Nucleosome-nucleosome interactions via histone tails and linker DNA regulate nuclear rigidity.
Nucleosome-nucleosome interactions via histone tails and linker DNA regulate nuclear rigidity.
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DOI：
10.1091/mbc.e16-11-0783
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发表时间：
2017-06-01
影响因子：
3.3
通讯作者：
Maeshima K
中科院分区：
文献类型：
--
作者：
Shimamoto Y;Tamura S;Masumoto H;Maeshima K
力校准的微针设置和受控的生化扰动表明，染色质充当类似弹簧的机械模块，控制细胞核的刚性。潜在的分子机制涉及连接 DNA 和通过组蛋白尾部的核小体间相互作用。细胞及其内部的细胞核在不同的生物过程中经历显着的机械应力，包括收缩、迁移和粘附。因此，必须保持细胞核的结构稳定性，以保护基因组的完整性。然而，尽管人们对核结构和组件有了广泛的了解，但潜在的物理和分子机制仍然很大程度上未知。我们通过对分离的人类细胞核进行基于微针的定量显微操作以及对染色质的一系列生化扰动来解决这个问题。我们发现细胞核的机械刚性取决于核小体纤维的连续性和核小体之间的相互作用。通过改变阳离子浓度、乙酰化组蛋白尾部或消化接头 DNA 来破坏这些染色质特征会导致核刚性丧失。相比之下，关键染色质组装因子（包括粘连蛋白、凝缩蛋白 II 和 CTCF）以及主要核膜蛋白核纤层蛋白的水平不受影响。结合使用活细胞和简单机械模型的原位证据，我们的研究结果揭示了基于染色质的核机械反应调节，并深入了解局部和整体染色质结构的重要性，例如与叉指或融化的核小体纤维相关的结构。
A force-calibrated microneedle setup and controlled biochemical perturbation reveal that chromatin acts as a spring-like mechanical module that controls the rigidity of cell nuclei. The underlying molecular mechanism involves linker DNA and internucleosomal interaction via histone tails. Cells, as well as the nuclei inside them, experience significant mechanical stress in diverse biological processes, including contraction, migration, and adhesion. The structural stability of nuclei must therefore be maintained in order to protect genome integrity. Despite extensive knowledge on nuclear architecture and components, however, the underlying physical and molecular mechanisms remain largely unknown. We address this by subjecting isolated human cell nuclei to microneedle-based quantitative micromanipulation with a series of biochemical perturbations of the chromatin. We find that the mechanical rigidity of nuclei depends on the continuity of the nucleosomal fiber and interactions between nucleosomes. Disrupting these chromatin features by varying cation concentration, acetylating histone tails, or digesting linker DNA results in loss of nuclear rigidity. In contrast, the levels of key chromatin assembly factors, including cohesin, condensin II, and CTCF, and a major nuclear envelope protein, lamin, are unaffected. Together with in situ evidence using living cells and a simple mechanical model, our findings reveal a chromatin-based regulation of the nuclear mechanical response and provide insight into the significance of local and global chromatin structures, such as those associated with interdigitated or melted nucleosomal fibers.