M3i

@article{chen_weckle_2006,
title = {Weckle is a zinc finger adaptor of the toll pathway in dorsoventral patterning of the Drosophila embryo},
author = {Li-Ying Chen and Juinn-Chin Wang and Yann Hyvert and Hui-Ping Lin and Norbert Perrimon and Jean-Luc Imler and Jui-Chou Hsu},
doi = {10.1016/j.cub.2006.05.050},
issn = {0960-9822},
year = {2006},
date = {2006-06-01},
journal = {Current biology: CB},
volume = {16},
number = {12},
pages = {1183--1193},
abstract = {BACKGROUND: The Drosophila Toll pathway takes part in both establishment of the embryonic dorsoventral axis and induction of the innate immune response in adults. Upon activation by the cytokine Spätzle, Toll interacts with the adaptor proteins DmMyD88 and Tube and the kinase Pelle and triggers degradation of the inhibitor Cactus, thus allowing the nuclear translocation of the transcription factor Dorsal/Dif. weckle (wek) was previously identified as a new dorsal group gene that encodes a putative zinc finger transcription factor. However, its role in the Toll pathway was unknown. RESULTS: Here, we isolated new wek alleles and demonstrated that cactus is epistatic to wek, which in turn is epistatic to Toll. Consistent with this, Wek localizes to the plasma membrane of embryos, independently of Toll signaling. Wek homodimerizes and associates with Toll. Moreover, Wek binds to and localizes DmMyD88 to the plasma membrane. Thus, Wek acts as an adaptor to assemble/stabilize a Toll/Wek/DmMyD88/Tube complex. Remarkably, unlike the DmMyD88/tube/pelle/cactus gene cassette of the Toll pathway, wek plays a minimal role, if any, in the immune defense against Gram-positive bacteria and fungi. CONCLUSIONS: We conclude that Wek is an adaptor to link Toll and DmMyD88 and is required for efficient recruitment of DmMyD88 to Toll. Unexpectedly, wek is dispensable for innate immune response, thus revealing differences in the Toll-mediated activation of Dorsal in the embryo and Dif in the fat body of adult flies.},
keywords = {Adaptor Proteins, Animals, Antigens, Biological, Body Patterning, Cell Membrane, Differentiation, dimerization, DNA-Binding Proteins, Embryo, Epistasis, Genetic, imler, Immunity, Immunologic, Innate, M3i, Models, Mutation, Nonmammalian, Phenotype, Phosphoproteins, Receptors, Signal Transducing, Toll-Like Receptors, Transcription Factors, Zinc Fingers},
pubstate = {published},
tppubtype = {article}
}

@article{weber_ligand-receptor_2005,
title = {Ligand-receptor and receptor-receptor interactions act in concert to activate signaling in the Drosophila toll pathway},
author = {Alexander N R Weber and Martin C Moncrieffe and Monique Gangloff and Jean-Luc Imler and Nicholas J Gay},
doi = {10.1074/jbc.M502074200},
issn = {0021-9258},
year = {2005},
date = {2005-01-01},
journal = {The Journal of Biological Chemistry},
volume = {280},
number = {24},
pages = {22793--22799},
abstract = {In Drosophila, the signaling pathway mediated by the Toll receptor is critical for the establishment of embryonic dorso-ventral pattern and for innate immune responses to bacterial and fungal pathogens. Toll is activated by high affinity binding of the cytokine Spätzle, a dimeric ligand of the cystine knot family. In vertebrates, a related family of Toll-like receptors play a critical role in innate immune responses. Despite the importance of this family of receptors, little is known about the biochemical events that lead to receptor activation and signaling. Here, we show that Spätzle binds to the N-terminal region of Toll and, using biophysical methods, that the binding is complex. The two binding events that cause formation of the cross-linked complex are non-equivalent: the first Toll ectodomain binds Spätzle with an affinity 3-fold higher than the second molecule suggesting that pathway activation involves negative cooperativity. We further show that the Toll ectodomains are able to form low affinity dimers in solution and that juxtamembrane sequences of Toll are critical for the activation or derepression of the pathway. These results, taken together, suggest a mechanism of signal transduction that requires both ligand-receptor and receptor-receptor interactions.},
keywords = {Amino Acid, Animals, Biophysical Phenomena, Biophysics, Body Patterning, Calorimetry, Cell Line, Cell Surface, Cross-Linking Reagents, Cytokines, dimerization, Electrophoresis, Humans, imler, ligands, Luciferases, M3i, Membrane Glycoproteins, Polyacrylamide Gel, Protein Binding, Protein Structure, Receptors, Recombinant Proteins, Sequence Homology, Signal Transduction, Tertiary, Time Factors, Toll-Like Receptors, Ultracentrifugation},
pubstate = {published},
tppubtype = {article}
}

@article{ligoxygakis_serpin_2003,
title = {A serpin regulates dorsal-ventral axis formation in the Drosophila embryo},
author = {Petros Ligoxygakis and Siegfried Roth and Jean-Marc Reichhart},
issn = {0960-9822},
year = {2003},
date = {2003-12-01},
journal = {Curr. Biol.},
volume = {13},
number = {23},
pages = {2097--2102},
abstract = {Extracellular serine protease cascades have evolved in vertebrates and invertebrates to mediate rapid, local reactions to physiological or pathological cues. The serine protease cascade that triggers the Toll signaling pathway in Drosophila embryogenesis shares several organizational characteristics with those involved in mammalian complement and blood clotting. One of the hallmarks of such cascades is their regulation by serine protease inhibitors (serpins). Serpins act as suicide substrates and are cleaved by their target protease, forming an essentially irreversible 1:1 complex. The biological importance of serpins is highlighted by serpin dysfunction diseases, such as thrombosis caused by a deficiency in antithrombin. Here, we describe how a serpin controls the serine protease cascade, leading to Toll pathway activation. Female flies deficient in Serpin-27A produce embryos that lack dorsal-ventral polarity and show uniform high levels of Toll signaling. Since this serpin has been recently shown to restrain an immune reaction in the blood of Drosophila, it demonstrates that proteolysis can be regulated by the same serpin in different biological contexts.},
keywords = {Animals, Body Patterning, Cell Surface, Crosses, Female, Genetic, Immunohistochemistry, M3i, Microinjections, Receptors, reichhart, Serine Proteinase Inhibitors, Serpins, Signal Transduction, Toll-Like Receptors},
pubstate = {published},
tppubtype = {article}
}

@article{levashina_constitutive_1999,
title = {Constitutive activation of toll-mediated antifungal defense in serpin-deficient Drosophila},
author = {Elena A Levashina and E Langley and C Green and David Gubb and M Ashburner and Jules A Hoffmann and Jean-Marc Reichhart},
issn = {0036-8075},
year = {1999},
date = {1999-09-01},
journal = {Science},
volume = {285},
number = {5435},
pages = {1917--1919},
abstract = {The antifungal defense of Drosophila is controlled by the spaetzle/Toll/cactus gene cassette. Here, a loss-of-function mutation in the gene encoding a blood serine protease inhibitor, Spn43Ac, was shown to lead to constitutive expression of the antifungal peptide drosomycin, and this effect was mediated by the spaetzle and Toll gene products. Spaetzle was cleaved by proteolytic enzymes to its active ligand form shortly after immune challenge, and cleaved Spaetzle was constitutively present in Spn43Ac-deficient flies. Hence, Spn43Ac negatively regulates the Toll signaling pathway, and Toll does not function as a pattern recognition receptor in the Drosophila host defense.},
keywords = {Animals, Antifungal Agents, Antimicrobial Cationic Peptides, Body Patterning, Cell Surface, Escherichia coli, Genes, Hemolymph, hoffmann, Insect, Insect Proteins, M3i, Membrane Glycoproteins, Micrococcus luteus, Mutagenesis, Peptides, Receptors, Recombinant Fusion Proteins, reichhart, Serine Proteinase Inhibitors, Serpins, Signal Transduction, Toll-Like Receptors, Up-Regulation},
pubstate = {published},
tppubtype = {article}
}