The mitochondrial apoptosis apparatus in the detection of microbial infection.

细胞凋亡是一种明确的细胞死亡机制。然而，最近的文献数据表明，凋亡途径也可以被激活到只有一个低水平;该过程然后“中止”和细胞保持活着。已经进一步显示，如果凋亡半胱天冬酶不存在或实验抑制，则线粒体凋亡可以诱导细胞因子分泌。结合这两个观察结果，我们提供的证据表明，低水平的，“流产”的细胞凋亡诱导分泌白细胞介素（IL）6和IL-8的上皮细胞。我们进一步发现，感染的上皮细胞与一些病毒和细菌诱导“流产性细胞凋亡”，鉴定为在细胞凋亡的情况下，但依赖于组件的细胞凋亡装置的基因组DNA的损伤。因此，线粒体凋亡缺陷的细胞在感染多种感染因子后分泌较少的IL-6和IL-8。在这里，我们建议研究的概念，流产凋亡作为一种机制的病原体识别人类细胞。在该项目的第一部分，我们将测试的假设，即模式识别受体（PRR）可以诱导流产凋亡，这种信号是他们的活动的一部分，在感染病毒（我们将使用牛痘病毒衍生物MVA）和细菌（沙眼衣原体）。PRRs的促凋亡活性以前已经描述过，我们认为流产的凋亡可能是这种信号传导的功能。我们将特异性地触发单个PRR并检测细胞凋亡的失败，或者去除单个PRR或信号成分并检测对MVA或C诱导的细胞凋亡失败的影响。沙眼Bcl-2的化学抑制可引发细胞凋亡。我们将在这里测试的作用，各种亲和抗凋亡Bcl-2家族成员在流产的细胞凋亡的调节。在项目的第二部分，我们将奋进了解线粒体下游细胞凋亡失败的信号事件。我们发现了信号分子STING在细胞凋亡中的作用，并且文献数据涉及线粒体DNA。我们进一步显示了在细胞凋亡过程中线粒体分子Smac释放到细胞质中。我们将跟踪这些观察结果，调查Smac释放及其后果，并将其与细胞色素c的释放进行比较。我们还将测试线粒体DNA的作用，并分析一些可能参与细胞因子诱导的核心信号事件。细胞凋亡是一个新的概念，其在微生物识别中的应用将是理解和建立这一概念的重要一步。

Apoptosis is a well-defined mechanism of cell death. However, recent literature data indicate that the apoptosis-pathway can also be activated to only a low level; the process is then ‘aborted’ and the cell stays alive. It has further been shown that mitochondrial apoptosis can induce cytokine secretion if apoptotic caspases are absent or experimentally inhibited. Combining these two observations, we provide evidence that low-level, ‘abortive’ apoptosis induces the secretion of interleukin (IL) 6 and IL-8 from epithelial cells. We further find that infection of epithelial cells with a number of viruses and bacteria induces ‘abortive apoptosis’, identified as damage to the genomic DNA in the absence of apoptosis but dependent on components of the apoptosis apparatus. Accordingly, cells with defects in mitochondrial apoptosis secreted less IL-6 and IL-8 upon infection with a number of infectious agents. We here propose to study the concept that abortive apoptosis serves as a mechanism of pathogen recognition by human cells. In the first part of the project we will test the hypothesis that pattern recognition receptors (PRR) can induce abortive apoptosis, and that this signaling is part of their activity during infection with a virus (we will use the vaccinia virus derivative MVA) and a bacterium (Chlamydia trachomatis). Pro-apoptotic activity of PRRs has been described before; we believe that abortive apoptosis may be a function of this signaling. We will either specifically trigger individual PRR and test for abortive apoptosis, or take away individual PRR or signaling components and test for the effect on abortive apoptosis induced by MVA or C. trachomatis. Chemical inhibition of Bcl-2 can trigger abortive apoptosis. We will here test the roles of the various pro- and anti-apoptotic Bcl-2-family members in the regulation of abortive apoptosis. In the second part of the project we will endeavor to understand signaling events in the reception of abortive apoptosis downstream of mitochondria. We find a role of the signaling molecule STING in abortive apoptosis, and literature data implicate mitochondrial DNA. We further show the release of the mitochondrial molecule Smac into the cytosol during abortive apoptosis. We will follow up on these observations, investigate Smac-release and its consequences and compare it to the release of cytochrome c. We will also test for the role of mitochondrial DNA and will analyse some of the core signaling events that are likely involved in cytokine induction. Abortive apoptosis is a novel concept, and the demonstration of its use in microbe recognition would be an important step to understand and to establish this concept.