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Τρίτη 5 Σεπτεμβρίου 2017

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

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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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