Landscape of Double-Stranded DNA Breaks in Postmortem Brains from Alzheimer's Disease and Non-Demented Individuals

Background: Alzheimer's disease (AD) brains accumulate DNA double-strand breaks (DSBs), which could contribute to neurodegeneration and dysfunction. The genomic distribution of AD brain DSBs is unclear. Objective: To map genome-wide DSB distributions in AD and age-matched control brains. Methods: We obtained autopsy brain tissue from 3 AD and 3 age-matched control individuals. The donors were men between the ages of 78 to 91. Nuclei extracted from frontal cortex tissue were subjected to Cleavage Under Targets & Release Using Nuclease (CUT&RUN) assay with an antibody against gamma H2AX, a marker of DSB formation. gamma H2AX-enriched chromatins were purified and analyzed via high-throughput genomic sequencing. Results: The AD brains contained 18 times more DSBs than the control brains and the pattern of AD DSBs differed from the control brain pattern. In conjunction with published genome, epigenome, and transcriptome analyses, our data revealed aberrant DSB formation correlates with AD-associated single-nucleotide polymorphisms, increased chromatin accessibility, and upregulated gene expression. Conclusion: Our data suggest in AD, an accumulation of DSBs at ectopic genomic loci could contribute to an aberrant upregulation of gene expression.

Automated summary

This study identified an accumulation of DNA double-strand breaks (DSBs) in Alzheimer's disease (AD) brains, which differed from the pattern in control brains. The aberrant DSB formation was associated with AD-associated genetic variations, increased chromatin accessibility, and upregulated gene expression.