Department of Spinal Surgery, Affiliated Nanhua Hospital, University of South China, Hengyang, Hunan 421000, P.R. China.
Mol Med Rep. 2020 Dec;22(6):4734-4742. doi: 10.3892/mmr.2020.11545. Epub 2020 Sep 28.
Sulfiredoxin‑1 (SRX1) is a conserved endogenous antioxidative protein, which is involved in the response to cellular damage caused by oxidative stress. Oxidative stress and inflammation are the primary pathological changes in spinal cord injuries (SCI). The aim of present study was to explore the roles of SRX1 in SCI. Using reverse transcription‑quantitative PCR and western blotting, the present study discovered that the expression levels of SRX1 were downregulated in the spinal cord tissues of SCI model rats. Massive irregular cavities and decreased Nissl bodies were observed in the model group compared with the sham group. Thus, to determine the underlying mechanisms, neuron‑like PC12 cells were cultured in vitro. Western blotting analysis indicated that SRX1 expression levels were downregulated following the exposure of cells to lipopolysaccharide (LPS). Following the transfection with the SRX1 overexpression plasmid and stimulation with LPS, the results of the Cell Counting Kit‑8 assay indicated that the cell viability was increased compared with LPS stimulation alone. Furthermore, the expression levels of proinflammatory cytokines secreted by LPS‑treated PC12 cells were downregulated following SRX1 overexpression. Increased malondialdehyde content, decreased superoxide dismutase activity and reactive oxygen species production were also identified in PC12 cells treated with LPS using commercial detection kits, whereas the overexpression of SRX1 partially reversed the effects caused by LPS stimulation. The aforementioned results were further verified by determining the expression levels of antioxidative proteins using western blotting analysis. In addition, nuclear factor erythroid‑2‑related factor 2 (NRF2), a transcription factor known to regulate SRX1, was indicated to participate in the protective effect of SRX1 against oxidative stress. Inhibition of NRF2 further downregulated the expression levels of SRX1, NAD(P)H dehydrogenase quinone 1 and heme oxygenase‑1 in the presence of LPS, while activation of NRF2 reversed the effects of LPS on the expression levels of these proteins. In conclusion, the results of the present study indicated that the anti‑inflammatory and antioxidative effects of SRX1 may depend on NRF2, providing evidence that SRX1 may serve as a novel molecular target to exert a neuroprotective effect in SCI.
硫氧还蛋白 1（SRX1）是一种保守的内源性抗氧化蛋白，参与细胞对氧化应激引起的损伤的反应。氧化应激和炎症是脊髓损伤（SCI）的主要病理变化。本研究旨在探讨 SRX1 在 SCI 中的作用。通过逆转录定量 PCR 和 Western blot 分析，本研究发现 SRX1 在 SCI 模型大鼠脊髓组织中的表达水平下调。与假手术组相比，模型组可见大量不规则腔和尼氏体减少。因此，为了确定潜在的机制，在体外培养神经元样 PC12 细胞。Western blot 分析表明，细胞暴露于脂多糖（LPS）后 SRX1 表达水平下调。用 SRX1 过表达质粒转染并用 LPS 刺激后，CCK-8 细胞计数试剂盒检测结果表明，与 LPS 刺激单独作用相比，细胞活力增加。此外，SRX1 过表达后，LPS 处理的 PC12 细胞分泌的促炎细胞因子的表达水平下调。使用商业检测试剂盒还发现，LPS 处理的 PC12 细胞中的丙二醛含量增加，超氧化物歧化酶活性和活性氧产生减少，而过表达 SRX1 部分逆转了 LPS 刺激引起的这些作用。通过 Western blot 分析测定抗氧化蛋白的表达水平进一步验证了上述结果。此外，核因子红细胞 2 相关因子 2（NRF2），一种已知调节 SRX1 的转录因子，表明参与了 SRX1 对氧化应激的保护作用。在 LPS 存在的情况下，NRF2 的抑制进一步下调了 SRX1、NAD（P）H 脱氢醌 1 和血红素加氧酶-1 的表达水平，而 NRF2 的激活逆转了 LPS 对这些蛋白表达水平的影响。综上所述，本研究结果表明，SRX1 的抗炎和抗氧化作用可能依赖于 NRF2，为 SRX1 作为 SCI 中发挥神经保护作用的新型分子靶点提供了证据。
