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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-β-D-manno-heptose-1,7-bisphosphate (βHBP) 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.

Original publication

DOI

10.1186/s12964-019-0323-9

Type

Journal article

Journal

Cell Communication and Signaling : CCS

Publication Date

31/01/2019

Volume

17

Addresses

Department of Biosciences, Division of Microbiology, University of Salzburg, Paris-Lodron University of Salzburg, Billroth Str. 11, A-5020, Salzburg, Austria.

Keywords

Cell Line, Tumor, Humans, Helicobacter pylori, Helicobacter Infections, Protein Kinase C, Proto-Oncogene Proteins c-abl, Phosphotyrosine, Phosphothreonine, Apoptosis, Cell Movement, Protein Transport, Phosphorylation, Models, Biological