title: [Analysis of irradiation-induced repair foci in mouse embryonic stem cells].
abstract: Somatic cells in response to DNA damage activate two important protective mechanisms: G1 checkpoint control and a program for recognizing and repairing DNA defects (DDR signaling). Both mechanisms are triggered by the activation of common sensor kinases ATM and ATR, which in turn phosphorylate downstream targets. Mouse embryonic stem cells (mESCs) lack of G1 checkpoint and undergo only temporary G2 delay after DNA damage. We have analyzed the ability of mESCs to detect DNA damage and to form repair foci after irradiation. We showed irradiation-induced activation of ATM and ATR is followed by formation of γH2AX foci co-localized with DNA repair proteins Rad51, DNA-PK and adapter protein 53BP1. Furthermore, we checked contribution of ATM/Chk2 and ATR/Chk1 cascades to cell cycle control and viability of mESCs after DNA damage. Inhibition of ATR/Chk1 cascade leads to accumulation of G1 phase cells, whereas perturbation of ATM/Chk2 activity causes no such effect. Moreover, inhibition of ATR/Chk1 activity, but not ATM/Chk2, substantially augments the killing effect of ionizing radiation on mESCs. In summary, our results indicate that mESCs are capable of recognizing DNA damage and forming repair foci, but their DDR signaling it seems to be distinct from somatic cells and tightly connected with maintaining of pluripotency and self-renewal.
authors.forename: I I
authors.initials: II
authors.lastname: Suvorova
authors.forename: V A
authors.initials: VA
authors.lastname: Pospelov
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics / Q000528:radiation effects*; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D059565:G2 Phase Cell Cycle Checkpoints / Q000528:radiation effects*; D005720:Gamma Rays; D005786:Gene Expression Regulation; D006657:Histones / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006657:Histones; D009687:Nuclear Proteins; C498302:Trp53bp1 protein, mouse; D000071857:Tumor Suppressor p53-Binding Protein 1; C475961:gamma-H2AX protein, mouse; C576897:Atr protein, mouse; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D051747:DNA-Activated Protein Kinase; C497264:Prkdc protein, mouse; D051135:Rad51 Recombinase; C495154:Rad51 protein, mouse