DNA damage response signaling to mitochondria drives senescence

Cellular senescence is a stress-induced permanent cell cycle arrest typically accompanied by expression of the cyclin-dependent kinase inhibitor p16. Recent studies have suggested that p16-expressing senescent cells accumulate in the body with age and play a causative role in aging. Various stresses, such as telomere shortening and oncogene activation, induce cellular senescence by generating DNA damage. However, how DNA damage leads to p16 expression is incompletely understood. We identified BNIP3 in a genome-wide siRNA screen for genes involved in p16 expression upon DNA damage. Mass spectrometric analysis of BNIP3-binding proteins yielded the DDR kinase ATM and components of the mitochondrial contact site and cristae organizing system (MICOS) complex. We found that BNIP3 increases the number of mitochondrial cristae upon DNA damage by electron microscopy. Metabolomic analysis linked BNIP3 to altered acetyl-CoA metabolism during DNA damage-induced senescence. We found that BNIP3 facilitates the oxidation of fatty acids to acetyl-CoA, an acetyl group donor, and promotes histone acetylation around the p16 gene and associated p16 expression. Our findings suggest that DDR signaling to mitochondria via BNIP3 promotes p16 expression through fatty acid oxidation and histone acetylation.