Unrestrained poly-ADP-ribosylation provides insights into chromatin regulation and human disease

• Published in: Molecular cell Vol. 81; no. 12; pp. 2640 - 2655.e8
• Main Authors: Prokhorova, Evgeniia, Agnew, Thomas, Wondisford, Anne R., Tellier, Michael, Kaminski, Nicole, Beijer, Danique, Holder, James, Groslambert, Josephine, Suskiewicz, Marcin J., Zhu, Kang, Reber, Julia M., Krassnig, Sarah C., Palazzo, Luca, Murphy, Shona, Nielsen, Michael L., Mangerich, Aswin, Ahel, Dragana, Baets, Jonathan, O’Sullivan, Roderick J., Ahel, Ivan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 17.06.2021; Cell Press
• Subjects: Adenosine Diphosphate Ribose - metabolism; ADP-Ribosylation; ARH3/ADPRHL2; BRCA; cancer; cancer therapy; Cell Line, Tumor; Chromatin; DNA; DNA Damage; Fibroblasts - metabolism; Glycoside Hydrolases - genetics; Glycoside Hydrolases - metabolism; Glycoside Hydrolases - physiology; HEK293 Cells; HeLa Cells; histones; human diseases; Humans; hydrolases; mitosis; neurodegeneration; neurodegenerative diseases; PARG; PARP inhibitor; Poly Adenosine Diphosphate Ribose - metabolism; Poly ADP Ribosylation - physiology; Primary Cell Culture; telomere; toxicity; BRCA; PARG; DNA damage; telomere; PARP inhibitor; neurodegeneration; cancer; chromatin; ADP-ribosylation; ARH3/ADPRHL2
• ISSN: 1097-2765; 1097-4164; 1097-4164
• DOI: 10.1016/j.molcel.2021.04.028

ARH3/ADPRHL2 and PARG are the primary enzymes reversing ADP-ribosylation in vertebrates, yet their functions in vivo remain unclear. ARH3 is the only hydrolase able to remove serine-linked mono(ADP-ribose) (MAR) but is much less efficient than PARG against poly(ADP-ribose) (PAR) chains in vitro. Here, by using ARH3-deficient cells, we demonstrate that endogenous MARylation persists on chromatin throughout the cell cycle, including mitosis, and is surprisingly well tolerated. Conversely, persistent PARylation is highly toxic and has distinct physiological effects, in particular on active transcription histone marks such as H3K9ac and H3K27ac. Furthermore, we reveal a synthetic lethal interaction between ARH3 and PARG and identify loss of ARH3 as a mechanism of PARP inhibitor resistance, both of which can be exploited in cancer therapy. Finally, we extend our findings to neurodegeneration, suggesting that patients with inherited ARH3 deficiency suffer from stress-induced pathogenic increase in PARylation that can be mitigated by PARP inhibition. [Display omitted] •Chromatin serine-linked MARylation is constantly produced throughout the cell cycle•ADP-ribosylation reactions consist of distinct initiation and elongation steps•PARG and ARH3 suppression is synthetically lethal because of accumulation of PARylation•ARH3 deficiency increases PARPi resistance that can be exploited therapeutically Prokhorova et al. show that accumulation of PARylation, but not MARylation, is highly toxic to the cell, perturbing DNA synthesis, chromatin organization, and transcription and eventually leading to PARP-dependent cell death. This underlies the synthetic lethality between PARG and ARH3 in cancers and the development of neurodegeneration in ARH3/ADPRHL2-deficient patients.