Abstract

Objective

Microglial activation is an essential pathological mechanism of spinal cord ischemia-reperfusion injury (SCIRI). Previous studies showed dexmedetomidine (DEX) could alleviate SCIRI while the mechanism was not clear. This study aims to investigate the role of DEX in microglial activation and clarify the underlying mechanism.

Methods

The motion function of mice was quantified using the Basso Mouse Scale for Locomotion. The expression of long non-coding RNA (lncRNA) small nucleolar RNA host gene 14 (SNHG14) was determined by qRT-PCR. The expression of high-mobility group box 1 (HMGB1) was measured by western blot. The activation of microglia was evaluated by the expression of ED-1 and the levels of TNF-α and IL-6. The interplay between SNHG14 and HMGB1 was confirmed with RNA pull-down and RIP assay. The stability of HMGB1 was measured by ubiquitination assay and cycloheximide-chase assay.

Results

DEX inhibited microglial activation and down-regulated SNHG14 expression in SCIRI mice and oxygen and glucose deprivation/reoxygenation (OGD/R)-treated primary microglia. Functionally, SNHG14 overexpression reversed the inhibitory effect of DEX on OGD/R-induced microglial activation. Further investigation confirmed that SNHG14 bound to HMGB1, positively regulated HMGB1 expression by enhancing its stability. In addition, the silence of HMGB1 eliminated the pro-activation impact of SNHG14 overexpression on DEX-treated microglia under the OGD/R condition. Finally, in vivo experiments showed SNHG14 overexpression abrogated the therapeutic effect of DEX on SCIRI mice by up-regulating HMGB1.

Conclusion

DEX accelerated HMGB1 degradation via down-regulating SNHG14, thus inhibiting microglial activation in SCIRI mice.

中文翻译：

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右美托咪定通过 SNHG14/HMGB1 通路抑制脊髓缺血再灌注损伤小鼠小胶质细胞活化

摘要

客观的

小胶质细胞活化是脊髓缺血再灌注损伤（SCIRI）的重要病理机制。以往的研究表明，右美托咪定（DEX）可以缓解SCIRI，但机制尚不清楚。本研究旨在探讨 DEX 在小胶质细胞激活中的作用并阐明其潜在机制。

方法

使用 Basso Mouse Scale for Locomotion 对小鼠的运动功能进行量化。通过qRT-PCR测定长非编码RNA（lncRNA）小核仁RNA宿主基因14（SNHG14）的表达。通过蛋白质印迹测量高迁移率组框1（HMGB1）的表达。通过ED-1的表达以及TNF-α和IL-6的水平评估小胶质细胞的活化。SNHG14 和 HMGB1 之间的相互作用通过 RNA 下拉和 RIP 分析得到证实。HMGB1的稳定性通过泛素化测定和放线菌酮-追踪测定来测量。

结果

DEX 在 SCIRI 小鼠和氧和葡萄糖剥夺/复氧 (OGD/R) 处理的原代小胶质细胞中抑制小胶质细胞活化并下调 SNHG14 表达。在功能上，SNHG14 过表达逆转了 DEX 对 OGD/R 诱导的小胶质细胞活化的抑制作用。进一步的研究证实，SNHG14 与 HMGB1 结合，通过增强其稳定性正向调节 HMGB1 的表达。此外，HMGB1 的沉默消除了在 OGD/R 条件下 SNHG14 过表达对 DEX 处理的小胶质细胞的促激活影响。最后，体内实验表明 SNHG14 过表达通过上调 HMGB1 消除了 DEX 对 SCIRI 小鼠的治疗作用。

结论

DEX通过下调 SNHG14加速 HMGB1 降解，从而抑制 SCIRI 小鼠的小胶质细胞活化。