Physiological institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany.
Cell Death Dis. 2018 Feb 20;9(3):300. doi: 10.1038/s41419-018-0373-8.
Pyroptosis is a highly inflammatory form of programmed cell death that is caused by infection with intracellular pathogens and activation of canonical or noncanonical inflammasomes. The purinergic receptor P2X is activated by the noncanonical inflammasome and contributes essentially to pyroptotic cell death. The Ca activated phospholipid scramblase and ion channel TMEM16F has been shown earlier to control cellular effects downstream of purinergic P2X receptors that ultimately lead to cell death. As pyroptotic cell death is accompanied by an increases in intracellular Ca, we asked whether TMEM16F is activated during pyroptosis. The N-terminal cleavage product of gasdermin D (GD-N) is an executioner of pyroptosis by forming large plasma membrane pores. Expression of GD-N enhanced basal Ca levels and induced cell death. We observed that GD-N induced cell death in HEK293 and HAP1 cells, which was depending on expression of endogenous TMEM16F. GD-N activated large whole cell currents that were suppressed by knockdown or inhibition of TMEM16F. The results suggest that whole cell currents induced by the pore forming domain of gasdermin-D, are at least in part due to activation of TMEM16F. Knockdown of other TMEM16 paralogues expressed in HAP1 cells suggest TMEM16F as a crucial element during pyroptosis and excluded a role of other TMEM16 proteins. Thus TMEM16F supports pyroptosis and other forms of inflammatory cell death such as ferroptosis. Its potent inhibition by tannic acid may be part of the anti-inflammatory effects of flavonoids.
细胞焦亡是一种由胞内病原体感染和经典或非经典炎性小体激活引起的高度炎症形式的细胞程序性死亡。嘌呤能受体 P2X 被非经典炎性小体激活，对细胞焦亡起主要作用。钙激活的磷脂翻转酶和离子通道 TMEM16F 先前已被证明可控制嘌呤能 P2X 受体下游的细胞效应，最终导致细胞死亡。由于细胞焦亡伴随着细胞内 Ca 浓度的增加，我们询问 TMEM16F 是否在细胞焦亡过程中被激活。Gasdermin D（GD-N）的 N 端裂解产物是通过形成大的质膜孔来执行细胞焦亡的执行者。GD-N 的表达增强了基础 Ca 水平并诱导细胞死亡。我们观察到 GD-N 在 HEK293 和 HAP1 细胞中诱导细胞死亡，这取决于内源性 TMEM16F 的表达。GD-N 激活了全细胞电流，该电流可被 TMEM16F 的敲低或抑制所抑制。结果表明，由 Gasdermin-D 的孔形成结构域诱导的全细胞电流至少部分归因于 TMEM16F 的激活。在 HAP1 细胞中敲低其他 TMEM16 同源物表明 TMEM16F 是细胞焦亡和排除其他 TMEM16 蛋白的关键元素。因此，TMEM16F 支持细胞焦亡和其他形式的炎症性细胞死亡，如铁死亡。单宁酸对其的强烈抑制可能是类黄酮抗炎作用的一部分。
