Konfokales Laser-Scanning-Mikroskop
Final Report Abstract
The innate immune system can detect invading pathogens and tissue damage through a range of signaling receptors that can directly sense pathogen associated molecular patterns or danger associated molecules. A number of cytosolic receptors of the Nod-like receptor (NLR) and PYHIN protein families can assemble large cytoplasmic multi-protein complexes together with the protein apoptosis related speck like protein (ASC). These signaling platforms, termed 'inflammasomes', activate the inflammatory caspase-1, which cleaves and activates members of the pro-inflammatory interleukin-1b cytokines. Activated caspase-1 can further initiate cell death and the release of a multitude of intracellular molecules. We are particularly interested in the NLRP3 and AIM2 inflammasomes. AIM2 inflammasomes form in response to cytosolic double stranded DNA and the NLRP3 inflammasome is activated by a broad number of stimuli, including bacterial toxins, crystals and endogenous danger signals. We are examining the effects of cholesterol crystals formed in atherosclerosis that are known activators of the NLRP3 inflammasome in myeloid cells and how associated tissue pathologies can be circumvented by pharmacologically dissolving the crystals. We are furthermore performing chemical biology screens to uncover mechanisms leading to NLRP3 inflammasome activation. The Fluorescence Lifetime Correlation Spectroscopy (FLCS) module is being used for testing the oligomerization state of NLRP3 before and after inflammasome activation, both in cellfree lysates and live cells. We also examined the structure-function relation of DNA-binding of Aim2 and IFI16 receptors. Additionally to the study of inflammasome activation by microscopy we focus on the elucidation of activation mechanisms of other innate immune signaling receptors. For example, Toll-like receptors (TLRs) are a family of transmembrane signaling receptors that play a key role in innate immunity. TLRs are able to recognize a wide range of microbes by virtue of highly conserved molecular signatures, such as bacterial cell wall components or microbial nucleic acids. In addition, TLRs function in the recognition of sterile tissue damage. They can sense the appearance of host derived molecules in non-physiological cellular compartments and can be activated by modifications on host molecules that appear under cellular stress situations. TLRs directly interact with ligands, and the signal strength, duration and the influence of other signaling pathways ultimately shapes the cellular response. Our research is focused on the molecular mechanisms of the most proximal events of TLR activation and on factors that modulate and threshold their signaling. We investigated how the structure of lipid-like ligands can orchestrate qualitatively different downstream signaling pathways in the TLR2-TLR1/6 heterodimers. We are also examining the influence of trafficking proteins on intracellular, nucleic acid-sensing TLRs (TLR7, 8 and 9), and how the scavenger receptor RAGE helps to bring nucleic acid-type ligands into intracellular signaling compartments. We are also investigating how nucleic acids can be sensed in the cytosol of cells. We are studying how the enzyme cGAS and the receptor STING are activated inside cell upon sensing of nucleic acids.
Publications
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Structures of the HIN domain:DNA complexes reveal ligand binding and activation mechanisms of the AIM2 inflammasome and IFI16 receptor. Immunity. 2012 Apr 20;36(4):561-71
Jin T, Perry A, Jiang J, Smith P, Curry JA, Unterholzner L, Jiang Z, Horvath G, Rathinam VA, Johnstone RW, Hornung V, Latz E, Bowie AG, Fitzgerald KA, Xiao TS
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ASC speck formation as a readout for inflammasome activation. Methods Mol Biol. 2013;1040:91-101
Stutz A, Horvath GL, Monks BG, Latz E
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CD36 coordinates NLRP3 inflammasome activation by facilitating intracellular nucleation of soluble ligands into particulate ligands in sterile inflammation. Nat Immunol. 2013 Aug;14(8):812-20
Sheedy FJ, Grebe A, Rayner KJ, Kalantari P, Ramkhelawon B, Carpenter SB, Becker CE, Ediriweera HN, Mullick AE, Golenbock DT, Stuart LM, Latz E, Fitzgerald KA, Moore KJ
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Cell intrinsic immunity spreads to bystander cells via the intercellular transfer of cGAMP. Nature. 2013 Nov 28;503(7477):530-4
Ablasser A, Schmid-Burgk JL, Hemmerling I, Horvath GL, Schmidt T, Latz E, Hornung V
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Chemical genetics reveals a kinase-independent role for protein kinase R in pyroptosis. Nat Chem Biol. 2013 Jun;9(6):398-405
Hett EC, Slater LH, Mark KG, Kawate T, Monks BG, Stutz A, Latz E, Hung DT
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Evidence for novel hepaciviruses in rodents. PLoS Pathog. 2013;9(6):e1003438
Drexler JF, Corman VM, Müller MA, Lukashev AN, Gmyl A, Coutard B, Adam A, Ritz D, Leijten LM, van Riel D, Kallies R, Klose SM, Gloza-Rausch F, Binger T, Annan A, Adu-Sarkodie Y, Oppong S, Bourgarel M, Rupp D, Hoffmann B, Schlegel M, Kümmerer BM, Krüger DH, Schmidt-Chanasit J, Setién AA, Cottontail VM, Hemachudha T, Wacharapluesadee S, Osterrieder K, Bartenschlager R, Matthee S, Beer M, Kuiken T, Reusken C, Leroy EM, Ulrich RG, Drosten C
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Middle East respiratory syndrome coronavirus accessory protein 4a is a type I interferon antagonist. J Virol. 2013 Nov;87(22):12489-95
Niemeyer D, Zillinger T, Muth D, Zielecki F, Horvath G, Suliman T, Barchet W, Weber F, Drosten C, Müller MA
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RAGE is a nucleic acid receptor that promotes inflammatory responses to DNA. J Exp Med 2013 Oct 21;210(11):2447-63
Sirois CM, Jin T, Miller AL, Bertheloot D, Nakamura H, Horvath GL, Mian A, Jiang J, Schrum J, Bossaller L, Pelka K, Garbi N, Brewah Y, Tian J, Chang C, Chowdhury PS, Sims GP, Kolbeck R, Coyle AJ, Humbles AA, Xiao TS, Latz E
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HDL mediates antiinflammatory transcriptional reprogramming of macrophages via ATF3. Nature immunology, 2014 15(2), 152-160
De Nardo D, Labzin LI, Kono H, Seki R, Schmidt SV, Beyer M, Xu D, Zimmer S, Lahrmann C, Schilberg FA, Vogelhuber J, Kraut M, Ulas T, Kerksiek A, Krebs W, Bode N, Grebe A, Fitzgerald ML, Hernandez NJ, Williams B, Knolle PA, Kneiling M, Rocken M, Lutjohann D, Wright SD, Schultze JL, Latz E
