The mismatch DNA repair heterodimer, hMSH2/6, regulates BLM helicase.
The human MSH2/6 complex is essential for mismatch recognition during the repair of replication errors. Although mismatch repair components have been implicated in DNA homologous recombination repair, the exact function of hMSH2/6 in this pathway is unclear. Here, we show that the recombinant hMSH2/6 protein complex stimulated the ability of the Bloom's syndrome gene product, BLM, to process Holliday junctions in vitro, an activity that could also be regulated by p53. Consistent with these observations, hMSH6 colocalized with BLM and phospho-ser15-p53 in hydroxyurea-induced RAD51 nuclear foci that may correspond to the sites of presumed stalled DNA replication forks and more likely the resultant DNA double-stranded breaks. In addition, we show that hMSH2 and hMSH6 coimmunoprecipitated with BLM, p53, and RAD51. Both the number of RAD51 foci and the amount of the BLM-p53-RAD51 complex are increased in hMSH2- or hMSH6-deficient cells. These data suggest that hMSH2/6 formed a complex with BLM-p53-RAD51 in response to the damaged DNA forks during double-stranded break repair.
Yang
Qin
Q
Laboratory of Human Carcinogenesis, National Cancer Institute, NIH, Bldg 37, Rm 3068, 37 Convent Drive, Bethesda, MD 20892-4255, USA.
Zhang
Ran
R
Wang
Xin W
XW
Linke
Steven P
SP
Sengupta
Sagar
S
Hickson
Ian D
ID
Pedrazzi
Graziella
G
Perrera
Claudia
C
Stagljar
Igor
I
Littman
Susan J
SJ
Modrich
Paul
P
Harris
Curtis C
CC
D000251:Adenosine Triphosphatases / Q000032:analysis / Q000378:metabolism*; D020137:Base Pair Mismatch; D045744:Cell Line, Tumor; D004265:DNA Helicases / Q000032:analysis / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D019281:Dimerization; D005260:Female; D006801:Humans; D051718:MutS Homolog 2 Protein; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D051135:Rad51 Recombinase; D053484:RecQ Helicases; D016159:Tumor Suppressor Protein p53 / Q000032:analysis
D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein; D004265:DNA Helicases; D053484:RecQ Helicases