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Catherine C. Hedrick - One of the best experts on this subject based on the ideXlab platform.

Heba Nowyhed - One of the best experts on this subject based on the ideXlab platform.

Anthony L. Defranco - One of the best experts on this subject based on the ideXlab platform.

  • Quantitative proteomic analysis of B cell Lipid Rafts reveals that ezrin regulates antigen receptor–mediated Lipid Raft dynamics
    Nature Immunology, 2006
    Co-Authors: Neetu Gupta, Bernd Wollscheid, Julian D. Watts, Barbara Scheer, Ruedi Aebersold, Anthony L. Defranco
    Abstract:

    Ligation of the B cell antigen receptor (BCR) with antigen induces Lipid Raft coalescence, a process that occurs after crosslinking of a variety of signaling receptors and is thought to potentiate cellular activation. To investigate Lipid Raft dynamics during BCR signaling, we quantitatively analyzed the B cell Lipid Raft proteome. BCR engagement induced dissociation of the adaptor protein ezrin from Lipid Rafts as well as threonine dephosphorylation of ezrin and its concomitant detachment from actin, indicating a transient uncoupling of Lipid Rafts from the actin cytoskeleton. Expression of constitutively active ezrin chimeras inhibited the BCR-induced coalescence of Lipid Rafts. Our data demonstrate that the release of ezrin from Lipid Rafts acts as a critical trigger that regulates Lipid Raft dynamics during BCR signaling.

  • quantitative proteomic analysis of b cell Lipid Rafts reveals that ezrin regulates antigen receptor mediated Lipid Raft dynamics
    Nature Immunology, 2006
    Co-Authors: Neetu Gupta, Bernd Wollscheid, Julian D. Watts, Barbara Scheer, Ruedi Aebersold, Anthony L. Defranco
    Abstract:

    Ligation of the B cell antigen receptor (BCR) with antigen induces Lipid Raft coalescence, a process that occurs after crosslinking of a variety of signaling receptors and is thought to potentiate cellular activation. To investigate Lipid Raft dynamics during BCR signaling, we quantitatively analyzed the B cell Lipid Raft proteome. BCR engagement induced dissociation of the adaptor protein ezrin from Lipid Rafts as well as threonine dephosphorylation of ezrin and its concomitant detachment from actin, indicating a transient uncoupling of Lipid Rafts from the actin cytoskeleton. Expression of constitutively active ezrin chimeras inhibited the BCR-induced coalescence of Lipid Rafts. Our data demonstrate that the release of ezrin from Lipid Rafts acts as a critical trigger that regulates Lipid Raft dynamics during BCR signaling.

  • visualizing Lipid Raft dynamics and early signaling events during antigen receptor mediated b lymphocyte activation
    Molecular Biology of the Cell, 2003
    Co-Authors: Neetu Gupta, Anthony L. Defranco
    Abstract:

    Recent biochemical evidence indicates that an early event in signal transduction by the B-cell antigen receptor (BCR) is its translocation to specialized membrane subdomains known as Lipid Rafts. We have taken a microscopic approach to image Lipid Rafts and early events associated with BCR signal transduction. Lipid Rafts were visualized on primary splenic B lymphocytes from wild-type or anti-hen egg lysozyme BCR transgenic mice, and on a mature mouse B-cell line Bal 17 by using fluorescent conjugates of cholera toxin B subunit or a Lyn-based chimeric protein, which targets green fluorescent protein to the Lipid Raft compartment. Time-lapse imaging of B cells stimulated via the BCR with the antigen hen egg lysozyme, or surrogate for antigen anti-IgM, demonstrated that Lipid Rafts are highly dynamic entities, which move laterally on the surface of these cells and coalesce into large regions. These regions of aggregated Lipid Rafts colocalized with the BCR and tyrosine-phosphorylated proteins. Microscopic imaging of live B cells also revealed an inducible colocalization of Lipid Rafts with the tyrosine kinase Syk and the receptor tyrosine phosphatase CD45. These two proteins play indispensable roles in BCR-mediated signaling but are not detectable in biochemically purified Lipid Raft fractions. Strikingly, BCR stimulation also induced the formation of long, thread-like filopodial projections, similar to previously described structures called cytonemes. These B-cell cytonemes are rich in Lipid Rafts and actin filaments, suggesting that they might play a role in long-range communication and/or transportation of signaling molecules during an immune response. These results provide a window into the morphological and molecular organization of the B-cell membrane during the early phase of BCR signaling.

Paola Marcovecchio - One of the best experts on this subject based on the ideXlab platform.

Shilpi Chandra - One of the best experts on this subject based on the ideXlab platform.