RAD54L promotes nascent DNA degradation and radial chromosome formation in FANC-deficient cells

Interstrand crosslinks are cytotoxic lesions that inhibit essential processes including replication and transcription. Replication fork reversal occurs in response to interstrand crosslink inducing drug, MMC, but how replication fork reversal promotes repair of interstrand crosslinks is poorly understood. Here, we investigated the role of the RAD54L translocase in interstrand crosslink repair. We found RAD54L is required to promote nascent DNA degradation in FANCD2 and FANCA-depleted cells consistent with a previous study indicating RAD54L promotes replication fork reversal. We further show RAD54L activity is required for formation of radial chromosomes in FANCD2-deficient cells suggesting fork reversal may be required to generate the intermediate undergoing aberrant fusion in FANC-deficient cells. Finally, we demonstrate FANCD2 foci accumulate and DSBs persist in RAD54L-deficient cells indicating RAD54L is required for efficient repair of DSBs. Together, our results indicate RAD54L plays multiple roles in efficient processing and repair of interstrand crosslinks.