BACKGROUND: Helicobacter pylori infection poses a significant health burden worldwide, and its virulence factor CagA plays a pivotal role in its pathogenesis. METHODS: In this study, the interaction between H. pylori-infected AGS cells and silver nanoparticles (AgNPs) was investigated, with a focus on the modulation of CagA-mediated responses, investigated by western blotting. Both, the dose-dependent efficacy against H. pylori (growth curves, CFU assay) and the impact of the nanoparticles on AGS cells (MTT assay) were elucidated. RESULTS: AGS cells infected with H. pylori displayed dramatic morphological changes, characterized by elongation and a migratory phenotype, attributed to CagA activity. Preincubation of H. pylori with AgNPs affected these morphological changes in a concentration-dependent manner, suggesting a correlation between AgNPs concentration and CagA function. CONCLUSION: Our study highlights the nuanced interplay between host-pathogen interactions and the therapeutic potential of AgNPs in combating H. pylori infection and offers valuable insights into the multifaceted dynamics of CagA mediated responses.

• Klíčová slova
• AGS, CagA, H. pylori, IL-8, infection, minimum inhibitory concentration, silver nanoparticles,
• MeSH
• antibakteriální látky farmakologie   MeSH
• antigeny bakteriální * metabolismus   MeSH
• bakteriální proteiny * metabolismus   MeSH
• buněčné linie MeSH
• epitelové buňky mikrobiologie   MeSH
• faktory virulence metabolismus   MeSH
• Helicobacter pylori * účinky léků   MeSH
• infekce vyvolané Helicobacter pylori * mikrobiologie   farmakoterapie   MeSH
• interakce hostitele a patogenu MeSH
• kovové nanočástice * MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• signální transdukce * účinky léků   MeSH
• stříbro * farmakologie   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• antigeny bakteriální * MeSH
• bakteriální proteiny * MeSH
• cagA protein, Helicobacter pylori MeSH Prohlížeč
• faktory virulence MeSH
• stříbro * MeSH

Transcription-replication conflicts (TRCs) induce formation of cotranscriptional RNA:DNA hybrids (R-loops) stabilized by G-quadruplexes (G4s) on the displaced DNA strand, which can cause fork stalling. Although it is known that these stalled forks can resume DNA synthesis in a process initiated by MUS81 endonuclease, how TRC-associated G4/R-loops are removed to allow fork passage remains unclear. Here, we identify the mismatch repair protein MutSβ, an MLH1-PMS1 heterodimer termed MutLβ, and the G4-resolving helicase FANCJ as factors that are required for MUS81-initiated restart of DNA replication at TRC sites in human cells. This DNA repair process depends on the G4-binding activity of MutSβ, the helicase activity of FANCJ, and the binding of FANCJ to MLH1. Furthermore, we show that MutSβ, MutLβ, and MLH1-FANCJ interaction mediate FANCJ recruitment to G4s. These data suggest that MutSβ, MutLβ, and FANCJ act in conjunction to eliminate G4/R-loops at TRC sites, allowing replication restart.

• MeSH
• DNA-helikasy genetika   metabolismus   MeSH
• DNA genetika   MeSH
• lidé MeSH
• proteiny FANC * genetika   metabolismus   MeSH
• R-smyčka * MeSH
• replikace DNA MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA-helikasy MeSH
• DNA MeSH
• proteiny FANC * MeSH

Helicobacter pylori infection is a major risk factor for the development of gastric cancer. The bacteria reside in close proximity to gastric surface mucous as well as stem and progenitor cells. Here, we take advantage of wild-type and genetically engineered murine gastric organoids and organoid-derived monolayers to study the cellular targets of H. pylori-induced DNA damage and replication stress and to explore possible interactions with preexisting gastric cancer driver mutations. We find using alkaline comet assay, single-molecule DNA fiber assays, and immunofluorescence microscopy of DNA repair foci that H. pylori induces transcription-dependent DNA damage in actively replicating, Leucine-rich-repeat containing G-Protein-Coupled Receptor 5 (Lgr5)-positive antral stem and progenitor cells and their Troy-positive corpus counterparts, but not in other gastric epithelial lineages. Infection-dependent DNA damage is aggravated by Apc inactivation, but not by Trp53 or Smad4 loss, or Erbb2 overexpression. Our data suggest that H. pylori induces DNA damage in stem and progenitor cells, especially in settings of hyperproliferation due to constitutively active Wnt signaling.

• MeSH
• Helicobacter pylori * genetika   MeSH
• infekce vyvolané Helicobacter pylori * genetika   mikrobiologie   MeSH
• kmenové buňky MeSH
• lidé MeSH
• myši MeSH
• nádory žaludku * patologie   MeSH
• poškození DNA MeSH
• receptory spřažené s G-proteiny genetika   MeSH
• tumor supresorové geny MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adenomatous polyposis coli protein, mouse MeSH Prohlížeč
• receptory spřažené s G-proteiny MeSH

R-loops are three-stranded nucleic acid structures composed of an RNA:DNA hybrid and displaced DNA strand. These structures can halt DNA replication when formed co-transcriptionally in the opposite orientation to replication fork progression. A recent study has shown that replication forks stalled by co-transcriptional R-loops can be restarted by a mechanism involving fork cleavage by MUS81 endonuclease, followed by ELL-dependent reactivation of transcription, and fork religation by the DNA ligase IV (LIG4)/XRCC4 complex. However, how R-loops are eliminated to allow the sequential restart of transcription and replication in this pathway remains elusive. Here, we identified the human DDX17 helicase as a factor that associates with R-loops and counteracts R-loop-mediated replication stress to preserve genome stability. We show that DDX17 unwinds R-loops in vitro and promotes MUS81-dependent restart of R-loop-stalled forks in human cells in a manner dependent on its helicase activity. Loss of DDX17 helicase induces accumulation of R-loops and the formation of R-loop-dependent anaphase bridges and micronuclei. These findings establish DDX17 as a component of the MUS81-LIG4-ELL pathway for resolution of R-loop-mediated transcription-replication conflicts, which may be involved in R-loop unwinding.

• MeSH
• DEAD-box RNA-helikasy genetika   metabolismus   MeSH
• DNA-helikasy metabolismus   MeSH
• DNA metabolismus   MeSH
• endonukleasy metabolismus   MeSH
• lidé MeSH
• R-smyčka * MeSH
• replikace DNA * genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DDX17 protein, human MeSH Prohlížeč
• DEAD-box RNA-helikasy MeSH
• DNA-helikasy MeSH
• DNA MeSH
• endonukleasy MeSH