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Hernandez JR, Xiong C, Pietrantonio PV. A fluorescently-tagged tick kinin neuropeptide triggers peristalsis and labels tick midgut muscles. Sci Rep 2024; 14:10863. [PMID: 38740831 DOI: 10.1038/s41598-024-61570-w] [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: 02/17/2024] [Accepted: 05/07/2024] [Indexed: 05/16/2024] Open
Abstract
Ticks are blood-feeding arthropods that require heme for their successful reproduction. During feeding they also acquire pathogens that are subsequently transmitted to humans, wildlife and/or livestock. Understanding the regulation of tick midgut is important for blood meal digestion, heme and nutrient absorption processes and for aspects of pathogen biology in the host. We previously demonstrated the activity of tick kinins on the cognate G protein-coupled receptor. Herein we uncovered the physiological role of the kinin receptor in the tick midgut. A fluorescently-labeled kinin peptide with the endogenous kinin 8 sequence (TMR-RK8), identical in the ticks Rhipicephalus microplus and R. sanguineus, activated and labeled the recombinant R. microplus receptor expressed in CHO-K1 cells. When applied to the live midgut the TMR-RK8 labeled the kinin receptor in muscles while the labeled peptide with the scrambled-sequence of kinin 8 (TMR-Scrambled) did not. The unlabeled kinin 8 peptide competed TMR-RK8, decreasing confocal microscopy signal intensity, indicating TMR-RK8 specificity to muscles. TMR-RK8 was active, inducing significant midgut peristalsis that was video-recorded and evaluated with video tracking software. The TMR-Scrambled peptide used as a negative control did not elicit peristalsis. The myotropic function of kinins in eliciting tick midgut peristalsis was established.
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Affiliation(s)
- Jonathan R Hernandez
- Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA
| | - Caixing Xiong
- Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA
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2
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Tsarouhas V, Liu D, Tsikala G, Engström Y, Strigini M, Samakovlis C. A surfactant lipid layer of endosomal membranes facilitates airway gas filling in Drosophila. Curr Biol 2023; 33:5132-5146.e5. [PMID: 37992718 DOI: 10.1016/j.cub.2023.10.058] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 09/14/2023] [Accepted: 10/26/2023] [Indexed: 11/24/2023]
Abstract
The mechanisms underlying the construction of an air-liquid interface in respiratory organs remain elusive. Here, we use live imaging and genetic analysis to describe the morphogenetic events generating an extracellular lipid lining of the Drosophila airways required for their gas filing and animal survival. We show that sequential Rab39/Syx1A/Syt1-mediated secretion of lysosomal acid sphingomyelinase (Drosophila ASM [dASM]) and Rab11/35/Syx1A/Rop-dependent exosomal secretion provides distinct components for lipid film assembly. Tracheal inactivation of Rab11 or Rab35 or loss of Rop results in intracellular accumulation of exosomal, multi-vesicular body (MVB)-derived vesicles. On the other hand, loss of dASM or Rab39 causes luminal bubble-like accumulations of exosomal membranes and liquid retention in the airways. Inactivation of the exosomal secretion in dASM mutants counteracts this phenotype, arguing that the exosomal secretion provides the lipid vesicles and that secreted lysosomal dASM organizes them into a continuous film. Our results reveal the coordinated functions of extracellular vesicle and lysosomal secretions in generating a lipid layer crucial for airway gas filling and survival.
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Affiliation(s)
- Vasilios Tsarouhas
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden; Science for Life Laboratory, SciLifeLab, 171 65 Stockholm, Sweden.
| | - Dan Liu
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden
| | - Georgia Tsikala
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden; IMBB, 70013 Heraklion, Crete, Greece
| | - Ylva Engström
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden
| | | | - Christos Samakovlis
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden; Science for Life Laboratory, SciLifeLab, 171 65 Stockholm, Sweden; ECCPS, Justus Liebig University of Giessen, 35390 Giessen, Germany.
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Malhotra P, Basu S. The Intricate Role of Ecdysis Triggering Hormone Signaling in Insect Development and Reproductive Regulation. INSECTS 2023; 14:711. [PMID: 37623421 PMCID: PMC10455322 DOI: 10.3390/insects14080711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/10/2023] [Accepted: 08/12/2023] [Indexed: 08/26/2023]
Abstract
Insect growth is interrupted by molts, during which the insect develops a new exoskeleton. The exoskeleton confers protection and undergoes shedding between each developmental stage through an evolutionarily conserved and ordered sequence of behaviors, collectively referred to as ecdysis. Ecdysis is triggered by Ecdysis triggering hormone (ETH) synthesized and secreted from peripheral Inka cells on the tracheal surface and plays a vital role in the orchestration of ecdysis in insects and possibly in other arthropod species. ETH synthesized by Inka cells then binds to ETH receptor (ETHR) present on the peptidergic neurons in the central nervous system (CNS) to facilitate synthesis of various other neuropeptides involved in ecdysis. The mechanism of ETH function on ecdysis has been well investigated in holometabolous insects such as moths Manduca sexta and Bombyx mori, fruit fly Drosophila melanogaster, the yellow fever mosquito Aedes aegypti and beetle Tribolium castaneum etc. In contrast, very little information is available about the role of ETH in sequential and gradual growth and developmental changes associated with ecdysis in hemimetabolous insects. Recent studies have identified ETH precursors and characterized functional and biochemical features of ETH and ETHR in a hemimetabolous insect, desert locust, Schistocerca gregaria. Recently, the role of ETH in Juvenile hormone (JH) mediated courtship short-term memory (STM) retention and long-term courtship memory regulation and retention have also been investigated in adult male Drosophila. Our review provides a novel synthesis of ETH signaling cascades and responses in various insects triggering diverse functions in adults and juvenile insects including their development and reproductive regulation and might allow researchers to develop sustainable pest management strategies by identifying novel compounds and targets.
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Affiliation(s)
| | - Saumik Basu
- Department of Entomology, Washington State University, Pullman, WA 99164, USA;
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Ahmad S, Jamil M, Jaworski CC, Luo Y. Comparative transcriptomics of the irradiated melon fly ( Zeugodacus cucurbitae) reveal key developmental genes. Front Physiol 2023; 14:1112548. [PMID: 36733910 PMCID: PMC9887199 DOI: 10.3389/fphys.2023.1112548] [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: 12/01/2022] [Accepted: 01/02/2023] [Indexed: 01/18/2023] Open
Abstract
Irradiation can be used as an insect pest management technique to reduce post-harvest yield losses. It causes major physiological changes, impairing insect development and leading to mortality. This technique is used to control the melon fly Zeugodacus cucurbitae, a major pest of Cucurbitaceae in Asia. Here, we applied irradiation to melon fly eggs, and the larvae emerged from irradiated eggs were used to conduct comparative transcriptomics and thereby identify key genes involved in the development and survival. We found 561 upregulated and 532 downregulated genes in irradiated flies compared to non-irradiated flies. We also observed abnormal small-body phenotypes in irradiated flies. By screening the 532 downregulated genes, we selected eight candidate genes putatively involved in development based in described functions in public databases and in the literature. We first established the expression profile of each candidate gene. Using RNA interference (RNAi), we individually knocked down each gene in third instar larvae and measured the effects on development. The knockdown of ImpE2 ecdysone-inducible gene controlling life stage transitions-led to major body size reductions in both pupae and adults. The knockdown of the tyrosine-protein kinase-like tok (Tpk-tok) caused severe body damage to larvae, characterized by swollen and black body parts. Adults subject to knockdown of the eclosion hormone (Eh_1) failed to shed their old cuticle which remained attached to their bodies. However, no obvious developmental defects were observed following the knockdown of the heat shock protein 67B1-like (Hsp67), the insulin receptor (Insr), the serine/threonine-protein kinase Nek4 (Nek4), the tyrosine-protein kinase transmembrane receptor Ror (Ror_1) and the probable insulin-like peptide 1 (Insp_1). We argue that irradiation can be successfully used not only as a pest management technique but also for the screening of essential developmental genes in insects via comparative transcriptomics. Our results demonstrate that ImpE2 and Eh_1 are essential for the development of melon fly and could therefore be promising candidates for the development of RNAi-based pest control strategies.
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Affiliation(s)
- Shakil Ahmad
- School of Plant Protection, Hainan University, Haikou, Hainan, China
| | - Momana Jamil
- School of Plant Protection, Hainan University, Haikou, Hainan, China
| | - Coline C. Jaworski
- Université Côte d’Azur, INRAE, CNRS, UMR ISA, Nice, France,Beijing Academy of Agriculture and Forestry, Institute of Plant and Environment Protection, Beijing, China
| | - Yanping Luo
- School of Plant Protection, Hainan University, Haikou, Hainan, China,*Correspondence: Yanping Luo,
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Zhou Y, Zhang Y, Zhang Y, Zhao Y, Xu W, Ye D, He Q, Iqbal C, Feng H, Li X, Zhang L, Qin Y, Yang X. Insect kinin mimics act as potential control agents for aphids: Structural modifications of Trp 4. J Pept Sci 2023; 29:e3444. [PMID: 35900188 DOI: 10.1002/psc.3444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/23/2022] [Accepted: 07/25/2022] [Indexed: 12/24/2022]
Abstract
Insect kinins are endogenous, biologically active peptides with various physiological functions. The use of insect kinins in plant protection is being evaluated by many groups. Some kinins have been chosen as lead compounds for pest control. We previously reported an insect kinin mimic IV-3 that had insecticidal activity. And by introducing a strong electron withdrawing group (-CF3 ) on the benzene ring (Phe2 ), we discovered a compound, L7 , with better activity than lead IV-3. In this work, taking L7 as the lead compound, we designed and synthesized 13 compounds to evaluate the influence of position 4 (Trp4 ) of insect kinin on insecticidal activity, by replacing the H atom on tryptophan with -CH3 and -Cl or substituting the indole ring of tryptophan with the benzene, naphthalene, pyridine, imidazole, cyclohexane, and alkyl carboxamides. The aphid bioassay results showed that the compounds M1 , M3 , and M5 were more active than the positive control, pymetrozine. Especially, replacing the side chain by an indole ring with 4-Cl substitution (M1 , LC50 = 0.0029 mmol/L) increased the aphicidal activity. The structure-activity relationships (SARs) indicated that the side chain benzene ring at this position may be important to the aphicidal activity. In addition, the toxicity prediction by Toxtree, and the toxicity experiments on Apis mellifera suggested that M1 was no toxicity risk on a non-target organism. It could be used as a selective and bee-friendly insecticide to control aphids.
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Affiliation(s)
- Yuanlin Zhou
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Yimeng Zhang
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Yongheng Zhang
- Guangxi Key Laboratory of Agro-Environment and Agro-Product Safety, Agricultural College, Guangxi University, Nanning, China
| | - Yingru Zhao
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Weilong Xu
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Dexing Ye
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Qi He
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Chandni Iqbal
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Haoyuan Feng
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Xuesheng Li
- Guangxi Key Laboratory of Agro-Environment and Agro-Product Safety, Agricultural College, Guangxi University, Nanning, China
| | - Li Zhang
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Yaoguo Qin
- Department of Entomology and MOA Key Laboratory for Monitoring and Environment-Friendly Control of Crop Pests, College of Plant Protection, China Agricultural University, Beijing, China
| | - Xinling Yang
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
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Bagnat M, Daga B, Di Talia S. Morphogenetic Roles of Hydrostatic Pressure in Animal Development. Annu Rev Cell Dev Biol 2022; 38:375-394. [PMID: 35804476 PMCID: PMC9675319 DOI: 10.1146/annurev-cellbio-120320-033250] [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] [Indexed: 11/09/2022]
Abstract
During organismal development, organs and systems are built following a genetic blueprint that produces structures capable of performing specific physiological functions. Interestingly, we have learned that the physiological activities of developing tissues also contribute to their own morphogenesis. Specifically, physiological activities such as fluid secretion and cell contractility generate hydrostatic pressure that can act as a morphogenetic force. Here, we first review the role of hydrostatic pressure in tube formation during animal development and discuss mathematical models of lumen formation. We then illustrate specific roles of the notochord as a hydrostatic scaffold in anterior-posterior axis development in chordates. Finally, we cover some examples of how fluid flows influence morphogenetic processes in other developmental contexts. Understanding how fluid forces act during development will be key for uncovering the self-organizing principles that control morphogenesis.
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Affiliation(s)
- Michel Bagnat
- Department of Cell Biology, Duke University, Durham, North Carolina, USA;
| | - Bijoy Daga
- Department of Cell Biology, Duke University, Durham, North Carolina, USA;
| | - Stefano Di Talia
- Department of Cell Biology, Duke University, Durham, North Carolina, USA;
- Department of Orthopaedic Surgery, Duke University, Durham, North Carolina, USA
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7
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Zhou YL, Li XL, Zhang YM, Shi Y, Li HH, Zhang Z, Iqbal C, Ye DX, Li XS, Zhao YR, Xu WL, Smagghe G, Yang XL. A novel bee-friendly peptidomimetic insecticide: Synthesis, aphicidal activity and 3D-QSAR study of insect kinin analogs at Phe 2 modification. PEST MANAGEMENT SCIENCE 2022; 78:2952-2963. [PMID: 35419934 DOI: 10.1002/ps.6920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 04/07/2022] [Accepted: 04/14/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND As one of the most abundant and destructive pests in agriculture, aphids cause significant damage to crops due to their sap-taking and as virus vectors. Chemical insecticides are the most effective method to control aphids, but they bring insecticide resistance problems and harm nontarget organisms, especially bees, therefore the search for novel eco-friendly aphid control agents with low bee toxicity is urgent. Insect kinins are a class of small neuropeptides that control important functions in insects. In our previous study, we found insect kinin analog IV-3 has good aphicidal activity and the location of the aromatic ring on the side chain of Phe2 is the key to the formation of the β-turn resulting in the biological activity of insect kinin analogs. However, there are few studies on insect kinin Phe2 substitution and modification, and its structure-activity relationship is still unclear. RESULTS In this project, 44 insect kinin analogs with the Phe2 modification, replacing it with different natural or unnatural amino acids, were designed and synthesized based on the lead IV-3 to explore the role of the Phe2 residues. Bioassays with soybean aphids of Aphis glycines indicated that nine analogs have better aphicidal activity than the lead IV-3. In particular, compound L25 exhibits excellent aphicidal activity (LC50 = 0.0047 mmol L-1 ) and has low toxicity to bees. Furthermore, a reliable three-dimensional quantitative structure-activity relationship (3D-QSAR) was established to produce a helpful clue that introducing hydrophobic groups away from the backbone chain is beneficial to improve aphicidal activity. CONCLUSION The residue Phe2 of insect kinin analogs is the key position and has a significant impact on the activity. L25 has a high toxicity for aphids, while a low toxicity to bees, and therefore can be considered as a lead compound to develop new biosafe aphid control agents. Finally, we provide a useful 3D-QSAR model as theoretical guidance for further structural optimization. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Yuan-Lin Zhou
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193, PR China
| | - Xin-Lu Li
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193, PR China
| | - Yi-Meng Zhang
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193, PR China
| | - Yan Shi
- Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, 9000, Belgium
- College of Plant Health and Medicine, Qingdao Agricultural University, Shandong Province, Qingdao, 266109, China
| | - Hong-Hong Li
- Guangxi Key Laboratory of Agro-Environment and Agro-Product Safety, Agricultural College, Guangxi University, Nanning, Guangxi Province, 530004, China
| | - Zhe Zhang
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193, PR China
| | - Chandni Iqbal
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193, PR China
| | - De-Xing Ye
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193, PR China
| | - Xue-Sheng Li
- Guangxi Key Laboratory of Agro-Environment and Agro-Product Safety, Agricultural College, Guangxi University, Nanning, Guangxi Province, 530004, China
| | - Ying-Ru Zhao
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193, PR China
| | - Wei-Long Xu
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193, PR China
| | - Guy Smagghe
- Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, 9000, Belgium
| | - Xin-Ling Yang
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, 100193, PR China
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Shen CH, Xu QY, Fu KY, Guo WC, Jin L, Li GQ. Ecdysis triggering hormone is essential for larva-pupa-adult transformation in Leptinotarsa decemlineata. INSECT MOLECULAR BIOLOGY 2021; 30:241-252. [PMID: 33368728 DOI: 10.1111/imb.12691] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 11/12/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
In Drosophila melanogaster, ecdysis triggering hormone (ETH) is the key factor triggering ecdysis behaviour and promoting trachea clearance. However, whether ETH plays the dual roles in non-dipteran insects is unknown. In this survey, we found that Ldeth mRNA levels were positively correlated with circulating 20-hydroxyecdysone (20E) titers in Leptinotarsa decemlineata. Ingestion of an ecdysteroid agonist halofenozide or 20E stimulated the transcription of Ldeth, whereas RNA interference (RNAi) of ecdysteroidogenesis (LdPTTH or LdSHD) or 20E signalling (LdEcR, LdUSP or LdFTZ-F1) genes inhibited the expression, indicating ETH acts downstream of 20E. RNAi of Ldeth at the final instar stage impaired pupation. More than 80% of the Ldeth-depleted beetles remained as prepupae, completely wrapped in the old larval cuticles. These prepupae became withered, dried and darkened gradually, and finally died in soil. The remaining Ldeth hypomorphs pupated and emerged as abnormal adults, bearing smaller and wrinkle elytrum and hindwing. Moreover, the tracheae in the Ldeth hypomorphs were full of liquid. We accordingly proposed that the failure of trachea clearance disenabled air-swallowing after pupa-adult ecdysis and impacted wing expansion. Our results suggest that ETH plays the dual roles, initiation of ecdysis and motivation of trachea clearance, in a coleopteran.
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Affiliation(s)
- C-H Shen
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Q-Y Xu
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - K-Y Fu
- Institute of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi, China
| | - W-C Guo
- Institute of Microbiological Application, Xinjiang Academy of Agricultural Science, Urumqi, China
| | - L Jin
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - G-Q Li
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
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Xiong C, Baker D, Pietrantonio PV. A random small molecule library screen identifies novel antagonists of the kinin receptor from the cattle fever tick, Rhipicephalus microplus (Acari: Ixodidae). PEST MANAGEMENT SCIENCE 2021; 77:2238-2251. [PMID: 33415807 DOI: 10.1002/ps.6249] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 12/17/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND The southern cattle tick, Rhipicephalus microplus, is a primary vector of the deadly bovine disease babesiosis. Worldwide populations of ticks have developed resistance to acaricides, underscoring the need for novel target discovery for tick control. The arthropod-specific R. microplus kinin receptor is such a target, previously validated by silencing, which resulted in female reproductive fitness costs, including a reduced percentage of eggs hatching. RESULTS In order to identify potent small molecules that bind and activate or inhibit the kinin receptor, a high-throughput screening (HTS) assay was developed using a CHO-K1 cell line expressing the recombinant tick kinin receptor (BMLK3 ). A total of ~20 000 molecules from a random in-house small molecule library were screened in a 'dual-addition' calcium fluorescence assay. This was followed by dose-response validation of the hit molecules identified both from HTS and an in silico screen of ~390 000 molecules. We validated 29 antagonists, 11 of them were full antagonists with IC50 values between 0.67 and 8 μmol L-1 . To explore the structure-activity relationships (SAR) of the small molecules, we tested the activities of seven analogs of the most potent identified antagonist, additionally discovering three full antagonists and four partial antagonists. These three potent antagonists (IC50 < 3.2 μmol L-1 ) were validated in vitro using the recombinant mosquito kinin receptor and showed similar antagonistic activities. In vivo, these three compounds also inhibited the mosquito hindgut contraction rate induced by a myotropic kinin agonist analog 1728. CONCLUSION Antagonists identified in this study could become pesticide leads and are reagents for probing the kinin signaling system. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Caixing Xiong
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Dwight Baker
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
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10
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Nässel DR. Leucokinin and Associated Neuropeptides Regulate Multiple Aspects of Physiology and Behavior in Drosophila. Int J Mol Sci 2021; 22:1940. [PMID: 33669286 PMCID: PMC7920058 DOI: 10.3390/ijms22041940] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 12/17/2022] Open
Abstract
Leucokinins (LKs) constitute a family of neuropeptides identified in numerous insects and many other invertebrates. LKs act on G-protein-coupled receptors that display only distant relations to other known receptors. In adult Drosophila, 26 neurons/neurosecretory cells of three main types express LK. The four brain interneurons are of two types, and these are implicated in several important functions in the fly's behavior and physiology, including feeding, sleep-metabolism interactions, state-dependent memory formation, as well as modulation of gustatory sensitivity and nociception. The 22 neurosecretory cells (abdominal LK neurons, ABLKs) of the abdominal neuromeres co-express LK and a diuretic hormone (DH44), and together, these regulate water and ion homeostasis and associated stress as well as food intake. In Drosophila larvae, LK neurons modulate locomotion, escape responses and aspects of ecdysis behavior. A set of lateral neurosecretory cells, ALKs (anterior LK neurons), in the brain express LK in larvae, but inconsistently so in adults. These ALKs co-express three other neuropeptides and regulate water and ion homeostasis, feeding, and drinking, but the specific role of LK is not yet known. This review summarizes Drosophila data on embryonic lineages of LK neurons, functional roles of individual LK neuron types, interactions with other peptidergic systems, and orchestrating functions of LK.
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Affiliation(s)
- Dick R Nässel
- Department of Zoology, Stockholm University, S-10691 Stockholm, Sweden
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11
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Nässel DR, Wu SF. Leucokinins: Multifunctional Neuropeptides and Hormones in Insects and Other Invertebrates. Int J Mol Sci 2021; 22:1531. [PMID: 33546414 PMCID: PMC7913504 DOI: 10.3390/ijms22041531] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 12/27/2022] Open
Abstract
Leucokinins (LKs) constitute a neuropeptide family first discovered in a cockroach and later identified in numerous insects and several other invertebrates. The LK receptors are only distantly related to other known receptors. Among insects, there are many examples of species where genes encoding LKs and their receptors are absent. Furthermore, genomics has revealed that LK signaling is lacking in several of the invertebrate phyla and in vertebrates. In insects, the number and complexity of LK-expressing neurons vary, from the simple pattern in the Drosophila larva where the entire CNS has 20 neurons of 3 main types, to cockroaches with about 250 neurons of many different types. Common to all studied insects is the presence or 1-3 pairs of LK-expressing neurosecretory cells in each abdominal neuromere of the ventral nerve cord, that, at least in some insects, regulate secretion in Malpighian tubules. This review summarizes the diverse functional roles of LK signaling in insects, as well as other arthropods and mollusks. These functions include regulation of ion and water homeostasis, feeding, sleep-metabolism interactions, state-dependent memory formation, as well as modulation of gustatory sensitivity and nociception. Other functions are implied by the neuronal distribution of LK, but remain to be investigated.
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Affiliation(s)
- Dick R. Nässel
- Department of Zoology, Stockholm University, S-10691 Stockholm, Sweden
| | - Shun-Fan Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China;
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12
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Shen CH, Xu QY, Fu KY, Guo WC, Jin L, Li GQ. Two Splice Isoforms of Leptinotarsa Ecdysis Triggering Hormone Receptor Have Distinct Roles in Larva-Pupa Transition. Front Physiol 2020; 11:593962. [PMID: 33335488 PMCID: PMC7736071 DOI: 10.3389/fphys.2020.593962] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 11/11/2020] [Indexed: 12/13/2022] Open
Abstract
Insect ecdysis triggering hormone (ETH) receptors (ETHRs) are rhodopsin-like G protein-coupled receptors. Upon binding its ligand ETH, ETHR initiates a precisely programed ecdysis behavior series and physiological events. In Drosophila melanogaster, the ethr gene produces two functionally distinct splicing isoforms, ethra and ethrb. ETH/ETHRA activates eclosion hormone (EH), kinin, crustacean cardioactive peptide (CCAP), and bursicon (burs and pburs) neurons, among others, in a rigid order, to elicit the behavioral sequences and physiological actions for ecdysis at all developmental stages, whereas ETH/ETHRB is required at both pupal and adult ecdysis. However, the role of ETHRB in regulation of molting has not been clarified in any non-drosophila insects. In the present paper, we found that 20-hydroxyecdysone (20E) signaling triggers the expression of both ethra and ethrb in a Coleopteran insect pest, the Colorado potato beetle Leptinotarsa decemlineata. RNA interference (RNAi) was performed using double-stranded RNAs (dsRNAs) targeting the common (dsethr) or isoform-specific (dsethra, dsethrb) regions of ethr. RNAi of dsethr, dsethra, or dsethrb by the final-instar larvae arrested larva development. The arrest was not rescued by feeding 20E. All the ethra depleted larvae stopped development at prepupae stage; the body cavity was expanded by a large amount of liquid. Comparably, more than 80% of the ethrb RNAi larvae developmentally halted at the prepupae stage. The remaining Ldethrb hypomorphs became pupae, with blackened wings and highly-expressed burs, pburs and four melanin biosynthesis genes. Therefore, ETHRA and ETHRB play isoform-specific roles in regulation of ecdysis during larva-pupa transition in L. decemlineata.
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Affiliation(s)
- Chen-Hui Shen
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Qing-Yu Xu
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Kai-Yun Fu
- Institute of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi, China
| | - Wen-Chao Guo
- Institute of Microbiological Application, Xinjiang Academy of Agricultural Science, Urumqi, China
| | - Lin Jin
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Guo-Qing Li
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
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Xiong C, Kaczmarek K, Zabrocki J, Nachman RJ, Pietrantonio PV. Activity of native tick kinins and peptidomimetics on the cognate target G protein-coupled receptor from the cattle fever tick, Rhipicephalus microplus (Acari: Ixodidae). PEST MANAGEMENT SCIENCE 2020; 76:3423-3431. [PMID: 31794138 DOI: 10.1002/ps.5704] [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: 09/16/2019] [Revised: 11/13/2019] [Accepted: 11/28/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Kinins are multifunctional neuropeptides that regulate key insect physiological processes such as diuresis, feeding, and ecdysis. However, the physiological roles of kinins in ticks are unclear. Furthermore, ticks have an expanded number of kinin paracopies in the kinin gene. Silencing the kinin receptor (KR) in females of Rhipicephalus microplus reduces reproductive fitness. Thus, it appears the kinin signaling system is important for tick physiology and its disruption may have potential for tick control. RESULTS We determined the activities of endogenous kinins on the KR, a G protein-coupled receptor, and identified potent peptidomimetics. Fourteen predicted R. microplus kinins (Rhimi-K), and 11 kinin analogs containing aminoisobutyric acid (Aib) were tested. The latter incorporated tick kinin sequences and/or were modified for enhanced resistance to arthropod peptidases. A high-throughput screen using a calcium fluorescence assay in 384-well plates was performed. All tested kinins and Aib analogs were full agonists. The most potent kinin and two kinin analogs were equipotent. Analogs 2414 ([Aib]FS[Aib]WGa) and 2412 ([Aib]FG[Aib]WGa) were the most active with EC50 values of 0.9 and 1.1 nM, respectively, matching the EC50 of the most potent tick kinin, Rhimi-K-14 (QDSFNPWGa) (EC50 = 1 nM). The potent analog 2415 ([Aib]FR[Aib]WGa, EC50 = 6.8 nM) includes both Aib molecules for resistance to peptidases and a positively charged residue, R, for enhanced water solubility and amphiphilic character. CONCLUSION These tick kinins and pseudopeptides expand the repertoire of reagents for tick physiology and toxicology towards finding novel targets for tick management. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Caixing Xiong
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Krzysztof Kaczmarek
- Institute of Organic Chemistry, Lodz University of Technology, Lodz, Poland
- Insect Neuropeptide Lab, Insect Control and Cotton Disease Research Unit, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, College Station, TX, USA
| | - Janusz Zabrocki
- Institute of Organic Chemistry, Lodz University of Technology, Lodz, Poland
- Insect Neuropeptide Lab, Insect Control and Cotton Disease Research Unit, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, College Station, TX, USA
| | - Ronald J Nachman
- Insect Neuropeptide Lab, Insect Control and Cotton Disease Research Unit, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, College Station, TX, USA
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Papakyrikos AM, Kim MJ, Wang X. Drosophila PTPMT1 Has a Function in Tracheal Air Filling. iScience 2020; 23:101285. [PMID: 32629421 PMCID: PMC7334580 DOI: 10.1016/j.isci.2020.101285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 05/28/2020] [Accepted: 06/14/2020] [Indexed: 01/02/2023] Open
Abstract
The fly trachea is the equivalent of the mammalian lung and is a useful model for human respiratory diseases. However, little is known about the molecular mechanisms underlying tracheal air filling during larval development. In this study, we discover that PTPMT1 has a function in tracheal air filling. PTPMT1 is a widely conserved, ubiquitously expressed mitochondrial phosphatase. To reveal PTPMT1's functions in genetically tractable invertebrates and whether those functions are tissue specific, we generate a Drosophila model of PTPMT1 depletion. We find that fly PTPMT1 mutants show impairments in tracheal air filling and subsequent activation of innate immune responses. On a cellular level, these defects are preceded by aggregation of mitochondria within the tracheal epithelial cells. Our work demonstrates a cell-type-specific role for PTPMT1 in fly tracheal epithelial cells to support air filling and to prevent immune activation. The establishment of this model will facilitate exploration of PTPMT1's physiological functions in vivo.
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Affiliation(s)
- Amanda M Papakyrikos
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA; Graduate Program in Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Min Joo Kim
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Xinnan Wang
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Xiong C, Kaczmarek K, Zabrocki J, Pietrantonio PV, Nachman RJ. Evaluation of Aib and PEG-polymer insect kinin analogs on mosquito and tick GPCRs identifies potent new pest management tools with potentially enhanced biostability and bioavailability. Gen Comp Endocrinol 2019; 278:58-67. [PMID: 30107140 DOI: 10.1016/j.ygcen.2018.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/02/2018] [Accepted: 08/01/2018] [Indexed: 11/22/2022]
Abstract
Insect kinins modulate aspects of diuresis, digestion, development, and sugar taste perception in tarsi and labellar sensilla in mosquitoes. They are, however, subject to rapid biological degradation by endogenous invertebrate peptidases. A series of α-aminoisobutyric (Aib) acid-containing insect kinin analogs incorporating sequences native to the Aedes aegypti mosquito aedeskinins were evaluated on two recombinant kinin invertebrate receptors stably expressed in cell lines, discovering a number of highly potent and biostable insect kinin mimics. On the Ae. aegypti mosquito kinin receptor, three highly potent, biostable Aib analogs matched the activity of the Aib-containing biostable insect kinin analog 1728, which previously showed disruptive and/or aversive activity in aphid, mosquito and kissing bug. These three analogs are IK-Aib-19 ([Aib]FY[Aib]WGa, EC50 = 18 nM), IK-Aib-12 (pQKFY[Aib]WGa, EC50 = 23 nM) and IK-Aib-20 ([Aib]FH[Aib]WGa, EC50 = 28 nM). On the Rhipicephalus (Boophilus) microplus tick receptor, IK-Aib-20 ([Aib]FH[Aib]WGa, EC50 = 2 nM) is more potent than 1728 by a factor of 3. Seven other potentially biostable analogs exhibited an EC50 range of 5-10 nM, all of which match the potency of 1728. Among the multi-Aib hexapeptide kinin analogs tested the tick receptor has a preference for the positively-charged, aromatic H over the aromatic residues Y and F in the X1 variable position ([Aib]FX1[Aib]WGa), whereas the mosquito receptor does not distinguish between them. In contrast, in a mono-Aib pentapeptide analog framework (FX1[Aib]WGa), both receptors exhibit a preference for Y over H in the variable position. Among analogs incorporating polyethylene glycol (PEG) polymer attachments at the N-terminus that can confer enhanced bioavailability and biostability, three matched or surpassed the potency of a positive control peptide. On the tick receptor IK-PEG-9 (P8-R[Aib]FF[Aib]WGa) was the most potent. Two others, IK-PEG-8 (P8-RFFPWGa) and IK-PEG-6 (P4-RFFPWGa), were most potent on the mosquito receptor, with the first surpassing the activity of the positive control peptide. These analogs and others in the IK-Aib series expand the toolbox of potent analogs accessible to invertebrate endocrinologists studying the structural requirements for bioactivity and the as yet unknown role of the insect kinins in ticks. They may contribute to the development of selective, environmentally friendly pest arthropod control agents.
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Affiliation(s)
- Caixing Xiong
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | - Krzysztof Kaczmarek
- Insect Control and Cotton Disease Research Unit, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F/B Road, College Station, TX 77845, USA; Institute of Organic Chemistry, Lodz University of Technology, 90-924 Lodz, Poland
| | - Janusz Zabrocki
- Insect Control and Cotton Disease Research Unit, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F/B Road, College Station, TX 77845, USA; Institute of Organic Chemistry, Lodz University of Technology, 90-924 Lodz, Poland
| | | | - Ronald J Nachman
- Insect Control and Cotton Disease Research Unit, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F/B Road, College Station, TX 77845, USA.
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Brock CM, Temeyer KB, Tidwell J, Yang Y, Blandon MA, Carreón-Camacho D, Longnecker MT, Almazán C, Pérez de León AA, Pietrantonio PV. The leucokinin-like peptide receptor from the cattle fever tick, Rhipicephalus microplus, is localized in the midgut periphery and receptor silencing with validated double-stranded RNAs causes a reproductive fitness cost. Int J Parasitol 2019; 49:287-299. [PMID: 30673587 DOI: 10.1016/j.ijpara.2018.11.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 10/31/2018] [Accepted: 11/04/2018] [Indexed: 12/25/2022]
Abstract
The cattle fever tick, Rhipicephalus microplus (Canestrini) (Acari: Ixodidae), is a one-host tick that infests primarily cattle in tropical and sub-tropical regions of the world. This species transmits deadly cattle pathogens, especially Babesia spp., for which a recombinant vaccine is not available. Therefore, disease control depends on tick vector control. Although R. microplus was eradicated in the USA, tick populations in Mexico and South America have acquired resistance to many of the applied acaricides. Recent acaricide-resistant tick reintroductions detected in the U.S. underscore the need for novel tick control methods. The octopamine and tyramine/octopamine receptors, both G protein-coupled receptors (GPCR), are believed to be the main molecular targets of the acaricide amitraz. This provides the proof of principle that investigating tick GPCRs, especially those that are invertebrate-specific, may be a feasible strategy for discovering novel targets and subsequently new anti-tick compounds. The R. microplus leucokinin-like peptide receptor (LKR), also known as the myokinin- or kinin receptor, is such a GPCR. While the receptor was previously characterized in vitro, the function of the leucokinin signaling system in ticks remains unknown. In this work, the LKR was immunolocalized to the periphery of the female midgut and silenced through RNA interference (RNAi) in females. To optimize RNAi experiments, a dual-luciferase system was developed to determine the silencing efficiency of LKR-double stranded RNA (dsRNA) constructs prior to testing those in ticks placed on cattle. This assay identified two effective dsRNAs. Silencing of the LKR with these two validated dsRNA constructs was verified by quantitative real time PCR (qRT-PCR) of female tick dissected tissues. Silencing was significant in midguts and carcasses. Silencing caused decreases in weights of egg masses and in the percentages of eggs hatched per egg mass, as well as delays in time to oviposition and egg hatching. A role of the kinin receptor in tick reproduction is apparent.
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Affiliation(s)
- Christina M Brock
- Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA
| | - Kevin B Temeyer
- Knipling-Bushland U.S. Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, United States Department of Agriculture - Agricultural Research Service, 2700 Fredericksburg Road Kerrville, TX 78028-9184, USA
| | - Jason Tidwell
- Cattle Fever Tick Research Laboratory, United States Department of Agriculture - Agricultural Research Service, 22675 N. Moorefield Rd. Building 6419 Edinburg, TX 78541-5033, USA
| | - Yunlong Yang
- Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA
| | - Maria A Blandon
- Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA
| | - Diana Carreón-Camacho
- Universidad Autónoma de Tamaulipas, Facultad de Medicina Veterinaria y Zootecnia, CP87000 Victoria, Tamaulipas, Mexico
| | - Michael T Longnecker
- Department of Statistics, Texas A&M University, College Station, TX 77843-2475, USA
| | - Consuelo Almazán
- Universidad Autónoma de Tamaulipas, Facultad de Medicina Veterinaria y Zootecnia, CP87000 Victoria, Tamaulipas, Mexico
| | - Adalberto A Pérez de León
- Knipling-Bushland U.S. Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, United States Department of Agriculture - Agricultural Research Service, 2700 Fredericksburg Road Kerrville, TX 78028-9184, USA
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17
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Pietrantonio PV, Xiong C, Nachman RJ, Shen Y. G protein-coupled receptors in arthropod vectors: omics and pharmacological approaches to elucidate ligand-receptor interactions and novel organismal functions. CURRENT OPINION IN INSECT SCIENCE 2018; 29:12-20. [PMID: 30551818 PMCID: PMC6296246 DOI: 10.1016/j.cois.2018.05.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 05/21/2018] [Accepted: 05/23/2018] [Indexed: 05/04/2023]
Abstract
Regulation of many physiological processes in animals, certainly those controlled by neuropeptide hormones, involves G protein-coupled receptors (GPCRs). Our work focusing on endocrine regulation of diuresis and water balance in mosquitoes and ticks started in 1997 with the kinin receptor, at the dawn of the omics era. After the genomic revolution, we began work on the endocrinology of reproduction in the red imported fire ant. We will use the template of this comparative work to summarize key points about GPCRs and signaling, and emphasize the most recent developments in the pharmacology of arthropod neuropeptide GPCRs. We will discuss omics' contributions to the advancement of this field, and its influence on peptidomimetic design while emphasizing work on blood feeding arthropods.
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Affiliation(s)
- Patricia V Pietrantonio
- Department of Entomology, Texas A&M University (TAMU), College Station, TX 77843-2475, United States.
| | - Caixing Xiong
- Department of Entomology, TAMU, College Station, TX 77843-2475, United States
| | - Ronald James Nachman
- Southern Plains Agricultural Research Center, USDA-ARS, College Station, TX 77845, United States
| | - Yang Shen
- Department of Electrical and Computer Engineering, TAMU, College Station, TX 77843-3128, United States
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Nässel DR. Substrates for Neuronal Cotransmission With Neuropeptides and Small Molecule Neurotransmitters in Drosophila. Front Cell Neurosci 2018; 12:83. [PMID: 29651236 PMCID: PMC5885757 DOI: 10.3389/fncel.2018.00083] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 03/08/2018] [Indexed: 01/11/2023] Open
Abstract
It has been known for more than 40 years that individual neurons can produce more than one neurotransmitter and that neuropeptides often are colocalized with small molecule neurotransmitters (SMNs). Over the years much progress has been made in understanding the functional consequences of cotransmission in the nervous system of mammals. There are also some excellent invertebrate models that have revealed roles of coexpressed neuropeptides and SMNs in increasing complexity, flexibility, and dynamics in neuronal signaling. However, for the fly Drosophila there are surprisingly few functional studies on cotransmission, although there is ample evidence for colocalization of neuroactive compounds in neurons of the CNS, based both on traditional techniques and novel single cell transcriptome analysis. With the hope to trigger interest in initiating cotransmission studies, this review summarizes what is known about Drosophila neurons and neuronal circuits where different neuropeptides and SMNs are colocalized. Coexistence of neuroactive substances has been recorded in different neuron types such as neuroendocrine cells, interneurons, sensory cells and motor neurons. Some of the circuits highlighted here are well established in the analysis of learning and memory, circadian clock networks regulating rhythmic activity and sleep, as well as neurons and neuroendocrine cells regulating olfaction, nociception, feeding, metabolic homeostasis, diuretic functions, reproduction, and developmental processes. One emerging trait is the broad role of short neuropeptide F in cotransmission and presynaptic facilitation in a number of different neuronal circuits. This review also discusses the functional relevance of coexisting peptides in the intestine. Based on recent single cell transcriptomics data, it is likely that the neuronal systems discussed in this review are just a fraction of the total set of circuits where cotransmission occurs in Drosophila. Thus, a systematic search for colocalized neuroactive compounds in further neurons in anatomically defined circuits is of interest for the near future.
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Affiliation(s)
- Dick R Nässel
- Department of Zoology, Stockholm University, Stockholm, Sweden
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