Genetically encoded tool for manipulation of Δ{Psi}m identifies the latter as the driver of integrative stress response induced by ATP Synthase dysfunction

Mitochondrial membrane potential ({Delta}{Psi}m) is one of the key parameters controlling cellular bioenergetics. Investigation of the role of {Delta}{Psi}m in live cells is complicated by a lack of tools for its direct manipulation without off-target effects. Here, we adopted the uncoupling protein UCP1 from brown adipocytes as a genetically encoded tool for direct manipulation of {Delta}{Psi}m. We validated the ability of exogenously expressed UCP1 to induce uncoupled respiration and lower {Delta}{Psi}m in mammalian cells. UCP1 expression lowered {Delta}{Psi}m to the same extent as chemical uncouplers but did not inhibit cell proliferation, suggesting that it manipulates {Delta}{Psi}m without the off-target effects of chemical uncouplers. Using UCP1, we revealed that elevated {Delta}{Psi}m is the driver of the Integrated Stress Response induced by ATP synthase inhibition in mammalian cells.