Giuseppe Bardi

Publications (3)33.49 Total impact

• Article: Vav-dependent and vav-independent phosphatidylinositol 3-kinase activation in murine B cells determined by the nature of the stimulus.

  Elena Vigorito, Giuseppe Bardi, Janet Glassford, Eric W-F Lam, Elizabeth Clayton, Martin Turner
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  ABSTRACT: We show in this study that B cell activation following high avidity ligation of IgM or coligation of membrane Ig with CD19 elicits similar levels of Ca(2+) flux using different mechanisms. Each form of activation requires the function of Vav and PI3K. However, Vav regulates Ca(2+) flux independently of PI3K following anti-IgM cross-linking. By contrast, Vav function is essential for PI3K activation following membrane Ig (mIg)/CD19 coligation. Inhibition of PI3K revealed anti-IgM-stimulated Ca(2+) flux has a PI3K-independent component, while Ca(2+) flux following mIg/CD19 coligation is totally PI3K dependent. The p85alpha and p110delta subunits of PI3K both participate in anti-IgM and mIg/CD19 coligation-induced Ca(2+) flux, although the defects are not as severe as observed after pharmacological inhibition. This may reflect the recruitment of additional PI3K subunits, as we found that p110alpha becomes associated with CD19 upon B cell activation. These data show that the nature of the Ag encountered by B cells determines the contribution of Vav proteins to PI3K activation. Our results indicate that the strong signals delivered by multivalent cross-linking agents activate B cells in a qualitatively different manner from those triggered by coreceptor recruitment.
  The Journal of Immunology 10/2004; 173(5):3209-14. · 5.79 Impact Factor
• Source

  Available from: David Chantry

  Article: A crucial role for the p110delta subunit of phosphatidylinositol 3-kinase in B cell development and activation.

  Elizabeth Clayton, Giuseppe Bardi, Sarah E Bell, David Chantry, C Peter Downes, Alexander Gray, Lisa A Humphries, David Rawlings, Helen Reynolds, Elena Vigorito, Martin Turner
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  ABSTRACT: Mice lacking the p110delta catalytic subunit of phosphatidylinositol 3-kinase have reduced numbers of B1 and marginal zone B cells, reduced levels of serum immunoglobulins, respond poorly to immunization with type II thymus-independent antigen, and are defective in their primary and secondary responses to thymus-dependent antigen. p110delta(-/-) B cells proliferate poorly in response to B cell receptor (BCR) or CD40 signals in vitro, fail to activate protein kinase B, and are prone to apoptosis. p110delta function is required for BCR-mediated calcium flux, activation of phosphlipaseCgamma2, and Bruton's tyrosine kinase. Thus, p110delta plays a critical role in B cell homeostasis and function.
  Journal of Experimental Medicine 10/2002; 196(6):753-63. · 13.85 Impact Factor
• Source

  Available from: Sarah E Bell

  Article: A Crucial Role for the p110δ Subunit of Phosphatidylinositol 3-Kinase in B Cell Development and Activation

  Elizabeth Clayton, Giuseppe Bardi, Sarah E. Bell, David Chantry, C. Peter Downes, Alexander Gray, Lisa A. Humphries, David Rawlings, Helen Reynolds, Elena Vigorito, Martin Turner
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  ABSTRACT: Mice lacking the p110δ catalytic subunit of phosphatidylinositol 3-kinase have reduced numbers of B1 and marginal zone B cells, reduced levels of serum immunoglobulins, respond poorly to immunization with type II thymus-independent antigen, and are defective in their primary and secondary responses to thymus-dependent antigen. p110δ−/− B cells proliferate poorly in response to B cell receptor (BCR) or CD40 signals in vitro, fail to activate protein kinase B, and are prone to apoptosis. p110δ function is required for BCR-mediated calcium flux, activation of phosphlipaseCγ2, and Bruton's tyrosine kinase. Thus, p110δ plays a critical role in B cell homeostasis and function.
  Journal of Experimental Medicine 09/2002; 196(6):753-763. · 13.85 Impact Factor