Aging and environmental exposures alter tissue-specific DNA methylation dependent upon CpG island context

Area of Science:

• Epigenetics
• Genomics
• Human Physiology

Background:

• Epigenetic modifications, like DNA methylation, regulate gene transcription crucial for development and differentiation.
• While epigenetic alterations are linked to diseases, variations in normal tissues due to aging and environment are not well understood.
• Understanding individual epigenomic dynamics is vital for population-based studies.

Purpose of the Study:

• To investigate tissue-specific DNA methylation differences in non-pathologic human tissues.
• To determine how aging and environmental exposures contribute to normal variations in DNA methylation.
• To explore the relationship between epigenomic states and gene expression variability.

Main Methods:

• Analysis of 217 non-pathologic human tissues from 10 anatomic sites.
• Examination of 1,413 autosomal CpG loci across 773 genes.
• Unsupervised modeling to identify methylation profile classes and their association with age and tissue origin.

Main Results:

• Methylation profile classes significantly correlated with age and predicted tissue origin.
• Solid tissues showed significant, CpG island-dependent correlations between age and methylation.
• CpG island loci gained methylation with age, while non-CpG island loci lost methylation, a pattern consistent across tissues.

Conclusions:

• Data demonstrate age- and exposure-related differences in tissue-specific DNA methylation.
• Significant age-associated methylation patterns are dependent on CpG island context.
• Findings provide insights into aging's role in disease susceptibility and inform epigenome reference construction.