2026-09-14 国立遺伝学研究所
分裂期染色体形成のモデル
＜関連情報＞
- https://www.nig.ac.jp/highlights/15354/
- https://www.cell.com/trends/genetics/abstract/S0168-9525(26)00198-8
有糸分裂染色体：染色体足場モデルからコンデンシンと物理的力まで Mitotic chromosomes: from the chromosome scaffold model to condensins and physical forces
Kazuhiro Maeshima ∙ Masa A. Shimazoe ∙ Sachiko Tamura
Trends in Genetics Published:September 14, 2026
DOI:https://doi.org/10.1016/j.tig.2026.08.005
Highlights
Recent imaging and genomics suggest that mitotic chromosome assembly is a dynamic process driven by condensins, topoisomerase IIα, and physical forces.
Condensins shape chromosome axes and loops and constrain nucleosome motion, but condensin depletion in human cells does not necessarily reduce global chromosome compaction.
Histone-tail electrostatics, linker histone H1, free Mg2+, and depletion attraction/macromolecular crowding have emerged as physical forces contributing to mitotic chromosome compaction.
Interphase euchromatin and heterochromatin form condensed domains, suggesting that mitotic chromosomes may assemble from pre-existing chromatin domains as ‘building blocks’ rather than from scratch.
Abstract
Mitotic chromosome organization and assembly remain fundamental questions in genetics. Since the chromosome scaffold model proposed in 1977 highlighted the role of nonhistone proteins in determining chromosome shape and size, key nonhistone proteins, including condensins and topoisomerase IIα (topoIIα), have been shown to play critical roles in organizing chromosome axes and chromatin loops. Emerging evidence from biochemistry, imaging, and genomics suggests that mitotic chromosome assembly is a dynamic process driven by the interplay of condensin-mediated looping, topoIIα-dependent entanglement/disentanglement, and multiple physical forces, including electrostatic nucleosome interactions, linker histone H1, free Mg2+, and depletion attraction. In this review, we discuss how these mechanisms contribute to chromosome assembly and propose that interphase chromatin domains function as dynamic building blocks of mitotic chromosomes.
