T cell receptor signal strength in Treg and iNKT cell development demonstrated by a novel fluorescent reporter mouse

Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55414, USA.
Journal of Experimental Medicine (Impact Factor: 12.52). 06/2011; 208(6):1279-89. DOI: 10.1084/jem.20110308
Source: PubMed


The ability of antigen receptors to engage self-ligands with varying affinity is crucial for lymphocyte development. To further explore this concept, we generated transgenic mice expressing GFP from the immediate early gene Nr4a1 (Nur77) locus. GFP was up-regulated in lymphocytes by antigen receptor stimulation but not by inflammatory stimuli. In T cells, GFP was induced during positive selection, required major histocompatibility complex for maintenance, and directly correlated with the strength of T cell receptor (TCR) stimulus. Thus, our results define a novel tool for studying antigen receptor activation in vivo. Using this model, we show that regulatory T cells (T(reg) cells) and invariant NKT cells (iNKT cells) perceived stronger TCR signals than conventional T cells during development. However, although T(reg) cells continued to perceive strong TCR signals in the periphery, iNKT cells did not. Finally, we show that T(reg) cell progenitors compete for recognition of rare stimulatory TCR self-ligands.

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    • "To better understand how glucose deprivation alters TH1 cell functions, we examined how glycolysis affects TCR signaling after TCR stimulation using several approaches. First, we observed that the induction of the immediate early gene Nur77 (as measured using a Nur77-eGFP reporter that reads out TCR signaling in a Ca 2+ -dependent manner;Moran et al., 2011) was suppressed in glucose-poor conditions or in the presence of 2-DG (Figure 3A). In contrast, the amount of phosphorylated ERK1/2 (pERK1/2) or AKT (pAKTS473 and pAKTT308) was minimally affected following activation of TH1 CD4 T cells in glucose-deprived conditions (Figure S3). "
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    • "Furthermore, these T cells could produce IL-17A (Figure 1D), a cytokine that previous studies identified as pathogenic in autoimmune uveitis (Chi et al., 2008; Luger et al., 2008; Wang et al., 2012). To directly visualize the activation in vivo, we crossed the R161H mice to Nr4a1 GFP reporter mice, in which intensity of GFP fluorescence reflects the level of Nur77 expression, and hence the strength of antigen receptor signaling (Moran et al., 2011). As early as 17 days of age, and well before clinical onset of disease, GFP signal in freshly explanted intestinal tissue of R161H-Nr4a1 GFP mice was prominent , especially in the ileum, compared to ''polyclonal'' Nr4a1 GFP controls (Figure 1E and Movies S1 and S2) and was similar in intensity to the signal in adult R161H mice (Figure 1F and Movies S3 and S4). "
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    ABSTRACT: Activated retina-specific T cells that have acquired the ability to break through the blood-retinal barrier are thought to be causally involved in autoimmune uveitis, a major cause of human blindness. It is unclear where these autoreactive T cells first become activated, given that their cognate antigens are sequestered within the immune-privileged eye. We demonstrate in a novel mouse model of spontaneous uveitis that activation of retina-specific T cells is dependent on gut commensal microbiota. Retina-specific T cell activation involved signaling through the autoreactive T cell receptor (TCR) in response to non-cognate antigen in the intestine and was independent of the endogenous retinal autoantigen. Our findings not only have implications for the etiology of human uveitis, but also raise the possibility that activation of autoreactive TCRs by commensal microbes might be a more common trigger of autoimmune diseases than is currently appreciated. Copyright © 2015 Elsevier Inc. All rights reserved.
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    • "In T cells, expression of Nr4a receptors is induced by TCR signaling during T cell development in thymus [20] [21] [22]. Regulatory T cells (Treg cells) express high levels of Nr4a receptors, possibly as a result of thymic development and continuous TCR stimulation in the periphery [21] [22] [23] [24] [25]. In mutant mice that lack all Nr4a receptors in T cells, the Treg development is severely impaired [26]. "
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    ABSTRACT: Follicular T helper (Tfh) cells promote germinal center (GC) reaction and high-affinity antibody production. The molecular mechanisms that regulate development and function of Tfh cells are not fully understood. Here we report that ligand-independent nuclear receptors of the Nr4a family are highly expressed in Tfh cells. In a well-established adoptive transfer model, enforced expression of Nr4a receptors reduces helper T cell expansion but apparently increased the T cell capacity to promote the GC response. On the other hand, deletion of all Nr4a receptors in T cells did not significantly affect expansion or differentiation of Tfh cells or the development of GC reaction. These findings suggest that Nr4a receptors may promote but are not necessary for Tfh development or function in vivo. Copyright © 2015. Published by Elsevier B.V.
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