title: Recruitment of Oct4 protein to UV-damaged chromatin in embryonic stem cells.
abstract: BACKGROUND
  Oct4 is a specific marker of embryonic stem cell (ESC) pluripotency. However, little is known regarding how Oct4 responds to DNA damage. Here, we investigated whether Oct4 recognizes damaged chromatin in mouse ESCs stably expressing GFP-Oct4. These experiments should contribute to the knowledge of how ESC genomic integrity is maintained, which is crucial for potential application of human ESCs in regenerative medicine.
  
  
  RESULTS
  We used time-lapse confocal microscopy, microirradiation by UV laser (355 nm), induction of DNA lesions by specific agents, and GFP technology to study the Oct4 response to DNA damage. We found that Oct4 accumulates in UV-damaged regions immediately after irradiation in an adenosine triphosphate-dependent manner. Intriguingly, this event was not accompanied by pronounced Nanog and c-MYC recruitment to the UV-damaged sites. The accumulation of Oct4 to UV-damaged chromatin occurred simultaneously with H3K9 deacetylation and H2AX phosphorylation (γH2AX). Moreover, we observed an ESC-specific nuclear distribution of γH2AX after interference to cellular processes, including histone acetylation, transcription, and cell metabolism. Inhibition of histone deacetylases mostly prevented pronounced Oct4 accumulation at UV-irradiated chromatin.
  
  
  CONCLUSIONS
  Our studies demonstrate pluripotency-specific events that accompany DNA damage responses. Here, we discuss how ESCs might respond to DNA damage caused by genotoxic injury that might lead to unwanted genomic instability.
authors.affiliation: Department of Molecular Cytology and Cytometry, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic. bartova@ibp.cz
authors.forename: Eva
authors.initials: E
authors.lastname: Bártová
authors.forename: Gabriela
authors.initials: G
authors.lastname: Šustáčková
authors.forename: Lenka
authors.initials: L
authors.lastname: Stixová
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kozubek
authors.forename: Soňa
authors.initials: S
authors.lastname: Legartová
authors.forename: Veronika
authors.initials: V
authors.lastname: Foltánková
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000166:cytology*; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006657:Histones / Q000737:chemistry; D007700:Kinetics; D051379:Mice; D050814:Octamer Transcription Factor-3 / Q000378:metabolism*; D010766:Phosphorylation; D044968:Regenerative Medicine / Q000379:methods; D014158:Transcription, Genetic; D000071857:Tumor Suppressor p53-Binding Protein 1; D014466:Ultraviolet Rays
chemical_list: D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006657:Histones; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse; C498302:Trp53bp1 protein, mouse; D000071857:Tumor Suppressor p53-Binding Protein 1; D000255:Adenosine Triphosphate