The Deubiquitinating Enzyme Ubiquitin-Specific Peptidase 11 Potentiates TGF-β Signaling in CD4+ T Cells to Facilitate Foxp3+ Regulatory T and TH17 Cell Differentiation.

Abstract

Foxp3+ regulatory T (TREG) cells are central mediators in the control of peripheral immune responses. Genome-wide transcriptional profiles show canonical signatures for Foxp3+ TREG cells, distinguishing them from Foxp3- effector T (TEFF) cells. We previously uncovered distinct mRNA translational signatures differentiating CD4+ TEFF and TREG cells through parallel measurements of cytosolic (global) and polysome-associated (translationally enhanced) mRNA levels in both subsets. We show that the mRNA encoding for the ubiquitin-specific peptidase 11 (USP11), a known modulator of TGF-β signaling, was preferentially translated in TCR-activated TREG cells compared with conventional, murine CD4+ T cells. TGF-β is a key cytokine driving the induction and maintenance of Foxp3 expression in T cells. We hypothesized that differential translation of USP11 mRNA endows TREG cells with an advantage to respond to TGF-β signals. In an in vivo mouse model promoting TREG cells plasticity, we found that USP11 protein was expressed at elevated levels in stable TREG cells, whereas ectopic USP11 expression enhanced the suppressive capacity and lineage commitment of these cells in vitro and in vivo. USP11 overexpression in TEFF cells enhanced the activation of the TGF-β pathway and promoted TREG or TH17, but not Th1, cell differentiation in vitro and in vivo, an effect abrogated by USP11 gene silencing or the inhibition of enzymatic activity. Thus, USP11 potentiates TGF-β signaling in both TREG and TEFF cells, in turn driving increased suppressive function and lineage commitment in thymic-derived TREG cells and potentiating the TGF-β-dependent differentiation of TEFF cells to peripherally induced TREG and TH17 cells.