Epigenetic assimilation in the aging human brain

• Published in: Genome Biology Vol. 17; no. 1; p. 76
• Main Authors: Oh, Gabriel, Ebrahimi, Sasha, Wang, Sun-Chong, Cortese, Rene, Kaminsky, Zachary A., Gottesman, Irving I., Burke, James R., Plassman, Brenda L., Petronis, Art
• Format: Journal Article
• Language: English
• Published: England BioMed Central 28.04.2016
• Subjects: Age; Aged; Aged, 80 and over; Aging; Alzheimer disease; Alzheimer Disease - genetics; Alzheimer's disease; Assimilation; Bioinformatics; Brain; cell dedifferentiation; cell senescence; Cerebellum; Cerebral cortex; Consortia; Datasets; Deoxyribonucleic acid; DNA; DNA Methylation; Epigenesis, Genetic; Epigenetics; Female; Frontal Lobe - growth & development; Frontal Lobe - metabolism; Frontal Lobe - physiology; Genomes; Humans; Male; Middle Aged; Molecular modelling; Neurodegenerative diseases; risk factors; Stem cells; Studies; tissues; Transcription; transcription (genetics); transcriptomics; Twins; Alzheimer’s disease; Dedifferentiation; Transcriptome; Aging; DNA methylation; Epigenetics; Genomic organization; Epigenetic drift
• ISSN: 1474-760X; 1474-7596; 1474-760X
• DOI: 10.1186/s13059-016-0946-8

Epigenetic drift progressively increases variation in DNA modification profiles of aging cells, but the finale of such divergence remains elusive. In this study, we explored the dynamics of DNA modification and transcription in the later stages of human life. We find that brain tissues of older individuals (>75 years) become more similar to each other, both epigenetically and transcriptionally, compared with younger individuals. Inter-individual epigenetic assimilation is concurrent with increasing similarity between the cerebral cortex and the cerebellum, which points to potential brain cell dedifferentiation. DNA modification analysis of twins affected with Alzheimer's disease reveals a potential for accelerated epigenetic assimilation in neurodegenerative disease. We also observe loss of boundaries and merging of neighboring DNA modification and transcriptomic domains over time. Age-dependent epigenetic divergence, paradoxically, changes to convergence in the later stages of life. The newly described phenomena of epigenetic assimilation and tissue dedifferentiation may help us better understand the molecular mechanisms of aging and the origins of diseases for which age is a risk factor.