51
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Kemp C, Mueller S, Goto A, Barbier V, Paro S, Bonnay F, Dostert C, Troxler L, Hetru C, Meignin C, Pfeffer S, Hoffmann JA, Imler JL. Broad RNA interference-mediated antiviral immunity and virus-specific inducible responses in Drosophila. THE JOURNAL OF IMMUNOLOGY 2012; 190:650-8. [PMID: 23255357 DOI: 10.4049/jimmunol.1102486] [Citation(s) in RCA: 186] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The fruit fly Drosophila melanogaster is a good model to unravel the molecular mechanisms of innate immunity and has led to some important discoveries about the sensing and signaling of microbial infections. The response of Drosophila to virus infections remains poorly characterized and appears to involve two facets. On the one hand, RNA interference involves the recognition and processing of dsRNA into small interfering RNAs by the host RNase Dicer-2 (Dcr-2), whereas, on the other hand, an inducible response controlled by the evolutionarily conserved JAK-STAT pathway contributes to the antiviral host defense. To clarify the contribution of the small interfering RNA and JAK-STAT pathways to the control of viral infections, we have compared the resistance of flies wild-type and mutant for Dcr-2 or the JAK kinase Hopscotch to infections by seven RNA or DNA viruses belonging to different families. Our results reveal a unique susceptibility of hop mutant flies to infection by Drosophila C virus and cricket paralysis virus, two members of the Dicistroviridae family, which contrasts with the susceptibility of Dcr-2 mutant flies to many viruses, including the DNA virus invertebrate iridescent virus 6. Genome-wide microarray analysis confirmed that different sets of genes were induced following infection by Drosophila C virus or by two unrelated RNA viruses, Flock House virus and Sindbis virus. Overall, our data reveal that RNA interference is an efficient antiviral mechanism, operating against a large range of viruses, including a DNA virus. By contrast, the antiviral contribution of the JAK-STAT pathway appears to be virus specific.
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Affiliation(s)
- Cordula Kemp
- CNRS-UPR9022, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg Cedex, France
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52
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Teixeira L. Whole-genome expression profile analysis of Drosophila melanogaster immune responses. Brief Funct Genomics 2012; 11:375-86. [DOI: 10.1093/bfgp/els043] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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53
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Methylmercury tolerance is associated with the humoral stress factor gene Turandot A. Neurotoxicol Teratol 2012; 34:387-94. [PMID: 22546818 DOI: 10.1016/j.ntt.2012.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 04/12/2012] [Accepted: 04/15/2012] [Indexed: 11/22/2022]
Abstract
Methylmercury (MeHg) is an environmental neurotoxicant that targets the developing nervous system. In an effort to understand mechanisms of MeHg toxicity we have identified candidate genes that confer tolerance to MeHg using a Drosophila model. Whole genome transcript profiling of developing larval brains of MeHg-tolerant and non-tolerant flies has identified Turandot A (TotA) as a potential MeHg tolerance gene. TotA is a secreted humoral stress response factor in Drosophila that is a direct target of conserved innate immunity signaling pathways. Here we characterize TotA expression in newly generated isogenic lines (isolines) of flies derived from our previously established MeHg-tolerant and non-tolerant populations. TotA mRNA transcript and protein expression is seen to be higher in the tolerant isolines than the non-tolerant lines. Elevated TotA expression in the tolerant lines was seen to span all the larval developmental stages pointing toward a difference in the TotA gene regulation between the MeHg tolerant and non-tolerant strains. We show that TotA is most highly expressed in the fat body (liver equivalent) and is selectively upregulated in the fat body of tolerant flies relative to brain and gut tissues. Fat body-specific transgenic expression of TotA invokes MeHg tolerance as seen by enhanced development of flies reared on MeHg food. In addition, cell based assays show that high TotA expressing C6 cells are more tolerant to MeHg than the low TotA expressing S2 cells. Knockdown of TotA in the C6 cells trends toward a reduction in MeHg tolerance. Identification of TotA as a MeHg tolerance gene suggests a role for conserved cytokine/immune signaling pathways in modulating MeHg toxicity.
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Abstract
The deleterious and sometimes fatal outcomes of bacterial infectious diseases are the net result of the interactions between the pathogen and the host, and the genetically tractable fruit fly, Drosophila melanogaster, has emerged as a valuable tool for modeling the pathogen-host interactions of a wide variety of bacteria. These studies have revealed that there is a remarkable conservation of bacterial pathogenesis and host defence mechanisms between higher host organisms and Drosophila. This review presents an in-depth discussion of the Drosophila immune response, the Drosophila killing model, and the use of the model to examine bacterial-host interactions. The recent introduction of the Drosophila model into the oral microbiology field is discussed, specifically the use of the model to examine Porphyromonas gingivalis-host interactions, and finally the potential uses of this powerful model system to further elucidate oral bacterial-host interactions are addressed.
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Affiliation(s)
- Christina O Igboin
- Division of Oral Biology, College of Dentistry, The Ohio State University, Columbus, Ohio, USA
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55
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Ambegaokar SS, Jackson GR. Functional genomic screen and network analysis reveal novel modifiers of tauopathy dissociated from tau phosphorylation. Hum Mol Genet 2011; 20:4947-77. [PMID: 21949350 PMCID: PMC3221533 DOI: 10.1093/hmg/ddr432] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A functional genetic screen using loss-of-function and gain-of-function alleles was performed to identify modifiers of tau-induced neurotoxicity using the 2N/4R (full-length) isoform of wild-type human tau expressed in the fly retina. We previously reported eye pigment mutations, which create dysfunctional lysosomes, as potent modifiers; here, we report 37 additional genes identified from ∼1900 genes screened, including the kinases shaggy/GSK-3beta, par-1/MARK, CamKI and Mekk1. Tau acts synergistically with Mekk1 and p38 to down-regulate extracellular regulated kinase activity, with a corresponding decrease in AT8 immunoreactivity (pS202/T205), suggesting that tau can participate in signaling pathways to regulate its own kinases. Modifiers showed poor correlation with tau phosphorylation (using the AT8, 12E8 and AT270 epitopes); moreover, tested suppressors of wild-type tau were equally effective in suppressing toxicity of a phosphorylation-resistant S11A tau construct, demonstrating that changes in tau phosphorylation state are not required to suppress or enhance its toxicity. Genes related to autophagy, the cell cycle, RNA-associated proteins and chromatin-binding proteins constitute a large percentage of identified modifiers. Other functional categories identified include mitochondrial proteins, lipid trafficking, Golgi proteins, kinesins and dynein and the Hsp70/Hsp90-organizing protein (Hop). Network analysis uncovered several other genes highly associated with the functional modifiers, including genes related to the PI3K, Notch, BMP/TGF-β and Hedgehog pathways, and nuclear trafficking. Activity of GSK-3β is strongly upregulated due to TDP-43 expression, and reduced GSK-3β dosage is also a common suppressor of Aβ42 and TDP-43 toxicity. These findings suggest therapeutic targets other than mitigation of tau phosphorylation.
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Affiliation(s)
- Surendra S Ambegaokar
- Department of Neurology, University of Texas Medical Branch, 301 University Blvd., MRB 10.138, Galveston, TX 77555, USA
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56
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Ratzka C, Liang C, Dandekar T, Gross R, Feldhaar H. Immune response of the ant Camponotus floridanus against pathogens and its obligate mutualistic endosymbiont. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 41:529-536. [PMID: 21440063 DOI: 10.1016/j.ibmb.2011.03.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Revised: 03/01/2011] [Accepted: 03/11/2011] [Indexed: 05/30/2023]
Abstract
Numerous insect species harbor mutualistic endosymbionts that play a role in nutrient cycling or confer other fitness benefits to their hosts. Insect hosts face the problem of having to maintain such mutualistic bacteria while staging an immune response towards pathogens upon infection. In addition, hosts may regulate the number of endosymbionts present in their tissues via the innate immune system. Camponotus floridanus ants harbor the obligate endosymbiont Blochmannia floridanus in specialized midgut cells and ovaries. We identified genes transcriptionally induced in response to septic injury by suppression subtractive hybridization (SSH). Among these were genes involved in pathogen recognition (e.g. GNBP), signal transduction (e.g. MAPK-kinase), antimicrobial activity (e.g. defensin and hymenoptaecin), or general stress response (e.g. heat shock protein). A quantitative analysis of immune-gene expression revealed different expression kinetics of individual factors and also characteristic expression profiles after injection of gram-negative and gram-positive bacteria. Likewise, B. floridanus injected into the hemocoel elicited a comparable immune response of its host C. floridanus. Thus, the host immune system may contribute to controlling the endosymbiont population.
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Affiliation(s)
- Carolin Ratzka
- Lehrstuhl für Mikrobiologie, Biozentrum, Universität Würzburg, Germany
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57
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Walker J, Kwon SY, Badenhorst P, East P, McNeill H, Svejstrup JQ. Role of elongator subunit Elp3 in Drosophila melanogaster larval development and immunity. Genetics 2011; 187:1067-75. [PMID: 21288872 PMCID: PMC3070516 DOI: 10.1534/genetics.110.123893] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 01/12/2011] [Indexed: 12/23/2022] Open
Abstract
The Elongator complex has been implicated in several cellular processes, including gene expression and tRNA modification. We investigated the biological importance of the Elp3 gene in Drosophila melanogaster. Deletion of Elp3 results in larval lethality at the pupal stage. During early development, larval growth is dramatically impaired, with progression to the third instar delayed for ∼24 hr, and pupariation occurring only at day 14 after egg laying. Melanotic nodules appear after 4 days. Microarray analysis shows that stress response genes are induced and ecdysone-induced transcription factors are severely repressed in the mutant. Interestingly, the phenotypes of Elp3 flies are similar to those of flies lacking the domino gene, encoding a SWI/SNF-like ATP-dependent chromatin-remodeling enzyme. Indeed, the gene expression profiles of these mutants are also remarkably similar. Together, these data demonstrate that Drosophila Elp3 is essential for viability, normal development, and hematopoiesis and suggest a functional overlap with the chromatin remodeler Domino.
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Affiliation(s)
- Jane Walker
- Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD, United Kingdom.
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58
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Marcu O, Lera MP, Sanchez ME, Levic E, Higgins LA, Shmygelska A, Fahlen TF, Nichol H, Bhattacharya S. Innate immune responses of Drosophila melanogaster are altered by spaceflight. PLoS One 2011; 6:e15361. [PMID: 21264297 PMCID: PMC3019151 DOI: 10.1371/journal.pone.0015361] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 11/11/2010] [Indexed: 01/20/2023] Open
Abstract
Alterations and impairment of immune responses in humans present a health risk for space exploration missions. The molecular mechanisms underpinning innate immune defense can be confounded by the complexity of the acquired immune system of humans. Drosophila (fruit fly) innate immunity is simpler, and shares many similarities with human innate immunity at the level of molecular and genetic pathways. The goals of this study were to elucidate fundamental immune processes in Drosophila affected by spaceflight and to measure host-pathogen responses post-flight. Five containers, each containing ten female and five male fruit flies, were housed and bred on the space shuttle (average orbit altitude of 330.35 km) for 12 days and 18.5 hours. A new generation of flies was reared in microgravity. In larvae, the immune system was examined by analyzing plasmatocyte number and activity in culture. In adults, the induced immune responses were analyzed by bacterial clearance and quantitative real-time polymerase chain reaction (qPCR) of selected genes following infection with E. coli. The RNA levels of relevant immune pathway genes were determined in both larvae and adults by microarray analysis. The ability of larval plasmatocytes to phagocytose E. coli in culture was attenuated following spaceflight, and in parallel, the expression of genes involved in cell maturation was downregulated. In addition, the level of constitutive expression of pattern recognition receptors and opsonins that specifically recognize bacteria, and of lysozymes, antimicrobial peptide (AMP) pathway and immune stress genes, hallmarks of humoral immunity, were also reduced in larvae. In adults, the efficiency of bacterial clearance measured in vivo following a systemic infection with E. coli post-flight, remained robust. We show that spaceflight altered both cellular and humoral immune responses in Drosophila and that the disruption occurs at multiple interacting pathways.
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Affiliation(s)
- Oana Marcu
- Space Biosciences Division, NASA Ames Research Center, Mountain View, California, United States of America
- Carl Sagan Center, SETI Institute, Mountain View, California, United States of America
| | - Matthew P. Lera
- Space Biosciences Division, NASA Ames Research Center, Mountain View, California, United States of America
- Lockheed Martin Exploration & Science, NASA Ames Research Center, Mountain View, California, United States of America
| | - Max E. Sanchez
- Lockheed Martin Exploration & Science, NASA Ames Research Center, Mountain View, California, United States of America
| | - Edina Levic
- Space Biosciences Division, NASA Ames Research Center, Mountain View, California, United States of America
| | - Laura A. Higgins
- Space Biosciences Division, NASA Ames Research Center, Mountain View, California, United States of America
| | - Alena Shmygelska
- Space Biosciences Division, NASA Ames Research Center, Mountain View, California, United States of America
- Silicon Valley Campus of Carnegie Mellon University, NASA Ames Research Center, Mountain View, California, United States of America
| | - Thomas F. Fahlen
- Lockheed Martin Exploration & Science, NASA Ames Research Center, Mountain View, California, United States of America
| | - Helen Nichol
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Sharmila Bhattacharya
- Space Biosciences Division, NASA Ames Research Center, Mountain View, California, United States of America
- * E-mail:
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59
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Sharma A, Mishra M, Ram KR, Kumar R, Abdin MZ, Chowdhuri DK. Transcriptome analysis provides insights for understanding the adverse effects of endosulfan in Drosophila melanogaster. CHEMOSPHERE 2011; 82:370-376. [PMID: 21036383 DOI: 10.1016/j.chemosphere.2010.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Revised: 09/24/2010] [Accepted: 10/03/2010] [Indexed: 05/30/2023]
Abstract
Indiscriminate use of agrochemicals worldwide, particularly, persistent organic pollutants (POPs), is of concern. Endosulfan, a POP, is used by various developing/developed nations and is known to adversely affect the development and the hormonal profiles of humans and animals. However, little is known about the molecular players/pathways underlying the adverse effects of endosulfan. We therefore analyzed the global gene expression changes and subsequent adverse effects of endosulfan using Drosophila. We used Drosophila melanogaster keeping in view of its well annotated genome and the wealth of genetic/molecular reagents available for this model organism. We exposed third instar larvae of D. melanogaster to endosulfan (2.0 μg mL(-1)) for 24 h and using microarray, we identified differential expression of 256 genes in exposed organisms compared to controls. These genes are associated with cellular processes such as development, stress and immune response and metabolism. Microarray results were validated through quantitative PCR and biochemical assay on a subset of genes/proteins. Taking cues from microarray data, we analyzed the effect of endosulfan on development, emergence and survival of the organism. In exposed organisms, we observed deformities in hind-legs, reminiscent of those observed in higher organisms exposed to endosulfan. In addition, we observed delayed and/or reduced emergence in exposed organisms when compared to their respective controls. Together, our studies not only highlight the adverse effects of endosulfan on the organism but also provide an insight into the possible genetic perturbations underlying these effects, which might have potential implications to higher organisms.
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Affiliation(s)
- Anurag Sharma
- Embryotoxicology Section, Indian Institute of Toxicology Research, Lucknow 226 001, India
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60
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Kallio J, Myllymäki H, Grönholm J, Armstrong M, Vanha-aho LM, Mäkinen L, Silvennoinen O, Valanne S, Rämet M. Eye transformer is a negative regulator of Drosophila JAK/STAT signaling. FASEB J 2010; 24:4467-79. [PMID: 20624926 DOI: 10.1096/fj.10-162784] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
JAK/STAT signaling pathway is evolutionarily conserved and tightly regulated. We carried out a reporter-based genome-wide RNAi in vitro screen to identify genes that regulate Drosophila JAK/STAT pathway and found 5 novel regulators. Of these, CG14225 is a negative regulator structurally related to the Drosophila JAK/STAT pathway receptor Domeless, especially in the extracellular domain, and to the mammalian IL-6 receptor and the signal transducer gp130. CG14225 coimmunoprecipitates with Domeless and its associated kinase hopscotch in S2 cells. CG14225 RNAi caused hyperphosphorylation of the transcription factor Stat92E in S2 cells on stimulation with the Drosophila JAK/STAT pathway ligand unpaired. CG14225 RNAi in vivo hyperactivated JAK/STAT target genes on septic injury and enhanced unpaired-induced eye overgrowth, and was thus named the eye transformer (ET). In the gastrointestinal infection model, where JAK/STAT signaling is important for stem cell renewal, CG14225/ET RNAi was protective in vivo. In conclusion, we have identified ET as a novel negative regulator of the Drosophila JAK/STAT pathway both in vitro and in vivo, and it functions in regulating Stat92E phosphorylation.
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Affiliation(s)
- Jenni Kallio
- Laboratory of Experimental Immunology, Institute of Medical Technology, Tampere University, Tampere, Finland
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61
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Neisch AL, Speck O, Stronach B, Fehon RG. Rho1 regulates apoptosis via activation of the JNK signaling pathway at the plasma membrane. ACTA ACUST UNITED AC 2010; 189:311-23. [PMID: 20404112 PMCID: PMC2856900 DOI: 10.1083/jcb.200912010] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In the absence of moesin, RhoA slips out of its normal role as a GTPase to activate the JNK MAPK pathway and spur apoptosis. Precisely controlled growth and morphogenesis of developing epithelial tissues require coordination of multiple factors, including proliferation, adhesion, cell shape, and apoptosis. RhoA, a small GTPase, is known to control epithelial morphogenesis and integrity through its ability to regulate the cytoskeleton. In this study, we examine a less well-characterized RhoA function in cell survival. We demonstrate that the Drosophila melanogaster RhoA, Rho1, promotes apoptosis independently of Rho kinase through its effects on c-Jun NH2-terminal kinase (JNK) signaling. In addition, Rho1 forms a complex with Slipper (Slpr), an upstream activator of the JNK pathway. Loss of Moesin (Moe), an upstream regulator of Rho1 activity, results in increased levels of Rho1 at the plasma membrane and cortical accumulation of Slpr. Together, these results suggest that Rho1 functions at the cell cortex to regulate JNK activity and implicate Rho1 and Moe in epithelial cell survival.
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Affiliation(s)
- Amanda L Neisch
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
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62
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Lennox AL, Stronach B. POSH misexpression induces caspase-dependent cell death in Drosophila. Dev Dyn 2010; 239:651-64. [PMID: 20014406 DOI: 10.1002/dvdy.22186] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
POSH (Plenty of SH3 domains) is a scaffold for signaling proteins regulating cell survival. Specifically, POSH promotes assembly of a complex including Rac GTPase, mixed lineage kinase (MLK), MKK7, and Jun kinase (JNK). In Drosophila, genetic analysis implicated POSH in Tak1-dependent innate immune response, in part through regulation of JNK signaling. Homologs of the POSH signaling complex components, MLK and MKK7, are essential in Drosophila embryonic dorsal closure. Using a gain-of-function approach, we tested whether POSH plays a role in this process. Ectopic expression of POSH in the embryo causes dorsal closure defects due to apoptosis of the amnioserosa, but ectodermal JNK signaling is normal. Phenotypic consequences of POSH expression were found to be dependent on Drosophila Nc, the caspase-9 homolog, but only partially on Tak1 and not at all on Slpr and Hep. These results suggest that POSH may use different signaling complexes to promote cell death in distinct contexts.
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Affiliation(s)
- Ashley L Lennox
- Department of Biological Sciences, 202 Life Sciences Annex, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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63
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Mahapatra CT, Bond J, Rand DM, Rand MD. Identification of methylmercury tolerance gene candidates in Drosophila. Toxicol Sci 2010; 116:225-38. [PMID: 20375079 DOI: 10.1093/toxsci/kfq097] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Methylmercury (MeHg) is a ubiquitous environmental contaminant that preferentially targets the developing nervous system. Variable outcomes of prenatal MeHg exposure within a population point to a genetic component that regulates MeHg toxicity. We therefore sought to identify fundamental MeHg tolerance genes using the Drosophila model for genetic and molecular dissection of a MeHg tolerance trait. We observe autosomal dominance in a MeHg tolerance trait (development on MeHg food) in both wild-derived and laboratory-selected MeHg-tolerant strains of flies. We performed whole-genome transcript profiling of larval brains of tolerant (laboratory selected) and nontolerant (control) strains in the presence and absence of MeHg stress. Pairwise transcriptome comparisons of four conditions (+/-selection and +/-MeHg) identified a "down-down-up" expression signature, whereby MeHg alone and selection alone resulted in a greater number of downregulated transcripts, and the combination of selection + MeHg resulted in a greater number of upregulated transcripts. Functional annotation cluster analyses showed enrichment for monooxygenases/oxidoreductases, which include cytochrome P450 (CYP) family members. Among the 10 CYPs upregulated with selection + MeHg in tolerant strains, CYP6g1, previously identified as the dichlorodiphenyl trichloroethane resistance allele in flies, was the most highly expressed and responsive to MeHg. Among all the genes, Turandot A (TotA), an immune pathway-regulated humoral response gene, showed the greatest upregulation with selection + MeHg. Neural-specific transgenic overexpression of TotA enhanced MeHg tolerance during pupal development. Identification of TotA and CYP genes as MeHg tolerance genes is an inroad to investigating the conserved function of immune signaling and phase I metabolism pathways in MeHg toxicity and tolerance in higher organisms.
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Affiliation(s)
- Cecon T Mahapatra
- Department of Anatomy and Neurobiology, College of Medicine, University of Vermont, Burlington, Vermont 05405, USA
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64
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Reumer A, Bogaerts A, Van Loy T, Husson SJ, Temmerman L, Choi C, Clynen E, Hassan B, Schoofs L. Unraveling the protective effect of a Drosophila phosphatidylethanolamine-binding protein upon bacterial infection by means of proteomics. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2009; 33:1186-1195. [PMID: 19545586 DOI: 10.1016/j.dci.2009.06.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 06/12/2009] [Accepted: 06/13/2009] [Indexed: 05/28/2023]
Abstract
This study addresses the biological function of CG18594, a Drosophila melanogaster phosphatidylethanolamine-binding protein (PEBP) that we named PEBP1, by combining fly genetics, survival experiments and differential proteomics. We demonstrate that transgenic flies overexpressing PEBP1 are highly protected against bacterial infection due to the release of immunity-related proteins in their hemolymph. Apart from proteins that have been reported earlier to participate in insect immunity, we also identify proteins involved in metabolism and signaling, and, in addition, twelve (hypothetical) proteins with unknown function. This is the first report demonstrating an immune function for a Drosophila PEBP protein.
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Affiliation(s)
- Ank Reumer
- Department of Biology, Functional Genomics and Proteomics Unit, K.U. Leuven, Leuven, Belgium.
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65
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Coordination of multiple dual oxidase-regulatory pathways in responses to commensal and infectious microbes in drosophila gut. Nat Immunol 2009; 10:949-57. [PMID: 19668222 DOI: 10.1038/ni.1765] [Citation(s) in RCA: 235] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 06/08/2009] [Indexed: 01/23/2023]
Abstract
All metazoan guts are in permanent contact with the microbial realm. However, understanding of the exact mechanisms by which the strength of gut immune responses is regulated to achieve gut-microbe mutualism is far from complete. Here we identify a signaling network composed of complex positive and negative mechanisms that controlled the expression and activity of dual oxidase (DUOX), which 'fine tuned' the production of microbicidal reactive oxygen species depending on whether the gut encountered infectious or commensal microbes. Genetic analyses demonstrated that negative and positive regulation of DUOX was required for normal host survival in response to colonization with commensal and infectious microbes, respectively. Thus, the coordinated regulation of DUOX enables the host to achieve gut-microbe homeostasis by efficiently combating infection while tolerating commensal microbes.
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66
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Winter-Vann AM, Johnson GL. Integrated activation of MAP3Ks balances cell fate in response to stress. J Cell Biochem 2008; 102:848-58. [PMID: 17786929 DOI: 10.1002/jcb.21522] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In vivo, tissues and organs are exposed to numerous stressors that require cells to respond appropriately for viability and homeostasis. Cells respond to these stressors, which range from UV irradiation, heat shock, chemicals, and changes in osmolality, to oxidative stress and inflammatory cytokines, by activating pathways that protect cells from damage. If the stress is too great, cells commit to undergo apoptosis. Such cell fate decisions involve the stress-mediated activation of mitogen-activated protein kinase (MAPK) networks, ultimately under the control of MAPK kinase kinases, or MAP3Ks. It is the MAP3Ks that coordinate the localization, duration and magnitude of MAPK activation in response to cell stress. A single stressor may activate several MAP3Ks, each of which impacts the balance between survival and apoptotic signaling. In this prospect article, we review the specific MAP3Ks that integrate the physiological response to cell stressors. The interrelationships among different stressors are discussed, with an emphasis on how the balance of signaling through MAP3Ks controls the MAPK response to determine cell fate.
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Affiliation(s)
- Ann M Winter-Vann
- Department of Pharmacology, 1108 Mary Ellen Jones Bldg, Campus Box 7365, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7365, USA
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67
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Altincicek B, Knorr E, Vilcinskas A. Beetle immunity: Identification of immune-inducible genes from the model insect Tribolium castaneum. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2007; 32:585-595. [PMID: 17981328 DOI: 10.1016/j.dci.2007.09.005] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 09/10/2007] [Accepted: 09/27/2007] [Indexed: 05/25/2023]
Abstract
The red flour beetle, Tribolium castaneum, is an established genetically tractable model insect for evolutionary and developmental studies. Therefore, it may also represent a valuable model for comparative analysis of insect immunity. Here, we used the suppression subtractive hybridization method to identify Tribolium genes that are transcriptionally induced in response to injection of crude lipopolysaccharide (LPS). Determined genes encode proteins that share sequence similarities with counterparts from other insects known to mediate sensing of infection (e.g. Toll and PGRP) or to represent potential antimicrobial effectors (e.g. ferritin, c-type lysozyme, serine proteinase inhibitors, and defensins). Especially significant is the identification of thaumatin-like peptides, representing ancient antifungal peptides originally reported from plants, that are absent from the genomes of many other insects such as Drosophila, Anopheles, and Apis. We produced recombinant thaumatin-1 in bacteria and we found that it represents an antimicrobial peptide against filamentous fungi in Tribolium. Additionally, septic injury induces expression of genes involved in stress adaptation (e.g. heat-shock proteins) or insecticide resistance (e.g. cytochrome P450s) in Tribolium, suggesting that there may be crosstalk between the immune and stress responses.
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Affiliation(s)
- Boran Altincicek
- Institute of Phytopathology and Applied Zoology, Justus-Liebig-University of Giessen, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany.
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Abstract
To combat infection, the fruit fly Drosophila melanogaster relies on multiple innate defense reactions, many of which are shared with higher organisms. These reactions include the use of physical barriers together with local and systemic immune responses. First, epithelia, such as those beneath the cuticle, in the alimentary tract, and in tracheae, act both as a physical barrier and local defense against pathogens by producing antimicrobial peptides and reactive oxygen species. Second, specialized hemocytes participate in phagocytosis and encapsulation of foreign intruders in the hemolymph. Finally, the fat body, a functional equivalent of the mammalian liver, produces humoral response molecules including antimicrobial peptides. Here we review our current knowledge of the molecular mechanisms underlying Drosophila defense reactions together with strategies evolved by pathogens to evade them.
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Affiliation(s)
- Bruno Lemaitre
- Centre de Génétique Moléculaire, CNRS, 91198 Gif-sur-Yvette, France.
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Cherry S, Silverman N. Host-pathogen interactions in drosophila: new tricks from an old friend. Nat Immunol 2006; 7:911-7. [PMID: 16924255 DOI: 10.1038/ni1388] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Accepted: 07/19/2006] [Indexed: 12/13/2022]
Abstract
Insects rely solely on innate immune responses to combat a wide array of pathogens. With its powerful genetics, drosophila has proven especially powerful for the study of humoral innate immunity, characterized by the rapid induction of antimicrobial peptides. The two signaling pathways involved, Toll and Imd, have been studied intensely, but other aspects of the drosophila immune response are less well understood. A flurry of reports has focused on the mechanisms of phagocytosis, antiviral immunity and viral pathogenesis in drosophila. These studies have taken advantage of genome-wide RNA-mediated interference screening in drosophila cells, as well as more traditional genetic tools available in the fly. This review discusses advances in these exciting new areas of drosophila immunity.
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Affiliation(s)
- Sara Cherry
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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