Thymic atrophy impaired negative selection signal Nur77 in CD4^SP thymocytes.

<p>Panels A and B: results from directly stained young and naturally aged thymocytes. <b>(A)</b> Flow cytometric gate strategy shows CD4^SP gate. <b>(B)</b> Left panel shows Nur77 in CD4^SP population; right panel is summarized RQ-MFI results of Nur77 levels in CD4^SP thymocytes of WT young and naturally aged mice. Panels C–E: results from grafted FF- and FC-mOVA thymi, which were grafted under the kidney capsule of OT-II⁺ TCR-Tg mice with <i>Rag</i>^−/− background (OT-II⁺/<i>Rag</i>^−/−). <b>(C)</b> Image of grafted mOVA-Tg thymi under the kidney capsule of OT-II⁺/<i>Rag</i>^−/− mice, treated with TM x3. <b>(D)</b> A representative flow cytometric gate strategy shows Vα2⁺Vβ5⁺ thymocytes in CD4^SP population (these thymocytes were derived from OT-II⁺/<i>Rag</i>^−/− host mouse bone marrow progenitors) in the grafted FF- and FC-mOVA-Tg thymi. <b>(E)</b> Left panel: a representative histogram of Nur77 in the gates of CD4^SP and Vα2⁺Vβ5⁺ (primarily derived from OT-II⁺/<i>Rag</i>^−/− progenitors) thymocytes in the grafted FF- and FC-mOVA-Tg thymi; right panel: summarized results of RQ-MFI of Nur77 levels from the left panel. In panels B and E, a Student <i>t</i> test was used to determine statistical significance between groups, and all data are expressed as mean ± SEM. Each symbol represents an individual animal sample. Underlying data used in the generation of this figure (panels B and E) can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2003352#pbio.2003352.s007" target="_blank">S1 Data</a>. CD, cluster of differentiation; FC, <i>FoxN1</i>^fx/fx/CreER^T; FF, <i>FoxN1</i>^fx/fx without CreER^T for controls; <i>Foxn1</i>, Forkhead box protein N1; <i>FoxN1</i>^fx/fx, <i>loxp</i>-flanked <i>FoxN1</i> gene; mOVA-Tg, membrane-bound ovalbumin transgenic mouse; Nur77, orphan nuclear receptor; OT-II, MHC class-II restricted ovalbumin-specific TCR transgenic mouse; RQ-MFI, relative quantitative Mean Fluorescence Intensity; WT, wild-type.