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Blood, 1 March 2007, Vol. 109, No. 5, pp. 2014-2022. Prepublished online as a Blood First Edition Paper on October 24, 2006; DOI 10.1182/blood-2006-07-035279. This Article Full Text Full Text (PDF) Supplemental Figures All Versions of this Article: blood-2006-07-035279v1 109/5/2014    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 HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Crellin, N. K. Articles by Levings, M. K. Search for Related Content PubMed PubMed Citation Articles by Crellin, N. K. Articles by Levings, M. K. Related Collections Signal Transduction Immunobiology Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  IMMUNOBIOLOGY Altered activation of AKT is required for the suppressive function of human CD4+CD25+ T regulatory cells Natasha K. Crellin1,2, Rosa V. Garcia1,2, and Megan K. Levings1,2 1 Department of Surgery, University of British Columbia, Vancouver, Canada; 2 Immunity and Infection Research Centre, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada Suppression by T regulatory cells (Treg cells) is a major mechanism by which the immune system controls responses to self and nonharmful foreign proteins. Although there are many different types of Treg cells, the best characterized are those that constitutively express cell-surface IL-2R (CD25). We investigated whether altered T-cell–receptor (TCR)–mediated signaling in pure populations of ex vivo human CD4+CD25+ Treg cells might underlie their unique phenotype, including hyporesponsiveness to TCR–mediated activation and lack of cytokine production. CD4+CD25+ Treg cells displayed a consistent defect in phosphorylation of AKT at serine 473 and reduced phosphorylation of the AKT substrates FOXO and S6. Restoration of AKT activity via lentiviral-mediated expression of an inducibly active form of the kinase revealed that reduced activity of this pathway was necessary for the suppressive function of CD4+CD25+ Treg cells. These data represent the first demonstration of a causal association between altered signaling and the function of CD4+CD25+ Treg cells. Moreover, we have created the first system allowing inducible abrogation of suppression through manipulation of the suppressor cells. This system will be a powerful tool to further study the mechanism(s) of suppression by CD4+CD25+ Treg cells. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: S. Haxhinasto, D. Mathis, and C. Benoist The AKT-mTOR axis regulates de novo differentiation of CD4+Foxp3+ cells J. Exp. Med., March 17, 2008; 205(3): 565 - 574. [Abstract] [Full Text] [PDF] R. Zeiser, D. B. Leveson-Gower, E. A. Zambricki, N. Kambham, A. Beilhack, J. Loh, J.-Z. Hou, and R. S. Negrin Differential impact of mammalian target of rapamycin inhibition on CD4+CD25+Foxp3+ regulatory T cells compared with conventional CD4+ T cells Blood, January 1, 2008; 111(1): 453 - 462. [Abstract] [Full Text] [PDF]

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