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Beets I, Zels S, Vandewyer E, Demeulemeester J, Caers J, Baytemur E, Courtney A, Golinelli L, Hasakioğulları İ, Schafer WR, Vértes PE, Mirabeau O, Schoofs L. System-wide mapping of peptide-GPCR interactions in C. elegans. Cell Rep 2023; 42:113058. [PMID: 37656621 PMCID: PMC7615250 DOI: 10.1016/j.celrep.2023.113058] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 07/19/2023] [Accepted: 08/16/2023] [Indexed: 09/03/2023] Open
Abstract
Neuropeptides and peptide hormones are ancient, widespread signaling molecules that underpin almost all brain functions. They constitute a broad ligand-receptor network, mainly by binding to G protein-coupled receptors (GPCRs). However, the organization of the peptidergic network and roles of many peptides remain elusive, as our insight into peptide-receptor interactions is limited and many peptide GPCRs are still orphan receptors. Here we report a genome-wide peptide-GPCR interaction map in Caenorhabditis elegans. By reverse pharmacology screening of over 55,384 possible interactions, we identify 461 cognate peptide-GPCR couples that uncover a broad signaling network with specific and complex combinatorial interactions encoded across and within single peptidergic genes. These interactions provide insights into peptide functions and evolution. Combining our dataset with phylogenetic analysis supports peptide-receptor co-evolution and conservation of at least 14 bilaterian peptidergic systems in C. elegans. This resource lays a foundation for system-wide analysis of the peptidergic network.
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Affiliation(s)
- Isabel Beets
- Department of Biology, KU Leuven, 3000 Leuven, Belgium.
| | - Sven Zels
- Department of Biology, KU Leuven, 3000 Leuven, Belgium
| | | | - Jonas Demeulemeester
- The Francis Crick Institute, London NW1 1AT, UK; VIB - KU Leuven Center for Cancer Biology, 3000 Leuven, Belgium; Department of Oncology, KU Leuven, 3000 Leuven, Belgium
| | - Jelle Caers
- Department of Biology, KU Leuven, 3000 Leuven, Belgium
| | - Esra Baytemur
- Department of Biology, KU Leuven, 3000 Leuven, Belgium
| | - Amy Courtney
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | | | | | - William R Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Petra E Vértes
- Department of Psychiatry, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK
| | - Olivier Mirabeau
- Institut Pasteur, Université Paris Cité, Bioinformatics and Biostatistics Hub, Inserm U1224, Brain-Immune Communication Lab, 75015 Paris, France
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Fadda M, Hasakiogullari I, Temmerman L, Beets I, Zels S, Schoofs L. Regulation of Feeding and Metabolism by Neuropeptide F and Short Neuropeptide F in Invertebrates. Front Endocrinol (Lausanne) 2019; 10:64. [PMID: 30837946 PMCID: PMC6389622 DOI: 10.3389/fendo.2019.00064] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 01/23/2019] [Indexed: 12/19/2022] Open
Abstract
Numerous neuropeptide systems have been implicated to coordinately control energy homeostasis, both centrally and peripherally. However, the vertebrate neuropeptide Y (NPY) system has emerged as the best described one regarding this biological process. The protostomian ortholog of NPY is neuropeptide F, characterized by an RXRF(Y)amide carboxyterminal motif. A second neuropeptide system is short NPF, characterized by an M/T/L/FRF(W)amide carboxyterminal motif. Although both short and long NPF neuropeptide systems display carboxyterminal sequence similarities, they are evolutionary distant and likely already arose as separate signaling systems in the common ancestor of deuterostomes and protostomes, indicating the functional importance of both. Both NPF and short-NPF systems seem to have roles in the coordination of feeding across bilaterian species, but during chordate evolution, the short NPF system appears to have been lost or evolved into the prolactin releasing peptide signaling system, which regulates feeding and has been suggested to be orthologous to sNPF. Here we review the roles of both NPF and sNPF systems in the regulation of feeding and metabolism in invertebrates.
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Affiliation(s)
| | | | | | | | | | - Liliane Schoofs
- Department of Biology, Functional Genomics and Proteomics, KU Leuven, Leuven, Belgium
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Oranth A, Schultheis C, Tolstenkov O, Erbguth K, Nagpal J, Hain D, Brauner M, Wabnig S, Steuer Costa W, McWhirter RD, Zels S, Palumbos S, Miller III DM, Beets I, Gottschalk A. Food Sensation Modulates Locomotion by Dopamine and Neuropeptide Signaling in a Distributed Neuronal Network. Neuron 2018; 100:1414-1428.e10. [DOI: 10.1016/j.neuron.2018.10.024] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/14/2018] [Accepted: 10/12/2018] [Indexed: 01/02/2023]
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Dubos MP, Zels S, Schwartz J, Pasquier J, Schoofs L, Favrel P. Characterization of a tachykinin signalling system in the bivalve mollusc Crassostrea gigas. Gen Comp Endocrinol 2018; 266:110-118. [PMID: 29746853 DOI: 10.1016/j.ygcen.2018.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 04/06/2018] [Accepted: 05/06/2018] [Indexed: 12/20/2022]
Abstract
Although tachykinin-like neuropeptides have been identified in molluscs more than two decades ago, knowledge on their function and signalling has so far remained largely elusive. We developed a cell-based assay to address the functionality of the tachykinin G-protein coupled receptor (Cragi-TKR) in the oyster Crassostrea gigas. The oyster tachykinin neuropeptides that are derived from the tachykinin precursor gene Cragi-TK activate the Cragi-TKR in nanomolar concentrations. Receptor activation is sensitive to Ala-substitution of critical Cragi-TK amino acid residues. The Cragi-TKR gene is expressed in a variety of tissues, albeit at higher levels in the visceral ganglia (VG) of the nervous system. Fluctuations of Cragi-TKR expression is in line with a role for TK signalling in C. gigas reproduction. The expression level of the Cragi-TK gene in the VG depends on the nutritional status of the oyster, suggesting a role for TK signalling in the complex regulation of feeding in C. gigas.
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Affiliation(s)
- Marie-Pierre Dubos
- Normandy University, Université de Caen Normandie, UMR BOREA, MNHN, UPMC, UCBN, CNRS-7208, IRD-207, Esplanade de la Paix, 14032 Caen Cedex, France
| | - Sven Zels
- Department of Biology, Functional Genomics and Proteomics Group, KU Leuven, 3000 Leuven, Belgium
| | - Julie Schwartz
- Normandy University, Université de Caen Normandie, UMR BOREA, MNHN, UPMC, UCBN, CNRS-7208, IRD-207, Esplanade de la Paix, 14032 Caen Cedex, France
| | - Jeremy Pasquier
- Normandy University, Université de Caen Normandie, UMR BOREA, MNHN, UPMC, UCBN, CNRS-7208, IRD-207, Esplanade de la Paix, 14032 Caen Cedex, France
| | - Liliane Schoofs
- Department of Biology, Functional Genomics and Proteomics Group, KU Leuven, 3000 Leuven, Belgium
| | - Pascal Favrel
- Normandy University, Université de Caen Normandie, UMR BOREA, MNHN, UPMC, UCBN, CNRS-7208, IRD-207, Esplanade de la Paix, 14032 Caen Cedex, France.
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5
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Van Bael S, Zels S, Boonen K, Beets I, Schoofs L, Temmerman L. A Caenorhabditis elegans Mass Spectrometric Resource for Neuropeptidomics. J Am Soc Mass Spectrom 2018; 29:879-889. [PMID: 29299835 DOI: 10.1007/s13361-017-1856-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/13/2017] [Accepted: 11/19/2017] [Indexed: 06/07/2023]
Abstract
Neuropeptides are important signaling molecules used by nervous systems to mediate and fine-tune neuronal communication. They can function as neurotransmitters or neuromodulators in neural circuits, or they can be released as neurohormones to target distant cells and tissues. Neuropeptides are typically cleaved from larger precursor proteins by the action of proteases and can be the subject of post-translational modifications. The short, mature neuropeptide sequences often entail the only evolutionarily reasonably conserved regions in these precursor proteins. Therefore, it is particularly challenging to predict all putative bioactive peptides through in silico mining of neuropeptide precursor sequences. Peptidomics is an approach that allows de novo characterization of peptides extracted from body fluids, cells, tissues, organs, or whole-body preparations. Mass spectrometry, often combined with on-line liquid chromatography, is a hallmark technique used in peptidomics research. Here, we used an acidified methanol extraction procedure and a quadrupole-Orbitrap LC-MS/MS pipeline to analyze the neuropeptidome of Caenorhabditis elegans. We identified an unprecedented number of 203 mature neuropeptides from C. elegans whole-body extracts, including 35 peptides from known, hypothetical, as well as from completely novel neuropeptide precursor proteins that have not been predicted in silico. This set of biochemically verified peptide sequences provides the most elaborate C. elegans reference neurpeptidome so far. To exploit this resource to the fullest, we make our in-house database of known and predicted neuropeptides available to the community as a valuable resource. We are providing these collective data to help the community progress, amongst others, by supporting future differential and/or functional studies. Graphical Abstract ᅟ.
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Affiliation(s)
- Sven Van Bael
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Leuven, Belgium
| | - Sven Zels
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Leuven, Belgium
| | - Kurt Boonen
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Leuven, Belgium
| | - Isabel Beets
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Leuven, Belgium
| | - Liliane Schoofs
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Leuven, Belgium
| | - Liesbet Temmerman
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven (University of Leuven), Leuven, Belgium.
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Verjans ET, Zels S, Luyten W, Landuyt B, Schoofs L. Molecular mechanisms of LL-37-induced receptor activation: An overview. Peptides 2016; 85:16-26. [PMID: 27609777 DOI: 10.1016/j.peptides.2016.09.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/01/2016] [Accepted: 09/03/2016] [Indexed: 12/30/2022]
Abstract
The human cathelicidin peptide LL-37 plays a crucial role in the immune system on many levels, from the first line of defense in epithelial cells to restoring the tissue after infection. On host cells, the majority of the LL-37-induced effects are mediated via the direct or indirect activation of several structurally unrelated cell surface receptors or intracellular targets. How LL-37 is able to affect multiple receptors is currently not well understood. So far, the mechanistic details underlying receptor activation are poorly investigated and evidence for a conventional ligand/receptor interaction is scarce. Over the past few decades, a large number of studies have reported on the activation of a receptor and/or components of the downstream signal transduction pathway induced by LL-37. This review summarizes the current knowledge on molecular mechanisms underlying LL-37-induced receptor activation.
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Affiliation(s)
- Eddy-Tim Verjans
- KU Leuven, Department of Biology, Division of Neurobiology and Animal Physiology, Naamsestraat 59, 3000 Leuven, Belgium.
| | - Sven Zels
- KU Leuven, Department of Biology, Division of Neurobiology and Animal Physiology, Naamsestraat 59, 3000 Leuven, Belgium
| | - Walter Luyten
- KU Leuven, Department of Biology, Division of Neurobiology and Animal Physiology, Naamsestraat 59, 3000 Leuven, Belgium
| | - Bart Landuyt
- KU Leuven, Department of Biology, Division of Neurobiology and Animal Physiology, Naamsestraat 59, 3000 Leuven, Belgium
| | - Liliane Schoofs
- KU Leuven, Department of Biology, Division of Neurobiology and Animal Physiology, Naamsestraat 59, 3000 Leuven, Belgium
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Caers J, Van Hiel MB, Peymen K, Zels S, Van Rompay L, Van Den Abbeele J, Schoofs L, Beets I. Characterization of a neuropeptide F receptor in the tsetse fly, Glossina morsitans morsitans. J Insect Physiol 2016; 93-94:105-111. [PMID: 27677695 DOI: 10.1016/j.jinsphys.2016.09.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 09/21/2016] [Accepted: 09/22/2016] [Indexed: 06/06/2023]
Abstract
Neuropeptides related to mammalian neuropeptide Y (NPY) and insect neuropeptide F (NPF) are conserved throughout Metazoa and intimately involved in a wide range of biological processes. In insects NPF is involved in regulating feeding, learning, stress and reproductive behavior. Here we identified and characterized an NPF receptor of the tsetse fly, Glossina morsitans morsitans, the sole transmitter of Trypanosoma parasites causing sleeping sickness. We isolated cDNA sequences encoding tsetse NPF (Glomo-NPF) and its receptor (Glomo-NPFR), and examined their spatial and temporal expression patterns using quantitative PCR. In tsetse flies, npfr transcripts are expressed throughout development and most abundantly in the central nervous system, whereas low expression is found in the flight muscles and posterior midgut. Expression of npf, by contrast, shows low transcript levels during development but is strongly expressed in the posterior midgut and brain of adult flies. Expression of Glomo-npf and its receptor in the brain and digestive system suggests that NPF may have conserved neuromodulatory or hormonal functions in tsetse flies, such as in the regulation of feeding behavior. Cell-based activity studies of the Glomo-NPFR showed that Glomo-NPF activates the receptor up to nanomolar concentrations. The molecular data of Glomo-NPF and Glomo-NPFR paves the way for further investigation of its functions in tsetse flies.
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Affiliation(s)
- Jelle Caers
- Functional Genomics and Proteomics, Department of Biology, KU Leuven, Leuven, Belgium.
| | - Matthias B Van Hiel
- Functional Genomics and Proteomics, Department of Biology, KU Leuven, Leuven, Belgium.
| | - Katleen Peymen
- Functional Genomics and Proteomics, Department of Biology, KU Leuven, Leuven, Belgium.
| | - Sven Zels
- Functional Genomics and Proteomics, Department of Biology, KU Leuven, Leuven, Belgium.
| | - Liesbeth Van Rompay
- Functional Genomics and Proteomics, Department of Biology, KU Leuven, Leuven, Belgium.
| | - Jan Van Den Abbeele
- Unit of Veterinary Protozoology, Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium; Laboratory of Zoophysiology, Department of Physiology, University of Ghent, Krijgslaan 281, 9000 Ghent, Belgium.
| | - Liliane Schoofs
- Functional Genomics and Proteomics, Department of Biology, KU Leuven, Leuven, Belgium.
| | - Isabel Beets
- Functional Genomics and Proteomics, Department of Biology, KU Leuven, Leuven, Belgium.
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Zels S, Dillen S, Crabbé K, Spit J, Nachman RJ, Vanden Broeck J. Sulfakinin is an important regulator of digestive processes in the migratory locust, Locusta migratoria. Insect Biochem Mol Biol 2015; 61:8-16. [PMID: 25846060 DOI: 10.1016/j.ibmb.2015.03.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 03/10/2015] [Accepted: 03/27/2015] [Indexed: 06/04/2023]
Abstract
Sulfakinin (SK) is a sulfated insect neuropeptide that is best known for its function as a satiety factor. It displays structural and functional similarities with the vertebrate peptides gastrin and cholecystokinin. Peptidomic studies in multiple insects, crustaceans and arachnids have revealed the widespread occurrence of SK in the arthropod phylum. Multiple studies in hemi- and holometabolous insects revealed the pleiotropic nature of this neuropeptide: in addition to its activity as a satiety factor, SK was also reported to affect muscle contraction, digestive enzyme release, odor preference, aggression and metabolism. However, the main site of action seems to be the digestive system of insects. In this study, we have investigated whether SK can intervene in the control of nutrient uptake and digestion in the migratory locust (Locusta migratoria). We provide evidence that sulfakinin reduces food uptake in this species. Furthermore, we discovered that SK has very pronounced effects on the main digestive enzyme secreting parts of the locust gut. It effectively reduced digestive enzyme secretion from both the midgut and gastric caeca. SK injection also elicited a reduction in absorbance and proteolytic activity of the gastric caeca contents. The characteristic sulfation of the tyrosine residue is crucial for the observed effects on digestive enzyme secretion. In an attempt to provide potential leads for the development of peptidomimetic compounds based on SK, we also tested two mimetic analogs of the natural peptide ligand in the digestive enzyme secretion assay. These analogs were able to mimic the effect of the natural SK, but their effects were milder. The results of this study provide new insights into the action of SK on the digestive system in (hemimetabolous) insects.
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Affiliation(s)
- Sven Zels
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Naamsestraat 59, Leuven, Vlaams-Brabant, Belgium.
| | - Senne Dillen
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Naamsestraat 59, Leuven, Vlaams-Brabant, Belgium.
| | - Katleen Crabbé
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Naamsestraat 59, Leuven, Vlaams-Brabant, Belgium.
| | - Jornt Spit
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Naamsestraat 59, Leuven, Vlaams-Brabant, Belgium.
| | - Ronald J Nachman
- Areawide Pest Management Research Unit, Southern Plains Agricultural Research Center, USDA, College Station, TX, USA.
| | - Jozef Vanden Broeck
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Naamsestraat 59, Leuven, Vlaams-Brabant, Belgium.
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Lismont E, Vleugels R, Marchal E, Badisco L, Van Wielendaele P, Lenaerts C, Zels S, Tobe SS, Vanden Broeck J, Verlinden H. Molecular cloning and characterization of the allatotropin precursor and receptor in the desert locust, Schistocerca gregaria. Front Neurosci 2015; 9:84. [PMID: 25814925 PMCID: PMC4357254 DOI: 10.3389/fnins.2015.00084] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 02/25/2015] [Indexed: 12/25/2022] Open
Abstract
Allatotropins (ATs) are pleiotropic neuropeptides initially isolated from the tobacco hornworm, Manduca sexta. In 2008, the first receptor for AT-like peptides (ATR) was characterized in Bombyx mori. Since then, ATRs have also been characterized in M. sexta, Tribolium castaneum, Aedes aegypti and Bombus terrestris. These receptors show sequence similarity to vertebrate orexin (ORX) receptors. When generating an EST-database of the desert locust (Schistocerca gregaria) central nervous system, we found cDNA sequences encoding the Schgr-AT precursor and a fragment of its putative receptor. This receptor cDNA has now been completed and functionally expressed in mammalian cell lines. Activation of this receptor, designated as Schgr-ATR, by Schgr-AT caused an increase in intracellular calcium ions, as well as cyclic AMP (cAMP), with an EC50 value in the nanomolar range. In addition, the transcript distribution of both the Schgr-AT precursor and Schgr-ATR was investigated by means of quantitative real-time PCR. Moreover, we found more evidence for the myotropic and allatostimulatory actions of Schgr-AT in the desert locust. These data are discussed and situated in a broader context by comparison with literature data on AT and ATR in insects.
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Affiliation(s)
- Els Lismont
- Molecular Developmental Physiology and Signal Transduction, KU Leuven Leuven, Belgium
| | - Rut Vleugels
- Molecular Developmental Physiology and Signal Transduction, KU Leuven Leuven, Belgium
| | - Elisabeth Marchal
- Molecular Developmental Physiology and Signal Transduction, KU Leuven Leuven, Belgium ; Department of Cell and Systems Biology, University of Toronto Toronto, ON, Canada
| | - Liesbeth Badisco
- Molecular Developmental Physiology and Signal Transduction, KU Leuven Leuven, Belgium
| | | | - Cynthia Lenaerts
- Molecular Developmental Physiology and Signal Transduction, KU Leuven Leuven, Belgium
| | - Sven Zels
- Molecular Developmental Physiology and Signal Transduction, KU Leuven Leuven, Belgium
| | - Stephen S Tobe
- Department of Cell and Systems Biology, University of Toronto Toronto, ON, Canada
| | - Jozef Vanden Broeck
- Molecular Developmental Physiology and Signal Transduction, KU Leuven Leuven, Belgium
| | - Heleen Verlinden
- Molecular Developmental Physiology and Signal Transduction, KU Leuven Leuven, Belgium
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Huang J, Marchal E, Hult EF, Zels S, Vanden Broeck J, Tobe SS. Mode of action of allatostatins in the regulation of juvenile hormone biosynthesis in the cockroach, Diploptera punctata. Insect Biochem Mol Biol 2014; 54:61-68. [PMID: 25218044 DOI: 10.1016/j.ibmb.2014.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 08/27/2014] [Accepted: 09/02/2014] [Indexed: 06/03/2023]
Abstract
The FGLamide allatostatins (FGL/ASTs) are a family of neuropeptides with pleiotropic functions, including the inhibition of juvenile hormone (JH) biosynthesis, vitellogenesis and muscle contraction. In the cockroach, Diploptera punctata, thirteen FGLa/ASTs and one allatostatin receptor (AstR) have been identified. However, the mode of action of ASTs in regulation of JH biosynthesis remains unclear. Here, we determined the tissue distribution of Dippu-AstR. And we expressed Dippu-AstR in vertebrate cell lines, and activated the receptor with the Dippu-ASTs. Our results show that all thirteen ASTs activated Dippu-AstR in a dose dependent manner, albeit with different potencies. Functional analysis of AstR in multiple cell lines demonstrated that activation of the AstR receptor resulted in elevated levels of Ca(2+) and cAMP, which suggests that Dippu-AstR can act through the Gαq and Gαs protein pathways. The study on the target of AST action reveals that FGL/AST affects JH biosynthesis prior to the entry of acetyl-CoA into the JH biosynthetic pathway.
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Affiliation(s)
- Juan Huang
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Elisabeth Marchal
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada; Department of Biology, Zoological Institute, KU Leuven, B-3000 Leuven, Belgium
| | - Ekaterina F Hult
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Sven Zels
- Department of Biology, Zoological Institute, KU Leuven, B-3000 Leuven, Belgium
| | - Jozef Vanden Broeck
- Department of Biology, Zoological Institute, KU Leuven, B-3000 Leuven, Belgium
| | - Stephen S Tobe
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada.
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Spit J, Zels S, Dillen S, Holtof M, Wynant N, Vanden Broeck J. Effects of different dietary conditions on the expression of trypsin- and chymotrypsin-like protease genes in the digestive system of the migratory locust, Locusta migratoria. Insect Biochem Mol Biol 2014; 48:100-109. [PMID: 24650544 DOI: 10.1016/j.ibmb.2014.03.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 03/06/2014] [Accepted: 03/06/2014] [Indexed: 06/03/2023]
Abstract
While technological advancements have recently led to a steep increase in genomic and transcriptomic data, and large numbers of protease sequences are being discovered in diverse insect species, little information is available about the expression of digestive enzymes in Orthoptera. Here we describe the identification of Locusta migratoria serine protease transcripts (cDNAs) involved in digestion, which might serve as possible targets for pest control management. A total of 5 putative trypsin and 15 putative chymotrypsin gene sequences were characterized. Phylogenetic analysis revealed that these are distributed among 3 evolutionary conserved clusters. In addition, we have determined the relative gene expression levels of representative members in the gut under different feeding conditions. This study demonstrated that the transcript levels for all measured serine proteases were strongly reduced after starvation. On the other hand, larvae of L. migratoria displayed compensatory effects to the presence of Soybean Bowman Birk (SBBI) and Soybean Trypsin (SBTI) inhibitors in their diet by differential upregulation of multiple proteases. A rapid initial upregulation was observed for all tested serine protease transcripts, while only for members belonging to class I, the transcript levels remained elevated after prolonged exposure. In full agreement with these results, we also observed an increase in proteolytic activity in midgut secretions of locusts that were accustomed to the presence of protease inhibitors in their diet, while no change in sensitivity to these inhibitors was observed. Taken together, this paper is the first comprehensive study on dietary dependent transcript levels of proteolytic enzymes in Orthoptera. Our data suggest that compensatory response mechanisms to protease inhibitor ingestion may have appeared early in insect evolution.
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Affiliation(s)
- Jornt Spit
- Department of Animal Physiology and Neurobiology, Zoological Institute K.U.Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
| | - Sven Zels
- Department of Animal Physiology and Neurobiology, Zoological Institute K.U.Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - Senne Dillen
- Department of Animal Physiology and Neurobiology, Zoological Institute K.U.Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - Michiel Holtof
- Department of Animal Physiology and Neurobiology, Zoological Institute K.U.Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - Niels Wynant
- Department of Animal Physiology and Neurobiology, Zoological Institute K.U.Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - Jozef Vanden Broeck
- Department of Animal Physiology and Neurobiology, Zoological Institute K.U.Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
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Zels S, Verlinden H, Dillen S, Vleugels R, Nachman RJ, Broeck JV. Signaling Properties and Pharmacological Analysis of Two Sulfakinin Receptors from the Red Flour Beetle, Tribolium castaneum. PLoS One 2014; 9:e94502. [PMID: 24718573 PMCID: PMC3981819 DOI: 10.1371/journal.pone.0094502] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 03/17/2014] [Indexed: 11/26/2022] Open
Abstract
Sulfakinin is an insect neuropeptide that constitutes an important component of the complex network of hormonal and neural factors that regulate feeding and digestion. The key modulating functions of sulfakinin are mediated by binding and signaling via G-protein coupled receptors. Although a substantial amount of functional data have already been reported on sulfakinins in different insect species, only little information is known regarding the properties of their respective receptors. In this study, we report on the molecular cloning, functional expression and characterization of two sulfakinin receptors in the red flour beetle, Tribolium castaneum. Both receptor open reading frames show extensive sequence similarity with annotated sulfakinin receptors from other insects. Comparison of the sulfakinin receptor sequences with homologous vertebrate cholecystokinin receptors reveals crucial conserved regions for ligand binding and receptor activation. Quantitative reverse transcriptase PCR shows that transcripts of both receptors are primarily expressed in the central nervous system of the beetle. Pharmacological characterization using 29 different peptide ligands clarified the essential requirements for efficient activation of these sulfakinin receptors. Analysis of the signaling pathway in multiple cell lines disclosed that the sulfakinin receptors of T. castaneum can stimulate both the Ca2+ and cyclic AMP second messenger pathways. This in depth characterization of two insect sulfakinin receptors may provide useful leads for the further development of receptor ligands with a potential applicability in pest control and crop protection.
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Affiliation(s)
- Sven Zels
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Leuven, Vlaams-Brabant, Belgium
| | - Heleen Verlinden
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Leuven, Vlaams-Brabant, Belgium
| | - Senne Dillen
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Leuven, Vlaams-Brabant, Belgium
| | - Rut Vleugels
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Leuven, Vlaams-Brabant, Belgium
| | - Ronald J. Nachman
- Areawide Pest Management Research Unit, Southern Plains Agricultural Research Center, USDA, College Station, Texas, United States of America
| | - Jozef Vanden Broeck
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Leuven, Vlaams-Brabant, Belgium
- * E-mail:
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Dillen S, Verdonck R, Zels S, Van Wielendaele P, Vanden Broeck J. Identification of the short neuropeptide F precursor in the desert locust: evidence for an inhibitory role of sNPF in the control of feeding. Peptides 2014; 53:134-9. [PMID: 24128610 DOI: 10.1016/j.peptides.2013.09.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 09/27/2013] [Accepted: 09/27/2013] [Indexed: 01/08/2023]
Abstract
Peptides of the short neuropeptide F (sNPF) family have been shown to modulate feeding behavior in a wide variety of insect species. While these peptides stimulate feeding and food-searching behavior in Drosophila melanogaster and Apis mellifera, an opposite effect has recently been demonstrated in the desert locust, Schistocerca gregaria. In this study, we elaborate on these observations with the identification of the nucleotide sequence encoding the Schgr-sNPF precursor and the study of its role in the regulation of locust feeding behavior. We confirm that both Schgr-sNPF-like peptides, previously identified in mass spectrometric studies, are genuine precursor-encoded peptides. RNA interference mediated silencing of the Schgr-sNPF precursor transcript generates novel evidence for an inhibitory role of Schgr-sNPF in the regulation of feeding in S. gregaria. Furthermore, we show that starvation reduces the Schgr-sNPF precursor transcript level in the optic lobes, the primary visual centers of the locust brain. Our data indicate that Schgr-sNPF exerts an inhibitory effect on food uptake in the desert locust, which contrasts with effects of sNPF reported for several other insect species.
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Affiliation(s)
- Senne Dillen
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Belgium
| | - Rik Verdonck
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Belgium
| | - Sven Zels
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Belgium
| | - Pieter Van Wielendaele
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Belgium
| | - Jozef Vanden Broeck
- Molecular Developmental Physiology and Signal Transduction, Department of Biology, KU Leuven, Belgium.
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Van Wielendaele P, Wynant N, Dillen S, Zels S, Badisco L, Vanden Broeck J. Neuropeptide F regulates male reproductive processes in the desert locust, Schistocerca gregaria. Insect Biochem Mol Biol 2013; 43:252-259. [PMID: 23295785 DOI: 10.1016/j.ibmb.2012.12.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 12/08/2012] [Accepted: 12/11/2012] [Indexed: 06/01/2023]
Abstract
Although Neuropeptide F (NPF) has been identified in different insect species, its function has mainly been studied in the fruit fly, Drosophila melanogaster, where it regulates diverse physiological processes, such as learning, stress responses and male courtship behavior. In locusts, only a truncated form of the "full-length" NPF (the biologically active "trNPF") has been isolated. This 9 AA peptide stimulates oocyte maturation, food intake and weight increase in adult desert locusts (Schistocerca gregaria [Forskål]). In this study, we investigated whether this peptide is also involved in the regulation of male reproductive physiology in this orthopteran species. Daily injections of trNPF in adult males resulted in proportionally heavier testes and seminal vesicles, while RNAi-mediated knockdown of the Schgr-NPF precursor transcript gave rise to proportionally lighter testes and seminal vesicles. Furthermore, adult males precociously displayed courtship behavior when injected daily with trNPF, while this behavior was inhibited or delayed by RNAi knockdown of the Schgr-NPF precursor transcript. In order to further analyze these effects of trNPF on male reproductive physiology, fertility of males was tested by analyzing progeny numbers following copulation with untreated females. In this way, we showed that daily trNPF injection in adult males resulted in a larger egg pod size and a higher percentage of hatched eggs per egg pod after copulation, while RNAi knockdown caused the opposite effects. Taken together, we provide clear evidence for a role of trNPF in the regulation of reproductive physiology in adult males of the desert locust, S. gregaria. Possible modes of action of trNPF in influencing these reproductive processes in male locusts are discussed.
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Affiliation(s)
- Pieter Van Wielendaele
- Molecular Developmental Physiology and Signal Transduction, Department of Animal Physiology and Neurobiology, Zoological Institute, K.U. Leuven, Naamsestraat 59, P.O. Box 02465, B-3000 Leuven, Belgium.
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van Hoef V, Breugelmans B, Spit J, Simonet G, Zels S, Vanden Broeck J. Phylogenetic distribution of protease inhibitors of the Kazal-family within the Arthropoda. Peptides 2013; 41:59-65. [PMID: 23159789 DOI: 10.1016/j.peptides.2012.10.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 10/30/2012] [Accepted: 10/30/2012] [Indexed: 01/21/2023]
Abstract
In mammalian pancreatic cells, the pancreatic secretory trypsin inhibitor (PSTI) belonging to the Kazal-family prevents the premature activation of digestive enzymes and thus plays an important role in a protective mechanism against tissue destruction by autophagy. Although a similar protective mechanism exists in Arthropoda, the distribution of these inhibitors in this phylum remains obscure. A comprehensive in silico search of nucleotide databases, revealed the presence of members of the Kazal-family in the four major subphyla of the Arthropoda. Especially in the Hexapoda and the Crustacea these inhibitors are widespread, while in the Chelicerata and Myriapoda only a few Kazal-like protease inhibitors were found. A sequence alignment of inhibitors retrieved in the digestive system of insects revealed a conservation of the PSTI characteristics and strong resemblance to vertebrate PSTI. A phylogenetic analysis of these inhibitors showed that they generally cluster according to their order. The results of this data mining study provide new evidence for the existence of an ancient protective mechanism in metazoan digestive systems. Kazal-like inhibitors, which play an important protective role in the pancreas of vertebrates, also seem to be present in Arthropoda.
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Affiliation(s)
- Vincent van Hoef
- Department of Animal Physiology and Neurobiology, Zoological Institute KU Leuven, Leuven, Belgium.
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Van Wielendaele P, Dillen S, Zels S, Badisco L, Vanden Broeck J. Regulation of feeding by Neuropeptide F in the desert locust, Schistocerca gregaria. Insect Biochem Mol Biol 2013; 43:102-114. [PMID: 23103541 DOI: 10.1016/j.ibmb.2012.10.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 10/07/2012] [Accepted: 10/08/2012] [Indexed: 06/01/2023]
Abstract
Our knowledge on the physiological function of the insect Neuropeptide F (NPF) mostly comes from studies in the fruit fly, Drosophila melanogaster, where NPF was shown to regulate diverse processes, such as feeding, learning and responding to stress. In the desert locust, Schistocerca gregaria, only a truncated form of the "full-length" NPF (the biologically active "trNPF") has been isolated. In this study, we investigated whether this peptide is involved in the regulation of feeding in this orthopteran species. In the S. gregaria EST-database, an NPF-precursor encoding transcript was found. Alignment with other insect NPF-precursors showed relatively highest sequence conservation within the trNPF region (and the flanking dibasic cleavage site), as compared to other regions of the NPF-precursor. Quantitative real-time RT-PCR revealed that the Schgr-NPF-precursor encoding transcript occurs throughout the central nervous system with relatively high transcript levels in the brain, optic lobes and suboesophageal ganglion. It was also detected at relatively high levels in the midgut, which suggests that the encoded peptide also functions in the digestive system. Moreover, Schgr-NPF-transcript levels were notably higher in starved animals than in animals fed ad libitum, while transcript levels were also shown to be regulated after the consumption of a meal. Injection of locust trNPF in adults stimulated food intake, while RNAi knockdown reduced food intake. Furthermore, injection of trNPF in adults stimulated weight increase, while RNAi knockdown reduced weight gain. This effect of trNPF on body weight gain may result from its stimulatory effect on food intake. Taken together, we provide clear evidence for an important role of trNPF in the regulation of feeding in the desert locust, S. gregaria.
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Affiliation(s)
- Pieter Van Wielendaele
- Molecular Developmental Physiology and Signal Transduction, Department of Animal Physiology and Neurobiology, Zoological Institute, K.U. Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
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Spit J, Badisco L, Verlinden H, Van Wielendaele P, Zels S, Dillen S, Vanden Broeck J. Peptidergic control of food intake and digestion in insects 1This review is part of a virtual symposium on recent advances in understanding a variety of complex regulatory processes in insect physiology and endocrinology, including development, metabolism, cold hardiness, food intake and digestion, and diuresis, through the use of omics technologies in the postgenomic era. CAN J ZOOL 2012. [DOI: 10.1139/z2012-014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Like all heterotrophic organisms, insects require a strict control of food intake and efficient digestion of food into nutrients to maintain homeostasis and to fulfill physiological tasks. Feeding and digestion are steered by both external and internal signals that are transduced by a multitude of regulatory factors, delivered either by neurons innervating the gut or mouthparts, or by midgut endocrine cells. The present review gives an overview of peptide regulators known to control feeding and digestion in insects. We describe the discovery and functional role in these processes for insect allatoregulatory peptides, diuretic hormones, FMRFamide-related peptides, (short) neuropeptide F, proctolin, saliva production stimulating peptides, kinins, and tachykinins. These peptides control either gut myoactivity, food intake, and (or) release of digestive enzymes. Some peptides exert their action at multiple levels, possibly having a biological function that depends on their site of delivery. Many regulatory peptides have been physically extracted from different insect species. However, multiple peptidomics, proteomics, transcriptomics, and genome sequencing projects have led to increased discovery and prediction of peptide (precursor) and receptor sequences. In combination with physiological experiments, these large-scale projects have already led to important steps forward in unraveling the physiology of feeding and digestion in insects.
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Affiliation(s)
- J. Spit
- Department of Animal Physiology and Neurobiology, Zoological Institute, KU Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - L. Badisco
- Department of Animal Physiology and Neurobiology, Zoological Institute, KU Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - H. Verlinden
- Department of Animal Physiology and Neurobiology, Zoological Institute, KU Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - P. Van Wielendaele
- Department of Animal Physiology and Neurobiology, Zoological Institute, KU Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - S. Zels
- Department of Animal Physiology and Neurobiology, Zoological Institute, KU Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - S. Dillen
- Department of Animal Physiology and Neurobiology, Zoological Institute, KU Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
| | - J. Vanden Broeck
- Department of Animal Physiology and Neurobiology, Zoological Institute, KU Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
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Spit J, Breugelmans B, van Hoef V, Simonet G, Zels S, Broeck JV. Growth-inhibition effects of pacifastin-like peptides on a pest insect: the desert locust, Schistocerca gregaria. Peptides 2012; 34:251-7. [PMID: 21736908 DOI: 10.1016/j.peptides.2011.06.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 06/21/2011] [Accepted: 06/21/2011] [Indexed: 11/22/2022]
Abstract
The main reason for the varying degrees of success of peptidase inhibitors (PI) as biological insecticides is the existence of a poorly understood mechanism, which allows pest insects to compensate for PI present in their diet. To challenge this highly flexible physiological mechanism and to prolong the inhibitory effect of PI on insect growth, a number of measures were taken into account before and during experiments with a notorious pest insect, the desert locust, Schistocerca gregaria: (i) non-plant PI (pacifastin-related inhibitors) were used to reduce the risk of a specific co-evolutionary adaptation of the pest insect, (ii) based on the main types of digestive enzymes present in the midgut, mixtures of multiple PI with different enzyme specificity were selected, allowing for a maximal inhibition of the proteolytic activity and (iii) digestive peptidase samples were taken during oral administration experiments to study compensatory mechanisms. Contrary to larvae fed on a diet containing plant-derived PI, a significant growth impediment was observed in larvae that were fed a mixture of different pacifastin-like PI. Nevertheless, the growth inhibition effect of this PI mixture attenuated after a few days, Moreover, a comprehensive study of the observed responses after oral administration of PI revealed that S. gregaria larvae can adjust their secreted digestive enzyme activities in two distinct ways depending on the composition/concentration of the PI-mixture.
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Affiliation(s)
- Jornt Spit
- Department of Animal Physiology and Neurobiology, Zoological Institute K.U. Leuven, Leuven, Belgium.
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Caers J, Verlinden H, Zels S, Vandersmissen HP, Vuerinckx K, Schoofs L. More than two decades of research on insect neuropeptide GPCRs: an overview. Front Endocrinol (Lausanne) 2012; 3:151. [PMID: 23226142 PMCID: PMC3510462 DOI: 10.3389/fendo.2012.00151] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 11/14/2012] [Indexed: 11/30/2022] Open
Abstract
This review focuses on the state of the art on neuropeptide receptors in insects. Most of these receptors are G protein-coupled receptors (GPCRs) and are involved in the regulation of virtually all physiological processes during an insect's life. More than 20 years ago a milestone in invertebrate endocrinology was achieved with the characterization of the first insect neuropeptide receptor, i.e., the Drosophila tachykinin-like receptor. However, it took until the release of the Drosophila genome in 2000 that research on neuropeptide receptors boosted. In the last decade a plethora of genomic information of other insect species also became available, leading to a better insight in the functions and evolution of the neuropeptide signaling systems and their intracellular pathways. It became clear that some of these systems are conserved among all insect species, indicating that they fulfill crucial roles in their physiological processes. Meanwhile, other signaling systems seem to be lost in several insect orders or species, suggesting that their actions were superfluous in those insects, or that other neuropeptides have taken over their functions. It is striking that the deorphanization of neuropeptide GPCRs gets much attention, but the subsequent unraveling of the intracellular pathways they elicit, or their physiological functions are often hardly examined. Especially in insects besides Drosophila this information is scarce if not absent. And although great progress made in characterizing neuropeptide signaling systems, even in Drosophila several predicted neuropeptide receptors remain orphan, awaiting for their endogenous ligand to be determined. The present review gives a précis of the insect neuropeptide receptor research of the last two decades. But it has to be emphasized that the work done so far is only the tip of the iceberg and our comprehensive understanding of these important signaling systems will still increase substantially in the coming years.
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Affiliation(s)
| | | | | | | | | | - Liliane Schoofs
- *Correspondence: Liliane Schoofs, Department of Biology, Research Group of Functional Genomics and Proteomics, Naamsestraat 59, KU Leuven, 3000 Leuven, Belgium. e-mail:
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van Hoef V, Breugelmans B, Spit J, Simonet G, Zels S, Billen J, Vanden Broeck J. Functional analysis of a pancreatic secretory trypsin inhibitor-like protein in insects: silencing effects resemble the human pancreatic autodigestion phenotype. Insect Biochem Mol Biol 2011; 41:688-695. [PMID: 21571068 DOI: 10.1016/j.ibmb.2011.04.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 04/28/2011] [Accepted: 04/29/2011] [Indexed: 05/30/2023]
Abstract
INTRODUCTION In mammalian pancreatic cells, the pancreatic secretory trypsin inhibitor (PSTI) prevents the premature activation of digestive enzymes and thus plays an important role in a protective mechanism against tissue destruction by autophagy, a process which may ultimately cause diseases such as pancreatitis and pancreatic cancer. Insects, however, lack a pancreas and so far no PSTI-like peptides are functionally characterized. RESULTS In several insect species protease inhibitors that structurally resemble the mammalian PSTI were predicted in silico. A putative PSTI-like protein (LmPSTI) was cloned and sequenced in the African migratory locust, Locusta migratoria. For the first time the expression of an insect derived PSTI-like inhibitor was shown to be restricted to the digestive enzyme-producing organs in insects (midgut and caeca). LmPSTI was produced via a bacterial expression system and was found to be a potent inhibitor of bovine trypsin as well as endogenous locust gut enzymes. In the caeca, RNAi-mediated knockdown of LmPSTI resulted in a significantly upregulated expression (2-fold) of locust ATG8 transcripts (an ubiquitin-like protein crucial for autophagosome formation). These findings were confirmed by an ultrastructural study on caeca, revealing the presence of autophagy-related structures in RNAi-treated animals. CONCLUSION The results of this study lead us to believe that LmPSTI plays an important role in controlling the proteolytic activity in the digestive system of L. migratoria. These findings provide new evidence for the existence of an ancient protective mechanism in metazoan digestive systems and open new perspectives for the study of autophagy-related diseases in the digestive tract.
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Affiliation(s)
- Vincent van Hoef
- Department of Animal Physiology and Neurobiology, Zoological Institute K.U. Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
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