BACKGROUND Propofol is a known intravenous hypnotic drug used for induction and maintenance of sedation and general anesthesia. Emerging studies also reveal a neuroprotective effect of propofol in diverse diseases of neuronal injuries via modulating microglia activation. In this study, we aimed to uncover the downstream targets of propofol in this process. METHODS RNA sequencing analysis to identify genes implicated in the propofol-mediated neuroprotective effect. Quantitative real-time PCR, enzyme-linked immunosorbent assay, and Western blotting analysis were performed to analyze inflammatory gene expression, cytokine levels, and TGM2. BV2 cells and primary microglia were used for functional verification and mechanism studies. RESULTS The multifunctional enzyme transglutaminase 2 (TGM2) was identified as a putative functional mediator of propofol. TGM2 was significantly upregulated in lipopolysaccharide- (LPS-) primed BV2 cells. Genetic silencing of TGM2 abolished LPS-induced microglial activation. Notably, gain-of-function experiments showed that the proinflammatory effects of TGM2 were dependent on its GTP binding activity instead of transamidase activity. Then, TGM2 was revealed to activate the NF-κB signaling pathway to facilitate microglial activation. Propofol can inhibit TGM2 expression and NF-κB signaling in BV2 cells and primary microglia. Ectopic expression of TGM2 or constitutively active IKKβ (CA-IKKβ) can compromise propofol-induced anti-inflammatory effects. CONCLUSIONS Our findings suggest that TGM2-mediated activation of NF-κB signaling is an important mechanism in the propofol-induced neuroprotective effect that prevents microglial activation.

中文翻译：

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异丙酚通过靶向 TGM2/NF-κB 信号传导抑制小胶质细胞炎症。

背景技术丙泊酚是一种已知的用于镇静和全身麻醉的诱导和维持的静脉内催眠药。新兴研究还揭示了丙泊酚通过调节小胶质细胞活化在多种神经元损伤疾病中的神经保护作用。在本研究中，我们旨在揭示丙泊酚在此过程中的下游靶点。方法 RNA 测序分析以确定与丙泊酚介导的神经保护作用有关的基因。进行定量实时 PCR、酶联免疫吸附测定和蛋白质印迹分析以分析炎症基因表达、细胞因子水平和 TGM2。BV2 细胞和原代小胶质细胞用于功能验证和机制研究。结果多功能酶转谷氨酰胺酶2（TGM2）被鉴定为丙泊酚的推定功能介质。TGM2 在脂多糖 (LPS-) 引发的 BV2 细胞中显着上调。TGM2 的遗传沉默消除了 LPS 诱导的小胶质细胞活化。值得注意的是，功能获得性实验表明，TGM2 的促炎作用取决于其 GTP 结合活性而不是转酰胺酶活性。然后，发现 TGM2 激活 NF-κB 信号通路以促进小胶质细胞活化。丙泊酚可抑制 BV2 细胞和原代小胶质细胞中的 TGM2 表达和 NF-κB 信号传导。TGM2 或组成型活性 IKKβ (CA-IKKβ) 的异位表达会损害丙泊酚诱导的抗炎作用。