The study revealed that chromosomes are fluid, almost liquid, outside of their division phases.
Chromosome manipulation in live cells indicates that they are fluid.
Researchers from the CNRS, the Institut Curie and the University of the Sorbonne have succeeded for the first time in physically acting on chromosomes in living cells. They discovered that apart from the phases of cell division, the chromosomes are actually very fluid – almost liquid – by being subjected to different forces using magnets. The study was recently published in the prestigious journal Science.
When not in their dividing phases, chromosomes are fluid, but not quite liquid. Read also : High-tech imaging reveals details of a rare eye disease. This discovery was made possible by the first-ever direct mechanical manipulation of chromosomes in the nucleus of living cells.
Previously, chromosomes, which are extraordinarily long DNA molecules, were depicted as tangled like loose balls of thread and creating a sort of gel. The findings of this new publication present a completely different picture. Chromosomes are fluid and free to move, unrestricted by the other parts that make up the nucleus and can reorganize.
To reach these conclusions published in Science, scientists from the CNRS, the Institut Curie and Sorbonne University, working in the Nuclear Dynamics, Physico-chemistry and Cell Biology, and Cancer laboratories, in collaboration with scientists from the Massachusetts Institute of Technology, attached magnetic nanoparticles to a small portion of a chromosome in a living cell. Then they stretched the chromosome, exerting varying degrees of force, using a micro-magnet outside the cell. Thanks to this approach, the teams were able to measure the response of a chromosome to external forces, for the very first time in a living cell.
Thanks to these experiments, the scientists were able to observe that the range of forces exerted naturally in the nucleus – for example by DNA-replicating enzymes – is sufficient to substantially modify the conformation of a chromosome. This major discovery, at the interface of physics and biology, modifies the hitherto established representation of chromosomes. It also adds new elements to our understanding of biological processes, the biophysics of chromosomes and the organization of the genome.
Reference: “Live Cell Micromanipulation of a Genomic Locus Reveals Interphase Chromatin Mechanics” by Veer I. P. Keizer, Simon Grosse-Holz, Maxime Woringer, Laura Zambon, Koceila Aizel, Maud Bongaerts, Fanny Delille, Lorena Kolar- Znika, Vittore F. Scolari, Sebastian Hoffmann, Edward J. Banigan, Leonid A. Mirny, Maxime Dahan, Daniele Fachinetti, and Antoine Coulon, July 28, 2022, Science.DOI: 10.1126/science.abi9810
