| Summary: | DEPTOR is an evolutionarily conserved cell-intrinsic binding partner of mTOR that functions as a negative regulator of signaling responses. In this study, we show that DEPTOR is expressed within CD4 + T cells, and we observed that its relative level of expression modulates differentiation as well as glucose utilization within CD4 + T effectors in vitro. Using knock-in mice, we also find that induced expression of DEPTOR within CD4 + T regulatory cells stabilizes Foxp3 expression, shifts metabolism toward oxidative phosphorylation, and increases survival and suppressive function. In vivo, fully MHC mismatched cardiac allograft survival is significantly prolonged in knock-in recipients and sustained recipient expression of DEPTOR in combination with costimulatory blockade induces long-term graft survival. Furthermore, we show that the induced expression of DEPTOR in CD4 + T effectors fails to inhibit acute allograft rejection. Rather, prolonged survival is dominantly mediated via induced expression and function of DEPTOR within recipient CD4 + T regulatory cells. These collective findings identify DEPTOR as a novel protein that functions in CD4 + T cells to augment immunoregulation in vitro and in vivo.
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