Stabilization of stalled DNA replication forks by the BRCA2 breast cancer susceptibility protein.
How dividing mammalian cells overcome blocks to DNA replication by DNA damage, depleted nucleotide pools, or template-bound proteins is unclear. Here, we show that the response to blocked replication requires BRCA2, a suppressor of human breast cancer. By using two-dimensional gel electrophoresis, we demonstrate that Y-shaped DNA junctions at stalled replication forks disappear during genome-wide replication arrest in BRCA2-deficient cells, accompanied by double-strand DNA breakage. But activation of the replication checkpoint kinase Chk2 is unaffected, defining an unexpected function for BRCA2 in stabilizing DNA structures at stalled forks. We propose that in BRCA2 deficiency and related chromosomal instability diseases, the breakdown of replication forks, which arrest or pause during normal cell growth, triggers spontaneous DNA breakage, leading to mutability and cancer predisposition.
Lomonosov
Mikhail
M
University of Cambridge, CR UK Department of Oncology, Hutchison/MRC Research Centre, Cambridge CB2 2XZ, UK.
Anand
Shubha
S
Sangrithi
Mahesh
M
Davies
Rachel
R
Venkitaraman
Ashok R
AR
D000818:Animals; D024682:BRCA2 Protein / Q000502:physiology*; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D002478:Cells, Cultured; D064447:Checkpoint Kinase 2; D004247:DNA / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics / Q000502:physiology*; D004261:DNA Replication; D004198:Disease Susceptibility; D015180:Electrophoresis, Gel, Two-Dimensional; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006918:Hydroxyurea / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D018741:Replication Origin
D024682:BRCA2 Protein; D004791:Enzyme Inhibitors; D004247:DNA; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; C578633:Chek2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D006918:Hydroxyurea