Figure 5.

The IL-7Rα Extracellular Domain Suffices to Dampen IL-2 Signaling in Foxp3⁺ Treg Cells

(A) Number of LN T cells in IL-7Rα^311Tg/KO mice. Bar graph shows the total LN T cell numbers (mean ± SEM) from 2 WT, 5 IL-7Rα^KO, and 8 IL-7Rα^311Tg/KO mice. Unpaired two-tailed Student's t test, where ∗∗∗p < 0.001.

(B) Truncated IL-7Rα³¹¹ protein fails to transduce IL-7 signaling. IL-7Rα^311Tg/KO mice express only a truncated form of IL-7Rα protein, which lacks the 148 distal amino acids of the intracellular membrane domain (total 195 amino acids). WT or IL-7Rα^311Tg/KO LN cells were stimulated with IL-7 (0.1 ng/mL) and assessed for pSTAT5 contents. Results are representative of three independent experiments.

(C) IL-7Rα³¹¹ overexpression does not affect the IL-7 signaling of Foxp3⁺CD25⁺ Treg cells. Surface IL-7Rα expression (left) and IL-7-induced STAT5 phosphorylation (right) were assessed in Foxp3⁺CD25⁺ Treg cells from WT and IL-7Rα^311Tg mice. Results are representative of three independent experiments.

(D) Truncated IL-7Rα³¹¹ suppresses IL-2 signaling in trans in Foxp3⁺ Treg cells. WT or IL-7Rα^311Tg LN cells were stimulated with increasing concentrations of IL-2. pSTAT5 induction was determined in Foxp3⁺CD25⁺ CD4⁺ T cells. Results are shown as the fold increase over medium (mean ± SEM), and they are based on three independent experiments each with two mice.

Statistical significance was determined by two-way ANOVA, where ∗∗∗p < 0.001. See also Figure S6.