Contrasting somatic mutation patterns in aging human neurons and oligodendrocytes

Area of Science:

• Neuroscience
• Genetics
• Aging Research

Background:

• Understanding somatic mutations in brain cells is crucial for aging mechanisms.
• Limited data exists on mutational patterns across different brain cell types.

Purpose of the Study:

• To characterize somatic mutation patterns in oligodendrocytes and neurons.
• To compare mutation accumulation rates and genomic distributions between these cell types.

Main Methods:

• Whole-genome sequencing (WGS) of 86 single oligodendrocytes, 20 mixed glia, and 56 single neurons.
• Analysis of somatic single-nucleotide variants (sSNVs) and small insertions/deletions (indels).
• Correlation with single-nucleus RNA profiles and chromatin accessibility data.

Main Results:

• Both oligodendrocytes and neurons accumulate somatic mutations linearly with age.
• Oligodendrocytes showed an 81% faster accumulation of sSNVs and 28% slower accumulation of indels compared to neurons.
• Oligodendrocyte mutations were enriched in inactive genomic regions, similar to brain cancers, while neuronal mutations were enriched in active chromatin.

Conclusions:

• Distinct mutagenic processes operate in oligodendrocytes and neurons.
• Age-related somatic mutations in the brain vary significantly by cell type, impacting genomic regions differently.