Metformin inhibits nuclear egress of chromatin fragments in senescence and aging

Chronic inflammation promotes aging and age-associated diseases. While metabolic interventions can modulate inflammation, how metabolism and inflammation are connected remains unclear. Cytoplasmic chromatin fragments (CCFs) drive chronic inflammation through the cGAS-STING pathway in senescence and aging. However, CCFs are larger than nuclear pores, and how they translocate from the nucleus to the cytoplasm remains uncharacterized. Here we report that chromatin fragments exit the nucleus via nuclear egress, a membrane trafficking process that shuttles large complexes across the nuclear envelope. Inactivating critical nuclear egress proteins, the ESCRT-III or Torsin complex, traps chromatin fragments at the nuclear membrane and suppresses cGAS-STING activation and senescence-associated inflammation. Glucose limitation or metformin inhibits CCF formation through AMPK-dependent phosphorylation and autophagic degradation of ALIX, an ESCRT-III component. In aged mice, metformin reduces ALIX, CCFs, and cGAS-mediated inflammation in the intestine. Our study identifies a mechanism linking metabolism and inflammation and suggests targeting the nuclear egress of chromatin fragments as a strategy to suppress age-associated inflammation.