| 1. |
- Lindmark, H, et al.
(författare)
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Enteric bacteria counteract lipopolysaccharide induction of antimicrobial peptide genes.
- 2001
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Ingår i: J Immunol. - 0022-1767. ; 167, s. 6920-6923
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Tidskriftsartikel (refereegranskat)abstract
- The humoral immunity of Drosophila involves the production of antimicrobial peptides, which are induced by evolutionary conserved microbial molecules, like LPS. By using Drosophila mbn-2 cells, we found that live bacteria, including E. coli, Salmonella typhimurium, Erwinia carotovora, and Pseudomonas aeruginosa, prevented LPS from inducing antimicrobial peptide genes, while Micrococcus luteus and Streptococcus equi did not. The inhibitory effect was seen at bacterial levels from 20 per mbn-2 cell, while antimicrobial peptides were induced at lower bacterial concentrations (< or =2 bacteria per cell) also in the absence of added LPS. Gel shift experiment suggests that the inhibitory effect is upstream or at the level of the activation of the transcription factor Relish, a member of the NF-kappaB/Rel family. The bacteria have to be in physical contact with the cells, but not phagocytosed, to prevent LPS induction. Interestingly, the inhibiting mechanism is, at least for E. coli, independent of the type III secretion system, indicating that the inhibitory mechanism is unrelated to the one earlier described for YopJ from Yersinia.
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| 2. |
- Werner, Thomas, et al.
(författare)
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Functional diversity of the Drosophila PGRP-LC gene cluster in the response to lipopolysaccharide and peptidoglycan.
- 2003
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Ingår i: J Biol Chem. - 0021-9258. ; 278:29, s. 26319-22
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Tidskriftsartikel (refereegranskat)abstract
- The peptidoglycan recognition protein PGRP-LC is a major activator of the imd/Relish pathway in the Drosophila immune response. Three transcripts are generated by alternative splicing of the complex PGRP-LC gene. The encoded transmembrane proteins share an identical intracellular part, but each has a separate extracellular PGRP-domain: x, y, or a. Here we show that two of these isoforms play unique roles in the response to different microorganisms. Using RNA interference in Drosophila mbn-2 cells, we found that PGRP-LCx is the only isoform required to mediate signals from Gram-positive bacteria and purified bacterial peptidoglycan. By contrast, the recognition of Gram-negative bacteria and bacterial lipopolysaccharide requires both PGRP-LCa and LCx. The third isoform, LCy, is expressed at lower levels and may be partially redundant. Two additional PGRP domains in the gene cluster, z and w, are both included in a single transcript of a separate gene, PGRP-LF. Suppression of this transcript does not block the response to any of the microorganisms tested.
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| 3. |
- Hedengren, Marika, et al.
(författare)
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Expression and evolution of the Drosophila attacin/diptericin gene family.
- 2000
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Ingår i: Biochem Biophys Res Commun. - : Elsevier BV. - 0006-291X. ; 279:2, s. 574-81
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Tidskriftsartikel (refereegranskat)abstract
- We describe the genes for three new glycine-rich antimicrobial peptides in Drosophila, two attacins (AttC and AttD) and one diptericin (DptB). Their structures support the proposal that these glycine-rich antimicrobial peptides evolved from a common ancestor and are probably also related to proline-rich peptides such as drosocin. AttC is similar to the nearby AttA and AttB genes. AttD is more divergent and located on a different chromosome. Intriguingly, AttD may encode an intracellular attacin. DptB is linked in tandem to the closely related Diptericin. However, the DptB gene product contains a furin-like cleavage site and may be processed in an attacin-like fashion. All attacin and diptericin genes are induced after bacterial challenge. This induction is reduced in imd mutants, and unexpectedly also in Tl(-) mutants. The 18w mutation particularly affects the induction of AttC, which may be a useful marker for 18w signaling.
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| 4. |
- Kurucz, Eva, et al.
(författare)
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Hemese, a hemocyte-specific transmembrane protein, affects the cellular immune response in Drosophila.
- 2003
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 100:5, s. 2622-7
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Tidskriftsartikel (refereegranskat)abstract
- We have identified a previously undescribed transmembrane protein, Hemese, from Drosophila melanogaster blood cells (hemocytes), by using a monoclonal pan-hemocyte antibody. Heavy glycosylation is suggested by the heterogeneous size distribution, ranging between 37 and 70 kDa. Hemese expression is restricted to the cell surfaces of hemocytes of all classes, and to the hematopoietic organs. The sequence of the corresponding gene, Hemese (He), predicts a glycophorin-like protein of 15 kDa, excluding an N-terminal signal peptide, with a single hydrophobic transmembrane region. The extracellular region consists mainly of Ser/Thr-rich sequence of low complexity, with several potential O-glycosylation sites. Hemese contains phosphotyrosine and the cytoplasmic region has potential phosphorylation sites, suggesting an involvement in signal transduction. Depletion of Hemese by RNA interference has no obvious effect under normal conditions, but the cellular response to parasitic wasps is much enhanced. This finding indicates that Hemese plays a modulatory role in the activation or recruitment of the hemocytes.
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| 5. |
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| 6. |
- Ekengren, Sophia, et al.
(författare)
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A family of Turandot-related genes in the humoral stress response of Drosophila.
- 2001
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Ingår i: Biochem Biophys Res Commun. - 0006-291X. ; 284:4, s. 998-1003
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Tidskriftsartikel (refereegranskat)abstract
- The Drosophila Turandot A (TotA) gene was recently shown to encode a stress-induced humoral factor which gives increased resistance to the lethal effects of high temperature. Here we show that TotA belongs to a family of eight Tot genes distributed at three different sites in the Drosophila genome. All Tot genes are induced under stressful conditions such as bacterial infection, heat shock, paraquat feeding or exposure to ultraviolet light, suggesting that all members of this family play a role in Drosophila stress tolerance. The induction of the Tot genes differs in important respects from the heat shock response, such as the strong but delayed response to bacterial infection seen for several of the genes.
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| 7. |
- Ekengren, Sophia, et al.
(författare)
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A humoral stress response in Drosophila.
- 2001
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Ingår i: Curr Biol. - 0960-9822. ; 11:9, s. 714-8
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Tidskriftsartikel (refereegranskat)abstract
- The ability to react to unfavorable environmental changes is crucial for survival and reproduction, and several adaptive responses to stress have been conserved during evolution [1-3]. Specific immune and heat shock responses mediate the elimination of invading pathogens and of damaged proteins or cells [4-6]. Furthermore, MAP kinases and other signaling factors mediate cellular responses to a very broad range of environmental insults [7-9]. Here we describe a novel systemic response to stress in Drosophila. The Turandot A (TotA) gene encodes a humoral factor, which is secreted from the fat body and accumulates in the body fluids. TotA is strongly induced upon bacterial challenge, as well as by other types of stress such as high temperature, mechanical pressure, dehydration, UV irradiation, and oxidative agents. It is also upregulated during metamorphosis and at high age. Strikingly, flies that overexpress TotA show prolonged survival and retain normal activity at otherwise lethal temperatures. Although TotA is only induced by severe stress, it responds to a much wider range of stimuli than heat shock genes such as hsp70 or immune genes such as Cecropin A1.
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| 8. |
- Hultmark, Dan, et al.
(författare)
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A cytokine in the Drosophila stress response.
- 2003
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Ingår i: Dev Cell. - 1534-5807. ; 5:3, s. 360-1
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Tidskriftsartikel (refereegranskat)abstract
- The fruit fly, Drosophila melanogaster, has become a popular tool for studying immediate reactions to environmental hazards, such as the heat shock and innate immune responses. In mammals, protective responses to infections and other insults are coordinated by a complex network of cytokines that mediate cell-to-cell signaling. By contrast, the corresponding heat shock and innate immune responses in Drosophila have usually been regarded as cell-autonomous processes. However, in this issue of Developmental Cell, show that cytokines do play a role in mediating an acute phase response in this organism.
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| 9. |
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| 10. |
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