Project description:Marginal zone (MZ) B cells have innate-like response characteristics due to a unique ability receive and integrate Notch2 signals in the spleen. There is evidence showing MZ B cells receive these signals both in the marginal sinus and the B cell follicle. The relative strength and conservation of these Notch signals is not yet clear. Therefore, we generated mice in which S1pr1 is deleted in mature B cells. These mice have MZ B cells by phenotype but these cells are retained in the follicle and unable to transit to the marginal zone. In this experiment we examined the impact of Notch2 signaling in these cells and cre expressing control animals using in vivo anti-Notch2 antibody blockade followed by RNA-sequencing.
Project description:Marginal zone (MZ) B cells leverage Notch2 signals to attain rapid differentiation responses and positional cues with in the spenic environment. While it is known that a major player in Notch2 signaling in MZ B cells is the proto-oncogene Myc, it is not clear to what extent MZ B cells use Notch2 signals in Myc-independent manner. In this study we conditinally and inducibly deleted Myc in mature B cells and then used in vivo delivery of anti-Notch2 antibodies to separated Myc-dependent and -independent Notch2 signaling in MZ B cells.
Project description:Marginal zone B cells which make rapid mitosis-independent plasma cell responses are dependent on Notch2 signaling for their generation and maintenance. In order to determine the effect of ongoing Notch signaling on the maintenance of the MZ transcriptome, we performed RNA-seq on MZ and follicular B cells after 12, 24 and 48 hours of in vivo Notch2 antibody blockade
Project description:Marginal zozne B cells are poised to rapidly differentiate into plasma cells through biochemical pathways activated by Notch2 signaling. We sought to determine differences in chromatin accessability at plasma cell program-relevant loci between these cells and follicular B cells also located within the spleen but less receptive to Notch signaling. To ths end, we prepared ATAC-seq libriaries from steady state marginal zone and follicular B cells as well as newly formed plasma cells generated in Blimp1GFP/+ reporter mice 4 days post immunization with LPS.
Project description:Marginal zone (MZ) B cells optimize protection against blood-borne bacteria by rapidly producing plasma cells in response to Toll-like Receptor (TLR) ligands. Here, we demonstrate that forced Notch2 instructs this responsiveness for Notch2-independent follicular B cells. Upon stimulation with either TLR4 ligand LPS or B cell receptor crosslinking via anti-IgM, access to Notch2 ligands promoted early transcriptional changes to numerous activation programs. These changes include augmenting TLR response programs, early and late mitotic pathways, and key cell growth and protein secretion pathways critical for plasma cell differentiation. We conclude that t uniquely robust hyper-responsiveness can be ascribed to any B cell with access to Notch2 ligands.
Project description:Marginal zone (MZ) B cells leverage Notch2 signals to attain rapid differentiation responses and positional cues with in the spenic environment.To determine the likely molecular source of Notch2 signals we sought to block the Notch ligands delta-like ligand 1 (Dll1) and delta-like ligand 4 (Dll4) in wildtype mice using in-vivo treatment with monoclonal blocking antibodies. Splenic populations of MZ B cells and follicular B cells were sort purified after 12, 24 and 48 hours of blockade and analyzed by RNA-seq.
Project description:<p>Splenic Marginal Zone Lymphoma (SMZL) is a B-cell malignancy of unknown pathogenesis and thus orphan of targeted therapies. By integrating whole-exome sequencing and copy-number analysis of 8 paired tumor-normal DNAs from patients with SMZL, we show that the typical SMZL exome carries ~30 genetic alterations. Targeted resequencing of selected candidates in an extended panel of 40-117 samples revealed activating mutations of NOTCH2, a gene required for marginal-zone (MZ) development, as the most frequent and SMZL-specific lesion, accounting for approximately 20% of cases. Additional altered genes suggest that deregulation of signaling pathways normally involved in MZ development (NOTCH, NF-kappa B, and B-cell receptor) represents a critical event in SMZL pathogenesis. These findings have direct implications for the treatment of SMZL patients since drugs are available which can target NOTCH as well as other pathways deregulated in this disease.</p>
Project description:The purpose of this experiment is to delineate whether Akt over-expression is sufficient to induce a marginal zone-like phenotype in B cells at the molecular level. Mice expressing constitutively Akt in B cells have almost only marginal zone B cells in secondary lymphoid organs, as much as we can say through characterization of cell surface receptor by flow cytometry. These analyses were conducted in order to gain a more precise understanding of the relationship between WT marginal zone B cells and marginal zone B cells produced as a result of constitutive Akt signalling.
