Department of Medical Chemistry and Biophysics, Umeå University, 90187 Umeå, Sweden.
Apoptosis. 2011 Aug;16(8):783-94. doi: 10.1007/s10495-011-0606-0.
Type I interferons constitute a family of pleiotropic cytokines that have a key role in both adaptive and innate immunity. The interferon signalling pathways mediate transcriptional regulation of hundreds of genes, which result in mRNA degradation, decreased protein synthesis, cell cycle inhibition and induction of apoptosis. To elucidate regulatory networks important for interferon induced cell death, we generated interferon resistant U937 cells by selection in progressively increasing concentrations of interferon-α (IFN-α). The results show that IFN-α activates the death receptor signalling pathway and that IFN resistance was associated with cross-resistance to several death receptor ligands in a manner similar to previously described Fas resistant U937 cell lines. Increased expression of the long splice variant of the cellular FLICE-like inhibitor protein (cFLIP-L) was associated with the resistance to death receptor and IFN-α stimulation. Accordingly, inhibition of cFLIP-L expression with cycloheximide or through cFLIP short harpin RNA interference restored sensitivity to Fas and/or IFN-α. Thus, we now show that selection for interferon resistance can generate cells with increased expression of cFLIP, which protects the cells from both IFN-α and death receptor mediated apoptosis.
I 型干扰素是一类多功能细胞因子家族，在适应性和先天性免疫中都具有关键作用。干扰素信号通路介导数百个基因的转录调控，导致 mRNA 降解、蛋白质合成减少、细胞周期抑制和凋亡诱导。为了阐明与干扰素诱导细胞死亡相关的调控网络，我们通过在逐渐增加的干扰素-α（IFN-α）浓度下选择，生成了干扰素抗性 U937 细胞。结果表明，IFN-α 激活了死亡受体信号通路，而干扰素抗性与对几种死亡受体配体的交叉抗性有关，这种方式类似于先前描述的 Fas 抗性 U937 细胞系。细胞 FLICE 样抑制剂蛋白（cFLIP-L）的长剪接变体的表达增加与对死亡受体和 IFN-α刺激的抗性有关。因此，用环已酰亚胺或通过 cFLIP 短发夹 RNA 干扰抑制 cFLIP-L 的表达，恢复了对 Fas 和/或 IFN-α的敏感性。因此，我们现在表明，选择干扰素抗性可以产生表达增加的 cFLIP 的细胞，这可以保护细胞免受 IFN-α 和死亡受体介导的凋亡。
