The nucleoskeleton protein NuMA maintains local chromatin architecture partially through promoting linker histone H1’ binding to chromatin and nucleosome stacking [RNA-Seq]

Nucleoskeleton is generally considered to be the grid structure involved in regulation of genome expression and maintenance in the eukaryotic nucleus. However, its actual biological functions and mechanisms remain controversial. Here, we show the nuclear mitotic apparatus protein (NuMA), an essential regulator of the spindle, serve as one of the components of nucleoskeleton to regulates genome high-order architecture. In the interphase, fast depletion of NuMA leads to changes in chromatin organization, including increased accessibility of the genome, remodeling of nucleosome fibers and changes of transcription levels in certain heterochromatin regions. These effects are probably due to NuMA and linker histone H1’s interplay. We prove that NuMA interacts with linker histone H1 and linker DNA through its C-terminal domain. Such interaction facilitates H1’s binding to DNA and promotes nucleosome stacking, and might be part of the reason that NuMA maintains the local condensed state of heterochromatin. Collectively, our results reveal new biological functions of NuMA in the interphase, and also associates nucleoskeleton with genome organization at the mono-nucleosome level for the first time. This in-depth study on the mechanism of NuMA’s regulation on H1 and nucleosomes shed new light on how nucleoskeleton regulates genome architecture and gene expression.