Isolation of the bioactive peptides CCHamide-1 and CCHamide-2 from Drosophila and their putative role in appetite regulation as ligands for G protein-coupled receptors

Abstract

There are many orphan G protein-coupled receptors (GPCRs) for which ligands have not yet been identified. One such GPCR is the bombesin receptor subtype 3 (BRS-3). BRS-3 plays a role in the onset of diabetes and obesity. GPCRs in invertebrates are similar to those in vertebrates. Two Drosophila GPCRs (CG30106 and CG14593) belong to the BRS-3 phylogenetic subgroup. Here, we succeeded to biochemically purify the endogenous ligands of Drosophila CG30106 and CG14593 from whole Drosophila homogenates using functional assays with the reverse pharmacological technique, and identified their primary amino acid sequences. The purified ligands had been termed CCHamide-1 and CCHamide-2, although structurally identical to the peptides recently predicted from the genomic sequence searching. In addition, our biochemical characterization demonstrated two N-terminal extended forms of CCHamide-2. When administered to blowflies, CCHamide-2 increased their feeding motivation. Our results demonstrated these peptides actually present as the major components to activate these receptors in living Drosophila. Studies on the effects of CCHamides will facilitate the search for BRS-3 ligands.

Expression Patterns of the Drosophila Neuropeptide CCHamide-2 and Its Receptor May Suggest Hormonal Signaling from the Gut to the Brain

“…This structural work confirmed the sequences of the two D. melanogaster CCHamides and, also, that the two cysteine residues formed a cystine bridge, thereby making the peptides cyclic [4]. Both the structures of the two D. melanogaster CCHamides and the identities of their specific receptors were confirmed in December 2012 by Ida and co-workers [5]. …”

Chemical identity, function and regulation of enteroendocrine peptides in insects

“…While insulin-producing cells may be targeted by AstA neurons, it seems very likely that AstA released from EEs and not from neurons is responsible for the observed effect of AstA on AKH signaling and metabolism [42] since AstA neurons are not innervating the corpora cardiaca. Injections of CCHamide-2 into the hemolymph decrease the threshold of the proboscis extension reflex in blow flies, suggesting that the motivation to feed has been increased [43]. CCHamide-2 could act directly on the sensory neurons expressing sugar receptors to have such an effect, and it has recently been shown to act directly on the insulin producing cells in the brain [44].…”

Neuropeptides and peptide hormones identified in codling moth, Cydia pomonella (Lepidoptera: Tortricidae)

“…Comparison of the lepidopteran CCHamides show that these peptides are highly conserved (Figure c). Injection of Drosophila CCHamide 2 in blowflies increased feeding motivation (Ida et al, ), but the physiological function of CCHamides in lepidopterans remains unknown.…”

“…Injection of Drosophila CCHamide 2 in blowflies increased feeding motivation (Ida et al, 2012), but the physiological function of CCHamides in lepidopterans remains unknown.…”