Nuclear export of R-loop by the DDX1 and XPO1 complex promotes senescence-associated secretory phenotype and inflammaging.

Abstract

Cellular senescence contributes to inflammaging in part through the senescence-associated secretory phenotype (SASP). R-loops, three-stranded nucleic acid structures, contribute to innate immune response in cancers; however, the role of R-loops in senescence and inflammaging remains largely unknown. Here we show that nuclear-derived cytoplasmic R-loops promote the SASP and inflammaging. We detect an accumulation of nuclear-derived R-loops in the cytoplasm of senescent cells with an enrichment in alpha-satellite repeats. These cytoplasmic R-loops localize into cytoplasmic chromatin fragments (CCFs) and activate the cGAS-STING innate immune pathway to drive the SASP. We identify the exportin-1 (XPO1)-DEAD-Box helicase 1 (DDX1) complex as essential for the nuclear export of R-loops and their subsequent localization into CCFs. Inhibition of XPO1 with KPT-330 suppresses nuclear R-loop export and its localization into CCFs, attenuates the SASP, mitigates age-associated inflammation and extends healthspan. These findings reveal nuclear export of R-loops as a potential target for suppressing age-associated inflammation.