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Brahma S, Chatterjee S, Dey A. Role of eicosanoids in insect immunity: new insights and recent advances. INSECT SCIENCE 2024. [PMID: 39158024 DOI: 10.1111/1744-7917.13434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 06/30/2024] [Accepted: 07/12/2024] [Indexed: 08/20/2024]
Abstract
Viruses, bacteria, fungus, protozoans, and different metazoan parasites and parasitoids present a constant threat to insects. Insect immunity has two components: humoral and cell mediated. Humoral immunity can be achieved by various antimicrobial proteins, namely, cecropins, sarcotoxin, defensin, attacin, etc. The cell-mediated immunity comprises various cells having immune functions fostering nodulation, phagocytosis, microaggregation, encapsulation etc. Eicosanoids play a crucial role in insect immunity comparable to other animals. The above-mentioned are signaling molecules derived from polyunsaturated fatty acids and they exert numerous physiological effects, namely, inflammation, immune modulation, and regulation of cellular processes. The review article elucidates various roles of eicosanoids, namely, nodulation reaction, Toll signaling pathway, nitric oxide (NO) generation, Ca2+ mobilization, production of reactive oxygen species (ROS), actin polymerization and aquaporin activation. Eicosanoids can function in immune priming in insects drawing hemocytes. An agent named Duox was also identified serving as ROS generator in insect gut. Moreover, role of Repat gene in insect immunity was also studied. However, recently the role of prostacyclin (PGI2) was found to be negative as it inhibits platelet aggregation. In this brief review, we have tried to shed light on the various functions of eicosanoids in immunity of insect those have been discovered recently. This concise study will allow to decipher eicosanoids' function in insect immunity in a nutshell, and it will pave the way for more researches to understand the key players of insect immunity which may eventually help to develop novel vector and pest control strategies in near future.
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Affiliation(s)
- Shubhranil Brahma
- Department of Zoology, Iswar Chandra Vidyasagar College, Belonia, South Tripura, Tripura, India
| | - Somnath Chatterjee
- Department of Zoology, Dr. Bhupendra Nath Dutta Smriti Mahavidyalaya, Hatgobindapur, Purba Bardhaman, West Bengal, India
| | - Atrayee Dey
- Post Graduate Department of Zoology, Banwarilal Bhalotia College, Asansol, Paschim Bardhaman, West Bengal, India
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2
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Zhang ZT, Wang H, Dong H, Cong B. Comparative hemolymph proteomic analyses of the freezing and resistance-freezing Ostrinia furnacalis (Guenée). Sci Rep 2024; 14:2580. [PMID: 38297109 PMCID: PMC10830562 DOI: 10.1038/s41598-024-52792-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 01/23/2024] [Indexed: 02/02/2024] Open
Abstract
The Asian corn borer, Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae), is one of the most harmful pests of maize in Asia. It poses a significant threat to maize production, causing economic losses due to its strong ecological adaptation. In this study, we compared and analyzed the hemolymph proteome between freezing and resistance-freezing O. furnacalis strains using two-dimensional gel electrophoresis to gain insights into the mechanisms of cold resistance. The results revealed that 300-400 hemolymph protein spots were common, with 24 spots showing differences between the two strains. Spectrometry analysis revealed 21 protein spots, including 17 upregulated spots and 4 downregulated ones. The expression of upregulation/downregulation proteins plays a crucial role in the metabolism, energy supply, and defense reaction of insects. Proteomics research not only provides a method for investigating protein expression patterns but also identifies numerous attractive candidates for further exploration.
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Affiliation(s)
- Zhu-Ting Zhang
- Shenyang Agricultural University, Shenyang, 110866, Liaoning, People's Republic of China
- Kaili University, 556011, Kaili, People's Republic of China
| | - Huan Wang
- Shenyang Agricultural University, Shenyang, 110866, Liaoning, People's Republic of China.
| | - Hui Dong
- Shenyang Agricultural University, Shenyang, 110866, Liaoning, People's Republic of China.
| | - Bin Cong
- Shenyang Agricultural University, Shenyang, 110866, Liaoning, People's Republic of China
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Jin G, Kim Y. Screening of insect immune suppressors using a recombinant phospholipase A2 of a lepidopteran insect. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2024; 115:e22081. [PMID: 38288493 DOI: 10.1002/arch.22081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/28/2023] [Accepted: 12/31/2023] [Indexed: 02/01/2024]
Abstract
Phospholipase A2 (PLA2 ) catalyzes phospholipids at the sn-2 position to release free fatty acids, including arachidonic acid (AA) or its precursor. The free AA is then oxygenated into different eicosanoids, which mediate the diverse physiological processes in insects. Any inhibition of the PLA2 catalysis would give rise to serious malfunctioning in insect growth and development. An onion moth, Acrolepiopsis sapporensis, encodes four different PLA2 genes (As-PLA2 A-As-PLA2 D), in which As-PLA2 A is dominantly expressed at all developmental stages and in different larval tissues. RNA interference of the As-PLA2 A expression significantly reduced the PLA2 activity of A. sapporensis, which suffered from immunosuppression. A recombinant As-PLA2 A protein was purified from a bacterial expression system, which exhibited a typical Michaelis-Menten kinetics and hence susceptible to a specific inhibitor to sPLA2 and dithiothreitol. A total of 19 bacterial metabolites derived from Xenorhabdus and Photorhabdus were screened against the recombinant As-PLA2 A. Five potent metabolites were highly inhibitory and followed a competitive enzyme inhibition. These five inhibitors suppressed the immune responses of A. sapporensis by inhibiting hemocyte-spreading behavior and phenoloxidase activity. However, an addition of AA could significantly rescue the immunosuppression induced by the selected inhibitors. These studies suggest that the recombinant As-PLA2 A protein can be applied for high-throughput screening of insect immunosuppressive compounds.
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Affiliation(s)
- Gahyeon Jin
- Department of Plant Medicals, Andong National University, Andong, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, Korea
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Hrithik MTH, Kim Y. Immune responses of the Asian onion moth, Acrolepiopsis sapporensis, and their genetic factors from RNA-Seq analysis. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2023; 114:1-21. [PMID: 37459157 DOI: 10.1002/arch.22038] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/05/2023] [Accepted: 07/07/2023] [Indexed: 09/27/2023]
Abstract
A nonmodel insect, Acrolepiopsis sapporensis, has been analyzed in immune responses. The total hemocytes in the fifth instar larvae were 2.33 × 106 cells/mL. These hemocytes comprised at least five different types and different relative ratios: 47% granulocytes, 26% plasmatocytes, 11% oenocytoid, 8% prohemocytes, and 5% spherulocytes. Upon bacterial challenge, some of the hemocytes exhibited typical hemocyte-spreading behaviors, such as focal adhesion, and filopodial and lamellipodial cytoplasmic extensions. The hemocyte behaviors induced cellular immune responses demonstrated by nodule formation. In addition, the plasma collected from the immune-challenged larvae exhibited humoral immune responses by bacterial growth inhibition along with enhanced phenoloxidase enzyme activity. These cellular and humoral immune responses were further analyzed by determining the immune-associated genes from a transcriptome generated by RNA-Seq. A total of about 12 Gb sequences led to about 218,116 contigs, which were predicted to encode about 46,808 genes. Comparative expression analysis showed 8392 uniquely expressed genes in the immune-challenged larvae. Differentially expressed gene (DEG) analysis among the commonly expressed genes indicated that 782 genes were upregulated and 548 genes were downregulated in the expressions after bacterial challenge. These immune-associated genes included pattern recognition receptors, immune mediation/signaling genes, and various immune effectors. Specifically, the genetic components of the Toll, IMD, and JAK/STAT immune signaling pathways were included in the DEG database. These results demonstrate the immune responses of A. sapporensis larvae and suggest the genes associated with the immune responses in this nonmodel insect.
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Affiliation(s)
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, Korea
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Aspirin Inhibition of Prostaglandin Synthesis Impairs Mosquito Egg Development. Cells 2022; 11:cells11244092. [PMID: 36552860 PMCID: PMC9776805 DOI: 10.3390/cells11244092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 12/08/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
Several endocrine signals mediate mosquito egg development, including 20-hydroxyecdysone (20E). This study reports on prostaglandin E2 (PGE2) as an additional, but core, mediator of oogenesis in a human disease-vectoring mosquito, Aedes albopictus. Injection of aspirin (an inhibitor of cyclooxygenase (COX)) after blood-feeding (BF) inhibited oogenesis by preventing nurse cell dumping into a growing oocyte. The inhibitory effect was rescued by PGE2 addition. PGE2 was found to be rich in nurse cells and follicular epithelium after BF. RNA interference (RNAi) treatments of PG biosynthetic genes, including PLA2 and two COX-like peroxidases, prevented egg development. Interestingly, 20E treatment significantly increased the expressions of PG biosynthetic genes, while the RNAi of Shade (which is a 20E biosynthetic gene) expression prevented inducible expressions after BF. Furthermore, RNAi treatments of PGE2 receptor genes suppressed egg production, even under PGE2. These results suggest that a signaling pathway of BF-20E-PGE2 is required for early vitellogenesis in the mosquito.
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Ahmed S, Kim Y. PGE 2 mediates hemocyte-spreading behavior by activating aquaporin via cAMP and rearranging actin cytoskeleton via Ca 2. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 125:104230. [PMID: 34388674 DOI: 10.1016/j.dci.2021.104230] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/04/2021] [Accepted: 08/08/2021] [Indexed: 06/13/2023]
Abstract
Spreading behavior of hemocytes (= insect blood cells) is essential for cellular immune responses against various microbial pathogens. It is activated by prostaglandin E2 (PGE2) via its membrane receptor associated with secondary messenger, cAMP, in insects. This study observed an increase of calcium ion (Ca2+) level after an acute increase of cAMP induced by PGE2 treatment and clarified the intracellular signals underlying the hemocyte-spreading behavior. Inhibition of Ca2+ flux significantly impaired the hemocyte-spreading and subsequent cellular immune response, phagocytosis. The up-regulation of intracellular Ca2+ in response to PGE2 was dependent on cAMP because RNA interference (RNAi) of PGE2 receptor expression or inhibiting adenylate cyclase prevented Ca2+ mobilization. The up-regulation of Ca2+ was induced by inositol triphosphate (IP3) via its specific IP3 receptor. Furthermore, inhibition of ryanodine receptor impaired Ca2+ mobilization, suggesting Ca2+-induced Ca2+ release. However, the effective spreading behavior of hemocytes was dependent on both secondary messengers. Ca2+ signal stimulated by cAMP was required for activating small G proteins because RNAi treatments of small G proteins such as Rac1, RhoA, and Cdc42 failed to stimulate hemocyte-spreading. In contrast, aquaporin was activated by cAMP. Its activity was necessary for changing cell volume during hemocyte-spreading. These results indicate that PGE2 mediates hemocyte-spreading via cAMP signal to activate aquaporin and via Ca2+ signal to activate actin cytoskeletal rearrangement.
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Affiliation(s)
- Shabbir Ahmed
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea.
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Al Baki MA, Chandra Roy M, Lee DH, Stanley D, Kim Y. The prostanoids, thromboxanes, mediate hemocytic immunity to bacterial infection in the lepidopteran Spodoptera exigua. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 120:104069. [PMID: 33737116 DOI: 10.1016/j.dci.2021.104069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/04/2021] [Accepted: 03/06/2021] [Indexed: 06/12/2023]
Abstract
We report on a new insect prostanoid in a lepidopteran insect, Spodoptera exigua. Thromboxane B2 (TXB2) was detected by LC-MS/MS in extracts of larval epidermis, midgut, fat body and hemocytes, with highest amounts in hemocytes (about 300 ng/g tissue with substantial variation). Thromboxane A2 (TXA2) is an unstable intermediate that is non-enzymatically hydrolyzed into the stable TXB2. In S. exigua, both thromboxanes mediate at least two cellular immune responses to bacterial infection, hemocyte-spreading behavior and nodule formation. At the molecular level, a TXA2 synthase (SeTXAS) was identified from a group of 139 S. exigua cytochrome P450 monooxygenases. SeTXAS was highly similar to mammalian TXAS genes and is expressed in all developmental stages and four tested larval tissues. Immune challenge significantly enhanced SeTXAS expression, especially in hemocytes. RNA interference (RNAi) injections using gene-specific double stranded RNA led to reduced SeTXAS expression and suppressed the cellular immune responses, which were rescued following TXA2 or TXB2 injections. Unlike other PGs, TXA2 or TXB2 did not influence oocyte development in adult females. We infer that thromboxanes are present in insect tissues, where they mediate innate immune responses.
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Affiliation(s)
- Md Abdullah Al Baki
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea
| | - Miltan Chandra Roy
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea
| | - Dong-Hee Lee
- Industry Academy Cooperation Foundation, Andong National University, Andong, 36729, South Korea
| | - David Stanley
- Biological Control of Insect Research Laboratory, USDA/ARS, 1503 South Providence Road, Columbia, MO, 65203, USA
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, 36729, South Korea.
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Repat33 Acts as a Downstream Component of Eicosanoid Signaling Pathway Mediating Immune Responses of Spodoptera exigua, a Lepidopteran Insect. INSECTS 2021; 12:insects12050449. [PMID: 34069069 PMCID: PMC8156158 DOI: 10.3390/insects12050449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/09/2021] [Accepted: 05/13/2021] [Indexed: 11/17/2022]
Abstract
Repat (=response to pathogen) is proposed for an immune-associated gene family from Spodoptera exigua, a lepidopteran insect. In this gene family, 46 members (Repat1-Repat46) have been identified. They show marked variations in their inducible expression patterns in response to infections by different microbial pathogens. However, their physiological functions in specific immune responses and their interactions with other immune signaling pathways remain unclear. Repat33 is a gene highly inducible by bacterial infections. The objective of this study was to analyze the physiological functions of Repat33 in mediating cellular and humoral immune responses. Results showed that Repat33 was expressed in all developmental stages and induced in immune-associated tissues such as hemocytes and the fat body. RNA interference (RNAi) of Repat33 expression inhibited the hemocyte-spreading behavior which impaired nodule formation of hemocytes against bacterial infections. Such RNAi treatment also down-regulated expression levels of some antimicrobial genes. Interestingly, Repat33 expression was controlled by eicosanoids. Inhibition of eicosanoid biosynthesis by RNAi against a phospholipase A2 (PLA2) gene suppressed Repat33 expression while an addition of arachidonic acid (a catalytic product of PLA2) to RNAi treatment recovered such suppression of Repat33 expression. These results suggest that Repat33 is a downstream component of eicosanoids in mediating immune responses of S. exigua.
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Kim Y, Stanley D. Eicosanoid Signaling in Insect Immunology: New Genes and Unresolved Issues. Genes (Basel) 2021; 12:genes12020211. [PMID: 33535438 PMCID: PMC7912528 DOI: 10.3390/genes12020211] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 12/16/2022] Open
Abstract
This paper is focused on eicosanoid signaling in insect immunology. We begin with eicosanoid biosynthesis through the actions of phospholipase A2, responsible for hydrolyzing the C18 polyunsaturated fatty acid, linoleic acid (18:2n-6), from cellular phospholipids, which is subsequently converted into arachidonic acid (AA; 20:4n-6) via elongases and desaturases. The synthesized AA is then oxygenated into one of three groups of eicosanoids, prostaglandins (PGs), epoxyeicosatrienoic acids (EETs) and lipoxygenase products. We mark the distinction between mammalian cyclooxygenases and insect peroxynectins, both of which convert AA into PGs. One PG, PGI2 (also called prostacyclin), is newly discovered in insects, as a negative regulator of immune reactions and a positive signal in juvenile development. Two new elements of insect PG biology are a PG dehydrogenase and a PG reductase, both of which enact necessary PG catabolism. EETs, which are produced from AA via cytochrome P450s, also act in immune signaling, acting as pro-inflammatory signals. Eicosanoids signal a wide range of cellular immune reactions to infections, invasions and wounding, including nodulation, cell spreading, hemocyte migration and releasing prophenoloxidase from oenocytoids, a class of lepidopteran hemocytes. We briefly review the relatively scant knowledge on insect PG receptors and note PGs also act in gut immunity and in humoral immunity. Detailed new information on PG actions in mosquito immunity against the malarial agent, Plasmodium berghei, has recently emerged and we treat this exciting new work. The new findings on eicosanoid actions in insect immunity have emerged from a very broad range of research at the genetic, cellular and organismal levels, all taking place at the international level.
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Affiliation(s)
- Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, Korea
- Correspondence:
| | - David Stanley
- Biological Control of Insects Research Laboratory, USDA/Agricultural Research Service, 1503 South Providence Road, Columbia, MO 65203, USA;
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Ahmed S, Al Baki MA, Lee J, Seo DY, Lee D, Kim Y. The first report of prostacyclin and its physiological roles in insects. Gen Comp Endocrinol 2021; 301:113659. [PMID: 33166533 DOI: 10.1016/j.ygcen.2020.113659] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 11/03/2020] [Accepted: 11/04/2020] [Indexed: 12/13/2022]
Abstract
Prostaglandins (PGs) mediate physiological processes of insects as well as mammals. Prostaglandin I2 (PGI2) is a relatively well-known eicosanoid with potent hormone-like actions on various tissues of vertebrates, however, its presence and biosynthetic pathway have not been described in insects. This study demonstrated that fat bodies of the lepidopteran species, Spodoptera exigua, contained ~ 3.6 pg/g PGI2. To identify its biosynthetic pathway, a PGI2 synthase gene of S. exigua (Se-PGIS) was predicted from a transcriptome of S. exigua; 25.6% homology with human PGIS was demonstrated. Furthermore, a predicted three-dimensional structure of Se-PGIS was demonstrated to be 38.3% similar to the human PGIS ortholog, including catalytic residues. Se-PGIS was expressed in all developmental stages of S. exigua and most abundant larval and adult stages; immune challenging of larvae significantly up-regulated these expression levels. The inducible expression of Se-PGIS expression was followed by a greater than four-fold increase in the concentration of PGI2 in fat bodies 10 h after immune challenge. RNA interference (RNAi) against Se-PGIS was performed by injecting double-stranded RNA (dsRNA). Under these RNAi conditions, cellular immune responses (e.g., hemocyte-spreading behavior, nodulation, phenoloxidase activity) were not affected by bacterial challenge. The addition of PGI2 to larvae treated with an eicosanoid biosynthesis inhibitor did not rescue the immunosuppression. Interestingly, PGI2 injection significantly suppressed nodule formation in response to bacterial challenge. In addition to the negative effect of PGI2 against immunity, the Se-PGIS-RNAi treatment significantly interfered with immature development and severely impaired oocyte development in female adults; the addition of PGI2 to RNAi-treated females significantly recovered oocyte development. Se-PGIS RNAi treatment also impaired male fertility by reducing fecundity after mating with untreated females. These results suggest that PGI2 acts as a negative regulator of immune responses initiated by other factors and mediates S. exigua development and reproduction.
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Affiliation(s)
- Shabbir Ahmed
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea
| | - Md Abdullah Al Baki
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea
| | - Junbeom Lee
- Metabolomics Research Center for Functional Materials, Kyungsung University, Busan 48434, Republic of Korea
| | - Dong Yeon Seo
- Metabolomics Research Center for Functional Materials, Kyungsung University, Busan 48434, Republic of Korea
| | - Daeweon Lee
- Metabolomics Research Center for Functional Materials, Kyungsung University, Busan 48434, Republic of Korea; Department of Biology, Kyungsung University, Busan 48434, Republic of Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong 36729, Republic of Korea.
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Kim Y, Ahmed S, Al Baki MA, Kumar S, Kim K, Park Y, Stanley D. Deletion mutant of PGE 2 receptor using CRISPR-Cas9 exhibits larval immunosuppression and adult infertility in a lepidopteran insect, Spodoptera exigua. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2020; 111:103743. [PMID: 32464135 DOI: 10.1016/j.dci.2020.103743] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 05/06/2020] [Accepted: 05/08/2020] [Indexed: 06/11/2023]
Abstract
Prostaglandins (PGs) mediate various physiological processes in insects and other invertebrates, but there is very little information on PG receptors. This study identified a PGE2 receptor (SePGE2R) in the lepidopteran insect, Spodoptera exigua, and addressed its functional association with cellular immunity, development, and reproduction. SePGE2R is expressed in most developmental stages and tissues. After SePGR2R expression knock down by RNA interference (RNAi), larval nodule formation (clears bacterial infections from circulating hemolymph) was severely suppressed coupled with reduced F-actin growth in hemocytes. Treating female adults with RNAi prevented nurse cell dumping in follicles and interfered with oocyte development. SePGE2R was heterologously expressed in Sf9 cells, in which the endogenous S. frugiperda PGE2R was knocked down by small interfering RNA. This transiently expressed SePGE2R responded to PGE2, but not other PGs, with dose-dependent up-regulation of intracellular cAMP concentrations. Treating S. exigua larvae with PGE2 led to activation of a trimeric Gαs subunit, protein kinase A (PKA), and Rho family small intracellular G proteins in hemocytes. A deletion mutant of SePGE2R was generated using CRISPR/Cas9 which exhibited severely retarded larval development and adult reproduction. We infer that PGE2R mediates insect immune and reproductive processes via a PKA signal pathway.
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Affiliation(s)
- Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea.
| | - Shabbir Ahmed
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea
| | - Md Abdullah Al Baki
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea
| | - Sunil Kumar
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea; Department of Biological Sciences, Sungkyunkwan University, Suwon, 440-746, South Korea
| | - Kunwoo Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea
| | - Youngjin Park
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong 36729, South Korea; Plant Quarantine Technology Center, Animal and Plant Quarantine Agency, Gimcheon, 39660, South Korea
| | - David Stanley
- Biological Control of Insect Research Laboratory, USDA/Agricultural Research Service, Colombia, MO, USA
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Vatanparast M, Lee DH, Kim Y. Biosynthesis and immunity of epoxyeicosatrienoic acids in a lepidopteran insect, Spodoptera exigua. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2020; 107:103643. [PMID: 32067998 DOI: 10.1016/j.dci.2020.103643] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/10/2020] [Accepted: 02/10/2020] [Indexed: 06/10/2023]
Abstract
Eicosanoids mediate both cellular and humoral immune responses in insects. Epoxyeicosatrienoic acids (EETs) are a group of eicosanoids containing epoxide formed by epoxygenase (EPX) activity of cytochrome P450 (CYP). Although EETs have been considered to mediate immune responses in some insects, their synthetic machinery was little understood in insects. This study monitored EETs in a lepidopteran insect, Spodoptera exigua, immunized with bacteria and found all four EETs (5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET) from larval fat body at 247-1,736 pg/g levels. Then to predict EPXs, 140 CYPs were collected from S. exigua transcriptomes and compared with human EPXs. Four CYPs (SeEPX1-SeEPX4) sharing homologies with human EPXs were chosen and assessed in subsequent expression and functional analyses. All four EPXs were expressed in all development stages. In larval stage, all four EPXs were expressed in immune-associated tissues such as fat body and hemocytes. Furthermore, their expression levels were highly enhanced by bacterial challenge in different tissues. RNA interference (RNAi) using gene-specific double stranded RNA injection suppressed their expression levels by more than 55%. RNAi treatments interfered with hemocyte-spreading behavior and nodule formation upon bacterial challenge except RNAi treatment against SeEPX2. All four EETs stimulated cellular immune response measured by nodule formation in S. exigua. The suppressed immune responses by the RNAi treatments against three SeEPXs were rescued by the addition of 8,9-EET. However, other three EETs gave their specific rescue effect depending on SeEPX types under RNAi. In humoral immune response, all four RNAi treatments suppressed expression of antimicrobial peptide genes. This study reports the presence of all four EETs in larval fat body of S. exigua and suggests that four SeEPXs are associated with immune responses mediated by EETs.
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Affiliation(s)
- Mohammad Vatanparast
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea
| | - Dong-Hee Lee
- Industry Academy Cooperation Foundation, Andong National University, Andong, 36729, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea.
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Md Abdullah AB, Lee DW, Jung J, Kim Y. Deletion mutant of sPLA 2 using CRISPR/Cas9 exhibits immunosuppression, developmental retardation, and failure of oocyte development in legume pod borer, Maruca vitrata. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2020; 103:103500. [PMID: 31589887 DOI: 10.1016/j.dci.2019.103500] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/24/2019] [Accepted: 09/24/2019] [Indexed: 06/10/2023]
Abstract
Phospholipase A2 (PLA2) catalyzes release of free fatty acids linked to phospholipids at sn-2 position. Some of these released free fatty acids are used to synthesize eicosanoids that mediate various physiological processes in insects. Although a large number of PLA2s form a superfamily consisting of at least 16 groups, few PLA2s have been identified and characterized in insects. Furthermore, physiological functions of insect PLA2s remain unclear. Clustered regularly interspaced short parlindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) has been a useful research tool to validate gene function. This study identified and characterized a secretory PLA2 (sPLA2) from legume pod borer, Maruca vitrata (Lepidoptera: Crambidae), and validated its physiological functions using CRISPR/Cas9. An open reading frame of M. vitrata sPLA2 (Mv-sPLA2) encoding 192 amino acids contained signal peptide, calcium-binding domain, and catalytic site. Phylogenetic analysis indicated that Mv-sPLA2 was related to other Group III sPLA2s. Mv-sPLA2 was expressed in both larval and adult stages. It was inducible by immune challenge. RNA interference (RNAi) of Mv-sPLA2 significantly suppressed cellular immunity and impaired larval development. Furthermore, RNAi treatment in female adults prevented oocyte development. These physiological alterations were also observed in a mutant line of M. vitrata with Mv-sPLA2 deleted by using CRISPR/Cas9. Mv-sPLA2 was not detected in the mutant line from western blot analysis. Addition of an eicosanoid, PGE2, significantly rescued oocyte development of females of the mutant line. These results suggest that Mv-sPLA2 plays crucial role in immune, developmental, and reproductive processes of M. vitrata.
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Affiliation(s)
- Al Baki Md Abdullah
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea
| | - Dae-Weon Lee
- School of Chemistry and Life Sciences, Kyungsung University, Busan, 48434, South Korea
| | - Jinkyo Jung
- Division of Crop Cultivation and Environment Research, Department of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon, 16429, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea.
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Chandra Roy M, Lee D, Kim Y. Host Immunosuppression Induced by Steinernema feltiae, an Entomopathogenic Nematode, through Inhibition of Eicosanoid Biosynthesis. INSECTS 2019; 11:insects11010033. [PMID: 31906089 PMCID: PMC7023448 DOI: 10.3390/insects11010033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 12/27/2019] [Accepted: 12/28/2019] [Indexed: 02/06/2023]
Abstract
Steinernema feltiae K1 (Filipjev) (Nematode: Steinernematidae), an entomopathogenic nematode, was isolated and identified based on its morphological and molecular diagnostic characteristics. Its infective juveniles (IJs) were highly pathogenic to three lepidopteran (LC50 = 23.7–25.0 IJs/larva) and one coleopteran (LC50 = 39.3 IJs/larva) insect species. Infected larvae of the diamondback moth, Plutella xylostella (L.) (Insecta: Lepidoptera), exhibited significant reduction in phospholipase A2 (PLA2) activity in their plasma. The decrease of PLA2 activity was followed by significant septicemia of the larvae infected with S. feltiae. Insecticidal activity induced by S. feltiae was explained by significant immunosuppression in cellular immune responses measured by hemocyte nodule formation and total hemocyte count (THC). Although S. feltiae infection suppressed nodule formation and THC in the larvae, an addition of arachidonic acid (AA, a catalytic product of PLA2) rescued these larvae from fatal immunosuppression. In contrast, an addition of dexamethasone (a specific PLA2 inhibitor) enhanced the nematode’s pathogenicity in a dose-dependent manner. To discriminate the immunosuppressive activity of a symbiotic bacterium (Xenorhabdus bovienii (Proteobacteria: Enterobacterales)) from the nematode, kanamycin was applied to after nematode infection. It significantly inhibited the bacterial growth in the hemolymph. Compared to nematode treatment alone, the addition of antibiotics to nematode infection partially rescued the immunosuppression measured by phenol oxidase activity. Consequently, treatment with antibiotics significantly rescued the larvae from the insecticidal activity of S. feltiae. These results suggest that immunosuppression induced by infection of S. feltiae depends on its symbiotic bacteria by inhibiting eicosanoid biosynthesis, resulting in significant insect mortality. However, the addition of antibiotics or AA could not completely rescue the virulence of the nematode, suggesting that the nematode itself also plays a role in its insecticidal activity.
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Affiliation(s)
- Miltan Chandra Roy
- Department of Plant Medicals, Andong National University, Andong 36729, Korea;
| | - Dongwoon Lee
- School of Environmental Ecology and Tourism, Kyungpook National University, Sangju 37224, Korea;
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong 36729, Korea;
- Correspondence: ; Tel.: +82-54-820-5638
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