Abstract
The Fanconi anemia DNA repair pathway is pivotal for the efficient repair of DNA interstrand cross-links. Here, we show that FA-defective (Fancc−) DT40 cells arrest in G2 phase following cross-link damage and trigger apoptosis. Strikingly, cell death was reduced in Fancc− cells by additional deletion of the BRCA1 tumor suppressor, resulting in elevated clonogenic survival. Increased resistance to cross-link damage was not due to loss of toxic BRCA1-mediated homologous recombination but rather through the loss of a G2 checkpoint. This proapoptotic role also required the BRCA1-A complex member ABRAXAS (FAM175A). Finally, we show that BRCA1 promotes G2 arrest and cell death by prolonging phosphorylation of Chk1 on serine 345 after DNA damage to sustain arrest. Our data imply that DNA-induced cross-link death in cells defective in the FA pathway is dependent on the ability of BRCA1 to prolong cell cycle arrest in G2 phase.
Highlights
The Fanconi anemia DNA repair pathway is pivotal for the efficient repair of DNA interstrand cross-links
The Fanconi anemia (FA) repair pathway is dedicated to the repair of replication blocking lesions, such as interstrand DNA cross-links (ICL) and DNA-protein cross-links, which pose a major threat to the maintenance of genomic stability
Brca1Ϫ/Ϫ mutant DT40 were minimally sensitive to treatment with doses of cisplatin up to 2.5 M in a clonogenic survival assay and more resistant than wild-type cells to cisplatin in a MTS assay (Fig. 1A; see Fig. S1 in the supplemental material) [14]
Summary
The Fanconi anemia DNA repair pathway is pivotal for the efficient repair of DNA interstrand cross-links. Increased resistance to cross-link damage was not due to loss of toxic BRCA1-mediated homologous recombination but rather through the loss of a G2 checkpoint. This proapoptotic role required the BRCA1-A complex member ABRAXAS (FAM175A). Our data imply that DNA-induced cross-link death in cells defective in the FA pathway is dependent on the ability of BRCA1 to prolong cell cycle arrest in G2 phase. The Fanconi anemia (FA) repair pathway is dedicated to the repair of replication blocking lesions, such as interstrand DNA cross-links (ICL) and DNA-protein cross-links, which pose a major threat to the maintenance of genomic stability. Failure to repair DNA cross-link damage in cells defective in the FA pathway results in greatly elevated cell death. Bunting et al recently proposed that BRCA1 has another role in the FA pathway, upstream of its function in HR [9], to facilitate retention of FANCD2 at sites of cross-link repair by influencing local chromatin structure [4, 9, 10]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call