Signal transduction of the actin-binding protein cortactin in bacterial pathogenesis
Final Report Abstract
Cortactin is a multifunctional protein involved in many signaling processes of eukaryotic cells. Since its discovery as an actin-binding protein and substrate of Src kinase in the early 1990’s, cortactin has emerged as a key signaling protein in many cellular processes, including cell adhesion, migration, endocytosis, tumor invasion and morphogenesis. Given the central position of cortactin in signal transduction, it is not surprising that cortactin functions are targeted by many microbial pathogens during infection to manipulate cell functions. Thus, cortactin has been regarded as an Achilles` heel of the host actin cytoskeleton. While the list of cellular functions influenced by cortactin grows, very little is known about the regulation of the protein at the molecular level during microbial infection. The main goal this project was therefore to investigate the role of cortactin phosphorylation in cell signaling during infection with the human bacterial pathogens Helicobacter, Shigella and EPEC, and to identify novel cortactin binding partners by using a proteomic approach. In particular, we aimed to investigate the role of bacterial factors in the modulation of cortactin with emphasis on how those factors manipulate cortactin phosphorylation to hijack specific cellular signaling pathways, and phenotypical outcome of this interaction. Helicobacter pylori employs a type IV secretion system to deliver the bacterial effector protein CagA into the cytoplasm of gastric epithelial cells. In the host cell, CagA hijacks cellular tyrosine kinases that control the function of many proteins, including cortactin, leading to global rearrangements in the host cell architecture that are characterized by cellular elongation and cell scattering. The results of our work show that the CagA protein is a crucial factor for cortactin signaling in H. pylori infected cells. We discovered eight novel pathways of how H. pylori affects and recruits cortactin and its binding partners to control cell attachment, movement, polarity and cytokine release. Moreover, we identified two previously unknown cellular interaction partners of cortactin, the guanine exchange factor Vav2 and the partitioning-defective kinase Par1b. These interactions, which were characterized in detail, affect actin rearrangements and cell scattering, which results in loss of polarity, weakening of the cell-cell junctions, and contributes to the induction of cell motility. Furthermore, we created two CRISPR-Cas9 cortactin knockout cell lines and showed that cortactin is not involved in the actin pedestal formation of EPEC or actin tail formation and bacterial invasion of Shigella, although this has been previously reported in landmark papers by other groups. Taken together, the results of this study not only have important impact on our current understanding of cortactin’s function and its regulation at the molecular level but may also give important new hints to develop novel therapeutic schemes for treatment of certain human diseases where cortactin is involved. The work of this project resulted to date in the publication of one scientific book and 12 papers in international peerreviewed journals, including Nature Microbiology, EMBO journal, Cancers, Cellular Microbiology or Molecular Microbiology. Two more papers are currently in preparation.
Publications
- (2016). Helicobacter pylori adhesin HopQ engages in a virulence-enhancing interaction with human CEACAMs. Nature Microbiol. 2, 16189
Javaheri, A.; Kruse, T.; Moonens, K.; Mejías-Luque, R.; Debraekeleer, A.; Asche, C. I.; Tegtmeyer, N.; Kalali, B.; Bach, N. C.; Sieber, S. A.; Hill, D. J.; Königer, V.; Hauck, C. R.; Moskalenko, R.; Haas, R.; Busch, D. H.; Klaile, E.; Slevogt, H.; Schmidt, A.; Backert, S.; Remaut, H.; Singer, B. B.; Gerhard, M.
(See online at https://doi.org/10.1038/nmicrobiol.2016.189) - (2017). Molecular Pathogenesis and Signal Transduction by Helicobacter pylori. Springer-Verlag, ISBN 978-3-319-50520-6
Tegtmeyer, N.; Backert, S. (eds.)
(See online at https://doi.org/10.1007/978-3-319-50520-6) - (2017). Subversion of host kinases: a key network in cellular signaling hijacked by Helicobacter pylori CagA. Mol. Microbiol. 105, 358-372
Tegtmeyer, N.; Neddermann, M.; Asche, C. I.; Backert, S.
(See online at https://doi.org/10.1111/mmi.13707) - (2019). Expression of CEACAM1 or CEACAM5 in AZ-521 cells restores the type IV secretion deficiency for translocation of CagA by Helicobacter pylori. Cell. Microbiol. 21, e12965
Tegtmeyer, N.; Harrer, A.; Schmitt, V.; Singer, B. B.; Backert, S.
(See online at https://doi.org/10.1111/cmi.12965) - (2020). Cortactin: a major cellular target of the gastric carcinogen Helicobacter pylori. Cancers (Basel). 12(1), 159
Sharafutdinov, I.; Backert, S.; Tegtmeyer, N.
(See online at https://doi.org/10.3390/cancers12010159) - (2021). Cortactin is required for efficient FAK, Src and Abl tyrosine kinase activation and phosphorylation of Helicobacter pylori CagA. Int. J. Mol. Sci. 22(11), 6045
Knorr, J.; Sharafutdinov, I.; Fiedler, F.; Soltan Esmaeili, D.; Rohde, M.; Rottner, K.; Backert, S.; Tegtmeyer, N.
(See online at https://doi.org/10.3390/ijms22116045) - (2021). Helicobacter pylori CagA induces Cortactin Y-470 phosphorylation-dependent gastric epithelial cell scattering via Abl, Vav2 and Rac1 activation. Cancers (Basel). 13, 4241
Tegtmeyer, N.; Harrer, A.; Rottner, K.; Backert, S.
(See online at https://doi.org/10.3390/cancers13164241) - (2021). The Helicobacter pylori type IV secretion system upregulates epithelial cortactin expression by a CagA- and JNK- dependent pathway. Cell. Microbiol. 1, e13376
Sharafutdinov, I.; Backert, S.; Tegtmeyer, N.
(See online at https://doi.org/10.1111/cmi.13376)
