Asunto(s)
Apoptosis/genética , Leucemia/genética , FN-kappa B/genética , Proteínas Serina-Treonina Quinasas/genética , Antígenos CD34/genética , Reordenamiento Génico/genética , Humanos , Proteína de la Leucemia Mieloide-Linfoide/genética , Proteínas Nucleares/genética , Transducción de Señal/genética , Transcriptoma/genética , Quinasa de Factor Nuclear kappa BRESUMEN
Helicobacter pylori infection persists in more than half of the world's population and represents a risk factor for peptic ulcer disease and gastric cancer. Virulent strains of H. pylori carry a cag pathogenicity island (cagPAI), which encodes a type IV secretion system (T4SS) with the capability to inject the effector protein cytotoxin-associated gene A (CagA) into eukaryotic cells. Colonisation of the gastric epithelium by H. pylori provokes direct activation of the proinflammatory and survival factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). We investigated the impact of host cell receptor integrin α5ß1 and the bacterial adhesin HopQ on the NF-κB activation. We found that H. pylori induced early T4SS-dependent, but CagA-independent canonical NF-κB signalling in polarized, apical infected NCI-N87 cells. Integrin-dependent CagA translocation was hardly detectable, as integrin ß1 was sparsely located at the apical surface of polarized NCI-N87 cells. Knockdown experiments indicated that integrin α5ß1 and integrin linked kinase (ILK) were dispensable for NF-κB activation in H. pylori infection. Thus, there exists no common mechanism, which mediates integrin α5ß1-dependent H. pylori-triggered CagA translocation and the activation of NF-κB. Further, we report that H. pylori adhesin HopQ, which binds to a specific subset of carcinoembryonic antigen-related cell adhesion molecules (CEACAMs), promotes canonical NF-κB activation in AGS and NCI-N87 cells, but not in HeLa cells, which are devoid of these CEACAMs. Noteworthy, these effects were not mediated by reduced adhesion, indicating additional functions of HopQ.
Asunto(s)
Adhesinas Bacterianas/metabolismo , Antígenos CD/metabolismo , Moléculas de Adhesión Celular/metabolismo , Helicobacter pylori/genética , Helicobacter pylori/metabolismo , Integrina alfa5beta1/metabolismo , FN-kappa B/metabolismo , Adhesinas Bacterianas/genética , Antígenos Bacterianos/metabolismo , Proteínas Bacterianas/metabolismo , Línea Celular Tumoral , Islas Genómicas , Células HeLa , Humanos , Integrina alfa5beta1/genética , Interferencia de ARN , ARN Interferente Pequeño/genética , Transducción de Señal , Sistemas de Secreción Tipo IV/metabolismoRESUMEN
The pathogen Helicobacter pylori, which infects half of the world's population, is a major risk factor for the development of gastric diseases including chronic gastritis and gastric cancer. Among H. pylori's virulence factors is the cytotoxin-associated gene pathogenicity island (cagPAI), which encodes for a type IV secretion system (T4SS). The T4SS induces fast canonical nuclear factor-kappa B (NF-κB) signaling, a major factor increasing inflammation, supressing apoptotic cell death and thereby promoting the development of neoplasia. However, H. pylori's capability to mediate fast non-canonical NF-κB signaling is unresolved, despite a contribution of non-canonical NF-κB signaling to gastric cancer has been suggested. We analyzed signaling elements within non-canonical NF-κB in response to H.â¯pylori in epithelial cell lines by immunoprecipitation, immunoblot, electrophoretic mobility shift assay and RNA interference knockdown. In addition, tissue samples of H. pylori-infected patients were investigated by immunohistochemistry. Here, we provide evidence for a T4SS-dependent direct activation of non-canonical NF-κB signaling. We identified the lymphotoxin beta receptor (LTßR) to elicit the fast release of NF-κB inducing kinase (NIK) from the receptor complex leading to non-canonical NF-κB signaling. Further, NIK expression was increased in human biopsies of H. pylori-associated gastritis. Thus, NIK could represent a novel target to reduce Helicobacter pylori-induced gastric inflammation and pathology.