Mitochondrial dysfunction activates the AMPK signaling and autophagy to promote cell survival

Autophagy is a cellular self-eating process essential for stress response and maintainingtissue homeostasis by lysosomal degradation of unwanted or damaged proteins and organelles.Here, we show that cells with defective mitochondria induce autophagy to promotecell survival through activating the AMPK pathway. Loss of mitochondrial complex III proteincytochrome b activates the AMPK signaling and induced autophagy. Inhibiting mitochondria energeticsby mitochondria-targeted agents activates the AMPK signaling and induced autophagy.Genetic inhibition of AMPK inhibits autophagy induction in cells with defective mitochondria,while genetic inhibition of autophagy has no effect on AMPK activation. Mitochondria dysfunctionhas no effect of DNA repair of UV-induced DNA damage. However, mitochondria dysfunctionsensitizes cells to apoptosis induced by UV radiation. Genetic inhibition of autophagy orAMPK sensitized cells to apoptosis in cells with defective mitochondria. Our results demonstratethat AMPK and autophagy senses mitochondria dysfunction and serves as a mechanismfor survival. Our findings may provide new insights into the interplay between mitochondriafunction and autophagy process in maintaining tissue homeostasis, and suggest that this interactionmay play important roles in diseases such as cancer and neurodegeneration.