Pathogenic ARH3 mutations result in ADP-ribose chromatin scars during DNA strand break repair

Hana Hanzlikova,Richard Hailstone,Joseph G Gleeson,Jan Brazina,Ilona Kalasova,Zuzana Cihlarova,Jan Kubovciak,Ivan Ahel,Jana Sachova,Shereen Ghosh,Keith W Caldecott,Sebahattin Cirak,Evgeniia Prokhorova,Katerina Krejcikova

doi:10.1038/s41467-020-17069-9

Abstract

Neurodegeneration is a common hallmark of individuals with hereditary defects in DNA single-strand break repair; a process regulated by poly(ADP-ribose) metabolism. Recently, mutations in the ARH3 (ADPRHL2) hydrolase that removes ADP-ribose from proteins have been associated with neurodegenerative disease. Here, we show that ARH3-mutated patient cells accumulate mono(ADP-ribose) scars on core histones that are a molecular memory of recently repaired DNA single-strand breaks. We demonstrate that the ADP-ribose chromatin scars result in reduced endogenous levels of important chromatin modifications such as H3K9 acetylation, and that ARH3 patient cells exhibit measurable levels of deregulated transcription. Moreover, we show that the mono(ADP-ribose) scars are lost from the chromatin of ARH3-defective cells in the prolonged presence of PARP inhibition, and concomitantly that chromatin acetylation is restored to normal. Collectively, these data indicate that ARH3 can act as an eraser of ADP-ribose chromatin scars at sites of PARP activity during DNA single-strand break repair.

Highlights

Neurodegeneration is a common hallmark of individuals with hereditary defects in DNA single-strand break repair; a process regulated by poly(ADP-ribose) metabolism
That ARH3 mutations might trigger neurodegeneration by perturbing ADP-ribose metabolism during singlestrand break repair (SSBR) is consistent with reported involvement of this protein in degrading free poly(ADP-ribose) chains produced following H2O2-induced oxidative stress, a major inducer of singlestrand break (SSB), and by the protection against oxidative stress afforded in ARH3−/− cells and mice by poly (ADP-ribose) polymerase (PARP) inhibition[19,20]
Given the overlapping clinical phenotypes of ARH3-mutated and DNA single-strand break repair (SSBR) defective diseases we postulated that ARH3 mutations might result in defects in this DNA repair process

Summary

Introduction

Neurodegeneration is a common hallmark of individuals with hereditary defects in DNA single-strand break repair; a process regulated by poly(ADP-ribose) metabolism. We measured directly the level of poly(ADP-ribose) in nuclear chromatin in control and ARH3 patient cells before and after SSB-induced oxidative stress, using an antibody directed against the polymer.

Results

Conclusion