Analysis of the impact of N. meningitidis on receptor tyrosine kinase activation in mammalian cells and on the cell cycle

• Applicant: Professorin Dr. Alexandra Schubert-Unkmeir
• Subject Area: Parasitology and Biology of Tropical Infectious Disease Pathogens
• Term: from 2014 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 252750597

Neisseria meningitidis is an obligate commensal in humans, but occasionally may penetrate the mucosal membrane of the nasopharynx to enter the bloodstream and cause severe septicemia and/or acute purulent meningitis. Like many other bacterial pathogens N. meningitidis can activate host cell signal transduction pathways to establish adhesion and induce uptake. Our preliminary data indicated an important function of tyrosine phosphorylation of host proteins during the interaction of meningococci with mammalian cells, which results in cytoskeletal remodelling with subsequent engulfment of the pathogen. We could show, that Opc-mediated interaction of N. meningitidis with integrins results in activation of the non-receptor tyrosine kinases (RTKs) c-Src and the focal adhesion kinase, which couple to the uptake process of N. meningitidis. Besides activation of non-RTKs N. meningitidis also leads to phosphorylation of RTKs, including members of the ErbB family. Interestingly, a survey of activated RTKs revealed that several kinases are activated that have not been described before to be involved in the context of the interaction of N. meningitidis with host cells (e.g. insulin receptor, tyrosine-related kinase B receptor and ephrin receptors (EphA3 and EphB1), which we aim to analyse within the current proposal. In particular, the role of Ephrin receptors in (i) bacterial adhesion, invasion and (ii) modulation of endothelial barrier integrity will be determined. In the second part of this application we will focus on alterations of the cell cycle. Further recent data showed that N. meningitidis is also capable to interfere with the host cell cycle, and for example differently regulate expression of cyclins. We will analyse (i) changes in the abundance of major cyclins and their subcellular localization (ii) the transcriptome of mRNA levels encoding cell cycle-regulatory molecules in N. meningitidis-infected cells, and (iii) cell cycle phase arrest in response to meningococcal infection as well as the (IV) influence on bacterial adhesion/invasion/intracellular replication to certain cell cycle phenotypes. Interaction of N. meningitidis with epithelial cells of the nasopharyngeal mucosa will serve as a model to study the influence of this pathogen on cell cycle alteration that might either facilitate and promote infection or establish a carrier state.

• DFG Programme: Research Grants