Attenuation of the formation of DNA-repair foci containing RAD51 in Fanconi anaemia.
The role of the Fanconi anaemia genes in DNA repair was examined by a quantitative analysis of nuclear DNA repair foci in FA primary fibroblasts after ionising irradiation using antibodies directed against RAD51, MRE11 and BRCA1 for visualisation. IR induced foci detected with anti-RAD51, but not those detected with anti-MRE11, are reduced in fibroblasts of all eight FA complementation groups in comparison to control cells. Correction of FA-A, FA-C and FA-G cells by retroviral cDNA transfer specifically corrected the RAD51-foci response but did not affect formation of foci containing BRCA1 or MRE11. Since all FA cells, except FA-D1, lack the monoubiquitinated FANCD2-L protein, this isoform is likely to be involved in the formation of nuclear foci containing RAD51 in diploid FA cells. FA-D1 cells show the same attenuation in RAD51 foci formation, suggesting that the unknown FANCD1 protein is similarly involved in RAD51 foci formation, either independently or as a subsequent step in the FANCD2 pathway. These findings indicate that Fanconi anaemia cells have an impairment in the RAD51-dependent homologous recombination pathway for DNA repair, explaining their chromosomal instability and extreme sensitivity to DNA cross-linking agents.
Institut für Humangenetik, Charité-Campus Virchow-Klinikum, Humboldt Universität zu Berlin, Augustenburger Platz 1, 13353 Berlin, Germany. martin.digweed@charite.de
Martin
M
Digweed
Susanne
S
Rothe
Ilja
I
Demuth
Regina
R
Scholz
Detlev
D
Schindler
Markus
M
Stumm
Markus
M
Grompe
Andreas
A
Jordan
Karl
K
Sperling
D019313:BRCA1 Protein / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured / Q000528:radiation effects; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005199:Fanconi Anemia / Q000235:genetics* / Q000378:metabolism*; D005347:Fibroblasts / Q000528:radiation effects; D005455:Fluorescent Antibody Technique; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D000076228:MRE11 Homologue Protein; D051135:Rad51 Recombinase; D012190:Retroviridae; D014162:Transfection; D014965:X-Rays
D019313:BRCA1 Protein; D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; C121766:MRE11 protein, human; D049452:Green Fluorescent Proteins; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000076228:MRE11 Homologue Protein