Homeostasis and transitional activation of regulatory T cells require c-Myc

Regulatory T (Treg) cell activation and expansion during neonatal life and in response to inflammation are critical for immunosuppression, yet the mechanisms governing these events are incompletely understood. We report that the oncogene and transcriptional regulator c-Myc (Myc) controls immune homeostasis through regulation of Treg cell accumulation and functional activation. Myc activity is enriched in Treg cells generated during neonatal life and responding to inflammation. Myc-deficient Treg cells show cell-intrinsic defects in overall accumulation and ability to transition to an activated state during early life or acute inflammation. Consequently, loss of Myc in Treg cells results in a rapid, early-onset autoimmune disorder accompanied by uncontrolled effector CD4+ and CD8+ T cell responses. We also provide evidence that Myc regulates mitochondrial oxidative metabolism but is dispensable for fatty acid oxidation (FAO). Indeed, Treg cell-specific deletion of Cox10, which is required for oxidative phosphorylation, but not Cpt1a, the rate-limiting enzyme for FAO, results in impaired Treg cell function and maturation. Thus, Myc coordinates Treg cell accumulation, transitional activation and metabolic programming to orchestrate immune homeostasis.

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Saravia J, Zeng H, Dhungana Y, Bastardo Blanco D, Nguyen TM, Chapman NM, Wang Y, Kanneganti A, Liu S, Raynor JL, Vogel P, Neale G, Carmeliet P, Chi H