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Updated: Apr 19, 2026

Generation of Induced Regulatory T Cells from Primary Human Naïve and Memory T Cells
Published on: April 16, 2012
E3 Ubiquitin Ligase Cbl-b Regulates Thymic-Derived CD4+CD25+ Regulatory T Cell Development by Targeting Foxp3 for
Yixia Zhao1, Hui Guo1, Guilin Qiao2
1Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210;
Abstract:
CD28 costimulation is essential for the development of thymic-derived CD4(+)CD25(+)Foxp3(+) regulatory T cells ("tTregs"). E3 ubiquitin ligase Cbl-b has been shown to regulate CD28 dependence of T cell activation. In this paper, we report that the loss of Cbl-b partially but significantly rescues the defective development of tTregs in Cd28(-/-) mice. This partial rescue is independent of IL-2. Mechanistically, Cbl-b binds to Foxp3 upon TCR stimulation and, together with Stub1, targets Foxp3 for ubiquitination and subsequently degradation in the proteasome. As Cbl-b self-ubiquitination and proteasomal degradation is impaired in Cd28(-/-) T cells, the defective development of tTregs in Cd28(-/-) mice may in part be due to increased Foxp3 ubiquitination and degradation targeted by Stub1 and Cbl-b. Treating Cd28(-/-) mice with a proteasome inhibitor completely rescues defective tTreg development in these mice. Therefore, Cbl-b, together with Stub1, ubiquitinate Foxp3, and regulate tTreg development.
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