Natural killer (NKT) T cells exhibit tissue distribution, surface phenotype, and functional responses that are strikingly different from those of conventional T cells. The transcription factor PLZF is responsible for most of these properties, as its ectopic expression in conventional T cells is sufficient to confer to them an NKT-like phenotype. The molecular program downstream of PLZF, however, is largely unexplored.
PLZF Controls the Expression of a Limited Number of Genes Essential for NKT Cell Function.
Sex, Specimen part
View SamplesWe have determined the consequences of ICN1 overexpression from retroviral vectors introduced into bone marrow cells.
Oncogenesis of T-ALL and nonmalignant consequences of overexpressing intracellular NOTCH1.
No sample metadata fields
View SamplesSomatic hypermutation (SHM) and class switch recombination (CSR) increase the affinity and diversify the effector functions of antibodies during immune responses. Although SHM and CSR are fundamentally different, their independent roles in regulating B cell fate have been difficult to uncouple because a single enzyme, activation-induced cytidine deaminase (encoded by Aicda), initiates both reactions. Here, we used a combination of Aicda and antibody mutant alleles that separate the effects of CSR and SHM on polyclonal immune responses. We found that class-switching to IgG1 biased the fate choice made by B cells, favoring the plasma cell over memory cell fate without significantly affecting clonal expansion in the germinal center (GC). In contrast, SHM reduced the longevity of memory B cells by creating polyreactive specificities that were selected against over time. Our data define the independent contributions of SHM and CSR to the generation and persistence of memory in the antibody system. Overall design: IgG1 and IgM light zone (LZ) and dark zone (DZ) germinal center (GC) B cells were compared in immunized AIDcre/- IgH-96K/+ R26-LSL-YFP mice.
Independent Roles of Switching and Hypermutation in the Development and Persistence of B Lymphocyte Memory.
Specimen part, Cell line, Subject
View SamplesSomatic hypermutation (SHM) and class switch recombination (CSR) increase the affinity and diversify the effector functions of antibodies during immune responses. Although SHM and CSR are fundamentally different, their independent roles in regulating B cell fate have been difficult to uncouple because a single enzyme, activation-induced cytidine deaminase (encoded by Aicda), initiates both reactions. Here, we used a combination of Aicda and antibody mutant alleles that separate the effects of CSR and SHM on polyclonal immune responses. We found that class-switching to IgG1 biased the fate choice made by B cells, favoring the plasma cell over memory cell fate without significantly affecting clonal expansion in the germinal center (GC). In contrast, SHM reduced the longevity of memory B cells by creating polyreactive specificities that were selected against over time. Our data define the independent contributions of SHM and CSR to the generation and persistence of memory in the antibody system. Overall design: IgG1 and IgM light zone (LZ) germinal center (GC) B cells that were Nurr77-GFP+ or Nurr77-GFP- were compared in immunized AIDcre/- IgH-96K/+ Nurr77-GFP mice.
Independent Roles of Switching and Hypermutation in the Development and Persistence of B Lymphocyte Memory.
Specimen part, Cell line, Subject
View SamplesActivation 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.
Beta-catenin stabilization stalls the transition from double-positive to single-positive stage and predisposes thymocytes to malignant transformation.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
The requirement for cyclin D function in tumor maintenance.
Specimen part, Cell line
View SamplesD-cyclins represent components of cell cycle machinery. To test the efficacy of targeting D-cyclins in cancer treatment, we engineered mouse strains which allow acute and global ablation of individual D-cyclins in a living animal. Ubiquitous shutdown of cyclin D1 or inhibition of cyclin D associated kinase activity in mice bearing ErbB2-driven mammary carcinomas halted cancer progression and triggered tumor-specific senescence, without compromising the animals' health. Ablation of cyclin D3 in mice bearing T-cell acute lymphoblastic leukemias (T-ALL) triggered tumorspecific apoptosis. Such selective killing of leukemic cells can be also achieved by inhibiting cyclin D associated kinase activity in mouse and human T-ALL models. Hence, contrary to what one might expect from ablation of a cell cycle protein, acute shutdown of a D-cyclin leads not only to cell cycle arrest, but it also triggers tumor cell senescence or apoptosis, and it affects different tumor types through distinct cellular mechanisms. Inhibiting cyclin D-activity represents a highly-selective anticancer strategy which specifically targets cancer cells without significantly affecting normal tissues.
The requirement for cyclin D function in tumor maintenance.
Cell line
View SamplesD-cyclins represent components of cell cycle machinery. To test the efficacy of targeting D-cyclins in cancer treatment, we engineered mouse strains which allow acute and global ablation of individual D-cyclins in a living animal. Ubiquitous shutdown of cyclin D1 or inhibition of cyclin D associated kinase activity in mice bearing ErbB2-driven mammary carcinomas halted cancer progression and triggered tumor-specific senescence, without compromising the animals' health. Ablation of cyclin D3 in mice bearing T-cell acute lymphoblastic leukemias (T-ALL) triggered tumorspecific apoptosis. Such selective killing of leukemic cells can be also achieved by inhibiting cyclin D associated kinase activity in mouse and human T-ALL models. Hence, contrary to what one might expect from ablation of a cell cycle protein, acute shutdown of a D-cyclin leads not only to cell cycle arrest, but it also triggers tumor cell senescence or apoptosis, and it affects different tumor types through distinct cellular mechanisms. Inhibiting cyclin D-activity represents a highly-selective anticancer strategy which specifically targets cancer cells without significantly affecting normal tissues.
The requirement for cyclin D function in tumor maintenance.
Specimen part
View SamplesMice used were B6/129 F2's, 3-5 weeks of age, either wild type or with both copies of the autoimmune regulator gene (aire, GenBank #AF079536) disrupted. Thymi from five of these mice of both sexes were removed and pooled. After collagenase/dispase digestion, density gradient fractionation, and fluorescent antibody staining, cells with the phenotype CD45-, G8.8+, CDR1int and B7.1hi were FACS-sorted and total RNA was made from them. RNA was twice-amplified using a T7 polymerase-based method.
Projection of an immunological self shadow within the thymus by the aire protein.
No sample metadata fields
View SamplesCyclin C was cloned as a growth-promoting G1 cyclin, and was also shown to regulate gene transcription. Here we report that in vivo cyclin C acts as a haploinsufficient tumour suppressor, by controlling Notch1 oncogene levels. Cyclin C activates an 'orphan' CDK19 kinase, as well as CDK8 and CDK3. These cyclin-C-CDK complexes phosphorylate the Notch1 intracellular domain (ICN1) and promote ICN1 degradation. Genetic ablation of cyclin C blocks ICN1 phosphorylation in vivo, thereby elevating ICN1 levels in cyclin-C-knockout mice. Cyclin C ablation or heterozygosity collaborates with other oncogenic lesions and accelerates development of T-cell acute lymphoblastic leukaemia (T-ALL). Furthermore, the cyclin C encoding gene CCNC is heterozygously deleted in a significant fraction of human T-ALLs, and these tumours express reduced cyclin C levels. We also describe point mutations in human T-ALL that render cyclin-C-CDK unable to phosphorylate ICN1. Hence, tumour cells may develop different strategies to evade inhibition by cyclin C.
Cyclin C is a haploinsufficient tumour suppressor.
Specimen part
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