The role of Fanconi anemia proteins in DNA replication and repair

Fanconi anemia (FA) is a recessive genetic disorder characterized by hypersensitivity to crosslinking agents. FA proteins bind to DNA and form nuclear foci during DNA replication and in response to DNA damage. In addition, FA proteins interact with a number of DNA repair pathways. When the FA pathway is disrupted, spontaneous and damage-induced DNA breaks accumulate. The involvement of the FA pathway in the maintenance of genomic stability led us to investigate the role of the FA pathway in the maintenance of replication fork stability and the repair of interstrand crosslinks.;FANCD2 and the FA core complex bind to chromatin during DNA replication; however, the role of FA proteins during replication is unknown. Using Xenopus cell-free extracts, we show that FANCL depletion results in defective DNA replication restart following treatment with camptothecin, a drug that results in DSBs during DNA replication. This defect is more pronounced following treatment with Mitomycin C, presumably because of an additional role of the FA pathway in DNA crosslink repair. Moreover, we show that chromatin binding of FA core complex proteins during DNA replication follows origin assembly and origin firing and is dependent on the binding of RPA to ssDNA while FANCD2 additionally requires ATR, consistent with FA proteins acting at replication forks. Together, our data suggest that FA proteins play a role in replication restart at collapsed replication forks.