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Scopelliti A, Bauer C, Cordero JB, Vidal M. Bursicon-α subunit modulates dLGR2 activity in the adult Drosophila melanogaster midgut independently to Bursicon-β. Cell Cycle 2016; 15:1538-44. [PMID: 27191973 PMCID: PMC4934083 DOI: 10.1080/15384101.2015.1121334] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Bursicon is the main regulator of post molting and post eclosion processes during arthropod development. The active Bursicon hormone is a heterodimer of Burs-α and Burs-β. However, adult midguts express Burs-α to regulate the intestinal stem cell niche. Here, we examined the potential expression and function of its heterodimeric partner, Burs-β in the adult midgut. Unexpectedly, our evidence suggests that Burs-β is not significantly expressed in the adult midgut. burs-β mutants displayed the characteristic developmental defects but showed wild type-like adult midguts, thus uncoupling the developmental and adult phenotypes seen in burs-α mutants. Gain of function data and ex vivo experiments using a cAMP biosensor, demonstrated that Burs-α is sufficient to drive stem cell quiescence and to activate dLGR2 in the adult midgut. Our evidence suggests that the post developmental transactivation of dLGR2 in the adult midgut is mediated by Burs-α and that the β subunit of Bursicon is dispensable for these activities.
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Affiliation(s)
| | - Christin Bauer
- a The Beatson Institute for Cancer Research, Garscube Estate , Glasgow , UK
| | | | - Marcos Vidal
- a The Beatson Institute for Cancer Research, Garscube Estate , Glasgow , UK
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Zhao Y, Cocco C, Domenichini S, Samson ML, Rabinow L. The IMD innate immunity pathway of Drosophila influences somatic sex determination via regulation of the Doa locus. Dev Biol 2015; 407:224-31. [DOI: 10.1016/j.ydbio.2015.09.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/24/2015] [Accepted: 09/24/2015] [Indexed: 11/30/2022]
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Zhu Y, Fang Q, Liu Y, Gao LF, Yan ZC, Ye GY. THE ENDOPARASITOID Pteromalus puparum INFLUENCES HOST GENE EXPRESSION WITHIN FIRST HOUR OF PARASITIZATION. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2015; 90:140-153. [PMID: 26241821 DOI: 10.1002/arch.21250] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The small cabbage butterfly, Pieris rapae, is an important pest of cruciferous corps, and Pteromalus puparum is a predominant pupal endoparasitoid wasp of this butterfly. For successful development of parasitoid offspring, female parasitoids usually introduce one or several kinds of maternal factors into the hemocoels during oviposition to suppress host immunity. To investigate the early changes in host immune-related genes following parasitization, we analyzed transcriptomes of parasitized and unparasitized, control, host pupae. Approximately 17.7 and 19.3 million paired-end reads were generated from nonparasitized and parasitized host pupae, and assembled de novo into 45,639 transcripts and 27,659 nonredundant unigenes. The average unigene length was 790 bp. A total 18,377 of 27,659 unigenes were annotated and we identified 557 differentially expressed unigenes in host pupae at 1 h after parasitization, of which 21 were immune-related. Parasitization led to downregulation of most pattern recognition receptors and upregulation of all serine protease inhibitors. The transcirptomic profile of P. rapae is considerably affected by parasitization. This study provides valuable sources for future investigations of the molecular interaction between P. puparum and its host P. rapae.
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Affiliation(s)
- Yu Zhu
- State Key Laboratory of Rice Biology & Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Qi Fang
- State Key Laboratory of Rice Biology & Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Yang Liu
- State Key Laboratory of Rice Biology & Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Ling-Feng Gao
- State Key Laboratory of Rice Biology & Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Zhi-Chao Yan
- State Key Laboratory of Rice Biology & Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
| | - Gong-Yin Ye
- State Key Laboratory of Rice Biology & Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
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54
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Dong S, Zhang H, Chen X, Stanley D, Yu X, Song Q. The neuropeptide bursicon acts in cuticle metabolism. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2015; 89:87-97. [PMID: 25821138 DOI: 10.1002/arch.21227] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Bursicon is a heterodimeric neuropeptide formed of bursicon α (burs α) and bursicon β (burs β) that controls cuticle tanning and wing expansion in insects. Burs α-α and burs β-β homodimers are also formed; they act via an unknown receptor to induce expression of prophylactic immune and stress genes during molting. Based on the hypothesis that burs β-β and/or bursicon influence expression of additional genes acting after the molt, we prepared and sequenced six Drosophila cDNA libraries from groups of flies separately injected with burs β-β, bursicon, or blank control. Compared to the control, the burs β-β treatments led to upregulation (by at least 1.5-fold) of 262 genes at 0.5 h postinjection (PI) and 298 genes at 1 h PI; 323 genes at 0.5 h PI and 269 genes at 1h PI were downregulated (by at least 0.67). Similar changes were recorded following bursicon injections. Of these genes, expression of seven transcripts encoding cuticle proteins was upregulated and three downregulated by burs β-β; expression of nine transcripts encoding cuticle proteins were upregulated and four downregulated following bursicon treatments. Expression of dozens of genes involved in chitin metabolism was altered by the experimental treatments. We recorded parallel changes in expression of selected genes by transcriptome and qPCR analysis. These findings support our hypothesis that burs β-β and bursicon influence expression of additional genes acting after the molt. We report that burs β-β and bursicon act in cuticle synthesis and degradation by regulating the expression of cuticular protein and chitin metabolizing related genes.
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Affiliation(s)
- Shengzhang Dong
- Division of Plant Sciences, University of Missouri, Columbia, Missouri and Zhejiang Provincial Key Laboratory of Bio-metrology and Inspection & Quarantine, College of Life Sciences, China JiLiang University, Hangzhou, China
| | - Hongwei Zhang
- Division of Plant Sciences, University of Missouri, Columbia, Missouri
| | - Xi Chen
- Division of Plant Sciences, University of Missouri, Columbia, Missouri
| | - David Stanley
- Biological Control of Insects Research Laboratory, USDA/Agricultural Research Service, Columbia, Missouri
| | - Xiaoping Yu
- Zhejiang Provincial Key Laboratory of Bio-metrology and Inspection & Quarantine, College of Life Sciences, China JiLiang University, Hangzhou, China
| | - Qisheng Song
- Division of Plant Sciences, University of Missouri, Columbia, Missouri
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55
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Shi M, Dong S, Li MT, Yang YY, Stanley D, Chen XX. The endoparasitoid, Cotesia vestalis, regulates host physiology by reprogramming the neuropeptide transcriptional network. Sci Rep 2015; 5:8173. [PMID: 25640113 PMCID: PMC4313088 DOI: 10.1038/srep08173] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 01/09/2015] [Indexed: 12/01/2022] Open
Abstract
Endoparasitoids develop inside another insect by regulating host immunity and development via maternal factors injected into hosts during oviposition. Prior results have provided insights into parasitism-induced immunosuppression, including the neuropeptide accumulation in parasitized insects. Nonetheless, our understanding of neuropeptide influence on host development and behavior is not yet complete. We posed the hypothesis that parasitization alters expression of genes encoding pro-neuropeptides and used larvae of Plutella xylostella and its endoparasitoid, Cotesia vestalis to test our hypothesis. We prepared transcriptomes from the larval P. xylostella brain-CC-CA complex and identified transcripts encoding 19 neuropeptides. All corresponding cDNAs were confirmed by RACE. Our results demonstrate that parasitism significantly down-regulated, or delayed, expression of genes encoding pro-neuropeptides within 48 h post-parasitization. Changing expression of these genes may account for the previously reported decreased feeding behavior, reduced growth rates and aborted development in the host larvae. In effect, parasitization may operate at the molecular level within the CNS to create global changes in larval host biology. The significance of our finding is that, in addition to the known effects on immunity, parasitoids influence host pro-neuropeptide gene transcription. This finding reveals a new mechanism operating in host-parasitoid relationships to the advantage of the parasitoid.
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Affiliation(s)
- Min Shi
- Ministry of Agriculture Key Lab of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Shuai Dong
- Ministry of Agriculture Key Lab of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Ming-tian Li
- Ministry of Agriculture Key Lab of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Yan-yan Yang
- Ministry of Agriculture Key Lab of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - David Stanley
- Biological Control of Insects Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 1503 S. Providence Road, Columbia MO 65203, USA
| | - Xue-xin Chen
- Ministry of Agriculture Key Lab of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
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Vandersmissen HP, Van Hiel MB, Van Loy T, Vleugels R, Vanden Broeck J. Silencing D. melanogaster lgr1 impairs transition from larval to pupal stage. Gen Comp Endocrinol 2014; 209:135-47. [PMID: 25157788 DOI: 10.1016/j.ygcen.2014.08.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 08/10/2014] [Accepted: 08/14/2014] [Indexed: 12/27/2022]
Abstract
G protein-coupled receptors (GPCRs) play key roles in a wide diversity of physiological processes and signalling pathways. The leucine-rich repeats containing GPCRs (LGRs) are a subfamily that is well-conserved throughout most metazoan phyla and have important regulatory roles in vertebrates. Here, we report on the critical role of Drosophila melanogaster LGR1, the fruit fly homologue of the vertebrate glycoprotein hormone receptors, in development as a factor involved in the regulation of pupariation. Transcript profiling revealed that lgr1 transcripts are most abundant in third instar larvae and adult flies. The tissues displaying the highest transcript levels were the hindgut, the rectum and the salivary glands. Knockdown using RNA interference (RNAi) demonstrated that white pupa formation was severely suppressed in D. melanogaster lgr1 RNAi larvae. Associated with this developmental defect was a reduced ecdysteroid titer, which is in line with significantly reduced transcript levels detected for the Halloween genes shadow (sad) and spookier (spok) in the third instar lgr1 RNAi larvae compared to the control condition.
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Affiliation(s)
| | - Matthias Boris Van Hiel
- KU Leuven, Animal Physiology and Neurobiology, Naamsestraat 59, PO Box 2465, Leuven, Belgium.
| | - Tom Van Loy
- KU Leuven, Animal Physiology and Neurobiology, Naamsestraat 59, PO Box 2465, Leuven, Belgium.
| | - Rut Vleugels
- KU Leuven, Animal Physiology and Neurobiology, Naamsestraat 59, PO Box 2465, Leuven, Belgium.
| | - Jozef Vanden Broeck
- KU Leuven, Animal Physiology and Neurobiology, Naamsestraat 59, PO Box 2465, Leuven, Belgium.
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57
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Hepat R, Kim Y. JH modulates a cellular immunity of Tribolium castaneum in a Met-independent manner. JOURNAL OF INSECT PHYSIOLOGY 2014; 63:40-47. [PMID: 24607640 DOI: 10.1016/j.jinsphys.2014.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 02/12/2014] [Accepted: 02/20/2014] [Indexed: 06/03/2023]
Abstract
Juvenile hormone (JH) regulates diverse physiological processes in insects during entire developmental stages. Especially, the identification of Methoprene-tolerant (Met), a JH nuclear receptor, allows us to better understand molecular actions of JH to control gene expressions related with metamorphosis. However, several physiological processes including cellular immune response and some molecular actions of JH have been suspected to be mediated via its non-genomic actions. To prove its non-genomic action, JH nuclear signals were suppressed by RNA interference (RNAi) of Met or its downstream gene, Krüppel homolog 1 (Kr-h1), in the red flour beetle, Tribolium castaneum. These RNAi-treated larvae failed to undergo a normal development and suffered precocious metamorphosis. Hemocytes of T. castaneum exhibited their spreading behavior on extracellular matrix and nodule formation in response to bacterial challenge. When the larvae were treated with either RNAi of Met or Kr-h1, the hemocytes of the treated larvae were responsive to JH without any significant difference with those of control larvae. These results suggest that the response of hemocytes to JH is not mediated by its nuclear signal. On the other hand, the JH modulation of hemocyte behaviors of T. castaneum was significantly influenced by membrane and cytosolic protein activities, in which ethoxyzolamide (a specific inhibitor of carbonic anhydrase), calphostin C (a specific inhibitor of protein kinase C) or ouabain (a specific inhibitor of Na(+)-K(+) ATPase) significantly suppressed the responsiveness of hemocytes to JH.
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Affiliation(s)
- Rahul Hepat
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea
| | - Yonggyun Kim
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea.
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58
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Kim JK, Han SH, Kim CH, Jo YH, Futahashi R, Kikuchi Y, Fukatsu T, Lee BL. Molting-associated suppression of symbiont population and up-regulation of antimicrobial activity in the midgut symbiotic organ of the Riptortus-Burkholderia symbiosis. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 43:10-4. [PMID: 24201132 DOI: 10.1016/j.dci.2013.10.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/23/2013] [Accepted: 10/24/2013] [Indexed: 05/20/2023]
Abstract
The majority of insects possess symbiotic bacteria. Since symbiont titers can affect host phenotypes of biological importance, host insects are expected to evolve some mechanisms for regulating symbiont population. Here we report that, in the Riptortus-Burkholderia gut symbiosis, titers of the beneficial symbiont transiently decrease at the pre-molt stages in host development. This molting-associated suppression of the symbiont population is coincident with the increase of antimicrobial activity in the symbiotic midgut, which is observed in both symbiotic and aposymbiotic insects. Two genes, pyrrhocoricin-like antimicrobial peptide and c-type lysozyme, exhibit significantly increased expression in the symbiotic midgut at the pre-molt stages. These results suggest that the molting-associated up-regulation of antimicrobial activity in the symbiotic midgut represents a physiological mechanism of the host insect to regulate symbiosis, which is presumably for defending molting insects against injury and infection and/or for allocating symbiont-derived energy and resources to host molting.
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Affiliation(s)
- Jiyeun Kate Kim
- Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea
| | - Sang Heum Han
- Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea
| | - Chan-Hee Kim
- Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea
| | - Yong Hun Jo
- Division of Plant Biotechnology, College of Agriculture and Life Science, Chonnam National University, Gwangju 500-757, South Korea
| | - Ryo Futahashi
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan
| | - Yoshitomo Kikuchi
- National Institute of AIST, Hokkaido Center, Sapporo 062-8517, Japan
| | - Takema Fukatsu
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan
| | - Bok Luel Lee
- Global Research Laboratory of Insect Symbiosis, College of Pharmacy, Pusan National University, Pusan 609-735, South Korea.
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59
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Terhzaz S, Overend G, Sebastian S, Dow JAT, Davies SA. The D. melanogaster capa-1 neuropeptide activates renal NF-kB signaling. Peptides 2014; 53:218-24. [PMID: 23954477 DOI: 10.1016/j.peptides.2013.08.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 08/01/2013] [Accepted: 08/01/2013] [Indexed: 01/20/2023]
Abstract
The capa peptide family exists in a very wide range of insects including species of medical, veterinary and agricultural importance. Capa peptides act via a cognate G-protein coupled receptor (capaR) and have a diuretic action on the Malpighian tubules of Dipteran and Lepidopteran species. Capa signaling is critical for fluid homeostasis and has been associated with desiccation tolerance in the fly, Drosophila melanogaster. The mode of capa signaling is highly complex, affecting calcium, nitric oxide and cyclic GMP pathways. Such complex physiological regulation by cell signaling pathways may occur ultimately for optimal organismal stress tolerance to multiple stressors. Here we show that D. melanogaster capa-1 (Drome-capa-1) acts via the Nuclear Factor kappa B (NF-kB) stress signaling network. Human PCR gene arrays of capaR-transfected Human Embryonic Kidney (HEK) 293 cells showed that Drome-capa-1 increases expression of NF-kB, NF-kB regulated genes including IL8, TNF and PTGS2, and NF-kB pathway-associated transcription factors i.e. EGR1, FOS, cJUN. Furthermore, desiccated HEK293 cells show increased EGR1, EGR3 and PTGS2 - but not IL8, expression. CapaR-transfected NF-kB reporter cells showed that Drome-capa-1 increased NF-kB promoter activity via increased calcium. In Malpighian tubules, both Drome-capa-1 stimulation and desiccation result in increased gene expression of the D. melanogaster NF-kB orthologue, Relish; as well as EGR-like stripe and klumpfuss. Drome-capa-1 also induces Relish translocation in tubule principal cells. Targeted knockdown of Relish in only tubule principal cells reduces desiccation stress tolerance of adult flies. Together, these data suggest that Drome-capa-1 acts in desiccation stress tolerance, by activating NF-kB signaling.
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Affiliation(s)
- Selim Terhzaz
- Institute of Molecular, Cell and Systems Biology, College of Medical, Life and Veterinary Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Gayle Overend
- Institute of Molecular, Cell and Systems Biology, College of Medical, Life and Veterinary Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Sujith Sebastian
- Institute of Molecular, Cell and Systems Biology, College of Medical, Life and Veterinary Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Julian A T Dow
- Institute of Molecular, Cell and Systems Biology, College of Medical, Life and Veterinary Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Shireen-A Davies
- Institute of Molecular, Cell and Systems Biology, College of Medical, Life and Veterinary Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
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60
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Ming M, Obata F, Kuranaga E, Miura M. Persephone/Spätzle pathogen sensors mediate the activation of Toll receptor signaling in response to endogenous danger signals in apoptosis-deficient Drosophila. J Biol Chem 2014; 289:7558-68. [PMID: 24492611 DOI: 10.1074/jbc.m113.543884] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Apoptosis is an evolutionarily conserved mechanism that removes damaged or unwanted cells, effectively maintaining cellular homeostasis. It has long been suggested that a deficiency in this type of naturally occurring cell death could potentially lead to necrosis, resulting in the release of endogenous immunogenic molecules such as damage-associated molecular patterns (DAMPs) and a noninfectious inflammatory response. However, the details about how danger signals from apoptosis-deficient cells are detected and translated to an immune response are largely unknown. In this study, we found that Drosophila mutants deficient for Dronc, the key initiator caspase required for apoptosis, produced the active form of the endogenous Toll ligand Spätzle (Spz). We speculated that, as a system for sensing potential DAMPs in the hemolymph, the dronc mutants constitutively activate a proteolytic cascade that leads to Spz proteolytic processing. We demonstrated that Toll signaling activation required the action of Persephone, a CLIP domain serine protease that usually reacts to microbial proteolytic activities. Our findings show that the Persephone proteolytic cascade plays a crucial role in mediating DAMP-induced systemic responses in apoptosis-deficient Drosophila mutants.
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Affiliation(s)
- Ming Ming
- From the Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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61
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Park J, Stanley D, Kim Y. Rac1 mediates cytokine-stimulated hemocyte spreading via prostaglandin biosynthesis in the beet armyworm, Spodoptera exigua. JOURNAL OF INSECT PHYSIOLOGY 2013; 59:682-689. [PMID: 23660478 DOI: 10.1016/j.jinsphys.2013.04.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 04/09/2013] [Accepted: 04/24/2013] [Indexed: 06/02/2023]
Abstract
Cell spreading is an integral component of insect hemocytic immune reactions to infections and invasions. Cell spreading is accomplished by cytoskeleton rearrangement, which is activated by three major immune mediators, biogenic monoamines, plasmatocyte-spreading peptide (PSP), and eicosanoids, particularly prostaglandin E2 (PGE2). However, little is known about how these immune mediators activate hemocyte spreading at the intra-cellular level. A small G protein, Rac1, acts in cytoskeleton arrangements in mammalian cells. Based on this information, we identified a Rac1 transcript (SeRac1) in hemocytes prepared from Spodoptera exigua. SeRac1 was expressed in most developmental stages and in the two main immunity-conferring tissues, hemocytes and fat body, in larvae. In response to bacterial challenge, its expression was up-regulated by >37-fold at 2h post-injection and returned to a basal level about 2h later. Silencing SeRac1 expression inhibited hemocyte spreading in response to three immune mediators, octopamine, 5-hydroxytryptamine, and PSP. Addition of PGE2 to SeRac1-silenced larvae rescued the influence of these three mediators on hemocyte spreading. These compounds also increased phospholipase A2 activity via SeRac1, which leads to prostaglandin biosynthesis. We infer that SeRac1 transduces OA, 5-HT, and PSP signaling via activating biosynthesis of prostaglandins and possibly other eicosanoids.
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Affiliation(s)
- Jiyeong Park
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea
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Eicosanoids: Exploiting Insect Immunity to Improve Biological Control Programs. INSECTS 2012; 3:492-510. [PMID: 26466540 PMCID: PMC4553607 DOI: 10.3390/insects3020492] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 04/24/2012] [Accepted: 05/09/2012] [Indexed: 01/30/2023]
Abstract
Insects, like all invertebrates, express robust innate, but not adaptive, immune reactions to infection and invasion. Insect immunity is usually resolved into three major components. The integument serves as a physical barrier to infections. Within the hemocoel, the circulating hemocytes are the temporal first line of defense, responsible for clearing the majority of infecting bacterial cells from circulation. Specific cellular defenses include phagocytosis, microaggregation of hemocytes with adhering bacteria, nodulation and encapsulation. Infections also stimulate the humoral component of immunity, which involves the induced expression of genes encoding antimicrobial peptides and activation of prophenoloxidase. These peptides appear in the hemolymph of challenged insects 6-12 hours after the challenge. Prostaglandins and other eicosanoids are crucial mediators of innate immune responses. Eicosanoid biosynthesis is stimulated by infection in insects. Inhibition of eicosanoid biosynthesis lethally renders experimental insects unable to clear bacterial infection from hemolymph. Eicosanoids mediate specific cell actions, including phagocytosis, microaggregation, nodulation, hemocyte migration, hemocyte spreading and the release of prophenoloxidase from oenocytoids. Some invaders have evolved mechanisms to suppress insect immunity; a few of them suppress immunity by targeting the first step in the eicosanoid biosynthesis pathways, the enzyme phospholipase A₂. We proposed research designed to cripple insect immunity as a technology to improve biological control of insects. We used dsRNA to silence insect genes encoding phospholipase A₂, and thereby inhibited the nodulation reaction to infection. The purpose of this article is to place our view of applying dsRNA technologies into the context of eicosanoid actions in insect immunity. The long-term significance of research in this area lies in developing new pest management technologies to contribute to food security in a world with a rapidly growing human population.
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Caers J, Verlinden H, Zels S, Vandersmissen HP, Vuerinckx K, Schoofs L. More than two decades of research on insect neuropeptide GPCRs: an overview. Front Endocrinol (Lausanne) 2012; 3:151. [PMID: 23226142 PMCID: PMC3510462 DOI: 10.3389/fendo.2012.00151] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 11/14/2012] [Indexed: 11/30/2022] Open
Abstract
This review focuses on the state of the art on neuropeptide receptors in insects. Most of these receptors are G protein-coupled receptors (GPCRs) and are involved in the regulation of virtually all physiological processes during an insect's life. More than 20 years ago a milestone in invertebrate endocrinology was achieved with the characterization of the first insect neuropeptide receptor, i.e., the Drosophila tachykinin-like receptor. However, it took until the release of the Drosophila genome in 2000 that research on neuropeptide receptors boosted. In the last decade a plethora of genomic information of other insect species also became available, leading to a better insight in the functions and evolution of the neuropeptide signaling systems and their intracellular pathways. It became clear that some of these systems are conserved among all insect species, indicating that they fulfill crucial roles in their physiological processes. Meanwhile, other signaling systems seem to be lost in several insect orders or species, suggesting that their actions were superfluous in those insects, or that other neuropeptides have taken over their functions. It is striking that the deorphanization of neuropeptide GPCRs gets much attention, but the subsequent unraveling of the intracellular pathways they elicit, or their physiological functions are often hardly examined. Especially in insects besides Drosophila this information is scarce if not absent. And although great progress made in characterizing neuropeptide signaling systems, even in Drosophila several predicted neuropeptide receptors remain orphan, awaiting for their endogenous ligand to be determined. The present review gives a précis of the insect neuropeptide receptor research of the last two decades. But it has to be emphasized that the work done so far is only the tip of the iceberg and our comprehensive understanding of these important signaling systems will still increase substantially in the coming years.
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Affiliation(s)
| | | | | | | | | | - Liliane Schoofs
- *Correspondence: Liliane Schoofs, Department of Biology, Research Group of Functional Genomics and Proteomics, Naamsestraat 59, KU Leuven, 3000 Leuven, Belgium. e-mail:
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