The material properties of mitotic chromosomes

Chromosomes transform during the cell cycle, allowing tran-scription and replication during interphase and chromosome segregation during mitosis. Morphological changes are thought to be driven by the combined effects of DNA loop extrusion and a chromatin solubility phase transition. By extruding the chromatin fibre into loops, condensins enrich at an axial core and provide resistance to spindle pulling forces. Mitotic chromosomes are further compacted by deacetylation of histone tails, rendering chromatin insoluble and resistant to penetration by microtubules. Regulation of surface properties by Ki-67 allows independent chromosome movement in early mitosis and clustering during mitotic exit. Recent progress has provided insight into how the extraordinary material properties of chromatin emerge from these activities, and how these properties facilitate faithful chromosome segregation.

Automated summary

Chromosomes undergo transformations during the cell cycle, including transcription, replication, and segregation. These changes are driven by DNA loop extrusion and a chromatin solubility phase transition. Condensins enrich at an axial core, forming loops and providing resistance to spindle pulling forces. Mitotic chromosomes are further compacted by deacetylation of histone tails, making them insoluble and resistant to microtubule penetration. Ki-67 regulates surface properties, allowing independent chromosome movement in early mitosis and clustering during mitotic exit. Recent progress has shed light on the material properties of chromatin and how they facilitate accurate chromosome segregation.