Principal Investigator:

Functional characterization of guanylate binding
proteins (GBPs) in the host defense against pathogens

Guanylate binding proteins (GBPs) have essential effector functions in the defense against intracellularly replicating pathogens. We have demonstrated this by employing gene deficient mouse lines, thereby discovering that mGBPs are required for the survival of infections with the intracellular parasite Toxoplasma gondii. Moreover, using confocal live cell microscopy and MFIS (Multiparameter Fluorescence Imaging Spectroscopy) we could demonstrate that mGBP molecules accumulate in supramolecular complexes at the pathogen containing vacuole, can penetrate the vacuole and directly target the toxoplasma membrane. Furthermore, during the last RTG grant period, we have discovered that mGBP9 plays an important role in the defense against Chlamydia trachomatis, since mGBP9 recruits in a higher frequency to chlamydia inclusions compared to T. gondii parasitophorous vacuoles (PV). Therefore, the detailed elucidation of the molecular functions of mGBP9 in Chlamydia defense will be the focus of the next project period. In order to achieve this aim, we plan to analyze the mGBP9 recruitment to Chlamydia inclusions in detail using STED microcopy and to unravel the association of the chlamydial inclusion membranes and mGBP9. Also, MFIS/FRET analysis of mGBP9 and mGBP9 containing heteromers at Chlamydia inclusions is planned. To address the biological role(s) of mGBP9, a CRISPR/Cas9 targeting approach in embryonic fibroblasts and the generation of a mGBP9 deficient mouse line will be performed. These cell and mouse lines will be analyzed for Chlamydia replication. In addition to the elucidation of mGBP functions in C. trachomatis infections, also Chlamydia pneumoniae infections will be investigated. The mGBP9 deficient mouse line will be investigated for the activation of the adaptive immune response (T-cell priming, T cell functions, antibody responses, cytokine levels) after infections. Altogether, this project will deliver a novel understanding for the regulation and activation of the innate and adaptive immune response in the context of infections with intracellular pathogens by IFN-γ induced mGBPs.

Publications

Lindenberg V, Mölleken K, Kravets E, Stallmann S, Hegemann JH, Degrandi D, Pfeffer K. Broad recruitment of mGBP family members to Chlamydia trachomatis inclusions. PLoS One. 2017 Sep 25;12(9):e0185273. doi: 10.1371/journal.pone.0185273.

Kravets E, Degrandi D, Ma Q, Peulen TO, Klumpers V, Felekyan S, Kuhnemuth R, Weidtkamp-Peters S, Seidel CA, Pfeffer K. Guanylate binding proteins directly attack Toxoplasma gondii via supramolecular complexes. Elife. 2016 Jan 27;5. pii: e11479. doi: 10.7554/eLife.11479.

Meunier E, Wallet P, Dreier RF, Costanzo S, Anton L, Ruhl S, Dussurgey S, Dick MS, Kistner A, Rigard M, Degrandi D, Pfeffer K, Yamamoto M, Henry T, Broz P. Guanylatebinding proteins promote activation of the AIM2 inflammasome during infection with Francisella novicida. Nat Immunol. 2015;16(5):476-84.

Pilla DM, Hagar JA, Haldar AK, Mason AK, Degrandi D, Pfeffer K, Ernst RK, Yamamoto M, Miao EA, Coers J. Guanylate binding proteins promote caspase-11-dependent pyroptosis in response to cytoplasmic LPS. Proc Natl Acad Sci U S A. 2014;111(16):6046-51.

Trilling M, Le VT, Rashidi-Alavijeh J, Katschinski B, Scheller J, Rose-John S, Androsiac GE, Jonjic S, Poli V, Pfeffer K, Hengel H. "Activated" STAT proteins: a paradoxical consequence of inhibited JAK-STAT signaling in cytomegalovirus-infected cells. J Immunol. 2014;192(1):447-58.

Lubitz FP, Degrandi D, Pfeffer K, Mausberg AK. In astrocytes the accumulation of the immunity-related GTPases Irga6 and Irgb6 at the vacuole of Toxoplasma gondii is dependent on the parasite virulence. Scientific World Journal. 2013;2013:480231.

Arpaia N, Campbell C, Fan X, Dikiy S, van der Veeken J, deRoos P, Liu H, Cross JR, Pfeffer K, Coffer PJ, Rudensky AY. Metabolites produced by commensal bacteria promote peripheral regulatory T-cell generation. Nature. 2013;504(7480):451-5.

Degrandi D, Kravets E, Konermann C, Beuter-Gunia C, Klumpers V, Lahme S, Wischmann E, Mausberg AK, Beer-Hammer S, Pfeffer K. Murine Guanylate Binding Protein 2 (mGBP2) controls Toxoplasma gondii replication. Proc Natl Acad Sci U S A 2013;110:294-9.

Selleck EM, Fentress SJ, Beatty WL, Degrandi D, Pfeffer K, Virgin HW IV, Macmicking JD, Sibley LD. Guanylate-binding protein 1 (Gbp1) contributes to cell-autonomous immunity against Toxoplasma gondii. PLoS Pathog. 2013;9(4):e1003320.

Kravets E, Degrandi D, Weidtkamp-Peters S, Ries B, Konermann C, Felekyan S, Dargazanli JM, Praefcke GJ, Seidel CA, Schmitt L, Smits SH, Pfeffer K. The GTPase activity of murine guanylate-binding protein 2 (mGBP2) controls the intracellular localization and recruitment to the parasitophorous vacuole of Toxoplasma gondii. J Biol Chem 2012;287:27452-66.