RESUMO
The anti-tumor potency of poly(ADP-ribose) polymerase (PARP) inhibitors (PARPis) has been linked to trapping of PARP1 on damaged chromatin. However, little is known about their impact on PARP2, an isoform with overlapping functions at DNA lesions. Whether the release of PARP1/2 from DNA lesions is actively catalyzed by molecular machines is also not known. We found that PARPis robustly trap PARP2 and that the helicase ALC1 (CHD1L) is strictly required for PARP2 release. Catalytic inactivation of ALC1 quantitatively traps PARP2 but not PARP1. ALC1 manipulation impacts the response to single-strand DNA breaks through PARP2 trapping, potentiates PARPi-induced cancer cell killing, and mediates synthetic lethality upon BRCA deficiency. The chromatin remodeler ALC1 actively drives PARP2 turnover from DNA lesions, and PARP2 contributes to the cellular responses of PARPi. This suggests that disrupting the ATP-fueled remodeling forces of ALC1 might enable therapies that selectively target the DNA repair functions of PARPs in cancer.
Assuntos
Quebras de DNA de Cadeia Simples , DNA Helicases/metabolismo , Proteínas de Ligação a DNA/metabolismo , Neoplasias/enzimologia , Inibidores de Poli(ADP-Ribose) Polimerases/metabolismo , Poli(ADP-Ribose) Polimerases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Linhagem Celular Tumoral , DNA Helicases/genética , Proteínas de Ligação a DNA/genética , Humanos , Neoplasias/genética , Neoplasias/patologia , Poli(ADP-Ribose) Polimerase-1/genética , Poli(ADP-Ribose) Polimerase-1/metabolismo , Poli(ADP-Ribose) Polimerases/genética , Proteínas Proto-Oncogênicas/genéticaRESUMO
ADP-ribosylation is a dynamic post-translation modification that regulates the early phase of various DNA repair pathways by recruiting repair factors to chromatin. ADP-ribosylation levels are defined by the activities of specific transferases and hydrolases. However, except for the transferase PARP1/ARDT1 little is known about regulation of these enzymes. We found that MacroD2, a mono-ADP-ribosylhydrolase, is exported from the nucleus upon DNA damage, and that this nuclear export is induced by ATM activity. We show that the export is dependent on the phosphorylation of two SQ/TQ motifs, suggesting a novel direct interaction between ATM and ADP-ribosylation. Lastly, we show that MacroD2 nuclear export temporally restricts its recruitment to DNA lesions, which may decrease the net ADP-ribosylhydrolase activity at the site of DNA damage. Together, our results identify a novel feedback regulation between two crucial DNA damage-induced signaling pathways: ADP-ribosylation and ATM activation.