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Leyria J, El-Mawed H, Orchard I, Lange AB. Regulation of a Trehalose-Specific Facilitated Transporter (TRET) by Insulin and Adipokinetic Hormone in Rhodnius prolixus, a Vector of Chagas Disease. Front Physiol 2021; 12:624165. [PMID: 33643069 PMCID: PMC7902789 DOI: 10.3389/fphys.2021.624165] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/18/2021] [Indexed: 12/26/2022] Open
Abstract
Using the blood-sucking kissing bug, Rhodnius prolixus as an experimental model, we have studied the involvement of insulin-like peptides (ILPs) and adipokinetic hormone (AKH) signaling in carbohydrate metabolism, focusing on the regulation of the trehalose-specific facilitated transporter (Rhopr-TRET), particularly in the ovaries. We find that trehalose stores in ovaries increase after feeding, synchronously with the beginning of vitellogenesis, but that the transcript expression of enzymes involved in trehalose synthesis show no changes between unfed and blood-fed animals. However, an eightfold increase in Rhopr-TRET transcript expression is observed in the ovaries post-blood meal. In vivo and ex vivo assays using exogenous insulins and Rhopr-AKH, reveal that Rhopr-TRET is up-regulated in ovaries by both peptide families. In accordance with these results, when ILP and AKH signaling cascades are impaired using RNA interference, Rhopr-TRET transcript is down-regulated. In addition, trehalose injection induces an up-regulation of Rhopr-TRET transcript expression and suggests an activation of insulin signaling. Overall, the results support the hypothesis of a direct trehalose uptake by ovaries from the hemolymph through Rhopr-TRET, regulated by ILP and/or AKH. We also show that Rhopr-TRET may work cooperatively with AKH signaling to support the release of trehalose from the ovaries into the hemolymph during the unfed (starved) condition. In conclusion, the results indicate that in females of R. prolixus, trehalose metabolism and its hormonal regulation by ILP and AKH play critical roles in adapting to different nutritional conditions and physiological states.
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Affiliation(s)
- Jimena Leyria
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Hanine El-Mawed
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Ian Orchard
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Angela B Lange
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
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Sajjadian SM, Vatanparast M, Stanley D, Kim Y. Secretion of secretory phospholipase A 2 into Spodoptera exigua larval midgut lumen and its role in lipid digestion. INSECT MOLECULAR BIOLOGY 2019; 28:773-784. [PMID: 30980443 DOI: 10.1111/imb.12588] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In insects, lipid digestion is controversial because insects have no bile salts to solubilize dietary lipids. One hypothesis is that a secretory type of phospholipase A2 (sPLA2 ) provides lysophospholipid (LPL) from dietary phospholipids (PLs). We identified a sPLA2 , Se-sPLA2 , in beet armyworm, Spodoptera exigua, that hydrolyses PLs at sn-2. Our goal was to investigate its role in lipid digestion. Se-sPLA2 was expressed in the entire alimentary canal. Incubating the isolated midgut in a cell culture medium led to secretion of Se-sPLA2 and other proteins. Ex vivo RNA interference (RNAi) of Se-sPLA2 expression in isolated midgut culture led to significantly decreased Se-sPLA2 secretion into the medium. Feeding double-stranded RNA specific to Se-sPLA2 to larvae suppressed sPLA2 activity in gut contents. A recombinant Se-sPLA2 was susceptible to benzylideneacetone (BZA), a specific PLA2 inhibitor. After feeding BZA to larvae, we recorded significant decreases in gut content sPLA2 activity, body growth and total haemolymph lipid contents. RNAi against Se-sPLA2 resulted in reduced digestibility. Addition of a specific LPL, 1-palmitoyl-sn-glycero-3-phosphocholine, to BZA-treated larvae rescued digestibility and larval growth. These results strongly bolster our hypothesis that Se-sPLA2 secreted from the midgut acts in lipid digestion by providing necessary LPL to solubilize dietary neutral lipids.
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Affiliation(s)
- S M Sajjadian
- Department of Plant Medicals, Andong National University, Andong, Korea
| | - M Vatanparast
- Department of Plant Medicals, Andong National University, Andong, Korea
| | - D Stanley
- Biological Control of Insect Research Laboratory, USDA/Agricultural Research Service, Beltsville, MD, USA
| | - Y Kim
- Department of Plant Medicals, Andong National University, Andong, Korea
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Sajjadian SM, Vatanparast M, Kim Y. Toll/IMD signal pathways mediate cellular immune responses via induction of intracellular PLA 2 expression. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2019; 101:e21559. [PMID: 31062425 DOI: 10.1002/arch.21559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 06/09/2023]
Abstract
Phospholipase A2 (PLA2 ) hydrolyzes fatty acids from phospholipids at the sn-2 position. Two intracellular PLA2 s, iPLA2 A and iPLA2 B, have been found in Spodoptera exigua. Both are calcium-independent cellular PLA2 . Their orthologs have been found in other insects. These two iPLA2 s are different in ankyrin motif of N terminal region. The objective of this study was to determine whether Toll/immune deficiency (IMD) signal pathways could mediate cellular immune responses via induction of iPLA2 expression. Both iPLA 2 s were expressed in all developmental stages of S. exigua, showing the highest expression in the adult stage. During larval stage, hemocyte is the main tissue showing expression of these iPLA2 s. Both iPLA2 s exhibited similar expression patterns after immune challenge with different microbial pathogens such as virus, bacteria, and fungi. Promoter component analysis of orthologs encoded in S. frugiperda indicated nuclear factor-κB- and Relish-responsible elements on their promoters, suggesting their expression in S. exigua under Toll/IMD immune signaling pathways. RNA interference (RNAi) of MyD88 or Pelle under Toll pathway suppressed inducible expression levels of both iPLA2 s in response to Gram-positive bacteria containing Lys-type peptidoglycan or fungal infection. In contrast, RNAi against Relish under IMD pathway suppressed both iPLA2 s in response to infection with Gram-negative bacteria. Under RNAi conditions, hemocytes significantly lost cellular immune response measured by nodule formation. However, addition of arachidonic acid (a catalytic product of PLA2 ) rescued such immunosuppression. These results suggest that Toll/IMD signal pathways can mediate cellular immune responses via eicosanoid signaling by inducing iPLA2 expression.
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Affiliation(s)
- Seyede Minoo Sajjadian
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
| | - Mohammad Vatanparast
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
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Al Baki MA, Jung JK, Kim Y. Regulation of hemolymph trehalose titers by insulin signaling in the legume pod borer, Maruca vitrata (Lepidoptera: Crambidae). Peptides 2018; 106:28-36. [PMID: 29935203 DOI: 10.1016/j.peptides.2018.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 06/08/2018] [Accepted: 06/19/2018] [Indexed: 01/16/2023]
Abstract
A disaccharide, trehalose, is a main hemolymph sugar of the legume pod borer, Maruca vitrata larvae, but its titers fluctuated with feeding activity. During diurnal feeding in the photophase, hemolymph trehalose remained at a relatively low level (69 mM) and increased (98 mM) during scotophase. Starvation significantly increased the hemolymph trehalose level, in which the elevation of trehalose titers was dependent on the non-feeding period. The down-regulation of the trehalose level during the active feeding period seemed to result from mediation of the insulin/IGF signal (IIS). Injection of a porcine insulin suppressed the trehalose level in a dose-dependent manner. Genes associated with IIS of M. vitrata were predicted from its larval transcriptome, and their expression was confirmed in different developmental stages and tissues. All seven IIS genes selected were expressed in all developmental stages and different tissues. Silencing of four IIS genes (insulin receptor, Forkhead box O, a serine-threonine protein kinase, target of rapamycin) by RNA interference significantly modulated the hemolymph trehalose level. Starvation treatment changed expression of two trehalose metabolism-associated genes (trehalose phosphate synthase (TPS) and trehalase (TRE)) as well as the IIS genes. Silencing of TPS or TRE expression significantly down- or up-regulated the hemolymph trehalose level, respectively. In addition, silencing of IIS genes altered both TPS and TRE expression, indicating a functional link between IIS and trehalose metabolism. These results suggest that nutrients obtained from feeding activate IIS of M. vitrata, which then down-regulates the hemolymph trehalose level by altering trehalose metabolism.
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Affiliation(s)
- Md Abdullah Al Baki
- Department of Plant Medicals, Andong National University, Andong 37629, Republic of Korea
| | - Jin Kyo Jung
- Division of Crop Cultivation and Environment Research, Department of Central Area Crop Science, National Institute of Crop Science, Rural Development Administration, Suwon 16429, Republic of Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong 37629, Republic of Korea.
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Tang B, Wang S, Wang SG, Wang HJ, Zhang JY, Cui SY. Invertebrate Trehalose-6-Phosphate Synthase Gene: Genetic Architecture, Biochemistry, Physiological Function, and Potential Applications. Front Physiol 2018; 9:30. [PMID: 29445344 PMCID: PMC5797772 DOI: 10.3389/fphys.2018.00030] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 01/09/2018] [Indexed: 11/15/2022] Open
Abstract
The non-reducing disaccharide trehalose is widely distributed among various organisms. It plays a crucial role as an instant source of energy, being the major blood sugar in insects. In addition, it helps countering abiotic stresses. Trehalose synthesis in insects and other invertebrates is thought to occur via the trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP) pathways. In many insects, the TPP gene has not been identified, whereas multiple TPS genes that encode proteins harboring TPS/OtsA and TPP/OtsB conserved domains have been found and cloned in the same species. The function of the TPS gene in insects and other invertebrates has not been reviewed in depth, and the available information is quite fragmented. The present review discusses the current understanding of the trehalose synthesis pathway, TPS genetic architecture, biochemistry, physiological function, and potential sensitivity to insecticides. We note the variability in the number of TPS genes in different invertebrate species, consider whether trehalose synthesis may rely only on the TPS gene, and discuss the results of in vitro TPS overexpression experiment. Tissue expression profile and developmental characteristics of the TPS gene indicate that it is important in energy production, growth and development, metamorphosis, stress recovery, chitin synthesis, insect flight, and other biological processes. We highlight the molecular and biochemical properties of insect TPS that make it a suitable target of potential pest control inhibitors. The application of trehalose synthesis inhibitors is a promising direction in insect pest control because vertebrates do not synthesize trehalose; therefore, TPS inhibitors would be relatively safe for humans and higher animals, making them ideal insecticidal agents without off-target effects.
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Affiliation(s)
- Bin Tang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China.,Department of Medicine, Boston University School of Medicine, Boston, MA, United States
| | - Su Wang
- Beijing Key Laboratory of Environment Friendly Management on Fruit Diseases and Pests in North China, Institute of Plant and Environment Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Shi-Gui Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Hui-Juan Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Jia-Yong Zhang
- Key Lab of Wildlife Biotechnology, Conservation and Utilization of Zhejiang Province, College of Life Science and Chemistry, Zhejiang Normal University, Jinhua, China
| | - Shuai-Ying Cui
- Department of Medicine, Boston University School of Medicine, Boston, MA, United States
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