连接组蛋白H1.4的C端移码突变引起HIST1H1E综合征的异常染色质相分离机制

真核细胞的染色质包含有各种功能的区室，并且它们的某些特性类似于无膜细胞器，最近被证明是生物大分子通过弱多价相互作用介导的液-液相分离（LLPS）形成的。染色质可以被压缩成更高阶的染色质结构，许多连接组蛋白H1亚型可以稳定了核小体结构并促进了染色质的高阶折叠。近期我们证实，连接组蛋白H1.4（HIST1H1E）可以在体外与DNA或重构的核小体串形成LLPS。最近，涉及生殖细胞连接组蛋白H1.4的C末端尾部的移码突变被证实可以造成异常染色质重塑，细胞衰老和加速衰老，并已因果关系到尚未明确定义的HIST1H1E综合症（HIST1H1E Syndrome）。本项目旨在研究H1.4的C末端尾部的移码突变是如何影响其在体外和细胞内压缩组装的核小体串并形成染色质高级结构的能力，以及如何在体外影响H1.4与DNA及核小体串形成LLPS，以及细胞内异常染色质LLPS与HIST1H1E综合征发生的关系。

The chromatin of eukaryotic cells contains compartments with various functions, and some of their properties are similar to membraneless organelles, and recently it has been demonstrated that weak multivalent interactions of biomacromolecules can lead to the formation of many of these membraneless compartments via liquid-liquid phase separation. Chromatin can be compressed into higher-order chromatin structures, and a number of H1 linker histone isoforms can stabilize the nucleosomal structure and contributing to higher-order chromatin folding. Recently, we have confirmed that concatenated histone H1.4 can form liquid-liquid separation (LLPS) with DNA or reconstructed nucleosome strings in vitro. Recently, germline frameshift mutations involving the C-terminal tail of HIST1H1E, which has been proven to cause abnormal chromatin remodeling, cell aging and accelerated aging, have been causally linked to an as-yet poorly defined HIST1H1E syndrome (HIST1H1E Syndrome). This project aims to study how the frameshift mutation at the C-terminal tail of H1.4 affects the ability of H1.4 protein to compress and assemble nucleosome arrays in vitro and in cells, and how to influence the ability of H1.4 to form liquid-liquid separation from DNA and nucleosome strings in vitro, in order to explore the potential relationship between the phase separation ability of the frameshift mutation in the C-terminal tail of H1.4 and the pathology of HIST1H1E syndrome, and the relationship between abnormal intracellular chromatin LLPS and HIST1H1E syndrome.