Mitochondrial RNA cytosolic leakage drives the SASP [CRISPR/Cas9]

Senescent cells secrete proinflammatory factors known as the senescence-associated secretory phenotype (SASP), contributing to tissue dysfunction and aging. Mitochondrial dysfunction is a key feature of senescence, influencing SASP via mitochondrial DNA (mtDNA) release and cGAS/STING pathway activation. Here, we demonstrate that mitochondrial RNA (mtRNA) also accumulates in the cytosol of senescent cells, activating RNA sensors RIG-I and MDA5, leading to MAVS aggregation and SASP induction. Inhibition of these RNA sensors significantly reduces SASP factors. Furthermore, BAX and BAK play a key role in mtRNA leakage during senescence, and their deletion diminishes SASP expression in vitro and in a mouse model of Metabolic Dysfunction Associated Steatohepatitis (MASH). These findings highlight mtRNA's role in SASP regulation and its potential as a therapeutic target for mitigating age-related inflammation. Overall design: RNA-seq profiling of proliferating and senescent fibroblasts lacking proteins associated with cytosolic RNA signaling, including DDX58 (RIG-I), IFIH1 (MDA5) and MAVS. Moreover, RNA-seq was also performed in fibroblasts lacking mitochondria, which were subsequently transfected with isolated mitochondrial RNA (mtRNA). Finally, RNA-seq analysis was performed in livers from liver-specific Bax Bak KO animals with diet-induced metabolic dysfunction-associated steatohepatitis (MASH).