Department of Molecular Biology, Max-Planck Institute for Infection Biology, 10117 Berlin, Germany.
Department of Molecular Biology, Max-Planck Institute for Infection Biology, 10117 Berlin, Germany; Research Center for Infectious Diseases, ZINF, Institute for Molecular Infection Biology, IMIB, University of Würzburg, 97080 Würzburg, Germany.
Cell Rep. 2017 Sep 5;20(10):2384-2395. doi: 10.1016/j.celrep.2017.08.039.
Activation of transcription factor NF-κB is a hallmark of infection with the gastric pathogen Helicobacter pylori, associated with inflammation and carcinogenesis. Genome-wide RNAi screening revealed numerous host factors involved in H. pylori-, but not IL-1β- and TNF-α-dependent NF-κB regulation. Pathway analysis including CRISPR/Cas9-knockout and recombinant protein technology, immunofluorescence microscopy, immunoblotting, mass spectrometry, and mutant H. pylori strains identified the H. pylori metabolite D-glycero-β-D-manno-heptose 1,7-bisphosphate (βHBP) as a cagPAI type IV secretion system (T4SS)-dependent effector of NF-κB activation in infected cells. Upon pathogen-host cell contact, TIFA forms large complexes (TIFAsomes) including interacting host factors, such as TRAF2. NF-κB activation, TIFA phosphorylation, and TIFAsome formation depend on a functional ALPK1 kinase, highlighting the ALPK1-TIFA axis as a core innate immune pathway. ALPK1-TIFA-mediated NF-κB activation was independent of CagA protein translocation, indicating that CagA translocation and HBP delivery to host cells are distinct features of the pathogen's T4SS.
转录因子 NF-κB 的激活是幽门螺杆菌感染的一个标志，与炎症和癌变有关。全基因组 RNAi 筛选揭示了许多宿主因子参与了幽门螺杆菌，但不参与 IL-1β 和 TNF-α 依赖性 NF-κB 调节。包括 CRISPR/Cas9 敲除和重组蛋白技术、免疫荧光显微镜、免疫印迹、质谱和突变型幽门螺杆菌菌株在内的途径分析，确定了幽门螺杆菌代谢物 D-甘油-D-甘露庚糖 1,7-双磷酸（βHBP）是感染细胞中 cagPAI 型 IV 型分泌系统（T4SS）依赖性 NF-κB 激活的效应物。在病原体-宿主细胞接触时，TIFA 形成包括相互作用的宿主因子（如 TRAF2）在内的大型复合物（TIFAsomes）。NF-κB 激活、TIFA 磷酸化和 TIFAsome 形成依赖于功能性 ALPK1 激酶，突出了 ALPK1-TIFA 轴作为核心先天免疫途径。ALPK1-TIFA 介导的 NF-κB 激活不依赖于 CagA 蛋白易位，表明 CagA 易位和 HBP 递送到宿主细胞是病原体 T4SS 的独特特征。
