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Published on: March 31, 2010

The mismatch DNA repair heterodimer, hMSH2/6, regulates BLM helicase

Qin Yang1, Ran Zhang, Xin W Wang

  • 1Laboratory of Human Carcinogenesis, National Cancer Institute, NIH, Bldg 37, Rm 3068, 37 Convent Drive, Bethesda, MD 20892-4255, USA.

Oncogene
|April 6, 2004
PubMed

Insights

The human mismatch repair complex MSH2/6 aids Bloom

Area of Science:

  • Molecular Biology
  • DNA Repair Mechanisms
  • Genetics

Background:

  • The human MSH2/6 complex is crucial for DNA mismatch repair, correcting replication errors.
  • While mismatch repair proteins are linked to homologous recombination repair, the specific role of hMSH2/6 remains undefined.

Purpose of the Study:

  • To elucidate the function of the human MSH2/6 complex in DNA homologous recombination repair.
  • To investigate the interaction of hMSH2/6 with other DNA repair proteins, including BLM and p53.

Main Methods:

  • In vitro assays using recombinant hMSH2/6 protein complex.
  • Immunofluorescence microscopy to detect protein colocalization in hydroxyurea-induced nuclear foci.
  • Coimmunoprecipitation assays to identify protein-protein interactions.

Main Results:

  • Recombinant hMSH2/6 enhanced the Holliday junction processing activity of BLM in vitro, modulated by p53.
  • hMSH6 colocalized with BLM and phospho-ser15-p53 in RAD51 foci, indicative of DNA double-strand break sites.
  • hMSH2 and hMSH6 coimmunoprecipitated with BLM, p53, and RAD51; these complexes were elevated in MSH2/6-deficient cells.

Conclusions:

  • The hMSH2/6 complex interacts with the BLM-p53-RAD51 complex during the repair of damaged DNA forks.
  • These findings reveal a novel role for the MSH2/6 complex in homologous recombination repair, particularly in response to DNA double-strand breaks.

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