Physiological Chemistry Department, Genentech, Inc, South San Francisco, CA 94080, USA.
J Immunol. 2011 Jun 1;186(11):6553-61. doi: 10.4049/jimmunol.1100478. Epub 2011 Apr 20.
Apoptotic cell death is important for embryonic development, immune cell homeostasis, and pathogen elimination. Innate immune cells also undergo a very rapid form of cell death termed pyroptosis after activating the protease caspase-1. The hemichannel pannexin-1 has been implicated in both processes. In this study, we describe the characterization of pannexin-1-deficient mice. LPS-primed bone marrow-derived macrophages lacking pannexin-1 activated caspase-1 and secreted its substrates IL-1β and IL-18 normally after stimulation with ATP, nigericin, alum, silica, flagellin, or cytoplasmic DNA, indicating that pannexin-1 is dispensable for assembly of caspase-1-activating inflammasome complexes. Instead, thymocytes lacking pannexin-1, but not the P2X7R purinergic receptor, were defective in their uptake of the nucleic acid dye YO-PRO-1 during early apoptosis. Cell death was not delayed but, unlike their wild-type counterparts, Panx1(-/-) thymocytes failed to recruit wild-type peritoneal macrophages in a Transwell migration assay. These data are consistent with pannexin-1 liberating ATP and other yet to be defined "find me" signals necessary for macrophage recruitment to apoptotic cells.
细胞凋亡对于胚胎发育、免疫细胞内稳态和病原体清除至关重要。先天免疫细胞在激活蛋白酶 caspase-1 后，也会经历一种称为细胞焦亡的非常迅速的细胞死亡形式。半通道连接蛋白-1（pannexin-1）与这两个过程都有关。在这项研究中，我们描述了 pannexin-1 缺陷小鼠的特征。LPS 预处理的骨髓来源的巨噬细胞在缺乏 pannexin-1 的情况下，在用 ATP、 Nigericin、 Alum、二氧化硅、鞭毛蛋白或细胞质 DNA 刺激后，仍然可以正常激活 caspase-1 并分泌其底物 IL-1β 和 IL-18，这表明 pannexin-1 对于 caspase-1 激活的炎性小体复合物的组装是可有可无的。相反，缺乏 pannexin-1 的胸腺细胞，但不缺乏 P2X7R 嘌呤能受体，在早期细胞凋亡过程中，对核酸染料 YO-PRO-1 的摄取存在缺陷。细胞死亡并没有延迟，但与野生型细胞不同的是，Panx1(-/-) 胸腺细胞在 Transwell 迁移实验中未能招募野生型腹腔巨噬细胞。这些数据与 pannexin-1 释放 ATP 和其他尚未确定的“寻找我”信号一致，这些信号对于巨噬细胞向凋亡细胞的招募是必需的。
