Genome-wide changes in OGT-deficient mouse liver tissue

Over a billion people suffer from chronic liver diseases worldwide, which often leads to fibrosis and then cirrhosis. Treatments for fibrosis remain experimental, in part because no unifying mechanism has been identified that initiates liver fibrosis. O-linked beta-N-acetylglucosamine (O-GlcNAc) transferase (OGT) plays a pro-survival role under stress in many tissues. Here we report that OGT protects against hepatocyte necroptosis and initiation of liver fibrosis. Decreased O-GlcNAc levels were seen in patients with alcoholic liver cirrhosis and in mice with ethanol-induced liver injury. Liver-specific O-GlcNAc transferase (OGT) knockout (OGT-LKO) mice progressed to liver fibrosis at 10 weeks of age. OGT-deficient hepatocytes underwent necroptosis. These findings identify OGT as a key suppressor of hepatocyte necroptosis and OGT-LKO mice may serve as an effective spontaneous genetic model of liver fibrosis. Total RNA was harvested from the liver tissue of 5-week-old OGT-deleted mice (n=4) and their control littermates (WT, n=5). Both genders were used for the study. Mice were fasted for 6 h before sacrifice.全球范围内有超过十亿人群罹患慢性肝脏疾病，此类疾病多会逐步进展为肝纤维化，最终发展为肝硬化。当前肝纤维化的治疗手段仍处于实验阶段，部分原因在于尚未明确驱动肝纤维化起始的统一致病机制。O-连接β-N-乙酰葡糖胺（O-GlcNAc）转移酶（OGT）在多种组织的应激状态下发挥促存活功能。本研究证实，OGT可抑制肝细胞坏死性凋亡，阻断肝纤维化的起始进程。在酒精性肝硬化患者及乙醇诱导肝损伤的小鼠模型中，均检测到O-GlcNAc水平降低。肝脏特异性OGT敲除（OGT-LKO）小鼠在周龄达10周时即可进展为肝纤维化，且OGT缺陷的肝细胞会发生坏死性凋亡。上述研究结果表明，OGT是肝细胞坏死性凋亡的关键抑制因子，而OGT-LKO小鼠可作为一种有效的自发性肝纤维化遗传模型。本研究从5周龄OGT敲除小鼠（n=4）及其同窝野生型对照小鼠（WT，n=5）的肝组织中提取总RNA。实验涵盖雌雄两种性别，所有小鼠在处死前均禁食6小时。