Nuclear FOXO1 promotes lymphomagenesis in germinal center B cells
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ABSTRACT:
PROVIDER: PRJNA489254 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:FOXO1 acts as a tumor suppressor in solid tumors. The oncogenic PI3K pathway suppresses FOXO1 transcriptional activity by enforcing its nuclear exclusion upon AKT-mediated phosphorylation. We show here abundant nuclear expression of FOXO1 in Burkitt lymphoma (BL), a germinal center (GC) B cell derived lymphoma whose pathogenesis is linked to PI3K activation. Recurrent FOXO1 mutations which prevent AKT targeting and lock the transcription factor in the nucleus are used by BL to circumvent mutual exclusivity between PI3K and FOXO1 activation. Using genome editing in human and mouse lymphomas in which MYC and PI3K cooperate synergistically in tumor development we demonstrate pro-proliferative and anti-apoptotic activity of FOXO1 in BL and identify its nuclear localization as an oncogenic event in GC B cell derived lymphomagenesis.
2018-12-21 | GSE119437 | GEO
Project description:PI3K signaling and FOXO transcription factors play opposing roles at several B cell developmental stages. We show here abundant nuclear FOXO1 expression in the proliferative compartment of the germinal center (GC), its dark zone (DZ), and PI3K activity, downregulating FOXO1, in the GC light zone (LZ), where cells are selected for further differentiation. However, here FOXO1 is expressed in c-Myc+ cells destined for DZ reentry. Upon FOXO1 ablation by genetic means or induction of PI3K activity GCs become devoid of their DZ, due at least partly to the downregulation of the chemokine receptor CXCR4. While this is known to prevent proper cyclic selection of cells expressing high-affinity antibodies, the initiation of immunoglobulin switching is essentially dependent on FOXO1 activity. All samples were obtained from mouse germinal center (GC) B cells (Cgamma1-cre; YFP, P110*, FOXO1 f/f or PTEN f/f animals). Cells used for microarray analysis were FACS sorted cells.
2015-11-23 | E-GEOD-68043 | biostudies-arrayexpress
Project description:AICDA-induced epigenetic plasticity accelerates germinal center-derived lymphomagenesis
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Project description:PI3K signaling and FOXO transcription factors play opposing roles at several B cell developmental stages. We show here abundant nuclear FOXO1 expression in the proliferative compartment of the germinal center (GC), its dark zone (DZ), and PI3K activity, downregulating FOXO1, in the GC light zone (LZ), where cells are selected for further differentiation. However, here FOXO1 is expressed in c-Myc+ cells destined for DZ reentry. Upon FOXO1 ablation by genetic means or induction of PI3K activity GCs become devoid of their DZ, due at least partly to the downregulation of the chemokine receptor CXCR4. While this is known to prevent proper cyclic selection of cells expressing high-affinity antibodies, the initiation of immunoglobulin switching is essentially dependent on FOXO1 activity.
2015-11-23 | GSE68043 | GEO
Project description:The MEF2B transcription factor is frequently mutated in germinal center (GC)-derived B-cell lymphomas. Its N-terminal mutations drive lymphomagenesis by escaping interaction with transcriptional repressors, while the function of C-terminal mutations remains to be elucidated. Here, we show that MEF2B C-tail is physiologically phosphorylated at specific residues and phosphorylation at S324 is impaired by lymphoma-associated mutations. Lack of phosphorylation at S324 enhances the interaction of MEF2B with the SWI/SNF chromatin remodeling complex, leading to higher transcriptional activity. In addition, these mutants show an increased protein stability due to impaired interaction with the CUL3/KLHL12 ubiquitin complex. Mice expressing a phosphorylation-deficient lymphoma-associated MEF2B mutant display GC enlargement and develop GC-derived lymphomas, when crossed with Bcl2 transgenic mice. These results unveil converging mechanisms of action for a diverse spectrum of MEF2B mutations, all leading to its dysregulation and GC B-cell lymphomagenesis. These assorted mechanisms provide additional opportunities for the development of targeted therapeutic approaches.
2024-08-26 | PXD043998 | Pride
Project description:Productive B cell responses are critical to protect a host from infection. The spleen and lymph nodes are populated by resting follicular B cells, which can enter germinal centers upon antigen encounter. Once in the germinal center, B cells migrate between the dark and light zones, where they undergo somatic hypermutation and selection, respectively. While germinal center B cells have been studied, an intense molecular understanding of these cells/subsets (and the differences between them) is lacking.
2020-04-06 | PXD015524 | Pride
Project description:Germinal center (GC) B cells cycle between two states, the light zone (LZ) and the dark zone (DZ), and in the latter they proliferate and hypermutate their immunoglobulin genes. How this functional transition takes place is still controversial. In this study, we demonstrate that ablation of Foxo1 after GC development led to the loss of the DZ GC B cells and disruption of the GC architecture. Mechanistically, even upon provision of adequate T cell help, Foxo1-deficient GC B cells showed less proliferative expansion than controls. Moreover, we found that the transcription factor BATF was transiently induced in LZ GC B cells in a Foxo1-dependent manner and that deletion of BATF similarly led to GC disruption. Thus, our results are consistent with a model where the switch from the LZ to the DZ is triggered after receipt of T cell help, and suggest that Foxo1-mediated BATF up-regulation is at least partly involved in this switch.
2017-03-21 | GSE93554 | GEO
Project description:EZH2 mediates the humoral immune response and drives lymphomagenesis through de novo formation of bivalent chromatin domains and critical germinal center (GC) B cell promoters. We show that such formation is dependent on the presense of BCL6 and the presence of non-canonical PRC1-BCOR complex. We observe that BCL6 and EZH2 cooperate to accelerate diffuse large B cell lymphoma (DLBCL) development and combinatorial targeting of these repressors results in enhanced anti-lymphoma activity in vitro, in vivo, and in primary human DLBCLs. DLBCL cell lines treated with BCL6 inhibitor 79-6.1085
2016-07-20 | E-GEOD-73109 | biostudies-arrayexpress
Project description:Histone demethylase LSD1 is required for germinal center formation and BCL6 driven lymphomagenesis
| PRJNA486791 | ENA
Project description:The pathways regulating the formation of the germinal center (GC) dark- (DZ) and light- (LZ) zones are unknown. We show that FOXO1 expression is restricted to the GC DZ and is required for DZ formation, since its absence in mice leads to the complete loss of DZ gene programs and the formation of LZ-only GCs. FOXO1-negative GC B-cells display normal somatic hypermutation, but defective affinity maturation and class switch recombination. The function of FOXO1 in sustaining the DZ program involves the transactivation of the chemokine receptor CXCR4, and the cooperation with BCL6 in the trans-repression of genes involved in immune activation, DNA-repair and plasma cell differentiation. These results have also implications for understanding the role of FOXO1 mutations in lymphomagenesis. We used microarrays to determine the consequences of FOXO1 deletion in the GC B cell comparment, and correlate these data with phenotypic changes
2015-12-04 | GSE69216 | GEO