ALPK1- and TIFA-Dependent Innate Immune Response Triggered by the Helicobacter pylori Type IV Secretion System

Publication date: 5 September 2017
Source:Cell Reports, Volume 20, Issue 10
Author(s): Stephanie Zimmermann, Lennart Pfannkuch, Munir A. Al-Zeer, Sina Bartfeld, Manuel Koch, Jianping Liu, Cindy Rechner, Meike Soerensen, Olga Sokolova, Alla Zamyatina, Paul Kosma, André P. Mäurer, Frithjof Glowinski, Klaus-Peter Pleissner, Monika Schmid, Volker Brinkmann, Alexander Karlas, Michael Naumann, Marion Rother, Nikolaus Machuy, Thomas F. Meyer
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.

Graphical abstract

Teaser

Zimmermann et al. identify pathogen and host factors involved in NF-κB activation after infection with type IV secretion-proficient Helicobacter pylori. Central hits are ALPK1 and TIFA. ALPK1 is necessary for phosphorylation-dependent formation of TIFA complexes (TIFAsomes) with TRAF2. This yields HBP-ALPK1-TIFA-TRAF2-NF-κB as the core-regulon of H. pylori-induced innate immune activation.


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