Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China.
Cytokine. 2011 Aug;55(2):229-36. doi: 10.1016/j.cyto.2011.05.003. Epub 2011 May 28.
Recent studies have demonstrated that P2X7 plays a critical role in the immune system. Here, our results showed that P2X7 activated a NF-κB - but not an IFN-β-dependent luciferase reporter gene in HEK293T cells. P2X7 was involved in the LPS- and ATP-induced NF-κB activation but did not significantly impact the response to Zymosan in RAW264.7 cells. The activation of NF-κB and IFN-β induced by myeloid differentiation primary-response protein 88 (MyD88) was enhanced by P2X7 co-expression. The siRNA silencing MyD88 almost abolished the NF-κB activation induced by P2X7, and co-immunoprecipitation showed that P2X7 interacted with MyD88. The amino acids in the C-terminus, especially the LPS-binding region of P2X7, were critical for the cellular localization and immune function of P2X7. P2X7ΔC (190 amino acids deleted in the C-terminus) and P2X7 G586A variants localized throughout the cytoplasma with a little aggregation, which differs from the cell membrane localization of wild type P2X7. Both of them could not localize to Golgi or endoplasmic reticulum. P2X7ΔC and P2X7 G586A had impaired proteolytic cleavage of caspase-1 into the functional p20 subunit, which can activate pro-inflammatory cytokines such as IL-1β. P2X7 G586A also showed a slight interaction with MyD88 in our co-immunoprecipitation experiment. This interaction might result in the attenuated activation of NF-κB and IFN-β induced by MyD88.
最近的研究表明，P2X7 在免疫系统中发挥着关键作用。在这里，我们的结果表明，P2X7 在 HEK293T 细胞中激活了 NF-κB-但不是 IFN-β-依赖性荧光素酶报告基因。P2X7 参与 LPS 和 ATP 诱导的 NF-κB 激活，但对 RAW264.7 细胞中 Zymosan 的反应没有显著影响。髓样分化初级反应蛋白 88（MyD88）诱导的 NF-κB 和 IFN-β 的激活通过 P2X7 共表达得到增强。siRNA 沉默 MyD88 几乎完全消除了 P2X7 诱导的 NF-κB 激活，共免疫沉淀显示 P2X7 与 MyD88 相互作用。P2X7 羧基末端的氨基酸，特别是 LPS 结合区，对于 P2X7 的细胞定位和免疫功能至关重要。P2X7ΔC（羧基末端缺失 190 个氨基酸）和 P2X7 G586A 变体在细胞质中均匀分布，有少量聚集，与野生型 P2X7 的细胞膜定位不同。它们都不能定位到高尔基体或内质网。P2X7ΔC 和 P2X7 G586A 不能将半胱天冬酶-1 切割成具有功能的 p20 亚基，这会激活白细胞介素-1β等促炎细胞因子。在我们的共免疫沉淀实验中，P2X7 G586A 也与 MyD88 有轻微相互作用。这种相互作用可能导致 MyD88 诱导的 NF-κB 和 IFN-β 激活减弱。
