Augmented O-GlcNAc, signaling via glucosamine attenuates oxidative stress and apoptosis, following contrast-induced acute kidney injury in rats
Augmented O-GlcNAc, signaling via glucosamine attenuates oxidative stress and apoptosis, following contrast-induced acute kidney injury in rats
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DOI：
10.1016/j.freeradbiomed.2016.12.032
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发表时间：
2017-02-01
影响因子：
7.4
通讯作者：
Ding, Xiaoqiang
中科院分区：
文献类型：
--
作者：
Hu, Jiachang;Chen, Rongyi;Ding, Xiaoqiang
造影剂引起的急性肾损伤（CI-AM）是一种医源性肾损伤，与易感个体的大量发病率和死亡率相关。尽管对多种肾脏保护药物进行了广泛研究，但已证明可有效减少 CI-AKI 的策略有限。 O-连接 β-N-乙酰氨基葡萄糖 (O-GlcNAc) 是细胞内蛋白质的翻译后调节修饰，控制着多种蛋白质（包括细胞质和细胞核）的功能。越来越多的证据表明，O-GlcNAc 水平会因应激反应而增加，并且这种反应的急剧增强具有细胞保护作用。然而，增强的 O-GlcNAc 信号传导提供肾脏保护以抵抗造影剂损伤的潜在机制仍然未知。在这里，我们研究了通过葡萄糖胺增强的 O-GlcNAc 信号传导对 CI-AM 的影响，并探讨了潜在的分子机制，特别是其与 P13 激酶 (PI3K)/Akt 信号传导的关系。我们使用了一种新颖可靠的 CT-AKI 模型，由 5/6 肾切除 (NE) 大鼠组成，脱水 48 小时后通过尾静脉注射低渗透造影剂（碘海醇，10 mL/kg，3.5gI）。结果表明，葡萄糖胺增强的 O-GlcNAc 信号传导可防止肾脏免受碘海醇诱导的损伤，其特征是肾功能障碍、肾小管损伤、细胞凋亡和氧化应激减弱。此外，这种肾脏保护作用可以通过四氧嘧啶（一种 O-GlcNAc 转移酶抑制剂）治疗来阻断。增强的 O-GlcNAc 信号传导还增加了磷酸-Akt（Ser473，但不是 Thr308 和 Thr450）、磷酸-GSK-3 beta、Nrf2 和 Bcl-2 的蛋白表达水平，并降低了 Bar 和裂解的 caspase-3 的水平。四氧嘧啶和 PI3K 特异性抑制剂（Wortmannin 和 LY294002）均通过抑制 Akt 信号通路来阻断葡萄糖胺的保护。我们通过免疫沉淀和蛋白质印迹进一步鉴定了 O-GlcNAcylated Akt。我们证实 Akt 被 O-GlcNAc 酰化修饰，而葡萄糖胺预处理增加了 Akt 的 O-GlcNAc 酰化。总的来说，结果表明氨基葡萄糖通过增强 O-GlcNAc 和激活 PI3K/Akt 信号传导诱导针对 CI-AKI 的肾脏保护，使其成为预防 CI-AKI 的有前途的策略。
Contrast-induced acute kidney injury (CI-AM) is an iatrogenic renal injury and associated with substantial morbidity and mortality in susceptible individuals. Despite extensive study of a variety of agents for renal protection, limited strategies have been shown to be effective in the reduction of CI-AKI. O-linked beta-N-acetylglucosainine (O-GlcNAc) is a post-translational regulatory modification of intracellular proteins and governs the function of numerous proteins, both cytosolic and nuclear. Increasing evidence suggests that O-GlcNAc levels are increased in response to stress and that acute augmentation of this reaction is cytoprotective. However, the underlying mechanisms by which augmented O-GlcNAc signaling provides renoprotection against contrast media insults is still unknown. Here, we investigated the effect of augmented O-GlcNAc signaling via glucosamine on CI-AM and explored the underlying molecular mechanisms, particularly its relationship with P13-kinase (PI3K)/Akt signaling. We used a novel and reliable CT-AKI model consisting of 5/6 nephrectomized (NE) rats, and a low-osmolar contrast media (iohexol, 10 mL/kg, 3.5gI) injected via the tail vein after dehydration for 48 h. The results showed that augmented O-GlcNAc signaling by glucosamine prevented the kidneys against iohexol-induced injury characterized by the attenuation of renal dysfunction, tubular damage, apoptosis and oxidative stress. Furthermore, this renoprotection was blocked by treatment with alloxan, an O-GlcNAc transferase inhibitor. Augmented O-GlcNAc signaling also increased the protein expression levels of phospho-Akt (Ser473, but not Thr308 and Thr450), phospho-GSK-3 beta, Nrf2, and Bcl-2, and decreased the levels of Bar and cleaved caspase-3. Both alloxan and specific inhibitors of PI3K (Wortmannin and LY294002) blocked the protection of glucosamine via inhibiting Akt signaling pathway. We further identified O-GlcNAcylated Akt through immunoprecipitation and western blot. We confirmed that Akt was modified by O-GlcNAcylation, and glucosamine pretreatment increased the O-GlcNAcylation of Akt. Collectively, the results demonstrate that glucosamine induces renoprotection against CI-AKI through augmented O-GlcNAc and activation of PI3K/Akt signaling, making it a promising strategy for preventing CI-AKI.