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. Overall design: Comparative gene expression profiling analysis of RNA-seq data for wildtype and NuMA-depleted HCT116 cells

核骨架（nucleoskeleton）一般被认为是真核细胞核内参与基因组表达调控与稳态维持的网格状结构。然而其真实的生物学功能与作用机制仍存在争议。本研究证实，核有丝分裂器蛋白（nuclear mitotic apparatus protein，NuMA）作为纺锤体的关键调控因子，可作为核骨架的组分之一，参与调控基因组高级结构。在细胞间期，快速敲除NuMA会导致染色质组织发生改变，包括基因组可及性升高、核小体纤维重塑以及部分异染色质区域的转录水平变化。上述效应可能源于NuMA与连接组蛋白H1的相互作用。本研究证明，NuMA可通过其C端结构域与连接组蛋白H1及连接DNA发生相互作用。该相互作用可促进H1与DNA的结合以及核小体的堆叠，这或许是NuMA维持异染色质局部浓缩状态的原因之一。综上，本研究揭示了NuMA在细胞间期的全新生物学功能，同时首次将核骨架与单核小体层面的基因组组织建立了关联。这项针对NuMA调控H1与核小体机制的深入研究，为核骨架如何调控基因组结构与基因表达提供了全新视角。实验设计方案：对野生型与NuMA敲除HCT116细胞的RNA-seq数据进行比较基因表达谱分析。