Tuberous sclerosis complex 1 (Tsc1) enforces quiescence of naive T cells to promote immune homeostasis and function. Mus musculus

The mechanisms that regulate T cell quiescence are poorly understood. We report that tuberous sclerosis complex 1 (Tsc1) establishes a quiescent program in naïve T cells by controlling cell size, cell cycle entry, and responses to T cell receptor stimulation. Loss of quiescence predisposed Tsc1-deficient T cells to apoptosis that depleted conventional T cells and invariant natural killer T cells. Loss of Tsc1 function dampened in vivo immune responses to bacterial infection. Tsc1-deficient T cells exhibited increased mTORC1 but diminished mTORC2 activities, with mTORC1 activation essential for the disruption of immune homeostasis. Therefore, Tsc1-dependent control of mTOR is crucial in establishing naïve T cell quiescence to facilitate adaptive immune function. Overall design: Naïve CD4 and CD8 T cells from wild-type and Tsc1-deficient mice (in triplicates each group) were stimulated with or without TCR signaling. RNA was analyzed by microarrays. WT/KO for 0 and 4 hr for CD4 (triplicates), and WT/KO for 0 hr for CD8 (duplicates).