RUNX Poly(ADP-Ribosyl)ation and BLM Interaction Facilitate the Fanconi Anemia Pathway of DNA Repair

Abstract

Summary: 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 DNA repair 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. : Tay et al. demonstrate that the tumor suppressor genes RUNX1 and RUNX3 have an important regulatory role in the genome maintenance pathway controlled by FANCD2. DNA damage induces PARP-dependent PARylation of RUNX proteins, leading to their interaction with BLM to control the loading of FANCD2 on DNA damage sites. Keywords: RUNX1, RUNX3, Fanconi anemia, interstrand crosslink repair, PARP1, poly(ADP-ribosyl)ation, BLM, SILAC, DNA repair, FANCD2