Sch9S6K controls DNA repair and DNA damage response efficiency in aging cells. Lucca et al.

Abstract
Survival from UV-induced DNA lesions relies on nucleotide excision repair (NER) and the Mec1ATR DNA damage response (DDR). We study DDR and NER in aging cells and find that old cells struggle to repair DNA and
activate Mec1ATR. We employ pharmacological and genetic approaches to rescue DDR and NER during aging. Conditions activating Snf1AMPK rescue DDR functionality, but not NER, while inhibition of the TORC1-
Sch9S6K axis restores NER and enhances DDR by tuning PP2A activity, specifically in aging cells. Age-related
repair deficiency depends on Snf1AMPK-mediated phosphorylation of Sch9S6K on Ser160 and Ser163. PP2A
activity in old cells is detrimental for DDR and influences NER by modulating Snf1AMPK and Sch9S6K. Hence,
the DDR and repair pathways in aging cells are influenced by the metabolic tuning of opposing AMPK and
TORC1 networks and by PP2A activity. Specific Sch9S6K phospho-isoforms control DDR and NER efficiency,
specifically during aging.