Background

Dementia places a significant burden on both patients and caregivers. Since diabetes is a risk factor for dementia, it is imperative to identify the relationship between diabetes and cognitive disorders. Protein disulfide isomerase (PDI) is an enzyme for oxidative protein folding. PDI S-nitrosylation is observed in the brain tissues of Alzheimer's disease patients. The aim of this study is to clarify the relationship between PDI S-nitrosylation and diabetes.

Methods

We used SH-SY5Y cells cultured in high-glucose media.

Results

S-nitrosylated PDI level increased at 7 days and remained high till 28 days in SH-SY5Y cells cultured in high-glucose media. Using PDI wild-type- or PDI C343S-expressing SH-SY5Y cells, PDI C343 was identified as the site of glucose-induced S-nitrosylation. IRE1α and PERK were phosphorylated at day 14 in the SH-SY5Y cells cultured in high-glucose media, and the phosphorylated status was maintained to day 28. To determine the effect of S-nitrosylated PDI on endoplasmic reticulum stress signaling, SH-SY5Y cells were treated with S-nitrosocystein (SNOC) for 30 min, following which the medium was replaced with SNOC-free media and the cells were cultured for 24 h. Only phosphorylated IRE1α treated with SNOC was associated with PDI S-nitrosylation. Neohesperidin, a flavonoid in citrus fruits, is a natural antioxidant. The treatment with neohesperidin in the final 7 days of glucose loading reversed PDI S-nitrosylation and improved cell proliferation.

Conclusion

Glucose loading leads to S-nitrosylation of PDI C343 and induces neurodegeneration via IRE1α phosphorylation.

General significance

The results may be useful for designing curative treatment strategies for dementia.

中文翻译：

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葡萄糖诱导的氧化应激导致神经母细胞瘤细胞中蛋白质二硫键异构酶的 S-亚硝基化

背景

痴呆症给患者和护理人员都带来了沉重的负担。由于糖尿病是痴呆症的危险因素，因此必须确定糖尿病与认知障碍之间的关系。蛋白质二硫化物异构酶 (PDI) 是一种用于蛋白质氧化折叠的酶。在阿尔茨海默病患者的脑组织中观察到PDI S-亚硝基化。本研究的目的是阐明 PDI S-亚硝基化与糖尿病之间的关系。

方法

我们使用在高糖培养基中培养的 SH-SY5Y 细胞。

结果

在高葡萄糖培养基中培养的 SH-SY5Y 细胞中，S-亚硝基化 PDI 水平在第 7 天增加并保持高水平直至 28 天。使用表达 PDI 野生型或 PDI C343S 的 SH-SY5Y 细胞，PDI C343 被鉴定为葡萄糖诱导的S-亚硝基化位点。在高糖培养基中培养的 SH-SY5Y 细胞中，IRE1α 和 PERK 在第 14 天被磷酸化，磷酸化状态维持到第 28 天。 为了确定S-亚硝基化 PDI 对内质网应激信号传导的影响，SH-SY5Y 细胞用S-亚硝基半胱氨酸 (SNOC) 处理 30 分钟，然后将培养基更换为不含 SNOC 的培养基，并将细胞培养 24 小时。只有经 SNOC 处理的磷酸化 IRE1α 与 PDI S 相关-亚硝基化。新橙皮苷是柑橘类水果中的一种黄酮类化合物，是一种天然抗氧化剂。在葡萄糖负荷的最后 7 天用新橙皮苷处理逆转 PDI S-亚硝基化并改善细胞增殖。

结论

葡萄糖负荷导致PDI C343 的S-亚硝基化并通过 IRE1α 磷酸化诱导神经变性。

一般意义

结果可能有助于设计痴呆症的治愈性治疗策略。