PKA-Mediated Phosphorylation of ATR Promotes Recruitment of XPA to UV-Induced DNA Damage

• ATR is phosphorylated by PKA on Ser435 and recruits XPA to UV-induced DNA damage
• PKA phosphorylation of ATR enhances DNA repair and decreases mutagenesis
• PKA phosphorylation of ATR does not impact ATR-Chk1 signaling or cell-cycle arrest
• cAMP stimulation rescues defective NER associated with MC1R mutations

SummaryThe melanocortin 1 receptor (MC1R), which signals through cAMP, is a melanocytic transmembrane receptor involved in pigmentation, adaptive tanning, and melanoma resistance. We report MC1R-mediated or pharmacologically-induced cAMP signaling promotes nucleotide excision repair (NER) in a cAMP-dependent protein kinase A (PKA)-dependent manner. PKA directly phosphorylates ataxia telangiectasia and Rad3-related protein (ATR) at Ser435, which actively recruits the key NER protein xeroderma pigmentosum complementation group A (XPA) to sites of nuclear UV photodamage, accelerating clearance of UV-induced photolesions and reducing mutagenesis. Loss of Ser435 within ATR prevents PKA-mediated ATR phosphorylation, disrupts ATR-XPA binding, delays recruitment of XPA to UV-damaged DNA, and elevates UV-induced mutagenesis. This study mechanistically links cAMP-PKA signaling to NER and illustrates potential benefits of cAMP pharmacological rescue to reduce UV mutagenesis in MC1R-defective, melanoma-susceptible individuals.

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