NuMA interaction with chromatin is vital for proper nuclear architecture in human cells

Abstract

AbstractNuMA is an abundant long-coiled-coil protein that plays a prominent role in spindle organization during mitosis. In interphase, NuMA is localized to the nucleus and hypothesized to control gene expression and chromatin organization. However, because of the prominent mitotic phenotype upon NuMA loss, its precise function in the interphase nucleus remains elusive. Here, we report that NuMA is associated with chromatin in interphase and prophase but released upon nuclear envelope breakdown (NEBD) by the action of Cdk1. We uncovered that NuMA directly interacts with DNA via evolutionarily conserved sequences in its C-terminus. Notably, the expression of the DNA-binding mutant of NuMA affects chromatin decondensation at the mitotic exit, and nuclear shape in interphase. The impact on nuclear shape by mutant NuMA expression is due to its potential to polymerize into high-order fibrillar structures. This study links the chromatin binding ability of NuMA with the maintenance of nuclear shape and architecture, which has a well-studied role in regulating gene expression during development and diseases.