Identification of sulfakinin receptors (SKR) in Tenebrio molitor beetle and the influence of sulfakinins on carbohydrates metabolism

Abstract

Sulfakinins (SKs) are pleiotropic neuropeptides commonly found in insects, structurally and functionally homologous to the mammalian gastrin/cholecystokinin (CCK) neuropeptides. SKs together with sulfakinin receptors (SKRs) are involved in sulfakinin signaling responsible for variety of biological functions, including food intake or fatty acid metabolism. In the present study, we determined the distribution of SKRs in Tenebrio molitor larvae and characterized the impact of nonsulfated and sulfated SKs on carbohydrates and insulin-like peptides (ILPs) level in beetle hemolymph. Our results indicate the presence of both sulfakinin receptors, SKR1 and SKR2, in the nervous system of T. molitor. The distribution of SKR2 in peripheral tissues was more widespread than SKR1, and their transcripts have been found in fat body, gut and hemolymph. This is also the first evidence for SKRs presence in insect hemocytes indicating immunotropic activity of SKs. Moreover, in the present study, we have demonstrated that SKs regulate ILPs and carbohydrates level in insect hemolymph, and that sulfation is not crucial for peptides activity. Our study confirms the role of SKs in maintaining energy homeostasis in beetles.

Solanum nigrum Extract and Solasonine Affected Hemolymph Metabolites and Ultrastructure of the Fat Body and the Midgut in Galleria mellonella

“…The changes in carbohydrates and amino acids composition in the hemolymph were analyzed by the reverse-phase high-performance liquid chromatography (RP-HPLC) according to methods previously described by Słocińska et al [ 14 ]. For separation, a Dionex Ultimate 3000 (USA) chromatographic system comprising a dual-pump programmable solvent module and a Corona Charged Aerosol Detector (CAD) was used.…”

“…Some of the checked parameters were sugars, polyols, and proline levels in hemolymph, the insect circulating fluid. The hemolymph is a sensitive marker of changes in the insect organism; the content of particular components in this tissue is under control of the fat body and may depend on various conditions such as temperature, developmental stage, and metabolic state [ 12 , 13 , 14 ]. Still, not much is available about maintaining homeostasis of sugars, polyols, and proline during intoxication and, hence, other possible functions of these compounds.…”

Insulin-Like Peptides and Cross-Talk With Other Factors in the Regulation of Insect Metabolism

“…It was shown that knockdown of either neuropeptide affects the transcript levels of the other, suggesting possible feedback regulatory mechanism between the peptides ( Söderberg et al, 2012 ). Recently, it was also shown that SKs influence the ILP level in the haemolymph in the Tenebrio molitor beetle, which affects circulating carbohydrate levels ( Słocińska et al, 2020 ).…”

Comprehensive Quantitative Proteome Analysis of Aedes aegypti Identifies Proteins and Pathways Involved in Wolbachia pipientis and Zika Virus Interference Phenomenon

“…Exploring neuropeptides and hormones, neuropeptide sulfakinin (SK) (AAEL006451-PB) and insulin-like peptide (ILP) 1 (AAEL000937-PA) were down-regulated comparing WZ with Z. SK are a family of neuropeptides, homologous to mammalian gastrin/cholecystokinin (CCK), responsible for food uptake control in insects (Zels et al, 2015) while ILPs are known for signaling carbohydrates intake in cells (Nässel and Broeck, 2016). A recent study correlated SK influence in ILPs concentration, where a rise in SK concentration promotes ILPs production (Słocińska et al, 2020). SK down-regulation, observed in our data, may decrease in mosquito feeding satisfaction.…”