The human body is made up of more than forty trillion cells. Each of these cells has a total of two meters of well-packaged genomic DNA, the model of life. Recently, there have been many advances in understanding how DNA is packaged and organized as chromatin in the cell. In contrast, it is unclear how chromatin behaves in living cells.
Video 1: Film data (50 ms / frame) of single nucleosomes (basic units of chromatin) fluorescently labeled in a living human cell. Note that clear, well-separated points and their movements were displayed.
SOKENDAI graduate student Shiori Iida, JSPS colleague Yuji Itoh, technical staff Sachiko Tamura and Professor Kazuhiro Maeshima of the Genome Dynamics Laboratory (NIG), along with research scientist Soya Shinkai and the leader of the RIKEN BDR’s Shuichi Onami team and Professor Masato T. Kanemaki of the Molecular Cell Engineering Laboratory (NIG) have investigated the local movements of chromatin in living human cells using superresolution fluorescence microscopy.
Video 2: Film data (50 ms / frame) of single nucleosomes fluorescently labeled in living human cells; (left) G1-phase, (right) G2-phase. Note that there is not much difference in the movement of the nucleosome between phases G1 and G2, even as the nuclear size increases.
Both the amount of DNA and the nuclear size double during the period of preparation for cell division (interphase). It had previously been suggested that these drastic changes in the nuclear environment would affect chromatin movements. However, Iida et al. have revealed that the movement of chromatin maintains a steady state throughout the interphase. The movement of chromatin is directly related to the accessibility of DNA (readability of genomic information). Steady-state chromatin movement allows cells to perform cleaning tasks in similar environments during interphase.
Reference: Iida S, Shinkai S, Itoh Y, et al. The single nucleosome image reveals the steady-state movement of interface chromatin in living human cells. Science Adv. 2022; 8 (22): eabn5626. doi: 10.1126 / sciadv.abn5626
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