New Study Reveals Dual Nature of Chromatin Movement in Cells
A new MIT study has uncovered two distinct classes of chromatin dynamics, one constrained within ~200 nanometers and another capable of longer-range movement, offering new insights into gene regulation and DNA repair.
Key Findings
A groundbreaking study from MIT researchers has measured chromatin movement across an unprecedented range of timescales—from hundreds of microseconds to hours, covering seven orders of magnitude in time. The analysis identified two distinct classes of chromatin dynamics:
- Constrained movement: Chromatin regions that remain within approximately 200 nanometers and primarily contact neighboring genomic regions.
- Freer movement: Chromatin that can travel over longer distances, but only at longer timescales ranging from minutes to hours.
Methods
The research team employed MINFLUX super-resolution microscopy to track chromatin loci in living cells, combining this with traditional imaging techniques. This powerful approach allowed them to capture movement across timescales from 200 microseconds to several hours. Experiments were conducted across multiple mouse and human cell types.
Implications for Gene Regulation
The findings provide critical insight into gene expression regulation and DNA repair mechanisms. Chromatin movement is essential for genes to interact with regulatory elements and for DNA repair processes to function properly.
The constrained movement pattern suggests that for genomic regions within about 100,000 base pairs of each other, contact occurs routinely without requiring additional mechanisms.
Challenging Existing Models
The observed subdiffusive behavior proved stronger than predicted by current polymer models, including the Rouse model and fractal globule model. This discrepancy indicates that new theoretical models may need to account for interactions with the crowded nucleoplasm to accurately describe chromatin dynamics.
Attribution and Funding
The study was published in Nature Structural and Molecular Biology. Senior author Anders Sejr Hansen, associate professor of biological engineering at MIT, led the research alongside lead authors Matteo Mazzocca, Domenic Narducci, and Simon Grosse-Holz.
The research received support from the National Institutes of Health, National Science Foundation CAREER Award, Pew-Stewart Scholar for Cancer Research Award, and the Bridge Project.