title: Activation of the prereplication complex is blocked by mimosine through reactive oxygen species-activated ataxia telangiectasia mutated (ATM) protein without DNA damage.
abstract: Mimosine is an effective cell synchronization reagent used for arresting cells in late G1 phase. However, the mechanism underlying mimosine-induced G1 cell cycle arrest remains unclear. Using highly synchronous cell populations, we show here that mimosine blocks S phase entry through ATM activation. HeLa S3 cells are exposed to thymidine for 15 h, released for 9 h by washing out the thymidine, and subsequently treated with 1 mM mimosine for a further 15 h (thymidine → mimosine). In contrast to thymidine-induced S phase arrest, mimosine treatment synchronizes >90% of cells at the G1-S phase boundary by inhibiting the transition of the prereplication complex to the preinitiation complex. Mimosine treatment activates ataxia telangiectasia mutated (ATM)/ataxia telangiectasia and Rad3-related (ATR)-mediated checkpoint signaling without inducing DNA damage. Inhibition of ATM activity is found to induce mimosine-arrested cells to enter S phase. In addition, ATM activation by mimosine treatment is mediated by reactive oxygen species (ROS). These results suggest that, upon mimosine treatment, ATM blocks S phase entry in response to ROS, which prevents replication fork stalling-induced DNA damage.
authors.affiliation: From the Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Kubota
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Fukumoto
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ishibashi
authors.forename: Shuhei
authors.initials: S
authors.lastname: Soeda
authors.forename: Sho
authors.initials: S
authors.lastname: Kubota
authors.forename: Ryuzaburo
authors.initials: R
authors.lastname: Yuki
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakayama
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Aoyama
authors.forename: Noritaka
authors.initials: N
authors.lastname: Yamaguchi
authors.forename: Naoto
authors.initials: N
authors.lastname: Yamaguchi
mesh_terms: D054369:Agouti-Related Protein / Q000235:genetics / Q000378:metabolism; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism*; D019556:COS Cells; D002522:Chlorocebus aethiops; D004249:DNA Damage; D016193:G1 Phase / Q000187:drug effects* / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008898:Mimosine / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016196:S Phase / Q000187:drug effects* / Q000235:genetics
chemical_list: C515198:AGRP protein, human; D054369:Agouti-Related Protein; D017382:Reactive Oxygen Species; D008898:Mimosine; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins
keywords: Cell Cycle; Checkpoint Control; DNA Damage Response; DNA Replication; Oxidative Stress