Title: Characterization of sulfakinin and sulfakinin receptor and their roles in food intake in the red flour beetle, Tribolium castaneum Authors
Submitted to: General and Comparative Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 6, 2013
Publication Date: July 1, 2013
Citation: Yu, N., Nachman, R.J., Smagghe, G. 2013. Characterization of sulfakinin and sulfakinin receptor and their roles in food intake in the red flour beetle, Tribolium castaneum. General and Comparative Endocrinology. 188:196-203. Interpretive Summary: Insect pests have developed resistance to several conventional pesticides, and new approaches are needed for pest management. Although neuropeptides (short chains of amino acids) serve as potent messengers in insects to regulate vital functions, the neuropeptides hold little promise as pest control agents because they can be degraded in the target pest. New, selective control agents may be developed by designing mimics of these neuropeptides that resist degradation and either inhibit or over-stimulate critical neuropeptide-regulated life functions. Research was conducted that characterized the ‘sulfakinin’ neuropeptide and its active site in an important pest of stored grain, the red flour beetle. Neuropeptides of the ‘sulfakinin’ class were found to reduce food intake by up to 70% in the red flour beetle. The research also reveals that this activity occurs via a specific interaction with a neuropeptide active site and therefore represents an entirely novel mode of action. The discoveries revealed in this paper will aid in the design of neuropeptide-like compounds capable of disrupting both the feeding and digestive functions of pest insects. The work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling pest insects in an environmentally friendly fashion.
Technical Abstract: Sulfakinins (SK) are multifunctional neuropeptides widely found in insects that are structurally and functionally homologous to the mammalian gastrin/cholecystokinin (CCK)neuropeptides. CCK is involved in various biological processes such as the feeding regulation where it induces satiety. In this project we characterized SK and SK receptor (SKR) of an important pest and model beetle insect, the red flour beetle Tribolium castaneum, with the aim to better understand the SK signaling pathway and its function in food intake. The sk gene encoded a SK precursor with 113 amino acids and the skr gene a seven-transmembrane SKR with 554 amino acids. Both genes were expressed in the larval, pupal and adult stages with different expression levels in tested tissues. By RNA interference, sk dsRNA and skr dsRNA reduced the expression of the corresponding target gene by 80-90% and 30-50%, respectively, and stimulated food intake in the larvae. In parallel, we injected insects with a SK analog reducing food intake. In conclusion, the data are discussed in relation to the SK signaling pathway and its physiological/endocrinological role in regulating food intake and potential usage in the control of important pest insects.