Abstract
The cell adhesion protein and tumour suppressor E-cadherin exhibits important functions in the prevention of gastric cancer. As a class-I carcinogen, Helicobacter pylori (H. pylori) has developed a unique strategy to interfere with E-cadherin functions. In previous studies, we have demonstrated that H. pylori secretes the protease high temperature requirement A (HtrA) which cleaves off the E-cadherin ectodomain (NTF) on epithelial cells. This opens cell-to-cell junctions, allowing bacterial transmigration across the polarised epithelium. Here, we investigated the molecular mechanism of the HtrA-E-cadherin interaction and identified E-cadherin cleavage sites for HtrA. Mass-spectrometry-based proteomics and Edman degradation revealed three signature motifs containing the [VITA]-[VITA]-x-x-D-[DN] sequence pattern, which were preferentially cleaved by HtrA. Based on these sites, we developed a substrate-derived peptide inhibitor that selectively bound and inhibited HtrA, thereby blocking transmigration of H. pylori. The discovery of HtrA-targeted signature sites might further explain why we detected a stable 90 kDa NTF fragment during H. pylori infection, but also additional E-cadherin fragments ranging from 105 kDa to 48 kDa in in vitro cleavage experiments. In conclusion, HtrA targets E-cadherin signature sites that are accessible in in vitro reactions, but might be partially masked on epithelial cells through functional homophilic E-cadherin interactions.
Highlights
Can relieve Kaiso-dependent transcriptional repression in the nucleus[6,7]
The biological significance of HtrA-mediated E-cadherin cleavage has been shown for the Gram-negative pathogens Campylobacter jejuni (C. jejuni), enteropathogenic Escherichia coli (EPEC) and Shigella flexneri of the gastrointestinal tract[20,25,26], indicating that E-cadherin represents a primary target in bacterial pathogenesis
When the supernatant was analysed with the anti-EC5 antibody, the hCdh1NTF fragment enriched during H. pylori exposure was already visible after 4 h of H. pylori exposure and the levels increased during the 16 h of infection (Fig. 1B, upper panels)
Summary
Can relieve Kaiso-dependent transcriptional repression in the nucleus[6,7]. an intact E-cadherin complex plays a significant role in cell-to-cell adhesion and prevention of invasive growth and metastasis of many tumour types[8]. H. pylori-associated metastatic gastric cancer (GC) is the leading cause of cancer-related deaths worldwide because effective treatment strategies are missing Both the diffuse and intestinal GC types have been correlated with an altered functionality of the E-cadherin complex. H. pylori HtrA is highly active under extreme conditions[27], indicating that it is important for bacterial physiology in the environment of the stomach. This is supported by the finding that the htrA gene is essential and cannot be deleted or mutagenised in the H. pylori genome[21,28,29]. Previous studies investigating MMP-mediated E-cadherin cleavage and Edman sequencing of E-cadherin fragments have suggested the residue pattern L585↓S↓D587 (CDH1, P12830) in the EC4 domain as a target site[17]. Whether H. pylori HtrA targets the same sites or prefers another amino acid sequence is unknown, but this information is crucially important for understanding the HtrA-E-cadherin interaction and developing HtrA inhibitors
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
