Exosomes are key regulators of non-cell autonomous communication in senescence

SUMMARY Senescence is a cellular phenotype characterized by an irreversible cell cycle arrest and the secretion of inflammatory proteins, denominated senescence-associated secretory phenotype (SASP). The SASP is important in influencing the behavior of neighboring cells and altering the microenvironment; yet, until now this role has been mainly attributed to soluble factors. Here, we report that extracellular vesicles also alter the environment by transmitting the senescent phenotype to other cells via exosomes (extracellular vesicles of endocytic origin). A combination of functional assays, Cre-/oxP reporter systems, proteomic analysis and RNAi screens confirm that exosomes form part of the senescent secretome and mediate paracrine senescence via the activation of a non-canonical interferon (IFN) pathway. Altogether, we speculate that exosomes could be drivers of tissue degeneration both locally and systemically during aging and age- related disease.