组蛋白乙酰基转移酶1在肝癌细胞中介导的蛋白质乙酰化修饰谱分析

赖氨酸乙酰化是重要的蛋白质翻译后修饰之一，广泛存在于细胞的生理和病理过程。组蛋白乙酰基转移酶1（HAT1）作为第一个被鉴定的蛋白ε-氨基赖氨酸乙酰基转移酶，具有介导组蛋白和非组蛋白乙酰化的作用。然而，在肝癌细胞中HAT1介导的乙酰化蛋白质及其修饰位点目前仍不清楚。本研究首先揭示了HAT1在肝癌组织中呈高表达，并且与预后呈负相关。在建立HAT1敲除HepG2肝癌细胞系的基础上，应用乙酰化修饰蛋白质组学，对肝癌细胞的蛋白质乙酰化修饰谱进行了鉴定和分析，结果鉴定出HepG2肝癌细胞中547种蛋白质上的858个乙酰化修饰位点，发现HAT1影响了68种蛋白质上74个位点的赖氨酸乙酰化修饰。生物信息学分析确定了HAT1修饰的底物蛋白质与多种信号通路有关，涉及疾病发生过程、RNA生物学、剪接体和核小体组装、氧化应激、各种信号通路以及代谢途径等。我们进一步验证了HAT1介导的蛋白质乙酰化修饰能够促进肝癌细胞的异常脂代谢。应用CCK8、克隆形成和Edu细胞增殖检测等方法证实，HAT1对肝癌细胞的增殖具有明显的促进作用。为此，本研究揭示的肝癌细胞中HAT1介导的蛋白质乙酰化修饰位点，对进一步阐明肝癌发病的分子机制具有重要的理论意义，并为开发抗肝癌药物提供了精准的靶标。

Profiling of HAT1-meidated Lysine Acetylation Modification in Liver Cancer

Lysine acetylation has emerged as one of the most important post-translational modifications that participates in various biological and pathological processes. Histone acetyltransferase-1 (HAT1) as the first identified protein ε-amino lysine acetyltransferase is able to regulate the acetylation of histones and non histone proteins. However, the acetylation substrates and sites mediated by HAT1 in liver cancer are poorly understood. In this study, we demonstrated that HAT1 was highly expressed in the liver cancer tissues, which was negatively associated with the prognosis of patients. Based on the establishment of the HAT1-knockout HepG2 cell line, we employed a quantitative proteomics approach to study the profiling of acetylation mediated by HAT1 in HepG2 cells. Interestingly, we identified a total of 858 Kac sites on 547 proteins in the HepG2 cell line, in which HAT1 mediated the levels of Kac of 74 sites on 68 proteins. The pathways and metabolic processes that were affected by HAT1-dependent acetylation modification were analyzed by bioinformatics. The results show that Kac regulates disease development, RNA biology, spliceosome and nucleosome assembly, oxidative stress, various signaling pathways and metabolic pathways, etc.. Moreover, we verified that the HAT1-mediated acetylation modification could promote abnormal lipid metabolism. CCK8 assays, clone formation and Edu assays revealed that HAT1 could remarkably enhance the cell proliferation of liver cancer in vitro. Thus, our finding explored the profiling of HAT1-mediated protein acetylation in HepG2 cells, which provides new insights into the underlying mechanism by which HAT1 mediates the development of liver cancer. Clinically, the HAT1-mediated acetylation sites could be used for the precise targets of drug development.