RESUMO
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.
RESUMO
Chronic hepatitis B virus (HBV) infection is a primary cause for liver cancer. And the main challenge of curing hepatitis B is the elimination of the stable covalently closed circular DNA (cccDNA) of the viral genome. The formation of HBV cccDNA requires the filling of single-stranded region and the ligation of nicks in relaxed circular DNA (rcDNA) strands. Previously, our group reported that proliferating cell nuclear antigen (PCNA) was involved in the formation of HBV cccDNA. However, the underlying mechanism of the conversion of HBV rcDNA to cccDNA is poorly understood. In the present study, we aim to explore the mechanism by which PCNA contributes to the conversion of HBV rcDNA to cccDNA. Our data showed that PCNA was involved in the process of HBV rcDNA repair. The knockout of PCNA by the CRISPR/Cas9 system remarkably blocked the conversion of HBV rcDNA to cccDNA, while the ectopic expression of PCNA could effectively rescue the event (P<0. 001). Knockout of PCNA significantly slowed down the conversion kinetics of HBV rcDNA to cccDNA (P<0. 01). Mechanically, the DNA binding domain of PCNA was required for the process of HBV rcDNA repair to cccDNA (P<0. 01). Thus, we conclude that PCNA confers the conversion of HBV rcDNA to cccDNA by its DNA binding domain. Clinically, PCNA might serve as a novel target for antiviral therapy.
