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1.
Cell Commun Signal ; 17(1): 10, 2019 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-30704478

RESUMO

BACKGROUND: Deregulated c-Abl activity has been intensively studied in a variety of solid tumors and leukemia. The class-I carcinogen Helicobacter pylori (Hp) activates the non-receptor tyrosine kinase c-Abl to phosphorylate the oncoprotein cytotoxin-associated gene A (CagA). The role of c-Abl in CagA-dependent pathways is well established; however, the knowledge of CagA-independent c-Abl processes is scarce. METHODS: c-Abl phosphorylation and localization were analyzed by immunostaining and immunofluorescence. Interaction partners were identified by tandem-affinity purification. Cell elongation and migration were analyzed in transwell-filter experiments. Apoptosis and cell survival were examined by FACS analyses and MTT assays. In mice experiments and human biopsies, the involvement of c-Abl in Hp pathogenesis was investigated. RESULTS: Here, we investigated the activity and subcellular localization of c-Abl in vitro and in vivo and unraveled the contribution of c-Abl in CagA-dependent and -independent pathways to gastric Hp pathogenesis. We report a novel mechanism and identified strong c-Abl threonine 735 phosphorylation (pAblT735) mediated by the type-IV secretion system (T4SS) effector D-glycero-ß-D-manno-heptose-1,7-bisphosphate (ßHBP) and protein kinase C (PKC) as a new c-Abl kinase. pAblT735 interacted with 14-3-3 proteins, which caused cytoplasmic retention of c-Abl, where it potentiated Hp-mediated cell elongation and migration. Further, the nuclear exclusion of pAblT735 attenuated caspase-8 and caspase-9-dependent apoptosis. Importantly, in human patients suffering from Hp-mediated gastritis c-Abl expression and pAblT735 phosphorylation were drastically enhanced as compared to type C gastritis patients or healthy individuals. Pharmacological inhibition using the selective c-Abl kinase inhibitor Gleevec confirmed that c-Abl plays an important role in Hp pathogenesis in a murine in vivo model. CONCLUSIONS: In this study, we identified a novel regulatory mechanism in Hp-infected gastric epithelial cells by which Hp determines the subcellular localization of activated c-Abl to control Hp-mediated EMT-like processes while decreasing cell death.


Assuntos
Apoptose , Movimento Celular , Helicobacter pylori/metabolismo , Proteínas Proto-Oncogênicas c-abl/metabolismo , Linhagem Celular Tumoral , Infecções por Helicobacter/metabolismo , Infecções por Helicobacter/microbiologia , Humanos , Modelos Biológicos , Fosforilação , Fosfotreonina/metabolismo , Fosfotirosina/metabolismo , Proteína Quinase C/metabolismo , Transporte Proteico
2.
Cell Commun Signal ; 15(1): 15, 2017 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-28427431

RESUMO

Infections with the human pathogen Helicobacter pylori (H. pylori) are closely associated with the development of inflammatory disorders and neoplastic transformation of the gastric epithelium. Drastic changes in the micromilieu involve a complex network of H. pylori-regulated signal transduction pathways leading to the release of proinflammatory cytokines, gut hormones and a wide range of signaling molecules. Besides controlling embryonic development, the Hedgehog/GLI signaling pathway also plays important roles in epithelial proliferation, differentiation, and regeneration of the gastric physiology, but also in the induction and progression of inflammation and neoplastic transformation in H. pylori infections. Here, we summarize recent findings of H. pylori-associated Hedgehog/GLI signaling in gastric homeostasis, malignant development and the modulation of the gastric tumor microenvironment.


Assuntos
Proteínas Hedgehog/metabolismo , Helicobacter pylori/fisiologia , Transdução de Sinais , Neoplasias Gástricas/microbiologia , Neoplasias Gástricas/patologia , Proteína GLI1 em Dedos de Zinco/metabolismo , Animais , Humanos , Inflamação/microbiologia , Inflamação/patologia
3.
Infect Immun ; 84(9): 2671-80, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27382024

RESUMO

CagA is one of the most important virulence factors of the human pathogen Helicobacter pylori CagA expression can be associated with the induction of severe gastric disorders such as gastritis, ulceration, gastric cancer, or mucosa-associated lymphoid tissue (MALT) lymphoma. After translocation through a type IV secretion system into epithelial cells, CagA is tyrosine phosphorylated by kinases of the Src and Abl families, leading to drastic cell elongation and motility. While the functional role of CagA in epithelial cells is well investigated, knowledge about CagA phosphorylation and its associated signal transduction pathways in B cells is only marginal. Here, we established the B cell line MEC1 derived from a B cell chronic lymphocytic leukemia (B-CLL) patient as a new infection model to study the signal transduction in B cells controlled by H. pylori We observed that CagA was rapidly injected, strongly tyrosine phosphorylated, and cleaved into a 100-kDa N-terminal and a 40-kDa C-terminal fragment. To identify upstream signal transduction pathways of CagA phosphorylation in MEC1 cells, pharmacological inhibitors were employed to specifically target Src and Abl kinases. We observed that CagA phosphorylation was strongly inhibited upon treatment with an Src inhibitor and slightly diminished when the Abl kinase inhibitor imatinib mesylate (Gleevec) was applied. The addition of dasatinib to block c-Abl and Src kinases led to a complete loss of CagA phosphorylation. In conclusion, these results demonstrate an important role for Src and Abl tyrosine kinases in CagA phosphorylation in B cells, which represent druggable targets in H. pylori-mediated gastric MALT lymphoma.


Assuntos
Antígenos de Bactérias/metabolismo , Linfócitos B/microbiologia , Proteínas de Bactérias/metabolismo , Helicobacter pylori/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-abl/metabolismo , Quinases da Família src/metabolismo , Linfócitos B/efeitos dos fármacos , Linfócitos B/metabolismo , Linhagem Celular Tumoral , Mucosa Gástrica/microbiologia , Infecções por Helicobacter/metabolismo , Infecções por Helicobacter/microbiologia , Helicobacter pylori/efeitos dos fármacos , Humanos , Mesilato de Imatinib/farmacologia , Linfoma de Zona Marginal Tipo Células B/metabolismo , Linfoma de Zona Marginal Tipo Células B/microbiologia , Fosforilação/efeitos dos fármacos , Fosforilação/fisiologia , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Células U937
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