Characterization of the function of murine guanylate-binding protein 9 in the context of bacterial and parasitic infections

Abstract

Abstract Interferon-γ (IFNγ) signaling induces high expression of immunomodulatory molecules in most cell types. Among these molecules, the members of the murine guanylate-binding protein (mGBP) family comprise a group of eleven proteins (mGBP1-mGBP11) shown to have important functions in cell-autonomous immunity. Upon IFNγ stimulation, mGBPs localize in vesicle-like structures distributed within the cytoplasm. Previous studies have shown that after infection with several intracellularly replicating pathogens, mGBPs rapidly relocate towards the pathogen-containing vacuoles (PCV), such as the parasitophorous vacuole (PV) of Toxoplasma gondii or the inclusions of Chlamydia trachomatis. Accumulation of mGBP2 at the PV membrane leads to loss of membrane integrity and subsequent restriction of parasite replication. Although mGBP proteins share a high sequence identity, differences in localization frequencies could be detected. For instance, mGBP1 and mGBP2 show the highest frequencies of recruitment to both Toxoplasma and Chlamydia PCVs. However, mGBP9 recruitment was more frequent to chlamydial inclusions than to T. gondii PVs. Thus, the importance of individual mGBPs might vary depending on the type of the pathogen. To analyze these findings in more detail, we started with the generation of mgbp9−/− cell- and mouse lines. Therefore, the CRISPR/Cas9 gene editing system with homologous directed integration of a single-stranded oligodesoxynucleotide is used to generate mGBP9 deficient ES cells for mouse and cell line development. In-depth analyzes of mgbp9−/− cells and mice in T. gondii and C. trachomatis infection will lead to a better understanding of immunity against intracellular pathogens.