PARP-1 Activation Directs FUS to DNA Damage Sites to Form PARG-Reversible Compartments Enriched in Damaged DNA

Abstract

Summary: PARP-1 synthesizes long poly(ADP-ribose) chains (PAR) at DNA damage sites to recruit DNA repair factors. Among proteins relocated on damaged DNA, the RNA-binding protein FUS is one of the most abundant, raising the issue about its involvement in DNA repair. Here, we reconstituted the PARP-1/PAR/DNA system in vitro and analyzed at the single-molecule level the role of FUS. We demonstrate successively the dissociation of FUS from mRNA, its recruitment at DNA damage sites through its binding to PAR, and the assembly of damaged DNA-rich compartments. PARG, an enzyme family that hydrolyzes PAR, is sufficient to dissociate damaged DNA-rich compartments in vitro and initiates the nucleocytoplasmic shuttling of FUS in cells. We anticipate that, consistent with previous models, FUS facilitates DNA repair through the transient compartmentalization of DNA damage sites. The nucleocytoplasmic shuttling of FUS after the PARG-mediated compartment dissociation may participate in the formation of cytoplasmic FUS aggregates. : Using a single-molecule approach, Singatulina et al. reconstitute the DNA repair system leading to the specific recruitment of FUS, an mRNA-binding protein related to liquid-liquid phase separation biology, to DNA damage sites, thus revealing the capacity of FUS to form dynamic compartments in which damaged DNA is concentrated. Keywords: poly(ADP-ribose) polymerase 1, poly(ADP-ribose), RNA-binding proteins, liquid-liquid phase separation, DNA repair, atomic force microscopy, cancer, neurodegenerative disease