Department of Radiology, Affiliated Hospital 2 of Nantong University, Nantong, Jiangsu, China.
Department of Clinical Pharmacy, Affiliated Maternity and Child Health Care Hospital of Nantong University, Nantong, Jiangsu, China; Nantong Institute of Genetics and Reproductive Medicine, Affiliated Maternity & Child Healthcare Hospital of Nantong University, Nantong, Jiangsu, China.
Biomed Pharmacother. 2021 Jun;138:111477. doi: 10.1016/j.biopha.2021.111477. Epub 2021 Mar 23.
Protein O-GlcNAcylation is a dynamic post-translational protein modification that regulates fundamental cellular functions in both normal physiology and diseases. The levels of protein O-GlcNAcylation are determined by flux of the hexosamine biosynthetic pathway (HBP), which is a branch of glycolysis, and are directly controlled by a pair of enzymes: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). An increase in protein O-GlcNAcylation has been shown to have protective effects on ischemia-related insults in the heart and brain. To determine whether O-GlcNAcylation plays a beneficial role in ischemia-reperfusion (IR)-induced intestinal injury, we used pharmacological manipulation of O-GlcNAc to induce loss- and gain-of-function conditions and evaluated the viability and apoptosis of intestinal epithelioid cells in an in vitro oxygen-glucose deprivation (OGD) model and tissue injury grade in a small intestinal ischemia-reperfusion (SIIR) mouse model. We found that 1) Upregulation of O-GlcNAcylation induced by glucosamine (GlcN, increase in HBP flux) or thiamet G (an OGA inhibitor) enhanced intestinal cell survival in the OGD model. In contrast, downregulation of O-GlcNAcylation induced by DON (due to a reduction in HBP flux) or OMSI-1 (an OGT inhibitor) made the cells more susceptible to hypoxia injury. 2) Reducing the increase in O-GlcNAcylation levels with a combination of either GlcN with DON or thiamet G with OMSI-1 partly canceled its protective effect on OGD-induced cell injury. 3) In the in vivo SIIR mouse model, GlcN augmented intestinal protein O-GlcNAcylation and significantly alleviated intestinal injury by inhibiting cell apoptosis. These results indicate that acute increases in protein O-GlcNAcylation confer protection against intestinal ischemia insults, suggesting that O-GlcNAcylation, as an endogenous stress sensor, could be a universal protective mechanism and could be a potential therapeutic target for intestinal ischemic disease.
蛋白质 O-GlcNAc 修饰是一种动态的翻译后蛋白质修饰，调节正常生理和疾病中基本的细胞功能。蛋白质 O-GlcNAc 修饰的水平由己糖胺生物合成途径 (HBP) 的通量决定，HBP 是糖酵解的一个分支，并且直接由一对酶控制：O-GlcNAc 转移酶 (OGT) 和 O-GlcNAcase (OGA)。蛋白质 O-GlcNAc 修饰的增加已被证明对心脏和大脑与缺血相关的损伤具有保护作用。为了确定 O-GlcNAc 修饰是否在缺血再灌注 (IR) 诱导的肠道损伤中发挥有益作用，我们使用 O-GlcNAc 的药理学操作诱导失能和获得功能条件，并在体外氧葡萄糖剥夺 (OGD) 模型中评估肠道上皮细胞的活力和凋亡以及在小肠缺血再灌注 (SIIR) 小鼠模型中的组织损伤程度。我们发现：1）通过葡萄糖胺 (GlcN，增加 HBP 通量) 或噻唑甲酰胺 G(一种 OGA 抑制剂) 上调 O-GlcNAc 修饰诱导的，增强了 OGD 模型中的肠道细胞存活。相反，通过 DON(由于 HBP 通量减少) 或 OMSI-1(一种 OGT 抑制剂) 下调 O-GlcNAc 修饰使细胞对缺氧损伤更敏感。2）用 GlcN 与 DON 或噻唑甲酰胺 G 与 OMSI-1 联合降低 O-GlcNAc 修饰水平的增加部分抵消了其对 OGD 诱导的细胞损伤的保护作用。3）在体内 SIIR 小鼠模型中，GlcN 增加了肠道蛋白 O-GlcNAc 修饰，并通过抑制细胞凋亡显著减轻了肠道损伤。这些结果表明，蛋白质 O-GlcNAc 修饰的急性增加可抵抗肠道缺血损伤，提示 O-GlcNAc 修饰作为内源性应激传感器，可能是一种普遍的保护机制，并可能成为肠道缺血性疾病的潜在治疗靶点。
