title: Inhibition of ERK activation enhances the repair of double-stranded breaks via non-homologous end joining by increasing DNA-PKcs activation.
abstract: Non-homologous end joining (NHEJ) is one of the major pathways that repairs double-stranded DNA breaks (DSBs). Activation of DNA-PK is required for NHEJ. However, the mechanism leading to DNA-PKcs activation remains incompletely understood. We provide evidence here that the MEK-ERK pathway plays a role in DNA-PKcs-mediated NHEJ. In comparison to the vehicle control (DMSO), etoposide (ETOP)-induced DSBs in MCF7 cells were more rapidly repaired in the presence of U0126, a specific MEK inhibitor, based on the reduction of γH2AX and tail moments. Additionally, U0126 increased reactivation of luciferase activity, which resulted from the repair of restriction enzyme-cleaved DSBs. Furthermore, while inhibition of ERK activation using the dominant-negative MEK1K97M accelerated the repair of DSBs, enforcing ERK activation with the constitutively active MEK1Q56P reduced DSB repair. In line with MEK activating ERK1 and ERK2 kinases, knockdown of either ERK1 or ERK2 increased DSB repair. Consistent with the activation of DNA-PKcs being required for NHEJ, we demonstrated that inhibition of ERK activation using U0126, MEK1K97M, and knockdown of ERK1 or ERK2 enhanced ETOP-induced activation of DNA-PKcs. Conversely, enforcing ERK activation by MEK1Q56P reduced ETOP-initiated DNA-PKcs activation. Taken together, we demonstrate that ERK reduces NHEJ-mediated repair of DSBs via attenuation of DNA-PKcs activation.
authors.affiliation: The Genetics Laboratory, Maternity and Child Healthcare Hospital, Shenzhen, Guangdong, People's Republic of China. haowei727499@163.com
authors.forename: Fengxiang
authors.initials: F
authors.lastname: Wei
authors.forename: Judy
authors.initials: J
authors.lastname: Yan
authors.forename: Damu
authors.initials: D
authors.lastname: Tang
authors.forename: Xiaozeng
authors.initials: X
authors.lastname: Lin
authors.forename: Lizhi
authors.initials: L
authors.lastname: He
authors.forename: Yanyun
authors.initials: Y
authors.lastname: Xie
authors.forename: Lijian
authors.initials: L
authors.lastname: Tao
authors.forename: Shaojuan
authors.initials: S
authors.lastname: Wang
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D059766:DNA End-Joining Repair / Q000187:drug effects*; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D004789:Enzyme Activation / Q000187:drug effects; D005047:Etoposide / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000819:agonists* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D005047:Etoposide; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D048049:Extracellular Signal-Regulated MAP Kinases; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3