School of Integrated Chinese and Western Medicine, Hunan University of Chinese Medicine, Changsha, 410208, Hunan, China.
Key Laboratory of Hunan Province for Integrated Traditional Chinese and Western Medicine On Prevention and Treatment of Cardio-Cerebral Diseases, School of Integrated Chinese and Western Medicine, Hunan University of Chinese Medicine, Changsha, 410208, Hunan, China.
Sci Rep. 2024 May 27;14(1):12143. doi: 10.1038/s41598-024-62966-4.
Microglia are natural immune cells in the central nervous system, and the activation of microglia is accompanied by a reprogramming of glucose metabolism. In our study, we investigated the role of long non-coding RNA taurine-upregulated gene 1 (TUG1) in regulating microglial glucose metabolism reprogramming and activation. BV2 cells were treated with Lipopolysaccharides (LPS)/Interferon-γ (IFN-γ) to establish a microglial activation model. The glycolysis inhibitor 2-Deoxy-D-glucose (2-DG) was used as a control. The expression levels of TUG1 mRNA and proinflammatory cytokines such as Interleukin-1β (IL-1β), Interleukin -6, and Tumor Necrosis Factor-α mRNA and anti-inflammatory cytokines such as IL-4, Arginase 1(Arg1), CD206, and Ym1 were detected by RT-qPCR. TUG1 was silenced using TUG1 siRNA and knocked out using CRISPR/Cas9. The mRNA and protein expression levels of key enzymes involved in glucose metabolism, such as Hexokinase2, Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Lactate dehydrogenase, Glucose 6 phosphate dehydrogenase, and Pyruvate dehydrogenase (PDH), were determined by RT-qPCR and Western blotting. The glycolytic rate of microglial cells was measured using Seahorse. Differential metabolites were determined by metabolomics, and pathway enrichment was performed using these differential metabolites. Our findings revealed that the expression of TUG1 was elevated in proinflammatory-activated microglia and positively correlated with the levels of inflammatory factors. The expression of anti-inflammatory cytokines such as IL-4, Arg1, CD206, and Ym1 were decreased when induced with LPS/IFN-γ. However, this decrease was reversed by the treatment with 2-DG. Silencing of GAPDH led to an increase in the expression of TUG1 and inflammatory factors. TUG1 knockout (TUG1KO) inhibited the expression of glycolytic key enzymes and promoted the expression of oxidative phosphorylation key enzymes, shifting the metabolic profile of activated microglia from glycolysis to oxidative phosphorylation. Additionally, TUG1KO reduced the accumulation of metabolites, facilitating the restoration of the tricarboxylic acid cycle and enhancing oxidative phosphorylation in microglia. Furthermore, the downregulation of TUG1 was found to reduce the expression of both proinflammatory and anti-inflammatory cytokines under normal conditions. Interestingly, when induced with LPS/IFN-γ, TUG1 downregulation showed a potentially beneficial effect on microglia in terms of inflammation. Downregulation of TUG1 expression inhibits glycolysis and facilitates the shift of microglial glucose metabolism from glycolysis to oxidative phosphorylation, promoting their transformation towards an anti-inflammatory phenotype and exerting anti-inflammatory effects in BV2.
小胶质细胞是中枢神经系统中的天然免疫细胞,小胶质细胞的激活伴随着葡萄糖代谢的重编程。在我们的研究中,我们调查了长非编码 RNA 牛磺酸上调基因 1(TUG1)在调节小胶质细胞葡萄糖代谢重编程和激活中的作用。用脂多糖(LPS)/干扰素-γ(IFN-γ)处理 BV2 细胞以建立小胶质细胞激活模型。用 2-脱氧-D-葡萄糖(2-DG)作为对照。通过 RT-qPCR 检测 TUG1mRNA 和促炎细胞因子如白细胞介素-1β(IL-1β)、白细胞介素-6 和肿瘤坏死因子-αmRNA 和抗炎细胞因子如白细胞介素-4、精氨酸酶 1(Arg1)、CD206 和 Ym1 的表达水平。用 TUG1siRNA 沉默 TUG1 并用 CRISPR/Cas9 敲除。通过 RT-qPCR 和 Western blotting 测定参与葡萄糖代谢的关键酶,如己糖激酶 2、甘油醛-3-磷酸脱氢酶(GAPDH)、乳酸脱氢酶、葡萄糖 6 磷酸脱氢酶和丙酮酸脱氢酶(PDH)的 mRNA 和蛋白表达水平。用 Seahorse 测定小胶质细胞的糖酵解率。通过代谢组学确定差异代谢物,并使用这些差异代谢物进行途径富集。我们的研究结果表明,TUG1 在促炎激活的小胶质细胞中表达上调,并且与炎症因子的水平呈正相关。用 LPS/IFN-γ 诱导时,抗炎细胞因子如白细胞介素-4、Arg1、CD206 和 Ym1 的表达减少。然而,用 2-DG 处理可逆转这种减少。GAPDH 的沉默导致 TUG1 和炎症因子的表达增加。TUG1 敲除(TUG1KO)抑制糖酵解关键酶的表达,并促进氧化磷酸化关键酶的表达,使激活的小胶质细胞的代谢谱从糖酵解转变为氧化磷酸化。此外,TUG1KO 减少代谢物的积累,促进微胶质细胞三羧酸循环的恢复并增强氧化磷酸化。此外,在正常条件下,下调 TUG1 被发现可降低促炎和抗炎细胞因子的表达。有趣的是,当用 LPS/IFN-γ 诱导时,下调 TUG1 对小胶质细胞的炎症具有潜在的有益作用。下调 TUG1 的表达抑制糖酵解并促进小胶质细胞葡萄糖代谢从糖酵解向氧化磷酸化转变,促进其向抗炎表型转化,并在 BV2 中发挥抗炎作用。