Disruption of DNA-PK in Ku80 mutant xrs-6 and the implications in DNA double-strand break repair

Fanqing Chen, Scott R. Peterson, Michael D. Story, David J. Chen

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

The Chinese hamster ovary (CHO) mutant cell line xrs-6C is highly sensitive to radiation and is deficient in DNA double-strand break (DSB) repair. The repair defect of xrs-6C is complemented by the human DSB repair gene designated as XRCC5. This gene was recently identified as Ku80, which encodes the human autoantigen protein Ku p80. Ku80 protein forms heterodimer with the Ku70 subunit to form a complex that possesses a DNA end-binding activity. Ku70/Ku80 heterodimer can recruit the catalytic p350 subunit of the DNA-dependent protein kinase. It is demonstrated here that. while the Ku70 mRNA expression is normal in the xrs-6C mutant, Ku70 protein is undetectable. However, introduction of human Ku80 gene into the mutant lead to increased expression of Ku70 protein and restored Ku70 binding to DNA ends, suggesting that mutation of the Ku80 gene affected the formation of Ku70/Ku80 dimers and the stability of the Ku70 protein. We also demonstrated that, although p350 protein expression in the mutants was unaffected. the capacity of p350 to bind to DNA ends was impaired in the mutants. After introduction of the human Ku80 into the mutant, the association of p350 with DNA end was restored, accompanied by recovery in cell survival and DNA double-strand break repair. The results in this report show that mutation of the Ku80 gene disrupts formation of the Ku70/Ku80 dimer and compromises the ability of Ku protein to recruit the DNA-PK p350 subunit to DNA double-strand breaks, causing a dysfunction of DNA DSB repair in the cell.

Original languageEnglish (US)
Pages (from-to)9-19
Number of pages11
JournalMutation Research - DNA Repair
Volume362
Issue number1
DOIs
StatePublished - Jan 2 1996

Fingerprint

Double-Stranded DNA Breaks
Repair
DNA
Genes
Proteins
DNA-Activated Protein Kinase
Mutation
Protein Stability
Autoantigens
Mutant Proteins
Dimers
Cricetulus
Ovary
Catalytic Domain
Cell Survival
Cells
Radiation
Cell Line
Messenger RNA
Recovery

Keywords

  • DNA double-strand repair
  • DNA-dependent protein kinase
  • Ku autoantigen

ASJC Scopus subject areas

  • Toxicology
  • Genetics
  • Molecular Biology

Cite this

Disruption of DNA-PK in Ku80 mutant xrs-6 and the implications in DNA double-strand break repair. / Chen, Fanqing; Peterson, Scott R.; Story, Michael D.; Chen, David J.

In: Mutation Research - DNA Repair, Vol. 362, No. 1, 02.01.1996, p. 9-19.

Research output: Contribution to journalArticle

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