SETD8介导H4K20单甲基化修饰对MSCs抗衰老的作用机制

干细胞衰老是与表观遗传修饰密切相关的复杂生命现象。在终末分化细胞中，赖氨酸甲基转移酶SETD8介导的H4K20单甲基化抑制细胞衰老，但其在干细胞抗衰老中的作用尚不清楚。本研究前期实验发现体外培养23代的人脐带间充质干细胞（MSCs）和过氧化氢诱导的衰老MSCs中，P53等蛋白表达升高而阻滞细胞周期进程；SETD8蛋白表达降低，其靶标分子H4K20甲基化水平也降低。这些结果显示细胞周期和SETD8与MSCs衰老有关。基于这一发现，本项目将构建敲除和过表达SETD8的MSCs，检测其抗衰老能力，进而用H4K20 CHIP-seq和 RNA-seq技术，测定SETD8介导的H4K20单甲基化修饰对H4K20和染色质DNA相互作用和基因组表达的影响，确定其靶基因与相关信号通路，以探究其在MSCs抗衰老中的作用机制。本课题有望为优化MSCs组织修复功能、预防及治疗衰老相关疾病提供新依据。

Stem cell aging is a complex life phenomenon closely related to epigenetic modification. Lysine methyltransferase SETD8-mediated H4K20 monomethylation represses cellular senescence in terminally differentiated cells, but its role in stem cell antisenescence is unclear. Our preliminary experiments demonstrated that in human umbilical cord-derived MSCs (hUC-MSCs) cultured in vitro for 23 passages and senescent hUC-MSCs induced by hydrogen peroxide, increased expression of P53 and other proteins induced cell cycle arrest. The expression of SETD8 protein was decreased. The methylation level of H4K20, the target molecule of SETD8, was also decreased. The results indicated that the cell cycle and SETD8 were related to the senescence of MSCs. Based on these results, we will generate SETD8-/- MSCs and SETD8+/+ MSCs to explore the effect of SETD8 in MSC antisenescence. Then, CHIP-seq and RNA-seq will be used to determine the effect of SETD8-mediated H4K20 monomethylation on the interaction and genomic expression of H4K20 and chromatin DNA, and target genes and related signaling pathways will be identified. This study is expected to provide a new basis for optimizing the tissue repair function of MSCs, preventing and treating aging-associated diseases.