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Vanden Broeck J.,Zoological Institute Kuleuven
Advances in Experimental Medicine and Biology | Year: 2010

Various insect species have a severe impact on human welfare and environment and thus force us to continuously develop novel agents for pest control. Neuropeptides constitute a very versatile class of bioactive messenger molecules that initiate and/or regulate a wide array of vital biological processes in insects by acting on their respective receptors in the plasmamembrane of target cells. These receptors belong to two distinct categories of signal transducing proteins, i.e., heptahelical or G protein-coupled receptors (7TM, GPCR) and single transmembrane containing receptors. An increasing amount of evidence indicates that insect neuropeptide-receptor couples play crucial roles in processes as diverse as development, metabolism, ecdysis and reproduction. As such they gain growing interest as promising candidate targets for the development of a new generation of species- and receptor-specific insect control agents that may generate fewer side effects. In this chapter, we will present some examples of insect neuropeptide receptors and aim to demonstrate their fundamental importance in insect biology. © 2010 Landes Bioscience and Springer Science+Business Media.

Breugelmans B.,Zoological Institute Kuleuven | Van Hoef V.,Zoological Institute Kuleuven | Simonet G.,Zoological Institute Kuleuven | Van Soest S.,Zoological Institute Kuleuven | And 2 more authors.
Peptides | Year: 2011

Information on the structural characteristics and inhibitory activity of the pacifastin family is restricted to a handful of locust pacifastin-related inhibitors. In this report the optimization of a bacterial recombinant expression system is described, resulting in the high yield production of pacifastin-like inhibitors of the desert locust. Subsequently, the relative inhibitory activity of these peptides towards mammalian, locust and caterpillar digestive peptidases has been compared. In general, the enzyme specificity of locust pacifastin-like inhibitors towards trypsin- or chymotrypsin-like peptidases corresponds to the nature of the P1-residue at the reactive site. In addition, other structural characteristics, including specific core interactions, have been reported to result in a different affinity of pacifastin members towards digestive trypsin-like enzymes from mammals and arthropods. One remarkable observation in this study is a specifically designed pacifastin-like peptidase inhibitor, which, unlike other inhibitors of the same family, does not display this specificity and selectivity towards digestive enzymes from different animals. © 2010 Elsevier Inc. All rights reserved.

Spit J.,Zoological Institute Kuleuven | Zels S.,Zoological Institute Kuleuven | Dillen S.,Zoological Institute Kuleuven | Holtof M.,Zoological Institute Kuleuven | And 2 more authors.
Insect Biochemistry and Molecular Biology | Year: 2014

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. © 2014 Elsevier Ltd.

Van Hoef V.,Zoological Institute Kuleuven | Breugelmans B.,Zoological Institute Kuleuven | Spit J.,Zoological Institute Kuleuven | Simonet G.,Zoological Institute Kuleuven | And 2 more authors.
Peptides | Year: 2013

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. © 2012 Elsevier Inc.

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