Tay LS1, Krishnan V2, Sankar H1, Chong YL1, Chuang LSH1, Tan TZ1, Kolinjivadi AM1, Kappei D1, Ito Y3.
1Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore.
2Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore.
3Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore.
The Fanconi anemia (FA) pathway is a pivotal genome maintenance network that orchestrates the repair of DNA interstrand crosslinks (ICLs). The tumor suppressors RUNX1 and RUNX3 were shown to regulate the FA pathway independent of their canonical transcription activities, by controlling the DNA damage-dependent chromatin association of FANCD2. Here, in further biochemical characterization, we demonstrate that RUNX3 is modified by PARP-dependent poly(ADP-ribosyl)ation (PARylation), which in turn allows RUNX binding to DNArepair structures lacking transcription-related RUNX consensus motifs. SILAC-based mass spectrometric analysis revealed significant association of RUNX3 with core DNA repair complexes, including PARP1, even in unstressed cells. After DNA damage, the increased interaction between RUNX3 and BLM facilitates efficient FANCD2 chromatin localization. RUNX-Walker motif mutations from breast cancers are impaired for DNA damage-inducible PARylation, unveiling a potential mechanism for FA pathway inactivation in cancers. Our results reinforce the emerging paradigm that RUNX proteins are tumor suppressors with genome gatekeeper function.
BLM; DNA repair; FANCD2; Fanconi anemia; PARP1; RUNX1; RUNX3; SILAC; interstrand crosslink repair; poly(ADP-ribosyl)ation