BRCA1-BARD1 complexes are required for p53Ser-15 phosphorylation and a G1/S arrest following ionizing radiation-induced DNA damage

J Biol Chem. 2004 Jul 23;279(30):31251-8. doi: 10.1074/jbc.M405372200. Epub 2004 May 24.


BRCA1 is a major player in the DNA damage response. This is evident from its loss, which causes cells to become sensitive to a wide variety of DNA damaging agents. The major BRCA1 binding partner, BARD1, is also implicated in the DNA damage response, and recent reports indicate that BRCA1 and BARD1 co-operate in this pathway. In this report, we utilized small interfering RNA to deplete BRCA1 and BARD1 to demonstrate that the BRCA1-BARD1 complex is required for ATM/ATR (ataxia-telangiectasia-mutated/ATM and Rad3-related)-mediated phosphorylation of p53(Ser-15) following IR- and UV radiation-induced DNA damage. In contrast, phosphorylation of a number of other ATM/ATR targets including H2AX, Chk2, Chk1, and c-jun does not depend on the presence of BRCA1-BARD1 complexes. Moreover, prior ATM/ATR-dependent phosphorylation of BRCA1 at Ser-1423 or Ser-1524 regulates the ability of ATM/ATR to phosphorylate p53(Ser-15) efficiently. Phosphorylation of p53(Ser-15) is necessary for an IR-induced G(1)/S arrest via transcriptional induction of the cyclin-dependent kinase inhibitor p21. Consistent with these data, repressing p53(Ser-15) phosphorylation by BRCA1-BARD1 depletion compromises p21 induction and the G(1)/S checkpoint arrest in response to IR but not UV radia-tion. These findings suggest that BRCA1-BARD1 complexes act as an adaptor to mediate ATM/ATR-directed phosphorylation of p53, influencing G(1)/S cell cycle progression after DNA damage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ataxia Telangiectasia Mutated Proteins
  • BRCA1 Protein / chemistry*
  • BRCA1 Protein / genetics
  • BRCA1 Protein / metabolism*
  • Base Sequence
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Line
  • DNA Damage*
  • DNA Primers / genetics
  • DNA-Binding Proteins
  • Dimerization
  • G1 Phase
  • HeLa Cells
  • Humans
  • Macromolecular Substances
  • Models, Biological
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • RNA, Small Interfering / genetics
  • S Phase
  • Serine / chemistry
  • Tumor Suppressor Protein p53 / chemistry*
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • Tumor Suppressor Proteins / chemistry*
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*
  • Ubiquitin-Protein Ligases / chemistry*
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*


  • BRCA1 Protein
  • Cell Cycle Proteins
  • DNA Primers
  • DNA-Binding Proteins
  • Macromolecular Substances
  • RNA, Small Interfering
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins
  • Serine
  • BARD1 protein, human
  • Ubiquitin-Protein Ligases
  • ATM protein, human
  • ATR protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Protein-Serine-Threonine Kinases