mTORC1 Directs TNF-Induced Life-or-Death Decisions via Complex I Destabilization

The transition from tumor necrosis factor α (TNF)-induced plasma membrane-bound complex I to cytosolic death-inducing complex II switches cells from survival to death. However, the precise regulation of this fatal decision is incompletely understood. Here, we show that mTORC1 promotes this transition by destabilizing later-stage complex I without affecting its initial assembly. Inhibition of mTORC1 unleashes ATG9A and FIP200 activity, thereby promoting the accumulation of CHUK (IKKα) in complex I. CHUK scaffolds the kinase-active IKKβ to stabilize complex I and prevent complex II formation. Activation of this ATG9A/FIP200–CHUK/IKKβ axis protects against TNF-induced fulminant hepatitis while compromises antibacterial defense against Staphylococcus aureus . This mTORC1-governed life-or-death transition provides therapeutic insight into TNF-related pathologies—including cancer, metabolic tissue injury, and microbial infections—where mTORC1 activity is frequently suppressed.