single-positive (SP) thymocyte stage and predisposes DP thymocytes to transformation. b-Catenin induced thymic lymphomas have a leukemic arrest at the early DP stage. Lymphomagenesis requires Rag activity, which peaks at this developmental stage, as well as additional secondary genetic events. A consistent secondary event is the transcriptional upregulation of c-Myc, whose activity is required for transformation since its conditional ablation abrogates lymphomagenesis. In contrast, the expression of Notch receptors as well as targets is reduced in DP thymocytes with stabilized b-catenin and remains low in the lymphomas indicating that Notch activation is not required or selected for in b-catenin induced lymphomas. Thus, b-catenin activation may provide a mechanism for the induction of T-ALL that does not depend on Notch activation. Keywords: Lckcre, CD4Cre-Ctnnbex3, lymphoma, gene expression
Project description:Activation of b-catenin has been causatively linked to the etiology of colon cancer. Conditional stabilization of this molecule in pro-T-cells promotes thymocyte development without the requirement for preTCR signaling. We show here that activated b-catenin stalls the developmental transition from the double-positive (DP) to the single-positive (SP) thymocyte stage and predisposes DP thymocytes to transformation. b-Catenin induced thymic lymphomas have a leukemic arrest at the early DP stage. Lymphomagenesis requires Rag activity, which peaks at this developmental stage, as well as additional secondary genetic events. A consistent secondary event is the transcriptional upregulation of c-Myc, whose activity is required for transformation since its conditional ablation abrogates lymphomagenesis. In contrast, the expression of Notch receptors as well as targets is reduced in DP thymocytes with stabilized b-catenin and remains low in the lymphomas indicating that Notch activation is not required or selected for in b-catenin induced lymphomas. Thus, b-catenin activation may provide a mechanism for the induction of T-ALL that does not depend on Notch activation. Experiment Overall Design: This study was used to compare gene expression patterns of LckCre mice, CD4Cre-Ctnnbex3 mice before and after T-cell transformation. 5 independent Lckcre (control), 5 independent CD4Cre-Ctnnbex3 mice and 8 independent mice with lymphomas were used. Thymocytes or tumor masses were collected from Lckcre, CD4Cre-Ctnnbex3 mice. Total RNA isolation and purification followed by synthesis of dscDNA, Biotinylated cRNA and purification of Biotinylated cRNA. Then the hybridization to Affymetrix âMouse Expression Array 430 Genechipsâ was done. Data was analysed by dchip.
Project description:Analysis of ESET deficient thymocytes at gene expression level. Each thymocyte developmental stage (preselected DP, postselected DP and CD4SP) was analysed.
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:Analysis of ESET deficient thymocytes at gene expression level. Each thymocyte developmental stage (preselected DP, postselected DP and CD4SP) was analysed. Total RNA obtained from isolated subpopulations of thymocytes from ESET+/+ and ESET-/- mice were analysed.
Project description:NSrp70 deficiency (NSRP1f/fCD4Cre) profoundly perturbed the late development of DP thymocytes, leading to a significant reduction of single positive (SP) cells in the thymus and peripheral lymphoid tissues. To gain further insight how NSrp70 controls thymocyte development from DP stage, we performed RNA-seq analysis after sorting DP thymocytes from WT and Nsrp1 cKO mice.
Project description:NSrp70 deficiency (NSRP1f/fCD4Cre) profoundly perturbed the late development of DP thymocytes, leading to a significant reduction of single positive (SP) cells in the thymus and peripheral lymphoid tissues. To gain further insight into how NSrp70 controls thymocyte development from CD69+ DP stage, we performed RNA-seq analysis after sorting CD69+ DP thymocytes from WT and Nsrp1 cKO mice.
Project description:Both TCF-1 and its coactivator β-catenin are known to be required for supporting normal double positive (DP) thymocyte survival through upregulating Bcl-xL. However, the downstream factors mediating this effect remained unknown. We used microarray to compare the global expression difference among WT, TCF-1-deficient, and β-catenin transgenic thymocytes to search for the genes that are down-regulated and up-regulated in TCF-1-deficient and β-catenin transgenic thymocytes, respectively. We focus on the genes that are significantly down-regulated and up-regulated in TCF-1-deficient and β-catenin transgenic thymocytes, respectively, to select for those genes that are potential target genes of β-catenin/TCF-1 pathway. And then those genes are subject to IPA pathway analysis searching for genes that are involved in thymocyte development and cell death.
Project description:Both TCF-1 and its coactivator β-catenin are known to be required for supporting normal double positive (DP) thymocyte survival through upregulating Bcl-xL. However, the downstream factors mediating this effect remained unknown. We used microarray to compare the global expression difference among WT, TCF-1-deficient, and β-catenin transgenic thymocytes to search for the genes that are down-regulated and up-regulated in TCF-1-deficient and β-catenin transgenic thymocytes, respectively.
Project description:We report the changes in Tcrb interactome upon transitioning from DN to DP stage of thymocyte development Examination of the interactomes of Eb and Trbv5 viewpoints in RAG-deficient DN and DP thymocytes
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.