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: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: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: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.
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:In this study, to investigate the pathogenic role of transcriptional regulator LMO2 during T lineage development, we isolated DN1, DN3, DP, CD4SP, CD8SP thymocytes, splenic CD4+ T cells and splenic CD8+ T cells from wild type and LMO2 over-expressing C57BL/6J mice for RNA-seq, and DN3 (CD25+), DP thymocytes, splenic CD4+/CD8+ T cells from transgenic mice and wild type DN3 (CD25+) thymocytes for ChIP-seq.
Project description:The DNA binding factor Tcf-1 is one of the most prominently expressed genes in thymocytes yet its global DNA binding pattern remained unknown. Here we have assessed by ChIP-seq the Tcf-1 binding pattern in murine thymocytes in WT B6 mice and in mice expressing a stabilized form of the Tcf-1 binding partner beta-Catenin (CAT mice).
Project description:We report the identification of DN NKT cells developed from DN stage thymocytes. We analyzed the gene expression profiles of NKT cells that have developed from DN stage thymocytes isolated from DP-specific E8III-Cre transgenic Rag2-floxed mouse strain, and NKT cells developed from DP thymocytes sorted as YFP-reporter positive NKT cells that were isolated from E8III-Cre transgenic Rosa26-loxP-STOP-loxP mouse.
Project description:We applied single-cell sequencing to mouse thymocytes and analyzed the transcriptome data using Seurat. By applying unsupervised clustering, we defined thymocyte subtypes and validated DP cell subtypes by flow cytometry. We classified the cell cycle phases of each cell according to expression of cell cycle phase-specific genes. For immune synapse detection, we used immunofluorescent staining and ImageStream-based flow cytometry. We studied and integrated human thymocyte data to verify the conservation of our findings and also performed cross-species comparisons to examine species-specific gene regulation. We classified blast, rearrangement and selection subtypes of DP thymocytes and used the surface markers CD2 and Ly6d to identify these subtypes by flow cytometry. Based on this new classification, we found that the proliferation of blast DP cells is quite different from that of double-positive cells and other cell types, which tend to exit the cell cycle after a single round. At the DP cell selection stage, we observed that CD8-associated immune synapses formed between thymocytes, indicating that CD8sp selection occurred among thymocytes themselves. Moreover, cross-species comparison revealed species-specific transcription factors (TFs) that contribute to the transcriptional differences of thymocytes from humans and mice. Our study classified DP thymocyte subtypes of different developmental stages and provided new insight into the development of DP thymocytes at single-cell resolution, furthering our knowledge of the fundamental immunological process of thymopoiesis.
Project description:Dr. Jameson's research focus is on development and regulation of lymphocytes, especially T cells. Recent work has suggested that differential glycosylation effects the sensitivity of the T cell receptors and its coreceptors, suggesting that regulation of glycosylation may be a critical element in controlling T cell development, survival and functional activity. Determination of how glycosylation enzymes/substrates change in gene expression during development of mouse CD8 T cells. Highly purified pre-selection CD4+8+ thymocytes (using transgenic/knockout mice in our colony) are compared to mature CD8 T cells from the lymph node. The goal is to build on data suggesting that this developmental step involves regulated expression of sialyltransferases (and/or neuraminidases). Highly purified pre-selection CD4+8+ thymocytes (using transgenic/knockout mice in our colony) are compared to mature CD8 T cells from the lymph node. Pre-selection CD4+8+ (DP) thymocytes were sorted from TCRa-/- thymi. Post-selection (post-positive selection) DP thymocytes came from an OT-I TCR transgenic mouse. Naïve (CD44lo) CD8 T cells from lymph node of OT-I mice were used as naïve CD8 T cells. For activated cells, naïve OT-I T cells were activated for 48 hours in vitro with cognate antigen (SIINFEKL peptide/Kb) (displayed on cell sized latex beads) in the presence of IL-2 and IL-12.