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Blood, 2 April 2009, Vol. 113, No. 14, pp. 3198-3208. Prepublished online as a Blood First Edition Paper on February 3, 2009; DOI 10.1182/blood-2008-04-152942. This Article Full Text Full Text (PDF) Supplemental Methods All Versions of this Article: blood-2008-04-152942v1 113/14/3198    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Alcázar, I. Articles by Carrera, A. C. Search for Related Content PubMed PubMed Citation Articles by Alcázar, I. Articles by Carrera, A. C. Related Collections Immunobiology Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  IMMUNOBIOLOGY p85β phosphoinositide 3-kinase regulates CD28 coreceptor function Isabela Alcázar1,*, Isabel Cortés1, Angel Zaballos1, Carmen Hernandez1, David A. Fruman2, Domingo F. Barber1,*,, and Ana C. Carrera1, 1 Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain; and 2 Department of Molecular Biology & Biochemistry, and Center for Immunology, University of California Irvine CD28 is a receptor expressed on T cells that regulates their differentiation after antigen stimulation to long-term-survival memory T cells. CD28 enhances T-cell receptor signals and reduces expression of CBL ubiquitin ligases, which negatively control T-cell activation. In the absence of CD28 ligation during the primary stimulation, CBL levels remain high and T cells fail to mount an efficient secondary response. CD28 associates with p85, one of the regulatory subunits of phosphoinositide-3-kinase (PI3K), but the relevance of this interaction is debated. We examined here the contribution of the other ubiquitous PI3K regulatory subunit, p85β, in CD28 function. We describe that p85β bound to CD28 and to CBL with greater affinity than p85. Moreover, deletion of p85β impaired CD28-induced intracellular events, including c-CBL and CBL-b down-regulation as well as PI3K pathway activation. This resulted in defective differentiation of activated T cells, which failed to exhibit an efficient secondary immune response. Considering that p85β-deficient T cells fail in recall responses and that p85β binds to and regulates CD28 signals, the presented observations suggest the involvement of p85β in CD28-mediated activation and differentiation of antigen-stimulated T cells. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

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