Department of Anesthesiology, Eye & ENT Hospital, Fudan University, 83 Fenyang Road, Shanghai, 200031, China.
Department of Anesthesiology, Fudan University Shanghai Cancer Center, Fudan University, Shanghai 200032, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
Can J Physiol Pharmacol. 2020 Nov;98(11):818-825. doi: 10.1139/cjpp-2019-0699. Epub 2020 Nov 1.
Microglial inflammation, involved in the occurrence and development of sepsis-associated encephalopathy, exhibits upregulation of proinflammatory cytokine and proinflammatory enzyme expression, leading to inflammation-induced neuronal cell apoptosis. TIR domain containing adaptor molecule-2 (TICAM-2) participates in lipopolysaccharide (LPS) mediated BV2 cell inflammation. SET8 plays a crucial role in a variety of cellular signal pathways. In this study, we hypothesize that SET8 participates in LPS-mediated microglial inflammation via modulation of TICAM-2 expression. Our data indicated that LPS induced BV2 inflammation via upregulation of TICAM-2 expression. Moreover, LPS treatment inhibited SET8 expression, while it increased activating transcription factor 2 (ATF2) expression. The effects of sh-SET8 and ATF2 overexpression were similar to that of LPS treatments. Inhibition of TICAM-2 expression counteracted sh-SET8-mediated and ATF2 overexpression mediated BV2 cell inflammation. Further, SET8 was found to interact with ATF2. A mechanistic study found that H4K20me1, a downstream target of SET8, and ATF2 enriched at the TICAM-2 promoter region. Luciferase reporter assays indicated that sh-SET8 increased TICAM-2 promoter activity but augmented the effect of ATF2 overexpression on TICAM-2 promoter activity as well. Co-transfection of sh-SET8 with ATF2 overexpression more dramatically increased TICAM-2 expression in BV2 cells. The present study indicated that SET8 interacted with ATF2 to modulate TICAM-2 expression, which participated in LPS-mediated BV2 cell inflammation.
小胶质细胞炎症参与了脓毒症相关脑病的发生和发展，表现为促炎细胞因子和促炎酶表达上调，导致炎症诱导的神经元细胞凋亡。TIR 结构域包含衔接分子-2（TICAM-2）参与脂多糖（LPS）介导的 BV2 细胞炎症。SET8 在多种细胞信号通路中发挥关键作用。在本研究中，我们假设 SET8 通过调节 TICAM-2 的表达参与 LPS 介导的小胶质细胞炎症。我们的数据表明，LPS 通过上调 TICAM-2 的表达诱导 BV2 炎症。此外，LPS 处理抑制 SET8 的表达，同时增加激活转录因子 2（ATF2）的表达。sh-SET8 和 ATF2 过表达的作用与 LPS 处理相似。抑制 TICAM-2 的表达可逆转 sh-SET8 介导和 ATF2 过表达介导的 BV2 细胞炎症。进一步研究发现，SET8 与 ATF2 相互作用。机制研究发现，SET8 的下游靶标 H4K20me1 和 ATF2 富集在 TICAM-2 启动子区域。荧光素酶报告基因检测表明，sh-SET8 增加了 TICAM-2 启动子活性，但增强了 ATF2 过表达对 TICAM-2 启动子活性的作用。sh-SET8 与 ATF2 过表达共转染更显著地增加了 BV2 细胞中 TICAM-2 的表达。本研究表明，SET8 与 ATF2 相互作用调节 TICAM-2 的表达，参与 LPS 介导的 BV2 细胞炎症。
