Dipeptide repeat proteins inhibit homology-directed DNA double strand break repair in C9ORF72 ALS/FTD

Autor: Christian Mueller, Melina Ramic, Abbas Abdallah, Tania F. Gendron, Zane Zeier, Rustam Esanov, Mathew J. Rybin, Sadhana Anatha, Michael Benatar, Tyler C. Huff, Gabriel Gaidosh, Samuel Del’Olio, Claes Wahlestedt, Nancy T. Chee, Nadja S. Andrade, Wenjun Liu, Yanbin Zhang
Rok vydání: 2020
Předmět:
0301 basic medicine
Homology-directed repair
DNA Repair
DNA damage
DNA repair
RAD52
lcsh:Geriatrics
lcsh:RC346-429
Cell Line
Homology directed repair
03 medical and health sciences
Cellular and Molecular Neuroscience
chemistry.chemical_compound
0302 clinical medicine
Humans
DNA Breaks
Double-Stranded
Molecular Biology
lcsh:Neurology. Diseases of the nervous system
Single-strand annealing
DNA Repeat Expansion
C9orf72 Protein
Chemistry
Nuclear Proteins
Dipeptides
Amyotrophic lateral sclerosis
Molecular biology
Double Strand Break Repair
3. Good health
Induced pluripotent stem cells
lcsh:RC952-954.6
030104 developmental biology
DNA double strand break repair
Frontotemporal Dementia
CRISPR
Neurology (clinical)
Trinucleotide repeat expansion
Homologous recombination
Nucleophosmin
030217 neurology & neurosurgery
DNA
Research Article
Zdroj: Molecular Neurodegeneration, Vol 15, Iss 1, Pp 1-18 (2020)
Molecular Neurodegeneration
ISSN: 1750-1326
DOI: 10.1186/s13024-020-00365-9
Popis: Background The C9ORF72 hexanucleotide repeat expansion is the most common known genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two fatal age-related neurodegenerative diseases. The C9ORF72 expansion encodes five dipeptide repeat proteins (DPRs) that are produced through a non-canonical translation mechanism. Among the DPRs, proline-arginine (PR), glycine-arginine (GR), and glycine-alanine (GA) are the most neurotoxic and increase the frequency of DNA double strand breaks (DSBs). While the accumulation of these genotoxic lesions is increasingly recognized as a feature of disease, the mechanism(s) of DPR-mediated DNA damage are ill-defined and the effect of DPRs on the efficiency of each DNA DSB repair pathways has not been previously evaluated. Methods and results Using DNA DSB repair assays, we evaluated the efficiency of specific repair pathways, and found that PR, GR and GA decrease the efficiency of non-homologous end joining (NHEJ), single strand annealing (SSA), and microhomology-mediated end joining (MMEJ), but not homologous recombination (HR). We found that PR inhibits DNA DSB repair, in part, by binding to the nucleolar protein nucleophosmin (NPM1). Depletion of NPM1 inhibited NHEJ and SSA, suggesting that NPM1 loss-of-function in PR expressing cells leads to impediments of both non-homologous and homology-directed DNA DSB repair pathways. By deleting NPM1 sub-cellular localization signals, we found that PR binds NPM1 regardless of the cellular compartment to which NPM1 was directed. Deletion of the NPM1 acidic loop motif, known to engage other arginine-rich proteins, abrogated PR and NPM1 binding. Using confocal and super-resolution immunofluorescence microscopy, we found that levels of RAD52, a component of the SSA repair machinery, were significantly increased iPSC neurons relative to isogenic controls in which the C9ORF72 expansion had been deleted using CRISPR/Cas9 genome editing. Western analysis of post-mortem brain tissues confirmed that RAD52 immunoreactivity is significantly increased in C9ALS/FTD samples as compared to controls. Conclusions Collectively, we characterized the inhibitory effects of DPRs on key DNA DSB repair pathways, identified NPM1 as a facilitator of DNA repair that is inhibited by PR, and revealed deficits in homology-directed DNA DSB repair pathways as a novel feature of C9ORF72-related disease.
Databáze: OpenAIRE
Externí odkaz: