β-Catenin expression enhances IL-7 receptor signaling in thymocytes during positive selection

Differentiation of CD4⁺CD8⁺ double-positive thymocytes into CD8⁺ single-positive (SP) thymocytes is regulated by TCR and cytokine receptor signals. Previously, we have shown that expression of stabilized β-catenin, the major transcriptional cofactor of T cell factor, results in increase in both CD4SP and CD8SP thymocytes with a preferential effect on CD8SP thymocytes. In this report, using mice expressing stabilized β-catenin and mice with T cell specific deletion of β-catenin, we show that β-catenin expression augments IL-7Rα-chain expression and down-regulates suppressor of cytokine signaling-1 expression in thymocytes undergoing positive selection. Consequently, β-catenin expression augments IL-7R signaling in thymocytes during positive selection and promotes the development of CD8SP thymocytes.