Autophagy mediates the mitotic senescence transition

As a stress response, senescence is a dynamic process involving multiple effector mechanisms whose combination determines the phenotypic quality. Here we identify Autophagy as a new effector mechanism of senescence. Autophagy is activated during senescence and its activation is correlated with negative feedback in the PI3K-mammalian target of rapamycin (mTOR) pathway. A subset of autophagy-related genes are up-regulated during senescence: Overexpression of one of those genes, ULK3, induces Autophagy and senescence. Furthermore, inhibition of Autophagy delays the senescence phenotype, including senescence-associated secretion. Our data suggest that Autophagy, and its consequent protein turnover, mediate the acquisition of the senescence phenotype.