Chromatin binding of nuclear transport factor Importin α in human cultured cancer cells

We found that importin α, a key nuclear transport factor, is highly concentrated in the MN in cultured human cancer cells. Notably, importin α is not uniformly distributed across all MN; it is localized to approximately 40% of them.

This selective localization is characterized by an uncorrelated distribution relative to importin β1, CAS/CSE1L, and Ran, suggesting uncontrolled its nuclear-cytoplasmic recycling. Additionally, along with an association with euchromatin regions, we identified chromatin-regulating molecules as potential interactors with importin α and noted a significant reduction in the mobility of importin α within MN, indicating the establishment of a unique microenvironment in these importin α-enriched structures.