Reversible ALKBH5 cytosolic aggregation accelerates cellular senescence.

Cellular senescence is the major hallmark and therapeutic target of aging and age-related diseases. The role of ALKBH5, one of the main m6A demethylases, in cellular senescence emerges however remains contentious. Herein, we show the reversible ALKBH5 aggregation in cytoplasm promotes cellular senescence. Mechanically, ALKBH5 aggregation causes cytosolic retention, resulting in the m6A dysregulation and m6A hypermethylation of Cdk2, which promotes Cdk2 RNA instability to drive senescence. In addition, m6A imbalance aggravates ALKBH5 cytosolic aggregation in a feedback loop. We further demonstrate that ALKBH5 nuclear translocation required the formation of ALKBH5 droplet phase via binding Nucleoporin p62 (Nup62), while the aggregation of ALKBH5 traps with Nup62 in the cytoplasm. Reduced Nup62 prevents ALKBH5 nuclear entry leading to cellular senescence. Importantly, administration of m6A labeled RNA efficiently reverses ALKBH5 cytosolic aggregates and restores its nuclear entry to alleviate cellular senescence. Forced nuclear entry by NLS-ALKBH5 can prevent senescence in vitro and in vivo. Taken together, these findings unravel a novel paradigm for m6A epigenetic regulation in cellular senescence and offer promising therapeutic targets and strategies for the intervention of aging and age-associated diseases.