Chromatin Remodelling in Ageing

Chromatin as Part of Ageing Biology

Chromatin remodelling refers to changes in how DNA is packaged with histones and other proteins, which in turn affects which genes are accessible for transcription. In ageing research, these changes are usually discussed within the broader hallmark of epigenetic alterations because age-related shifts in chromatin state can influence genome stability, transcription, and cellular identity. [1] [2] [3]

Loss of Heterochromatin with Age

One recurring observation across model systems is that ageing is associated with erosion of heterochromatin, the more compact form of chromatin that helps silence repetitive DNA and maintain stable gene-expression programs. Reviews describe age-related reductions in repressive histone marks, altered lamina-associated organization, and weaker chromatin compartmentalization as part of this process. These changes are not identical in every tissue, but they support the general idea that chromatin structure becomes less tightly maintained with age. [2] [3] [4]

Histone Changes and Nucleosome Remodeling

Ageing is also linked to changes in histone abundance, histone variants, and post-translational histone modifications. Experimental work in yeast and mammalian systems suggests that reduced histone supply and altered nucleosome positioning can make chromatin less stable and expose DNA to abnormal transcriptional activity. Reviews interpret these findings as evidence that chromatin remodelling in ageing involves both structural loss and active reprogramming of regulatory regions. [3] [5] [6]

Consequences for Gene Expression

When chromatin states shift, transcription tends to become less tightly controlled. Age-related chromatin remodelling has been linked to transcriptional drift, increased cell-to-cell variability, and derepression of genomic regions that are normally kept silent. This does not mean all ageing cells follow the same expression pattern, but it does help explain why older tissues often show noisier and less coordinated gene regulation. [2] [3] [7]

Interaction with DNA Damage and Repair

Chromatin remodelling is closely tied to the DNA damage response because repair machinery must gain access to DNA packaged in nucleosomes. Over time, repeated damage signaling and imperfect repair can reshape local chromatin architecture, while pre-existing chromatin disruption can itself impair repair fidelity. For that reason, chromatin remodelling is usually treated as both a contributor to, and a consequence of, other ageing processes such as genomic instability and cellular senescence. [1] [3] [8] [9]

Why It Matters for Ageing Interpretation

Chromatin remodelling is important because it sits between molecular damage and large-scale functional decline. It can influence how cells preserve identity, respond to stress, and maintain stable patterns of gene expression over time. Current evidence supports chromatin change as a meaningful part of ageing biology, but the causal direction is still mixed: some chromatin shifts appear to drive dysfunction, while others likely reflect downstream responses to damage, inflammation, or altered metabolism. [1] [2] [3]

Summary

In ageing, chromatin remodelling refers to broad changes in genome packaging that affect gene regulation, DNA repair, and cellular stability. The literature most consistently points to heterochromatin loss, histone and nucleosome changes, and rising transcriptional dysregulation, but these processes are intertwined with other hallmarks rather than acting as a single isolated cause of ageing. [1] [2] [3]

References

1. Lopez-Otin, C. et al. "Hallmarks of aging: An expanding universe." Cell (2023). https://pmc.ncbi.nlm.nih.gov/articles/PMC10809922/
2. Sen, P., Shah, P. P., Nativio, R., & Berger, S. L. "Epigenetic Mechanisms of Longevity and Aging." Cell (2016). https://pmc.ncbi.nlm.nih.gov/articles/PMC5215349/
3. Pal, S., & Tyler, J. K. "Epigenetics and aging." Science Advances (2016). https://www.science.org/doi/10.1126/sciadv.1600584
4. Oberdoerffer, P., & Sinclair, D. A. "The role of nuclear architecture in genomic instability and ageing." Nature Reviews Molecular Cell Biology (2007). https://www.nature.com/articles/nrm2238
5. Feser, J., & Tyler, J. "Chromatin structure as a mediator of aging." FEBS Letters (2011). https://pmc.ncbi.nlm.nih.gov/articles/PMC3692085/
6. Hu, Z. et al. "Nucleosome loss leads to global transcriptional up-regulation and genomic instability during yeast aging." Genes & Development (2014). https://pmc.ncbi.nlm.nih.gov/articles/PMC4031919/
7. Stegeman, R., & Weake, V. M. "Transcriptional Signatures of Aging." Journal of Molecular Biology (2017). https://pmc.ncbi.nlm.nih.gov/articles/PMC5798495/
8. Sun, L., Yu, R., & Dang, W. "Chromatin Architectural Changes during Cellular Senescence and Aging." Genes (2018). https://pmc.ncbi.nlm.nih.gov/articles/PMC6263616/
9. Moskalev, A. A. et al. "The role of DNA damage and repair in aging through the prism of Koch-like criteria." Ageing Research Reviews (2013). https://pmc.ncbi.nlm.nih.gov/articles/PMC3779249/