Medical Research Center, Affiliated Hospital 2 of Nantong University, Nantong 226001, People's Republic of China.
Medical Research Center, Affiliated Hospital 2 of Nantong University, Nantong 226001, People's Republic of China; Department of Rehabilitation Medicine, Affiliated Hospital 2 of Nantong University, Nantong 226001, People's Republic of China.
Mol Immunol. 2021 Dec;140:250-266. doi: 10.1016/j.molimm.2021.10.017. Epub 2021 Nov 17.
Pyruvate kinase M2 (PKM2), a glycolytic rate-limiting enzyme, reportedly plays an important role in tumorigenesis and the inflammatory response by regulating the metabolic reprogramming. However, its contribution to microglial activation during neuroinflammation is still unknown. In this study, we observed an enhanced glycolysis level in the lipopolysaccharide (LPS)-activated microglia. Utilizing the glycolysis inhibitor 2-DG, we proved that LPS requires glycolysis to induce microglial pyroptosis. Moreover, the protein expression, dimer/monomer formation, phosphorylation and nuclear translocation of PKM2 were all increased by LPS. Silencing PKM2 or preventing its nuclear translocation by TEPP-46 significantly alleviated the LPS-induced inflammatory response and pyroptosis in microglia. Employing biological mass spectrometry combined with immunoprecipitation technology, we identified for the first time that PKM2 interacts with activating transcription factor 2 (ATF2) in microglia. Inhibition of glycolysis or preventing PKM2 nuclear aggregation significantly reduced the phosphorylation and activation of ATF2. Furthermore, knocking down ATF2 reduced the LPS-induced pyroptosis of microglia. In vivo, we showed the LPS-induced pyroptosis in the cerebral cortex tissues of mice, and first found that an increased PKM2 expression was co-localized with ATF2 in the inflamed mice brain. Collectively, our data suggested for the first time that PKM2, a key rate-limiting enzyme of the Warburg effect, directly interacts with the pro-inflammatory transcription factor ATF2 to bridge glycolysis and pyroptosis in microglia, which might be a pivotal crosstalk between metabolic reprogramming and neuroinflammation in the CNS.
丙酮酸激酶 M2（PKM2）是一种糖酵解限速酶，据报道通过调节代谢重编程在肿瘤发生和炎症反应中发挥重要作用。然而，其在神经炎症中小胶质细胞激活中的贡献尚不清楚。在本研究中，我们观察到脂多糖（LPS）激活的小胶质细胞中糖酵解水平增强。利用糖酵解抑制剂 2-DG，我们证明 LPS 需要糖酵解来诱导小胶质细胞细胞焦亡。此外，LPS 还增加了 PKM2 的蛋白表达、二聚体/单体形成、磷酸化和核转位。沉默 PKM2 或通过 TEPP-46 阻止其核转位可显著减轻 LPS 诱导的小胶质细胞炎症反应和细胞焦亡。采用生物质谱联合免疫沉淀技术，我们首次发现 PKM2 在小胶质细胞中与激活转录因子 2（ATF2）相互作用。抑制糖酵解或阻止 PKM2 核聚集显著降低了 ATF2 的磷酸化和激活。此外，敲低 ATF2 可减少 LPS 诱导的小胶质细胞细胞焦亡。在体内，我们显示了 LPS 在小鼠大脑皮质组织中诱导的细胞焦亡，并且首次发现炎症小鼠大脑中增加的 PKM2 表达与 ATF2 共定位。总之，我们的数据首次表明，作为瓦博格效应的关键限速酶，PKM2 直接与促炎转录因子 ATF2 相互作用，在小胶质细胞中架起糖酵解和细胞焦亡的桥梁，这可能是中枢神经系统代谢重编程和神经炎症之间的关键串扰。
