PP2A licenses the FANCD2/FANCI complex for chromosome loading

The Fanconi anemia (FA) pathway removes interstrand crosslinks (ICLs) between the Watson-Crick strands of the DNA double helix in humans. Central to the pathway is the FANCD2/FANCI complex, which must be loaded onto chromosomes. Here, we report the identification of a PP2A phosphatase complex, which specifically dephosphorylates an inhibitory cluster in FANCD2, thereby licensing its loading in response to DNA damage. We show that PP2A is required for normal monoubiquitination of the FANCD2/FANCI complex and for its loading onto chromosomes. We have fully reconstituted a coupled dephosphorylation-ubiquitination reaction in vitro using a highly purified PP2A complex. Using super-resolution live-cell single-molecule tracking, we show how PP2A switches on the FA pathway in response to ICLs and that cells are sensitive to ICL-forming drugs in the absence of PP2A. Our work uncovers a mechanism where PP2A facilitates the activation of the FA pathway by licensing chromosome loading of the FANCD2/FANCI complex. [Display omitted] •The PP2A protein phosphatase licenses the FANCD2/FANCI complex to be loaded onto chromosomes•PP2A promotes DNA interstrand crosslink repair in humans•Activation of the Fanconi anemia pathway depends on PP2A dephosphorylation of FANCD2•Sensitizing cancer cells by perturbing PP2A could provide clinical therapeutic opportunities Yang et al. demonstrate how the PP2A protein phosphatase complex specifically dephosphorylates FANCD2, thereby licensing the FANCD2/FANCI complex to be loaded onto chromosomes for DNA interstrand crosslink repair. Suppression of PP2A activity deregulates the Fanconi anemia pathway and sensitizes cells to DNA interstrand crosslinks.