A Potential Association between Helicobacter pylori CagA EPIYA and Multimerization Motifs with Cytokeratin 18 Cleavage Rate during Early Apoptosis

Abstract

Background and Aims: Helicobacter pylori is a highly diverse pathogen, which encounters epithelial cells as the initial defense barrier during its lifelong infection. The structure of epithelial cells can be disrupted through cleavage of microfilaments. Cytokeratin 18 (CK18) is an intermediate filament, the cleavage of which is considered an early event during apoptosis following activation of effector caspases. Methods: Helicobacter pylori strains were isolated from 76 dyspeptic patients. cagA 3’ variable region and CagA protein status were analyzed by PCR and western blotting, respectively. Eight hours post‐co‐culture of AGS cells with different H. pylori strains, flow cytometric analysis was performed using M30 monoclonal antibody specific to CK18 cleavage‐induced neo‐epitope. Results: Higher rates of CK18 cleavage were detected during co‐culture of AGS cells with H. pylori strains bearing greater numbers of cagA EPIYA‐C and multimerization (CM) motifs. On the other hand, H. pylori strains with greater numbers of EPIYA‐B relative to EPIYA‐C demonstrated a decrease in CK18 cleavage rate. Thus, H. pylori‐mediated cleavage of CK18 appeared proportional to the number of CagA EPIYA‐C and CM motifs, which seemed to be downplayed in the presence of EPIYA‐B motifs. Conclusions: Our observation associating the heterogeneity of cagA variants with the potential of H. pylori strains in the induction of CK18 cleavage as an early indication of apoptosis in gastric epithelial cells supports the fact that apoptosis may be a type‐specific trait. However, additional cagA‐targeted experiments are required to clearly identify the role of EPIYA and CM motifs in apoptosis and/or the responsible effector molecules.

Analysis of the intactness of Helicobacter pylori cag pathogenicity island in Iranian strains by a new PCR-based strategy and its relationship with virulence genotypes and EPIYA motifs

“…Western CagA consists of a combination of EPIYA-A and -B, followed by various number of EPIYA-C repeats (up to five EPIYA-C segments), whereas East Asian CagA contains a combination of EPIYA-A, -B, and -D segments (Hatakeyama, 2011;Jones et al, 2010). In the case of our strains, the Western type cagA (EPIYA-ABC) was the most prevalent variant in all of the patient groups studied, which is consistent with the previous studies from Iran (Saberi et al, 2012;Shokrzadeh et al, 2010;Vaziri et al, 2013). The C-terminal structure of CagA among our strains is also similar with the strains isolated from other countries including Sweden (Monstein et al, 2010), Turkey (Salih et al, 2010), Colombia (Sicinschi et al, 2010) and USA (Ogorodnik and Raffaniello, 2013).…”

EGR1 decreases the malignancy of human non-small cell lung carcinoma by regulating KRT18 expression

“…The microarray results showed that KRT18 was upregulated approximately 3.5-fold by EGR1 induction. KRT18, together with KRT8 (CK8), is an extremely important tumor marker in clinical diagnosis that is expressed in single-layer epithelial tissues of the body and is involved in carcinogenesis1819. The relationship between EGR1 and KRT18 was confirmed by dual luciferase assay.…”

A simple and cost‐efficient adherent culture platform for human gastric primary cells, as an in vitro model for Helicobacter pylori infection

“…GPCs of 2 donors were then evaluated as a model for extended infection of H. pylori . For this purpose, we selected a hypervirulent clinical strain of H. pylori , which had been previously evaluated for its virulence and toxicity by vacuolation and hummingbird functional assays. Considering the fact that H. pylori are gram‐negative microorganisms with a significant content of LPS, we sought to stain the bacteria, prior to GPC infection.…”