Robarts Dakota R, Kotulkar Manasi, Paine-Cabrera Diego, Venneman Kaitlyn K, Hanover John A, Zachara Natasha E, Slawson Chad, Apte Udayan
Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA.
Laboratory of Cell Biochemistry and Molecular Biology, NIDDK, NIH, Bethesda, MD, USA.
bioRxiv. 2023 Feb 17:2023.02.16.528884. doi: 10.1101/2023.02.16.528884.
BACKGROUND & AIMS: O-GlcNAcylation is a post-translational modification catalyzed by the enzyme O-GlcNAc transferase (OGT), which transfers a single N-acetylglucosamine sugar from UDP-GlcNAc to the protein on serine and threonine residues on proteins. Another enzyme, O-GlcNAcase (OGA), removes this modification. O-GlcNAcylation plays an important role in pathophysiology. Here, we report that O-GlcNAcylation is essential for hepatocyte differentiation, and chronic loss results in fibrosis and hepatocellular carcinoma.
Single-cell RNA-sequencing was used to investigate hepatocyte differentiation in hepatocyte-specific OGT-KO mice with increased hepatic O-GlcNAcylation and in OGA-KO mice with decreased O-GlcNAcylation in hepatocytes. HCC patient samples and the DEN-induced hepatocellular carcinoma (HCC) model were used to investigate the effect of modulation of O-GlcNAcylation on the development of liver cancer.
Loss of hepatic O-GlcNAcylation resulted in disruption of liver zonation. Periportal hepatocytes were the most affected by loss of differentiation characterized by dysregulation of glycogen storage and glucose production. OGT-KO mice exacerbated DEN-induced HCC development with increased inflammation, fibrosis, and YAP signaling. Consistently, OGA-KO mice with increased hepatic O-GlcNAcylation inhibited DEN-induced HCC. A progressive loss of O-GlcNAcylation was observed in HCC patients.
Our study shows that O-GlcNAcylation is a critical regulator of hepatic differentiation, and loss of O-GlcNAcylation promotes hepatocarcinogenesis. These data highlight increasing O-GlcNAcylation as a potential therapy in chronic liver diseases, including HCC.
O-连接的N-乙酰葡糖胺化（O-GlcNAcylation）是一种由O-GlcNAc转移酶（OGT）催化的翻译后修饰，该酶将单个N-乙酰葡糖胺糖从尿苷二磷酸-N-乙酰葡糖胺（UDP-GlcNAc）转移至蛋白质的丝氨酸和苏氨酸残基上。另一种酶O-GlcNA糖苷酶（OGA）则去除这种修饰。O-GlcNAcylation在病理生理学中发挥重要作用。在此，我们报告O-GlcNAcylation对肝细胞分化至关重要，长期缺失会导致肝纤维化和肝细胞癌。
利用单细胞RNA测序研究肝细胞特异性OGT基因敲除（KO）小鼠（肝脏O-GlcNAcylation增加）和OGA-KO小鼠（肝细胞中O-GlcNAcylation减少）的肝细胞分化情况。使用肝癌患者样本和二乙基亚硝胺（DEN）诱导的肝细胞癌（HCC）模型研究O-GlcNAcylation调节对肝癌发生发展的影响。
肝脏O-GlcNAcylation缺失导致肝小叶结构破坏。门周肝细胞受分化缺失影响最大，表现为糖原储存和葡萄糖生成失调。OGT-KO小鼠加剧了DEN诱导的HCC发展，炎症、纤维化和Yes相关蛋白（YAP）信号传导增加。同样，肝脏O-GlcNAcylation增加的OGA-KO小鼠抑制了DEN诱导的HCC。在肝癌患者中观察到O-GlcNAcylation逐渐缺失。
我们的研究表明，O-GlcNAcylation是肝脏分化的关键调节因子，O-GlcNAcylation缺失促进肝癌发生。这些数据凸显了增加O-GlcNAcylation作为慢性肝病（包括HCC）潜在治疗方法的可能性。
