Dynamic changes of BRCA1 subnuclear location and phosphorylation state are initiated by DNA damage.
BRCA1 localizes to discrete nuclear foci (dots) during S phase. Hydroxyurea-mediated DNA synthesis arrest of S phase MCF7 cells led to a loss of BRCA1 from these structures. Ultraviolet light, mitomycin C, or gamma irradiation produced a similar effect but with no concurrent arrest of DNA synthesis. BARD1 and Rad51, two proteins associated with the BRCA1 dots, behaved similarly. Loss of the BRCA1 foci was accompanied by a specific, dose-dependent change(s) in the state of BRCA1 phosphorylation. Three distinct DNA damaging agents preferentially induced this change in S phase. The S phase BRCA1 phosphorylation response to DNA damage occurred in cells lacking, respectively, two DNA damage-sensing protein kinases, DNA-PK and Atm, implying that neither plays a prime role in this process. Finally, after BRCA1 dot dispersal, BRCA1, BARD1, and Rad51 accumulated, focally, on PCNA+ replication structures, implying an interaction of BRCA1/BARD1/Rad51 containing complexes with damaged, replicating DNA. Taken together, the data imply that the BRCA1 S phase foci are dynamic physiological elements, responsive to DNA damage, and that BRCA1-containing multiprotein complexes participate in a replication checkpoint response.
Scully
R
R
The Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
Chen
J
J
Ochs
R L
RL
Keegan
K
K
Hoekstra
M
M
Feunteun
J
J
Livingston
D M
DM
D064007:Ataxia Telangiectasia Mutated Proteins; D019313:BRCA1 Protein / Q000378:metabolism*; D001943:Breast Neoplasms; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism* / Q000648:ultrastructure; D004249:DNA Damage; D004261:DNA Replication / Q000187:drug effects / Q000528:radiation effects; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D005260:Female; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D016350:Leucine Zippers; D018613:Microscopy, Confocal; D009687:Nuclear Proteins; D010766:Phosphorylation; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D016196:S Phase; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D014466:Ultraviolet Rays
D019313:BRCA1 Protein; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen; D011506:Proteins; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D006918:Hydroxyurea