Housekeeping

Steady-state DNA movement enables cells to perform housework in nuclear-like environments

Researchers in Japan have found that the local movement of DNA inside human cells remains stable throughout interphase, where the cell grows and replicates its DNA for cell division. The study suggests that this steady-state DNA movement allows cells to perform household chores in similar environments during interphase.

The team, led by Professor Kazuhiro Maeshima of the National Institute of Genetics, ROIS, published their findings on June 3 in Scientists progress.

To fit inside the cell nucleus, DNA is organized into chromatin, in which DNA strands are wrapped around clusters of histone proteins, like a thread around a coil, to form structures called nucleosomes. Nucleosomes can then be folded into even more compact structures and form chromatin. Previous research shows that chromatin continuously swings in living cells.

As the cell cycle progresses (namely the G1, S and G2 phases), where the genome DNA doubles and the nucleus becomes larger, the nuclear environment surrounding the chromatin changes drastically. Maeshima and colleagues at the National Institute of Genetics in Mishima, Japan posed this question: How does the behavior of chromatin change during interphase?

Maeshima’s group used a high-resolution optical microscopy technique to observe the behavior of individual nucleosomes inside living cells for a very short time, about one second.

Maeshima and colleagues revealed that local chromatin movement remains stable throughout interphase, although genome DNA is doubled by DNA replication and the nucleus grows. The researchers also showed that replication-free nuclear growth did not affect the steady-state movement of chromatin. Thus, local chromatin movement is independent of these nuclear changes during interphase.

This is an important finding because steady-state motion allows cells to carry out their routines, such as RNA transcription and DNA replication, in similar nuclear environments. Local chromatin movement may govern the accessibility of genomic DNA for target finding or machine recruitment. Steady-state movement of chromatin provides a robust cellular system in which DNA functions are unaffected by various nuclear changes.”


Shiori Iida, first author

“Cells can transiently alter chromatin movement from steady state to perform their ad hoc tasks in response to DNA damage, among many other tasks,” Maeshima said. He and his team aim to further explore how DNA movement is regulated, which proteins are involved in the regulatory process, and more about how DNA behaves during cell division. “Our ultimate goal is to understand how human genomic DNA inside the cell behaves to read the genetic information it contains,” Maeshima said.

Source:

Journal reference:

Iida, S. et al. (2022) Single-nucleosome imaging reveals steady-state movement of interphase chromatin in living human cells. Scientific advances. doi.org/10.1126/sciadv.abn5626.