ROS-activated ATM-dependent phospho-signaling

ATM (ataxia-telangiectasia mutated) protein plays a central role in phosphorylating a network of proteins in response to DNA double strand breaks. These phosphorylated proteins function in signalling pathways designed to maintain the stability of the genome and minimize the risk of disease by controlling cell cycle checkpoints, initiating DNA repair and regulating gene expression. We employed a modified TiSH global quantitative phosphoproteomics approach to identify cytoplasmic proteins altered in their phosphorylation state in control and A-T cells in response to oxidative damage. We demonstrated that ATM was activated by oxidative damage in the cytoplasm as well as in the nucleus and identified a total of 9,612 phosphorylation sites including 6,650 high confidence sites mapping to 2,536 unique proteins.