The DNA Repair Component EEPD1 Regulates Actin Polymerization

Endonuclease exonuclease phosphatase domain-containing protein 1 (EEPD1) is a DNase1 superfamily member that has DNA endonuclease activity. It plays a critical role in multiple DNA repair processes such as oxidative damage repair and stressed replication fork repair. Interestingly, EEPD1 is myristoylated and palmitoylated near its amino terminus in response to high levels of cholesterol, and this localizes EEPD1 protein to the inner cell membrane. Surprisingly, we found that EEPD1 promotes cortical branching actin polymerization and proper lamellipodia formation and is necessary for subsequent cell migration. EEPD1's enhancement of actin polymerization partially required its myristoylation and palmitoylation. EEPD1 depletion also resulted in marked abnormalities in nuclear morphology. Loss of EEPD1 resulted in loss of phosphorylation of SRC, RAC1, cortactin, and profilin, which are essential steps in signaling for actin polymerization. Loss of EEPD1 lowered SRC kinase activity, which would harm actin polymerization. In summary, EEPD1 is a novel, positive regulator of the signaling pathway for actin polymerization, linking actin regulation to nuclear morphology and DNA repair.