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Transcriptional profiling of SUDHL4 cells stimulated with megaCD40L and IgM/G for 24 hours

ABSTRACT: The transcription factor FOXO1 directs germinal center (GC) polarity and supports affinity maturation by silencing immune activation programs in GC B cells. Recurrent somatic mutations in GC-derived B cell non-Hodgkin lymphomas (B-NHL) often target and reportedly activate FOXO1 by preventing its negative regulation by PI3K. Herein, using ad hoc mouse models, engineered cell lines and primary tumor specimens, we show instead that FOXO1 mutant proteins display altered transcriptional activities suggestive of partial loss-of-function. These defects drive simultaneous hyperactivation of signaling pathways (Stress Activated Protein Kinase -SAPK/JNK, Phosphoinositide 3-kinase -PI3K/AKT) and gene expression programs typically activated in GC B cells upon positive selection. Such changes confer mutant B cells with competitive advantages in response to key immune signals, leading to abnormal amplification of GC responses. Evidence of these FOXO1 ‘mutant’ gene programs can be found in a fraction of human B-NHL and predict clinical outcome, thus implying the frequent co-option of positive selection programs during GC-derived B-NHL pathogenesis.

ORGANISM(S): Homo sapiens

PROVIDER: GSE143772 | GEO | 2021/07/30

REPOSITORIES: GEO

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Mapping of WT FOXO1 and M1L FOXO1 binding sites in SUDHL4 cells

Project description:The transcription factor FOXO1 directs germinal center (GC) polarity and supports affinity maturation by silencing immune activation programs in GC B cells. Recurrent somatic mutations in GC-derived B cell non-Hodgkin lymphomas (B-NHL) often target and reportedly activate FOXO1 by preventing its negative regulation by PI3K. Herein, using ad hoc mouse models, engineered cell lines and primary tumor specimens, we show instead that FOXO1 mutant proteins display altered transcriptional activities suggestive of partial loss-of-function. These defects drive simultaneous hyperactivation of signaling pathways (Stress Activated Protein Kinase -SAPK/JNK, Phosphoinositide 3-kinase -PI3K/AKT) and gene expression programs typically activated in GC B cells upon positive selection. Such changes confer mutant B cells with competitive advantages in response to key immune signals, leading to abnormal amplification of GC responses. Evidence of these FOXO1 ‘mutant’ gene programs can be found in a fraction of human B-NHL and predict clinical outcome, thus implying the frequent co-option of positive selection programs during GC-derived B-NHL pathogenesis.

2021-07-30 | GSE143774 | GEO

Transcriptional profiling of SUDHL4 cells edited by CRISPR-cas9 to induce point mutations in the FOXO1 locus

2021-07-30 | GSE143773 | GEO

PI3 Kinase and FOXO1 activity differentially control B cells in the germinal center light and dark zone

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

PI3 Kinase and FOXO1 activity differentially control B cells in the germinal center light and dark zone

2015-11-23 | GSE68043 | GEO

Nuclear FOXO1 promotes lymphomagenesis in germinal center B cells

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

Expression profiles of murine FOXO1+/+ and FOXO1-null GC B cells

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 GC B cell subpopulations were collected by Fluorescence Activated Cell Sorting (FACS) from B cell enriched fractions of splenic mononuclear cell pools (12 days after SRBC immunization). 20ng of total RNA (RIN>9) for each sample was used as a template for linear cDNA amplification (Ovation RNA amplification Kit, NuGen). cDNA was labeled using the Encore Biotin Labeling Kit (NuGen) and hybridized to Affymetrix Mouse 430.2 gene expression arrays

2015-12-04 | E-GEOD-69216 | biostudies-arrayexpress

Transcription profiling of human CD4+ leukemia Jurkat T-cells in which the PI3K pathway is constitutively turned-on and FOXO1 transcriptional activity strongly repressed

Project description:One major effect of PI3-kinase activation downstream of the serine/threonine kinase Akt is the phosphorylation of the transcription factor FOXO1 and its neutralization. FOXO1 has several ubiquitous targets genes in many cell types that control cell quiescence, oxydative stress or apoptosis. However, it has been demonstrated that FOXO1 also has specific targets depending of the cellular context. The role of FOXO1 to regulate specific genes in T lymphocytes has not been investigated yet. To examine this point, we used the CD4+ leukemia Jurkat T-cell line, in which the PI3K pathway is constitutively turned-on and FOXO1 transcriptional activity strongly repressed. These cells were transduced with lentiviruses coding for a constitutively active form of FOXO1 fused to GFP and having the three AKT phosphorylation sites mutated to alanine (FOXO1-AAA-GFP) to restore its transcriptional activity. GFP-transduced cells were used as a control and the gene activation levels in the two cell populations analyzed 48 hours post-infection.

2008-12-01 | E-TABM-391 | biostudies-arrayexpress

Glycolysis Promotes Phosphoinositide 3-Kinase Signaling In Support of T Helper 17 Cell-Mediated Autoimmunity

Project description:T helper (Th) cell differentiation is driven by antigen and accessory signals that activate phosphoinositide 3-kinase (PI3K) to induce transcriptional and metabolic reprogramming including aerobic glycolysis (the Warburg effect). Here, we show that ATP generated through glycolysis fuels PI3K signaling to promote pathogenic Th17 cell responses. Mice with T cell-specific ablation of the glycolytic enzyme lactate dehydrogenase A (LDHA) were resistant to Th17 cell-mediated experimental autoimmune encephalomyelitis in association with defective T cell activation, migration, proliferation, and differentiation. LDHA deficiency crippled the cellular redox balance and inhibited ATP production causing attenuated phosphoinositide (3,4,5)-trisphosphate generation, and diminished activation of the Akt kinase and phosphorylation of its transcription factor target Foxo1. Th17 cell-specific expression of an Akt-insensitive Foxo1 mutant recapitulated the Th17 cell differentiation defects caused by LDHA deficiency. Thus, PI3K signaling and glycolytic bioenergetics constitute a positive feedback regulatory circuit essential for Th17 cell-mediated autoimmunity.

2021-03-27 | GSE164959 | GEO

H3K27Ac mapping in isogenic CREBBP-WT, CREBBP-KO and EP300-KO SUDHL4 cell lines

Project description:Inactivating mutations of the CREBBP acetyltransferase and, at lower frequencies, its paralogue EP300 are among the most common genetic alterations in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL), the two most frequent B cell malignancies. Here we uncover unexpected distinct functions for CREBBP and EP300 in the germinal center (GC), i.e. the target structure for most human B cell lymphomas. We show that these proteins modulate non-overlapping transcriptional programs that are preferentially enriched in biological functions associated with the separate anatomic compartments of the GC. Consistently, deletion of CREBBP or EP300 have opposing effects on GC formation in vivo. Nonetheless, these proteins partially compensate for each other to maintain a minimal threshold of acetyltransferase activity and guarantee homeostatic control of the GC, which is completely abrogated by their combined loss. This synthetic lethal interaction is retained in DLBCL cells, identifying an Achille’s heel in CREBBP-mutant lymphomas that could be pharmacologically targeted by using a novel, selective small molecule inhibitor of the CREBBP/EP300 bromodomain. These data shed light on the unique roles of CREBBP and EP300 in the physiology and pathology of GC B cells, and provide a proof-of-principle for the development and testing of EP300 inhibition as a therapeutic strategy in these diseases.

2020-02-19 | GSE132365 | GEO

Expression profiles of murine FOXO1+/+ and FOXO1-null GC B cells

2015-12-04 | GSE69216 | GEO

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