The Identification And Functional Study Of APE1 Arginine Methylation

Apurinic/apyrimidinic endonuclease 1?APE1?is an essential multifunctional protein in mammals that plays critical roles in DNA base excision repair and redox signaling within the cell.Impaired APE1 function or dysregulation is associated with disease susceptibility and cancer progression and poor prognosis.Orchestrated regulatory mechanisms are crucial to ensure its function in specific subcellular location,at a specific time.This project aimed to identify a new post-translational modification?PTM?adding to APE1 PTM regulation network.It would provide some scientific evidence for targeting APE1 as diagnostic marker and individualized medicine.Here,we report arginine?R?methylation as a novel PTM that regulates APE1activity.Protein arginine methyl-transferase 1?PRMT1?was shown to methylate APE1in vitro.Site-directed mutagenesis identified R301 as the major methylation site.Using a methylation-specific antibody,we confirmed that APE1 is methylated in cells and that the R301K mutation significantly reduces its methylation.Baseline mitochondrial APE1 levels were low under standard culture conditions,but they could be induced by H₂O₂ or menadione?an oxidative injury inducing agent?.Methylation-deficient APE1showed reduced mitochondrial translocation compared to wild-type or methylation-mimic APE1.Methylation affected the interaction of APE1 with Tom20,a translocase in the outer mitochondrial membrane.Methylation-deficient APE1 resulted in increased mitochondrial DNA damage,irregular copy number of mitochondrial DNA,and increased cytochrome c release after stimuli.These data suggest that methylation of APE1 promotes its mitochondrial translocation and protects cells from oxidative damage.This work describes a novel PTM regulation model of APE1 subcellular distribution through arginine methylation,complementing APE1 PTM network.Arginine methylation specific antibody could be designed as a potential adjuvant in individualized therapeutics.