Actinomycin D and nutlin-3a (A + N) activate p53, partly through induction of phosphorylation on Ser392. The death of A549 cells induced by A + N morphologically resembles inflammation-inducing pyroptosis - cell destruction triggered by activated caspase-1. The treatment with A + N (or camptothecin) strongly upregulated caspase-1 and its two activators: IFI16 and NLRP1, however, caspase-1 activation was not detected. A549 cells may have been primed for pyroptosis, with the absence of a crucial trigger. The investigation of additional innate immunity elements revealed that A + N (or camptothecin) stimulated the expression of NLRX1, STING (stimulator of interferon genes) and two antiviral proteins, IFIT1 and IFIT3. IFI16 and caspase-1 are coded by p53-regulated genes which led us to investigate regulation of NLRP1, NLRX1, STING, IFIT1 and IFIT3 in p53-dependent mode. The upregulation of NLRP1, NLRX1 and STING was attenuated in p53 knockdown cells. The upsurge of the examined genes, and activation of p53, was inhibited by C16, an inhibitor of PKR kinase. PKR was tested due to its ability to phosphorylate p53 on Ser392. Surprisingly, C16 was active even in PKR knockdown cells. The ability of C16 to prevent activation of p53 and expression of innate immunity genes may be the source of its strong anti-inflammatory action. Moreover, cells exposed to A + N can influence neighboring cells in paracrine fashion, for instance, they shed ectodomain of COL17A1 protein and induce, in p53-dependent mode, the expression of gene for interleukin-7. Further, the activation of p53 also spurred the expression of SOCS1, an inhibitor of interferon triggered STAT1-dependent signaling. We conclude that, stimulation of p53 primes cells for the production of interferons (through upregulation of STING), and may activate negative-feedback within this signaling system by enhancing the production of SOCS1.

中文翻译：

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放线菌素D和nutlin-3a对p53的协同激活与先天免疫的关键调节因子和效应子的上调有关。

放线菌素D和nutlin-3a（A + N）激活p53，部分通过诱导Ser392上的磷酸化来实现。由A + N诱导的A549细胞死亡在形态上类似于炎症诱导的焦斑病-活化caspase-1触发的细胞破坏。A + N（或喜树碱）处理强烈上调了caspase-1及其两个激活因子：IFI16和NLRP1，但是未检测到caspase-1激活。在没有关键触发因素的情况下，A549细胞可能已经引发了凋亡。对其他先天免疫元件的研究表明，A + N（或喜树碱）刺激了NLRX1，STING（干扰素基因的刺激物）和两种抗病毒蛋白IFIT1和IFIT3的表达。IFI16和caspase-1由p53调控的基因编码，这使我们研究了NLRP1，NLRX1，STING，IFIT1和IFIT3处于p53依赖模式。在p53基因敲低细胞中，NLRP1，NLRX1和STING的上调被减弱。被检测基因的高潮和p53的激活被PKR激酶抑制剂C16抑制。由于PKR能够磷酸化Ser392上的p53，因此对其进行了测试。出人意料的是，即使在PKR敲低细胞中，C16仍具有活性。C16阻止p53激活和固有免疫基因表达的能力可能是其强大的抗炎作用的来源。此外，暴露于A + N的细胞可以旁分泌的方式影响邻近细胞，例如，它们脱落了COL17A1蛋白的胞外域，并以p53依赖性模式诱导白介素7基因的表达。此外，p53的激活还刺激了SOCS1的表达，SOCS1是干扰素触发的STAT1依赖信号转导的抑制剂。