The human body is composed of over forty trillion cells. Each of these cells has totally two meters of tightly packaged genomic DNA, the blueprint of life. Recently, there have been many advances in understanding how DNA is packaged and organized as chromatin in the cell. In contrast, how chromatin behaves in living cells remains unclear.
SOKENDAI graduate student Shiori Iida, JSPS Fellow Yuji Itoh, Technical Stuff Sachiko Tamura, and Professor Kazuhiro Maeshima of Genome Dynamics Laboratory (NIG), together with Research Scientist Soya Shinkai and Team Leader Shuichi Onami of RIKEN BDR, and Professor Masato T. Kanemaki of Molecular Cell Engineering Laboratory (NIG), have investigated the local movements of chromatin in living human cells using super-resolution fluorescence microscopy (Movie 1).
Both DNA amount and nuclear size become double during the preparation period for the cell division (interphase). Previously, it has been suggested that these drastic changes in the nuclear environment would affect chromatin movements. However, Iida et al. have revealed that chromatin motion keeps a steady state throughout the interphase. Chromatin motion is directly related to the accessibility of the DNA (readability of genomic information). Steady-state chromatin motion allows cells to conduct housekeeping tasks under similar environments during interphase.
This work was supported by JSPS and MEXT KAKENHI grants (20H05550、21H05763、19K23735、 20J00572、18H05412、19H05273、20H05936), a Japan Science and Technology Agency CREST grant (JPMJCR15G2), JST SPRING(JPMJSP2104), the Takeda Science Foundation, and the Uehara Memorial Foundation.
Figure: The swaying motion of chromatin keeps a steady state throughout the interphase (G1, S, G2 phases) despite increases in DNA amount and nuclear volume. Steady-state chromatin motion allows cells to conduct housekeeping tasks under similar environments during interphase.
Video1: Movie data (50 ms/frame) of single nucleosomes （basic units of chromatin） fluorescently labeled in a living human cell. Note that clear, well-separated dots and their movements were visualized.
Video2: Movie 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 nucleosome motion between G1 and G2 phase, even as nuclear size increases.
Press release (In Japanese only)
