Project description:Hardy’s Fraction D bone marrow pre-B cells and splenic follicular B cells were purified by flow cytometry according to MHC II expression from wild-type and ItgaxcreH2-Ab1c MHC II conditional mice and transcriptionally profiled by RNA-seq. Duplicate or triplicate samples for each genotype and level of MHC II expression were sequenced. This is part of ongoing investigation of a possible cell-intrinsic role of MHC II B cells.
Project description:The experiment elucidates the development of splenic B- and T lymphocytes in the absence of a vital gene. For this purpose, spleen cells of 5 wild type and 5 full knock-out mice were depleted of red blood cells and prepared for 10x single cell RNA-Seq sequencing. The library was prepared according to the manufacturers instructions.
Project description:Gene expression analysis of splenic follicular B cells and marginal zone B cells from B6 and CD19:KLF3 transgenic mice Comparing KLF3-transgenic and non-transgenic follicular B cells by RNA-microarray revealed that KLF3 regulates a subset of genes that was similarly up-/downregulated upon normal MZ B cell differentiation. Indeed, KLF3 expression overcame the lack of MZ B cells caused by different genetic alterations, such as CD19-deficiency or blockade of B-cell activating factor (BAFF)-receptor signaling, indicating that KLF3 may complement alternative NF-κB signaling. Thus, KLF3 is a driving force towards MZ B cell maturation. RNA of splenic follicular B cells and marginal zone B cells were obtained from 4 different mice per group (B6 and CD19:KLF3 mice). 16 samples = 8 individual mice x 2 B cell subsets.
Project description:This is a RNA-Seq study from paired mutant-wild type mouse haemopoietic cells (n=4 mutant strains with 6 mice per strain - 3 mutant & 3 wild type). We want to see the transcriptomic effects of these mutation on blood progenitors.
Project description:B lymphocyte development occurs in the bone marrow, while final differentiation and maturation can occur in both the bone marrow and the spleen. Here we provide evidence that signal regulatory protein ? (SIRP?), an Ig-superfamily ITIM-receptor expressed by myeloid but not by lymphoid cells, is involved in regulating B cell maturation. Lack of SIRP? signaling in adult SIRP?-mutant mice resulted in a reduced maturation of B cells in the bone marrow, evident by reduced numbers of semi-mature IgD+IgMhi follicular type-II (F-II) and mature IgD+IgMlo follicular type-I (F-I) B cells, as well as reduced blood B cell numbers. In addition, lack of SIRP? signaling also impaired follicular B cell maturation in the spleen. Maturing BM or splenic B cells of SIRP?-mutant mice were found to express higher levels of the pro-apoptotic protein BIM and apoptosis was increased among these B cells. Bone marrow reconstitution experiments revealed that the B cell maturation defect in bone marrow and blood was due to lack of SIRP? signaling in non-hematopoietic cells, while hematopoietic SIRP? signaling was important for follicular B cell maturation in the spleen. Adding on to our previous findings of a stromal cell defect in SIRP?-mutant mice was the finding that gene expression of receptor activator of nuclear factor-?B ligand (RANKL) was significantly lower in cultured bone marrow stromal cells of SIRP? mutant mice. These data suggest a novel and opposite contribution of SIRP? signaling within non-hematopoietic and hematopoietic cells, respectively, to maintain B cell maturation and to prevent apoptosis in the bone marrow and spleen of adult mice.
Project description:Complement receptors 1 and 2 (CR1/2 or CD35/CD21) recognize complement-opsonized antigens to initiate innate and adaptive immunity, respectively. CD35 stimulates phagocytosis on macrophages and antigen presentation on follicular dendritic cells (FDCs). CD21 helps activate B cells as part of the B cell coreceptor with CD19 and CD81. Differential splicing of transcripts from the mouse Cr2 gene generates isoforms with both shared and unique complement binding capacities and cell-type expression. In mouse models, genetic depletion of Cr2 causes either a delay or complete prevention of prion disease, but the relative importance of CD35 versus CD21 in promoting prion disease remains unknown. Here we show that both isoforms act as high-affinity cell surface prion receptors. However, mice lacking CD21 succumbed to terminal prion disease significantly later than mice lacking CD35 or wild-type and hemizygous mice. CD21-deficient mice contained fewer splenic prions than CD35 knockout mice early after infection that contributed to delayed prion neuroinvasion and terminal disease, despite forming follicular networks closer to proximal nerves. While we observed no difference in B cell networks, PrPC expression, or number of follicles, CD21-deficient mice formed more fragmented, less organized follicular networks with fewer Mfge8-positive FDCs and/or tingible body macrophages (TBM?s) than wild-type or CD35-deficient mice. In toto, these data demonstrate a more prominent role for CD21 for proper follicular development and organization leading to more efficient lymphoid prion replication and expedited prion disease than in mice expressing the CD35 isoform. IMPORTANCE Mammalian prion diseases are caused by prions, unique infectious agents composed primarily, if not solely, of a pathologic, misfolded form of a normal host protein, the cellular prion protein (PrPC). Prions replicate without a genetic blueprint, but rather contact PrPC and coerce it to misfold into more prions, which cause neurodegeneration akin to other protein-misfolding diseases like Alzheimer's disease. A single gene produces two alternatively spliced mRNA transcripts that encode mouse complement receptors CD21/35, which promote efficient prion replication in the lymphoid system and eventual movement to the brain. Here we show that CD21/35 are high-affinity prion receptors, but mice expressing only CD21 die from prion disease sooner than CD35-expressing mice, which contain less prions early after infection and exhibit delayed terminal disease, likely due to their less organized splenic follicles. Thus, CD21 appears to be more important for defining splenic architecture that influences prion pathogenesis.
Project description:Grb2 (growth-factor receptor-bound protein-2) is a signaling adaptor that interacts with numerous receptors and intracellular signaling molecules. However, its role in B-cell development and function remains unknown. Here we show that ablation of Grb2 in B cells results in enhanced B-cell receptor signaling; however, mutant B cells do not form germinal centers in the spleen after antigen stimulation. Furthermore, mutant mice exhibit defects in splenic architecture resembling that observed in B-cell-specific lymphotoxin-?-deficient mice, including disruption of marginal zone and follicular dendritic cell networks. We find that grb2(-/-) B cells are defective in lymphotoxin-? expression. Although lymphotoxin can be up-regulated by chemokine CXCL13 and CD40 ligand stimulation in wild-type B cells, elevation of lymphotoxin expression in grb2(-/-) B cells is only induced by anti-CD40 but not by CXCL13. Our results thus define Grb2 as a nonredundant regulator that controls lymphoid follicle organization and germinal center reaction. Loss of Grb2 has no effect on B-cell chemotaxis to CXCL13, indicating that Grb2 executes this function by connecting the CXCR5 signaling pathway to lymphotoxin expression but not to chemotaxis.
Project description:The formation of germinal centers (GCs) represents a crucial step in the humoral immune response. Recent studies using gene-targeted mice have revealed that the cytokines tumor necrosis factor (TNF), lymphotoxin (LT) alpha, and LTbeta, as well as their receptors TNF receptor p55 (TNFRp55) and LTbetaR play essential roles in the development of GCs. To establish in which cell types expression of LTbetaR, LTbeta, and TNF is required for GC formation, LTbetaR-/-, LTbeta-/-, TNF-/-, B cell-deficient (BCR-/-), and wild-type mice were used to generate reciprocal or mixed bone marrow (BM) chimeric mice. GCs, herein defined as peanut agglutinin-binding (PNA+) clusters of centroblasts/centrocytes in association with follicular dendritic cell (FDC) networks, were not detectable in LTbetaR-/- hosts after transfer of wild-type BM. In contrast, the GC reaction was restored in LTbeta-/- hosts reconstituted with either wild-type or LTbetaR-/- BM. In BCR-/- recipients reconstituted with compound LTbeta-/-/BCR-/- or TNF-/-/BCR-/- BM grafts, PNA+ cell clusters formed in splenic follicles, but associated FDC networks were strongly reduced or absent. Thus, development of splenic FDC networks depends on expression of LTbeta and TNF by B lymphocytes and LTbetaR by radioresistant stromal cells.
Project description:The secreted phosphatidylserine-binding protein milk fat globule epidermal growth factor 8 (Mfge8) mediates engulfment of apoptotic germinal center B cells by tingible-body macrophages (TBMphis). Impairment of this process can contribute to autoimmunity. We show that Mfge8 is identical to the mouse follicular dendritic cell (FDC) marker FDC-M1. In bone-marrow chimeras between wild-type and Mfge8(-/-) mice, all splenic Mfge8 was derived from FDCs rather than TBMphis. However, Mfge8(-/-) TBMphis acquired and displayed Mfge8 only when embedded in Mfge8(+/+) stroma, or when situated in lymph nodes draining exogenous recombinant Mfge8. These findings indicate a licensing role for FDCs in TBMphi-mediated removal of excess B cells. Lymphotoxin-deficient mice lacked FDCs and splenic Mfge8, and suffer from autoimmunity similar to Mfge8(-/-) mice. Hence, FDCs facilitate TBMphi-mediated corpse removal, and their malfunction may be involved in autoimmunity.