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Nature. 2017 Nov 16;551(7680):389-393. doi: 10.1038/nature24484. Epub 2017 Nov 8.

A ubiquitin-dependent signalling axis specific for ALKBH-mediated DNA dealkylation repair.

Author information

1
Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
2
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
3
Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, NTNU, NO-7491 Trondheim, Norway.
4
PROMEC Core Facility for Proteomics and Metabolomics, NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway.
5
Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA.
6
Adelaide Medical School and Robinson Research Institute, The University of Adelaide, Adelaide, South Australia 5000, Australia.
7
Healthy Mothers and Babies, South Australian Medical Research Institute, Adelaide, South Australia 5000, Australia.
8
Genetics of Learning Disability Service, Hunter Genetics, Waratah, New South Wales 2298, Australia.

Abstract

DNA repair is essential to prevent the cytotoxic or mutagenic effects of various types of DNA lesions, which are sensed by distinct pathways to recruit repair factors specific to the damage type. Although biochemical mechanisms for repairing several forms of genomic insults are well understood, the upstream signalling pathways that trigger repair are established for only certain types of damage, such as double-stranded breaks and interstrand crosslinks. Understanding the upstream signalling events that mediate recognition and repair of DNA alkylation damage is particularly important, since alkylation chemotherapy is one of the most widely used systemic modalities for cancer treatment and because environmental chemicals may trigger DNA alkylation. Here we demonstrate that human cells have a previously unrecognized signalling mechanism for sensing damage induced by alkylation. We find that the alkylation repair complex ASCC (activating signal cointegrator complex) relocalizes to distinct nuclear foci specifically upon exposure of cells to alkylating agents. These foci associate with alkylated nucleotides, and coincide spatially with elongating RNA polymerase II and splicing components. Proper recruitment of the repair complex requires recognition of K63-linked polyubiquitin by the CUE (coupling of ubiquitin conjugation to ER degradation) domain of the subunit ASCC2. Loss of this subunit impedes alkylation adduct repair kinetics and increases sensitivity to alkylating agents, but not other forms of DNA damage. We identify RING finger protein 113A (RNF113A) as the E3 ligase responsible for upstream ubiquitin signalling in the ASCC pathway. Cells from patients with X-linked trichothiodystrophy, which harbour a mutation in RNF113A, are defective in ASCC foci formation and are hypersensitive to alkylating agents. Together, our work reveals a previously unrecognized ubiquitin-dependent pathway induced specifically to repair alkylation damage, shedding light on the molecular mechanism of X-linked trichothiodystrophy.

PMID:
29144457
PMCID:
PMC6458054
DOI:
10.1038/nature24484
[Indexed for MEDLINE]
Free PMC Article

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