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2015 |
Paro, Simona; Imler, Jean-Luc; Meignin, Carine Sensing viral RNAs by Dicer/RIG-I like ATPases across species Article de journal Current Opinion in Immunology, 32 , p. 106–113, 2015, ISSN: 1879-0372. Résumé | Liens | BibTeX | Étiquettes: Adenosine Triphosphatases, Animals, DEAD-box RNA Helicases, Humans, imler, M3i, meignin, Protein Binding, Protein Interaction Domains and Motifs, Ribonuclease III, RNA, Viral, Virus Diseases, viruses @article{paro_sensing_2015, title = {Sensing viral RNAs by Dicer/RIG-I like ATPases across species}, author = {Simona Paro and Jean-Luc Imler and Carine Meignin}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0952791515000102}, doi = {10.1016/j.coi.2015.01.009}, issn = {1879-0372}, year = {2015}, date = {2015-02-01}, journal = {Current Opinion in Immunology}, volume = {32}, pages = {106--113}, abstract = {Induction of antiviral immunity in vertebrates and invertebrates relies on members of the RIG-I-like receptor and Dicer families, respectively. Although these proteins have different size and domain composition, members of both families share a conserved DECH-box helicase domain. This helicase, also known as a duplex RNA activated ATPase, or DRA domain, plays an important role in viral RNA sensing. Crystallographic and electron microscopy studies of the RIG-I and Dicer DRA domains indicate a common structure and that similar conformational changes are induced by dsRNA binding. Genetic and biochemical studies on the function and regulation of DRAs reveal similarities, but also some differences, between viral RNA sensing mechanisms in nematodes, flies and mammals.}, keywords = {Adenosine Triphosphatases, Animals, DEAD-box RNA Helicases, Humans, imler, M3i, meignin, Protein Binding, Protein Interaction Domains and Motifs, Ribonuclease III, RNA, Viral, Virus Diseases, viruses}, pubstate = {published}, tppubtype = {article} } Induction of antiviral immunity in vertebrates and invertebrates relies on members of the RIG-I-like receptor and Dicer families, respectively. Although these proteins have different size and domain composition, members of both families share a conserved DECH-box helicase domain. This helicase, also known as a duplex RNA activated ATPase, or DRA domain, plays an important role in viral RNA sensing. Crystallographic and electron microscopy studies of the RIG-I and Dicer DRA domains indicate a common structure and that similar conformational changes are induced by dsRNA binding. Genetic and biochemical studies on the function and regulation of DRAs reveal similarities, but also some differences, between viral RNA sensing mechanisms in nematodes, flies and mammals. |
2014 |
Tartey, Sarang; Matsushita, Kazufumi; Vandenbon, Alexis; Ori, Daisuke; Imamura, Tomoko; Mino, Takashi; Standley, Daron M; Hoffmann, Jules A; Reichhart, Jean-Marc; Akira, Shizuo; Takeuchi, Osamu Akirin2 is critical for inducing inflammatory genes by bridging IκB-ζ and the SWI/SNF complex Article de journal EMBO J., 33 (20), p. 2332–2348, 2014, ISSN: 1460-2075. Résumé | Liens | BibTeX | Étiquettes: Adaptor Proteins, Animals, Cell Nucleus, Chromatin Assembly and Disassembly, chromatin remodeling, Chromosomal Proteins, cytokine, Cytokines, Female, Gene Expression Regulation, gene regulation, Genetic, hoffmann, Humans, Immunity, Innate, innate immunity, Knockout, Listeria monocytogenes, M3i, Macrophages, Male, Mice, Multiprotein Complexes, Non-Histone, Nuclear Proteins, Promoter Regions, Protein Binding, reichhart, Repressor Proteins, Sequence Deletion, Signal Transducing, Transcriptional Activation @article{tartey_akirin2_2014, title = {Akirin2 is critical for inducing inflammatory genes by bridging IκB-ζ and the SWI/SNF complex}, author = {Sarang Tartey and Kazufumi Matsushita and Alexis Vandenbon and Daisuke Ori and Tomoko Imamura and Takashi Mino and Daron M Standley and Jules A Hoffmann and Jean-Marc Reichhart and Shizuo Akira and Osamu Takeuchi}, doi = {10.15252/embj.201488447}, issn = {1460-2075}, year = {2014}, date = {2014-10-01}, journal = {EMBO J.}, volume = {33}, number = {20}, pages = {2332--2348}, abstract = {Transcription of inflammatory genes in innate immune cells is coordinately regulated by transcription factors, including NF-κB, and chromatin modifiers. However, it remains unclear how microbial sensing initiates chromatin remodeling. Here, we show that Akirin2, an evolutionarily conserved nuclear protein, bridges NF-κB and the chromatin remodeling SWI/SNF complex by interacting with BRG1-Associated Factor 60 (BAF60) proteins as well as IκB-ζ, which forms a complex with the NF-κB p50 subunit. These interactions are essential for Toll-like receptor-, RIG-I-, and Listeria-mediated expression of proinflammatory genes including Il6 and Il12b in macrophages. Consistently, effective clearance of Listeria infection required Akirin2. Furthermore, Akirin2 and IκB-ζ recruitment to the Il6 promoter depend upon the presence of IκB-ζ and Akirin2, respectively, for regulation of chromatin remodeling. BAF60 proteins were also essential for the induction of Il6 in response to LPS stimulation. Collectively, the IκB-ζ-Akirin2-BAF60 complex physically links the NF-κB and SWI/SNF complexes in innate immune cell activation. By recruiting SWI/SNF chromatin remodellers to IκB-ζ, transcriptional coactivator for NF-κB, the conserved nuclear protein Akirin2 stimulates pro-inflammatory gene promoters in mouse macrophages during innate immune responses to viral or bacterial infection.}, keywords = {Adaptor Proteins, Animals, Cell Nucleus, Chromatin Assembly and Disassembly, chromatin remodeling, Chromosomal Proteins, cytokine, Cytokines, Female, Gene Expression Regulation, gene regulation, Genetic, hoffmann, Humans, Immunity, Innate, innate immunity, Knockout, Listeria monocytogenes, M3i, Macrophages, Male, Mice, Multiprotein Complexes, Non-Histone, Nuclear Proteins, Promoter Regions, Protein Binding, reichhart, Repressor Proteins, Sequence Deletion, Signal Transducing, Transcriptional Activation}, pubstate = {published}, tppubtype = {article} } Transcription of inflammatory genes in innate immune cells is coordinately regulated by transcription factors, including NF-κB, and chromatin modifiers. However, it remains unclear how microbial sensing initiates chromatin remodeling. Here, we show that Akirin2, an evolutionarily conserved nuclear protein, bridges NF-κB and the chromatin remodeling SWI/SNF complex by interacting with BRG1-Associated Factor 60 (BAF60) proteins as well as IκB-ζ, which forms a complex with the NF-κB p50 subunit. These interactions are essential for Toll-like receptor-, RIG-I-, and Listeria-mediated expression of proinflammatory genes including Il6 and Il12b in macrophages. Consistently, effective clearance of Listeria infection required Akirin2. Furthermore, Akirin2 and IκB-ζ recruitment to the Il6 promoter depend upon the presence of IκB-ζ and Akirin2, respectively, for regulation of chromatin remodeling. BAF60 proteins were also essential for the induction of Il6 in response to LPS stimulation. Collectively, the IκB-ζ-Akirin2-BAF60 complex physically links the NF-κB and SWI/SNF complexes in innate immune cell activation. By recruiting SWI/SNF chromatin remodellers to IκB-ζ, transcriptional coactivator for NF-κB, the conserved nuclear protein Akirin2 stimulates pro-inflammatory gene promoters in mouse macrophages during innate immune responses to viral or bacterial infection. |
2013 |
Kobayashi, Taira; Ogawa, Michinaga; Sanada, Takahito; Mimuro, Hitomi; Kim, Minsoo; Ashida, Hiroshi; Akakura, Reiko; Yoshida, Mitsutaka; Kawalec, Magdalena; Reichhart, Jean-Marc; Mizushima, Tsunehiro; Sasakawa, Chihiro The Shigella OspC3 effector inhibits caspase-4, antagonizes inflammatory cell death, and promotes epithelial infection Article de journal Cell Host Microbe, 13 (5), p. 570–583, 2013, ISSN: 1934-6069. Résumé | Liens | BibTeX | Étiquettes: Animal, Animals, Bacillary, Bacterial, Bacterial Proteins, Caspases, Cell Death, Cell Line, Disease Models, DNA, Dysentery, Enzyme Inhibitors, Epithelial Cells, Escherichia coli, Gene Knockout Techniques, Guinea Pigs, Host-Pathogen Interactions, Humans, Initiator, M3i, Protein Binding, Protein Interaction Mapping, reichhart, Salmonella typhimurium, Sequence Analysis, Shigella flexneri, Virulence Factors @article{kobayashi_shigella_2013, title = {The Shigella OspC3 effector inhibits caspase-4, antagonizes inflammatory cell death, and promotes epithelial infection}, author = {Taira Kobayashi and Michinaga Ogawa and Takahito Sanada and Hitomi Mimuro and Minsoo Kim and Hiroshi Ashida and Reiko Akakura and Mitsutaka Yoshida and Magdalena Kawalec and Jean-Marc Reichhart and Tsunehiro Mizushima and Chihiro Sasakawa}, doi = {10.1016/j.chom.2013.04.012}, issn = {1934-6069}, year = {2013}, date = {2013-05-01}, journal = {Cell Host Microbe}, volume = {13}, number = {5}, pages = {570--583}, abstract = {Caspase-mediated inflammatory cell death acts as an intrinsic defense mechanism against infection. Bacterial pathogens deploy countermeasures against inflammatory cell death, but the mechanisms by which they do this remain largely unclear. In a screen for Shigella flexneri effectors that regulate cell death during infection, we discovered that Shigella infection induced acute inflammatory, caspase-4-dependent epithelial cell death, which is counteracted by the bacterial OspC3 effector. OspC3 interacts with the caspase-4-p19 subunit and inhibits its activation by preventing caspase-4-p19 and caspase-4-p10 heterodimerization by depositing the conserved OspC3 X1-Y-X₂-D-X₃ motif at the putative catalytic pocket of caspase-4. Infection of guinea pigs with a Shigella ospC3-deficient mutant resulted in enhanced inflammatory cell death and associated symptoms, correlating with decreased bacterial burdens. Salmonella Typhimurium and enteropathogenic Escherichia coli infection also induced caspase-4-dependent epithelial death. These findings highlight the importance of caspase-4-dependent innate immune responses and demonstrate that Shigella delivers a caspase-4-specific inhibitor to delay epithelial cell death and promote infection.}, keywords = {Animal, Animals, Bacillary, Bacterial, Bacterial Proteins, Caspases, Cell Death, Cell Line, Disease Models, DNA, Dysentery, Enzyme Inhibitors, Epithelial Cells, Escherichia coli, Gene Knockout Techniques, Guinea Pigs, Host-Pathogen Interactions, Humans, Initiator, M3i, Protein Binding, Protein Interaction Mapping, reichhart, Salmonella typhimurium, Sequence Analysis, Shigella flexneri, Virulence Factors}, pubstate = {published}, tppubtype = {article} } Caspase-mediated inflammatory cell death acts as an intrinsic defense mechanism against infection. Bacterial pathogens deploy countermeasures against inflammatory cell death, but the mechanisms by which they do this remain largely unclear. In a screen for Shigella flexneri effectors that regulate cell death during infection, we discovered that Shigella infection induced acute inflammatory, caspase-4-dependent epithelial cell death, which is counteracted by the bacterial OspC3 effector. OspC3 interacts with the caspase-4-p19 subunit and inhibits its activation by preventing caspase-4-p19 and caspase-4-p10 heterodimerization by depositing the conserved OspC3 X1-Y-X₂-D-X₃ motif at the putative catalytic pocket of caspase-4. Infection of guinea pigs with a Shigella ospC3-deficient mutant resulted in enhanced inflammatory cell death and associated symptoms, correlating with decreased bacterial burdens. Salmonella Typhimurium and enteropathogenic Escherichia coli infection also induced caspase-4-dependent epithelial death. These findings highlight the importance of caspase-4-dependent innate immune responses and demonstrate that Shigella delivers a caspase-4-specific inhibitor to delay epithelial cell death and promote infection. |
2010 |
Whisstock, James C; Silverman, Gary A; Bird, Phillip I; Bottomley, Stephen P; Kaiserman, Dion; Luke, Cliff J; Pak, Stephen C; Reichhart, Jean-Marc; Huntington, James A Serpins flex their muscle: II. Structural insights into target peptidase recognition, polymerization, and transport functions Article de journal J. Biol. Chem., 285 (32), p. 24307–24312, 2010, ISSN: 1083-351X. Résumé | Liens | BibTeX | Étiquettes: Animals, Biological, Biological Transport, Biophysics, Catalytic Domain, Hormones, Humans, Kinetics, M3i, Models, Peptide Hydrolases, Protein Binding, Protein Conformation, Protein Structure, reichhart, Serpins, Substrate Specificity, Tertiary, Thrombin @article{whisstock_serpins_2010, title = {Serpins flex their muscle: II. Structural insights into target peptidase recognition, polymerization, and transport functions}, author = {James C Whisstock and Gary A Silverman and Phillip I Bird and Stephen P Bottomley and Dion Kaiserman and Cliff J Luke and Stephen C Pak and Jean-Marc Reichhart and James A Huntington}, doi = {10.1074/jbc.R110.141408}, issn = {1083-351X}, year = {2010}, date = {2010-08-01}, journal = {J. Biol. Chem.}, volume = {285}, number = {32}, pages = {24307--24312}, abstract = {Inhibitory serpins are metastable proteins that undergo a substantial conformational rearrangement to covalently trap target peptidases. The serpin reactive center loop contributes a majority of the interactions that serpins make during the initial binding to target peptidases. However, structural studies on serpin-peptidase complexes reveal a broader set of contacts on the scaffold of inhibitory serpins that have substantial influence on guiding peptidase recognition. Structural and biophysical studies also reveal how aberrant serpin folding can lead to the formation of domain-swapped serpin multimers rather than the monomeric metastable state. Serpin domain swapping may therefore underlie the polymerization events characteristic of the serpinopathies. Finally, recent structural studies reveal how the serpin fold has been adapted for non-inhibitory functions such as hormone binding.}, keywords = {Animals, Biological, Biological Transport, Biophysics, Catalytic Domain, Hormones, Humans, Kinetics, M3i, Models, Peptide Hydrolases, Protein Binding, Protein Conformation, Protein Structure, reichhart, Serpins, Substrate Specificity, Tertiary, Thrombin}, pubstate = {published}, tppubtype = {article} } Inhibitory serpins are metastable proteins that undergo a substantial conformational rearrangement to covalently trap target peptidases. The serpin reactive center loop contributes a majority of the interactions that serpins make during the initial binding to target peptidases. However, structural studies on serpin-peptidase complexes reveal a broader set of contacts on the scaffold of inhibitory serpins that have substantial influence on guiding peptidase recognition. Structural and biophysical studies also reveal how aberrant serpin folding can lead to the formation of domain-swapped serpin multimers rather than the monomeric metastable state. Serpin domain swapping may therefore underlie the polymerization events characteristic of the serpinopathies. Finally, recent structural studies reveal how the serpin fold has been adapted for non-inhibitory functions such as hormone binding. |
2009 |
Fraiture, Malou; Baxter, Richard H G; Steinert, Stefanie; Chelliah, Yogarany; Frolet, Cécile; Quispe-Tintaya, Wilber; Hoffmann, Jules A; Blandin, Stéphanie A; Levashina, Elena A Two mosquito LRR proteins function as complement control factors in the TEP1-mediated killing of Plasmodium Article de journal Cell Host Microbe, 5 (3), p. 273–284, 2009, ISSN: 1934-6069. Résumé | Liens | BibTeX | Étiquettes: Animals, Anopheles, APL1, Biological, blandin, Complement System Proteins, Hemolymph, hoffmann, Immunologic Factors, LRIM1, M3i, Models, Plasmodium, Protein Binding, Proteins, TEP1 @article{fraiture_two_2009, title = {Two mosquito LRR proteins function as complement control factors in the TEP1-mediated killing of Plasmodium}, author = {Malou Fraiture and Richard H G Baxter and Stefanie Steinert and Yogarany Chelliah and Cécile Frolet and Wilber Quispe-Tintaya and Jules A Hoffmann and Stéphanie A Blandin and Elena A Levashina}, doi = {10.1016/j.chom.2009.01.005}, issn = {1934-6069}, year = {2009}, date = {2009-03-01}, journal = {Cell Host Microbe}, volume = {5}, number = {3}, pages = {273--284}, abstract = {Plasmodium development within Anopheles mosquitoes is a vulnerable step in the parasite transmission cycle, and targeting this step represents a promising strategy for malaria control. The thioester-containing complement-like protein TEP1 and two leucine-rich repeat (LRR) proteins, LRIM1 and APL1, have been identified as major mosquito factors that regulate parasite loads. Here, we show that LRIM1 and APL1 are required for binding of TEP1 to parasites. RNAi silencing of the LRR-encoding genes results in deposition of TEP1 on Anopheles tissues, thereby depleting TEP1 from circulation in the hemolymph and impeding its binding to Plasmodium. LRIM1 and APL1 not only stabilize circulating TEP1, they also stabilize each other prior to their interaction with TEP1. Our results indicate that three major antiparasitic factors in mosquitoes jointly function as a complement-like system in parasite killing, and they reveal a role for LRR proteins as complement control factors.}, keywords = {Animals, Anopheles, APL1, Biological, blandin, Complement System Proteins, Hemolymph, hoffmann, Immunologic Factors, LRIM1, M3i, Models, Plasmodium, Protein Binding, Proteins, TEP1}, pubstate = {published}, tppubtype = {article} } Plasmodium development within Anopheles mosquitoes is a vulnerable step in the parasite transmission cycle, and targeting this step represents a promising strategy for malaria control. The thioester-containing complement-like protein TEP1 and two leucine-rich repeat (LRR) proteins, LRIM1 and APL1, have been identified as major mosquito factors that regulate parasite loads. Here, we show that LRIM1 and APL1 are required for binding of TEP1 to parasites. RNAi silencing of the LRR-encoding genes results in deposition of TEP1 on Anopheles tissues, thereby depleting TEP1 from circulation in the hemolymph and impeding its binding to Plasmodium. LRIM1 and APL1 not only stabilize circulating TEP1, they also stabilize each other prior to their interaction with TEP1. Our results indicate that three major antiparasitic factors in mosquitoes jointly function as a complement-like system in parasite killing, and they reveal a role for LRR proteins as complement control factors. |
2007 |
Weber, Alexander N R; Gangloff, Monique; Moncrieffe, Martin C; Hyvert, Yann; Imler, Jean-Luc; Gay, Nicholas J Role of the Spatzle Pro-domain in the generation of an active toll receptor ligand Article de journal The Journal of Biological Chemistry, 282 (18), p. 13522–13531, 2007, ISSN: 0021-9258. Résumé | Liens | BibTeX | Étiquettes: Animals, Cytokines, dimerization, imler, ligands, M3i, Post-Translational, Protein Binding, Protein Processing, Protein Structure, Signal Transduction, Tertiary, Toll-Like Receptors @article{weber_role_2007, title = {Role of the Spatzle Pro-domain in the generation of an active toll receptor ligand}, author = {Alexander N R Weber and Monique Gangloff and Martin C Moncrieffe and Yann Hyvert and Jean-Luc Imler and Nicholas J Gay}, doi = {10.1074/jbc.M700068200}, issn = {0021-9258}, year = {2007}, date = {2007-05-01}, journal = {The Journal of Biological Chemistry}, volume = {282}, number = {18}, pages = {13522--13531}, abstract = {The cytokine Spätzle is the ligand for Drosophila Toll, the prototype of an important family of membrane receptors that function in embryonic patterning and innate immunity. A dimeric precursor of Spätzle is processed by an endoprotease to produce a form (C-106) that cross-links Toll receptor ectodomains and establishes signaling. Here we show that before processing the pro-domain of Spätzle is required for correct biosynthesis and secretion. We mapped two loss-of-function mutations of Spätzle to a discrete site in the pro-domain and showed that the phenotype arises because of a defect in biosynthesis rather than signaling. We also report that the pro-domain and C-106 remain associated after cleavage and that this processed complex signals with the same characteristics as the C-terminal fragment. These results suggest that before activation the determinants on C-106 that bind specifically to Toll are sequestered by the pro-domain and that proteolytic processing causes conformational rearrangements that expose these determinants and enables binding to Toll. Furthermore, we show that the pro-domain is released when the Toll extracellular domain binds to the complex, a finding that has implications for the generation of a signaling-competent Toll dimer.}, keywords = {Animals, Cytokines, dimerization, imler, ligands, M3i, Post-Translational, Protein Binding, Protein Processing, Protein Structure, Signal Transduction, Tertiary, Toll-Like Receptors}, pubstate = {published}, tppubtype = {article} } The cytokine Spätzle is the ligand for Drosophila Toll, the prototype of an important family of membrane receptors that function in embryonic patterning and innate immunity. A dimeric precursor of Spätzle is processed by an endoprotease to produce a form (C-106) that cross-links Toll receptor ectodomains and establishes signaling. Here we show that before processing the pro-domain of Spätzle is required for correct biosynthesis and secretion. We mapped two loss-of-function mutations of Spätzle to a discrete site in the pro-domain and showed that the phenotype arises because of a defect in biosynthesis rather than signaling. We also report that the pro-domain and C-106 remain associated after cleavage and that this processed complex signals with the same characteristics as the C-terminal fragment. These results suggest that before activation the determinants on C-106 that bind specifically to Toll are sequestered by the pro-domain and that proteolytic processing causes conformational rearrangements that expose these determinants and enables binding to Toll. Furthermore, we show that the pro-domain is released when the Toll extracellular domain binds to the complex, a finding that has implications for the generation of a signaling-competent Toll dimer. |
2005 |
Weber, Alexander N R; Moncrieffe, Martin C; Gangloff, Monique; Imler, Jean-Luc; Gay, Nicholas J Ligand-receptor and receptor-receptor interactions act in concert to activate signaling in the Drosophila toll pathway Article de journal The Journal of Biological Chemistry, 280 (24), p. 22793–22799, 2005, ISSN: 0021-9258. Résumé | Liens | BibTeX | Étiquettes: 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 @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} } 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. |
2003 |
Weber, Alexander N R; Tauszig-Delamasure, Servane; Hoffmann, Jules A; Lelièvre, Eric; Gascan, Hugues; Ray, Keith P; Morse, Mary A; Imler, Jean-Luc; Gay, Nicholas J Binding of the Drosophila cytokine Spätzle to Toll is direct and establishes signaling Article de journal Nature Immunology, 4 (8), p. 794–800, 2003, ISSN: 1529-2908. Résumé | Liens | BibTeX | Étiquettes: Animals, Cell Surface, hoffmann, imler, Insect Proteins, M3i, Protein Binding, Protein Structure, Receptors, Signal Transduction, Tertiary, Toll-Like Receptors @article{weber_binding_2003, title = {Binding of the Drosophila cytokine Spätzle to Toll is direct and establishes signaling}, author = {Alexander N R Weber and Servane Tauszig-Delamasure and Jules A Hoffmann and Eric Lelièvre and Hugues Gascan and Keith P Ray and Mary A Morse and Jean-Luc Imler and Nicholas J Gay}, doi = {10.1038/ni955}, issn = {1529-2908}, year = {2003}, date = {2003-08-01}, journal = {Nature Immunology}, volume = {4}, number = {8}, pages = {794--800}, abstract = {The extracellular protein Spätzle is required for activation of the Toll signaling pathway in the embryonic development and innate immune defense of Drosophila. Spätzle is synthesized as a pro-protein and is processed to a functional form by a serine protease. We show here that the mature form of Spätzle triggers a Toll-dependent immune response after injection into the hemolymph of flies. Spätzle specifically bound to Drosophila cells and to Cos-7 cells expressing Toll. Furthermore, in vitro experiments showed that the mature form of Spätzle bound to the Toll ectodomain with high affinity and with a stoichiometry of one Spätzle dimer to two receptors. The Spätzle pro-protein was inactive in all these assays, indicating that the pro-domain sequence, which is natively unstructured, acts to prevent interaction of the cytokine and its receptor Toll. These results show that, in contrast to the human Toll-like receptors, Drosophila Toll requires only an endogenous protein ligand for activation and signaling.}, keywords = {Animals, Cell Surface, hoffmann, imler, Insect Proteins, M3i, Protein Binding, Protein Structure, Receptors, Signal Transduction, Tertiary, Toll-Like Receptors}, pubstate = {published}, tppubtype = {article} } The extracellular protein Spätzle is required for activation of the Toll signaling pathway in the embryonic development and innate immune defense of Drosophila. Spätzle is synthesized as a pro-protein and is processed to a functional form by a serine protease. We show here that the mature form of Spätzle triggers a Toll-dependent immune response after injection into the hemolymph of flies. Spätzle specifically bound to Drosophila cells and to Cos-7 cells expressing Toll. Furthermore, in vitro experiments showed that the mature form of Spätzle bound to the Toll ectodomain with high affinity and with a stoichiometry of one Spätzle dimer to two receptors. The Spätzle pro-protein was inactive in all these assays, indicating that the pro-domain sequence, which is natively unstructured, acts to prevent interaction of the cytokine and its receptor Toll. These results show that, in contrast to the human Toll-like receptors, Drosophila Toll requires only an endogenous protein ligand for activation and signaling. |
1995 |
Lemaitre, Bruno; Kromer-Metzger, E; Michaut, Lydia; Nicolas, E; Meister, Marie; Georgel, Philippe; Reichhart, Jean-Marc; Hoffmann, Jules A A recessive mutation, immune deficiency (imd), defines two distinct control pathways in the Drosophila host defense Article de journal Proc. Natl. Acad. Sci. U.S.A., 92 (21), p. 9465–9469, 1995, ISSN: 0027-8424. Résumé | BibTeX | Étiquettes: Animals, Anti-Bacterial Agents, Antimicrobial Cationic Peptides, Bacterial Infections, Base Sequence, Gene Expression Regulation, Genes, Glycopeptides, hoffmann, Insect, Insect Hormones, Insect Proteins, M3i, Male, Mutation, Mycoses, Nucleic Acid, Peptides, Protein Binding, Recessive, Regulatory Sequences, reichhart, Reporter, Survival Analysis @article{lemaitre_recessive_1995, title = {A recessive mutation, immune deficiency (imd), defines two distinct control pathways in the Drosophila host defense}, author = {Bruno Lemaitre and E Kromer-Metzger and Lydia Michaut and E Nicolas and Marie Meister and Philippe Georgel and Jean-Marc Reichhart and Jules A Hoffmann}, issn = {0027-8424}, year = {1995}, date = {1995-10-01}, journal = {Proc. Natl. Acad. Sci. U.S.A.}, volume = {92}, number = {21}, pages = {9465--9469}, abstract = {In this paper we report a recessive mutation, immune deficiency (imd), that impairs the inducibility of all genes encoding antibacterial peptides during the immune response of Drosophila. When challenged with bacteria, flies carrying this mutation show a lower survival rate than wild-type flies. We also report that, in contrast to the antibacterial peptides, the antifungal peptide drosomycin remains inducible in a homozygous imd mutant background. These results point to the existence of two different pathways leading to the expression of two types of target genes, encoding either the antibacterial peptides or the antifungal peptide drosomycin.}, keywords = {Animals, Anti-Bacterial Agents, Antimicrobial Cationic Peptides, Bacterial Infections, Base Sequence, Gene Expression Regulation, Genes, Glycopeptides, hoffmann, Insect, Insect Hormones, Insect Proteins, M3i, Male, Mutation, Mycoses, Nucleic Acid, Peptides, Protein Binding, Recessive, Regulatory Sequences, reichhart, Reporter, Survival Analysis}, pubstate = {published}, tppubtype = {article} } In this paper we report a recessive mutation, immune deficiency (imd), that impairs the inducibility of all genes encoding antibacterial peptides during the immune response of Drosophila. When challenged with bacteria, flies carrying this mutation show a lower survival rate than wild-type flies. We also report that, in contrast to the antibacterial peptides, the antifungal peptide drosomycin remains inducible in a homozygous imd mutant background. These results point to the existence of two different pathways leading to the expression of two types of target genes, encoding either the antibacterial peptides or the antifungal peptide drosomycin. |
1975 |
Feyereisen, R; Lagueux, Marie; Hoffmann, Jules A The hemolymphatic transport of molting hormone during the development of Locusta migratoria L Article de journal C.R. Hebd. Seances Acad. Sci., Ser. D, Sci. Nat., 280 (14), p. 1709–1712, 1975. Résumé | BibTeX | Étiquettes: Age Factors, Animals, Carrier Proteins, Chromatography, Ecdysone, Ecdysterone, Gel, Grasshoppers, Hematopoietic System, hoffmann, Larva, M3i, Neurosecretory Systems, Protein Binding, Time Factors @article{feyereisen_hemolymphatic_1975, title = {The hemolymphatic transport of molting hormone during the development of Locusta migratoria L}, author = {R Feyereisen and Marie Lagueux and Jules A Hoffmann}, year = {1975}, date = {1975-04-01}, journal = {C.R. Hebd. Seances Acad. Sci., Ser. D, Sci. Nat.}, volume = {280}, number = {14}, pages = {1709--1712}, abstract = {Shortly after injection of radio-labelled ecdysone into fifth instar larvae of Locusta migratoria, 20-hydroxy-ecdysone (ecdysterone) is the main hormone found in the blood. Some 10% of the circulating hormone are bound to hemolymph macromolecules. The ratio of bound to free hormone is stage-dependent; it decreases considerably after previous injections of non-labelled ecdysone, but increases in insects in which ecdysone biosynthesis has been blocked by extirpation of the prothoracic glands or selective X-ray treatment of the hemocytopoietic tissue.}, keywords = {Age Factors, Animals, Carrier Proteins, Chromatography, Ecdysone, Ecdysterone, Gel, Grasshoppers, Hematopoietic System, hoffmann, Larva, M3i, Neurosecretory Systems, Protein Binding, Time Factors}, pubstate = {published}, tppubtype = {article} } Shortly after injection of radio-labelled ecdysone into fifth instar larvae of Locusta migratoria, 20-hydroxy-ecdysone (ecdysterone) is the main hormone found in the blood. Some 10% of the circulating hormone are bound to hemolymph macromolecules. The ratio of bound to free hormone is stage-dependent; it decreases considerably after previous injections of non-labelled ecdysone, but increases in insects in which ecdysone biosynthesis has been blocked by extirpation of the prothoracic glands or selective X-ray treatment of the hemocytopoietic tissue. |