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Lauritsen JP , Kurella S , Lee SY , Lefebvre JM , Rhodes M , Alberola-Ila J , Wiest DL
Egr2 is required for Bcl-2 induction during positive selection
J Immunol. 2008 Dec 1;181(11) :7778-85
PMID: 19017967    PMCID: PMC2587029   
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Abstract
The repertoire of TCR specificities is established by a selection process in the thymus, during which precursor survival and maturation is dictated by the nature of the TCR signals. The differences in signals that determine whether precursors will survive and mature or be induced to die remain poorly understood. Among the molecular effectors involved in executing the differentiation process initiated by TCR-ligand interactions is a family of Zn-finger transcription factors termed early growth response genes (Egr). Indeed, ablation of the Egr1 gene impairs ligand-induced maturation (positive selection) but not ligand-induced deletion (negative selection). The partial impairment of positive selection by Egr1 deficiency is not enhanced by simultaneous deletion of another Egr family member, Egr3. Accordingly, we asked whether this results from compensation by another family member, Egr2. In this manuscript, we demonstrate that deletion of Egr2 impairs positive selection of both CD4 and CD8 single-positive thymocytes. Interestingly, many of the genes involved in positive selection and T cell differentiation are up-regulated normally in the Egr2-deficient thymocytes. However, Bcl-2 up-regulation is not sustained during late stages of positive selection. This defect is at least partially responsible for the developmental blockade in Egr2-deficient thymocytes, as enforced expression of Bcl-2 rescues T cell development in Egr2(-/-) thymocytes. Taken together, these data suggest that Egr2 plays a central role in the up-regulation of the survival molecule Bcl-2 during positive selection.
Notes
Lauritsen, Jens-Peter Holst Kurella, Sridevi Lee, Sang-Yun Lefebvre, Juliette M Rhodes, Michele Alberola-Ila, Jose Wiest, David L AI059302/AI/NIAID NIH HHS/United States CA100144/CA/NCI NIH HHS/United States CA73656/CA/NCI NIH HHS/United States CA87407/CA/NCI NIH HHS/United States P01CA06927/CA/NCI NIH HHS/United States P30-DK-50306/DK/NIDDK NIH HHS/United States Research Support, N.I.H., Extramural United States Journal of immunology (Baltimore, Md. : 1950) J Immunol. 2008 Dec 1;181(11):7778-85.