Qualitative Regulation of B Cell Antigen Receptor Signaling by CD19: Selective Requirement for PI3-Kinase Activation, Inositol-1,4,5-Trisphosphate Production and Ca2+ Mobilization

Buhl, Anne Mette; Pleiman, Christopher M.; Rickert, Robert C.; Cambier, John C.

doi:10.1084/jem.186.11.1897

Cited by 167 publications

(128 citation statements)

References 80 publications

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“…However, the role of PI3K in Ag receptor-stimulated primary T and B cells differs in at least three respects. First, acute calcium mobilization is blocked by PI3K inhibitors in B cells (26) but not in T cells (30). Second, up-regulation of the activation marker CD25 is blocked by LY294002 in B cells (our unpublished observations) but not in T cells (16).…”

Section: Discussionmentioning

confidence: 98%

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Proliferation and Survival of Activated B Cells Requires Sustained Antigen Receptor Engagement and Phosphoinositide 3-Kinase Activation

Donahue

Fruman

2003

The Journal of Immunology

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In this study, we investigate the extracellular and intracellular signals that drive cell cycle progression of activated B cells in the absence of T cell help. We find that brief engagement of the B cell receptor is sufficient to induce a single cell division in a fraction of cells, but that survival during successive cell divisions requires sustained receptor stimulation. In contrast, T cells have been shown previously to commit to multiple cell divisions following brief TCR engagement. Both early and late B cell receptor signals are blocked by inhibitors of phosphoinositide 3-kinase and mammalian target of rapamycin and are associated with S6 kinase activation and increased cell size. The requirement for ongoing Ag receptor signaling can be overcome by engagement of CD40 but only partially by IL-4. Proliferation driven by LPS also requires sustained exposure to the stimulus. These findings reveal checkpoints that may limit T-independent B cell responses when Ag exposure is transient.

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Section: Discussionmentioning

confidence: 98%

“…Pretreatment with PI3K inhibitors reduces BCR-dependent calcium mobilization (26) as well as phosphorylation of Akt and S6K1 (Fig. 3 and Refs.…”

Section: Discussionmentioning

confidence: 99%

Proliferation and Survival of Activated B Cells Requires Sustained Antigen Receptor Engagement and Phosphoinositide 3-Kinase Activation

Donahue

Fruman

2003

The Journal of Immunology

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“…This did not account for all of the inhibition observed with Lyn, suggesting that additional mechanisms contribute to Lyn-mediated down-regulation of Btk pathways. These may include inhibition by the cell surface receptor PIR-B, a pathway shown to involve both Btk and Lyn (75,76 The reduced TNP-Ficoll responses in both CD19 Ϫ/Ϫ Btk lo and p85␣ ϩ/Ϫ Btk lo mice supports a model in which CD19 amplifies Btk activation via PI3K (61,62). p85␣ was more penetrant than CD19, however.…”

Section: Discussionmentioning

confidence: 81%

A sensitized genetic system for the analysis of murine B lymphocyte signal transduction pathways dependent on Bruton's tyrosine kinase

Satterthwaite

Willis

Kanchanastit

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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Modifier screens have been powerful genetic tools to define signaling pathways in lower organisms. The identification of modifier loci in mice has begun to allow a similar dissection of mammalian signaling pathways. Transgenic mice (Btk lo ) expressing 25% of endogenous levels of Bruton's tyrosine kinase (Btk) have B cell functional responses between those of wild-type and Btk ؊/؊ mice. We asked whether reduced dosage or complete deficiency of genes previously implicated as Btk regulators would modify the Btk lo phenotype. We used two independent assays of Btk-dependent B cell function. Proliferative response to B cell antigen receptor cross-linking in vitro was chosen as an example of a relatively simple, well-defined signaling system. In vivo response to type II T-independent antigens (TI-II) measures complex interactions among multiple cell types over time and may identify additional Btk pathways. All modifiers identified differentially affected these two assays, indicating that Btk mediates these processes via distinct mechanisms. Loss of Lyn, PTEN (phosphatase and tensin homolog), or SH2-containing inositol phosphatase suppressed the Btk lo phenotype in vitro but not in vivo, whereas CD19 and the p85␣ form of phosphoinositide 3-kinase behaved as Btk lo enhancers in vivo but not in vitro. Effects of Lyn, PTEN, or p85␣ haploinsufficiency were observed. Haploinsufficiency or complete deficiency of protein kinase C ␤, Fyn, CD22, G␣q, or G␣11 had no detectable effect on the function of Btk lo B cells. A transgenic system creating a reduction in dosage of Btk can therefore be used to identify modifier loci that affect B cell responses and quantitatively rank their contribution to Btk-mediated processes.In vivo genetic analysis is a powerful approach to define the relative contribution of signaling interactions to physiological processes. Small genomes, ease of mutagenesis, and rapid generation time have made Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae the major models for genetic dissection of eukaryotic signaling pathways. Although there are some examples of large-scale genetic screens in mice (1-3), time, space, and financial resources generally limit mammalian genetic studies to targeted mutations in known genes or the characterization of naturally occurring mutations.In a commonly used type of genetic screen, organisms carrying a defined mutation affecting the process of interest are further mutagenized and screened for second site mutations, or modifiers, that enhance (increase) or suppress (reduce) the severity of the parental phenotype (4, 5). The initial mutation often renders the system responsive to subtle changes in modifiers that would not be penetrant on an otherwise wild-type background. This sensitivity often permits a dominant screen, decreasing the time and resources required to identify new mutations.Complete deficiency of many signaling molecules results in loss of the cell type of interest or pleiotropic or lethal phenotypes, making the effects of additional m...

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“…Using such chimeric molecules expressed in Daudi cells, we previously demonstrated that CD19 Y391 was required for normal function but that Y482 and Y513 were not in this system (8,10). In CD45-transfected plasmacytoma cells, mutation of Y482 and Y513 in cotransfected CD19 reduced the magnitude of the increase in [Ca 2ϩ ] i induced by ligation of the BCR alone (28,29). However, CD19 has six additional cytoplasmic tyrosines of unknown function.…”

Section: D19 Is Expressed On All B Cells Until Late Differentiationmentioning

confidence: 99%

“…(28,29). In this study, we compared the role of all cytoplasmic tyrosines of CD19 in Ca 2ϩ and ERK2 signaling ( Fig.…”

Section: Replicationmentioning

confidence: 99%

Systematic Analysis of the Role of CD19 Cytoplasmic Tyrosines in Enhancement of Activation in Daudi Human B Cells: Clustering of Phospholipase C and Vav and of Grb2 and Sos with Different CD19 Tyrosines

Brooks

Li²,

Volanakis³

et al. 2000

The Journal of Immunology

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CD19 is a coreceptor on B cells that enhances the increase in cytoplasmic calcium and ERK2 activation when coligated with the B cell Ag receptor. Constructs containing point mutations and truncations were expressed in Daudi human B lymphoblastoid cells to systematically determine the requirement for individual CD19 cytoplasmic tyrosines in these responses. Evidence for activity was found for Y330, Y360, and Y421 as well as that previously published for Y391. Precipitates formed with phosphopeptides consisting of CD19 sequences flanking these residues were used to screen for cytoplasmic proteins that mediate signaling. Phosphopeptide Y330 precipitated Grb2 and Sos, whereas phosphopeptides Y391 and Y421 both precipitated Vav and phospholipase C-γ2. These molecules also were found associated with native CD19. In mapping studies with altered constructs, CD19 Y330 and/or Y360 were necessary for binding Grb2 and Sos. Vav associated with CD19 constitutively in unstimulated cells by a tyrosine-independent mechanism requiring the portion of CD19 encoded by exons 9–12. After B cell Ag receptor stimulation, Vav association was tyrosine-dependent, but binding was influenced by multiple residues. However, when maximally phosphorylated by pervanadate, Y391 and, to a lesser extent, Y421 were sufficient. CD19 Y391 was also both necessary and sufficient for binding phospholipase C-γ2. Thus, different tyrosines along the CD19 cytoplasmic domain provide scaffolding for the formation of complexes of different signaling molecules.

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Qualitative Regulation of B Cell Antigen Receptor Signaling by CD19: Selective Requirement for PI3-Kinase Activation, Inositol-1,4,5-Trisphosphate Production and Ca2+ Mobilization

Cited by 167 publications

References 80 publications

Proliferation and Survival of Activated B Cells Requires Sustained Antigen Receptor Engagement and Phosphoinositide 3-Kinase Activation

Proliferation and Survival of Activated B Cells Requires Sustained Antigen Receptor Engagement and Phosphoinositide 3-Kinase Activation

A sensitized genetic system for the analysis of murine B lymphocyte signal transduction pathways dependent on Bruton's tyrosine kinase

Systematic Analysis of the Role of CD19 Cytoplasmic Tyrosines in Enhancement of Activation in Daudi Human B Cells: Clustering of Phospholipase C and Vav and of Grb2 and Sos with Different CD19 Tyrosines

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