Natalisin, a tachykinin-like signaling system, regulates sexual activity and fecundity in insects

Abstract

An arthropod-specific peptidergic system, the neuropeptide designated here as natalisin and its receptor, was identified and investigated in three holometabolous insect species: Drosophila melanogaster, Tribolium castaneum, and Bombyx mori. In all three species, natalisin expression was observed in 3-4 pairs of the brain neurons: the anterior dorso-lateral interneurons, inferior contralateral interneurons, and small pars intercerebralis neurons. In B. mori, natalisin also was expressed in two additional pairs of contralateral interneurons in the subesophageal ganglion. Natalisin-RNAi and the activation or silencing of the neural activities in the natalisin-specific cells in D. melanogaster induced significant defects in the mating behaviors of both males and females. Knockdown of natalisin expression in T. castaneum resulted in significant reduction in the fecundity. The similarity of the natalisin C-terminal motifs to those of vertebrate tachykinins and of tachykinin-related peptides in arthropods led us to identify the natalisin receptor. A G protein-coupled receptor, previously known as tachykinin receptor 86C (also known as the neurokinin K receptor of D. melanogaster), now has been recognized as a bona fide natalisin receptor. Taken together, the taxonomic distribution pattern of the natalisin gene and the phylogeny of the receptor suggest that natalisin is an ancestral sibling of tachykinin that evolved only in the arthropod lineage.N europeptides are ancestral signaling molecules that function as cell-cell communication mediators in multicellular organisms. Large numbers of diverse neuropeptides are involved in the control of animal behavior, development, and physiology. Recent genomic approaches have revealed diverse groups of neuropeptides in different taxa, based on similarities in the amino acid sequences to neuropeptides discovered in earlier physiological and anatomical studies (1-4). Sequenced genomes of many insect species (5) provide an opportunity to explore the evolutionary processes of neuropeptides and their receptors. Furthermore, the tools available in biotechnology that are readily applicable in suitable insect model species have advanced our understanding of the functions of neuropeptides. Drosophila melanogaster has been the best model system, allowing functional studies of neuropeptides and their receptors by the use of highly advanced molecular genetic tools and various publicly available resources (6). A number of other insect species, especially those with sequenced genomes, such as Bombyx mori and Tribolium castaneum, also have been used for investigations into the functions of neuropeptide signals, using piggyBac transformation (7) and RNAi (8,9).Previous studies on insect neuropeptides and their G proteincoupled receptors (GPCRs) have described tachykinin-related peptides (TRPs) and two GPCRs as the receptors for the TRPs in D. melanogaster and other insect species (10-14). In vertebrates tachykinin and the TRPs form a group of ancestral neuropeptides that are found in a wide rang...

Identification and Characterization of Receptors for Ion Transport Peptide (ITP) and ITP-like (ITPL) in the Silkworm Bombyx mori

“…Indeed, a functional relationship between ITPL and TRPs has been suggested by the previous observation that ITP and TRPs co-localize in some neuroendocrine cells of the brain in D. melanogaster (38). In T. castaneum, the knockdown of ITPL results in a significant reduction in egg number (12), which is also observed when the gene expression of natalisin and its receptor are suppressed (37). These facts demonstrate the participation of both ITPL and TRP signaling systems in the regulation of female fecundity.…”

“…In this context, BNGR-A24, -A32, and -A33 may also show selectivity for B. mori TRPs. Recently, BNGR-A32 and -A33 have been identified as receptors for novel neuropeptides, natalisins with the C-terminal FXXXRa and YXXXRa (where "a" represents amidation) consensus sequences, respectively (37). In contrast, BNGR-A24 responds to B. mori natalisin 1 with an EC 50 of over 1 ϫ 10 Ϫ7 M, indicating that BNGR-A24 may not be a specific natalisin receptor but may share several ligands.…”

Peptidomics of Neuropeptidergic Tissues of the Tsetse FlyGlossina morsitans morsitans

“…The natalisin protein precursor, thus named as it increases fecundity and sexual activity in several insects [82], contains five putative neuropeptides in Drosophila. We identified a natalisin gene in the genome of tsetse flies (GMOY006483) encoding three putative neuropeptides, but could only detect one, NTL3, in the brain and TG.…”

Neprilysins: An Evolutionarily Conserved Family of Metalloproteases That Play Important Roles in Reproduction in Drosophila

“…To identify other potential substrates of neprilysins in Drosophila that might contribute to the phenotypes we report here, we looked for potential cleavage sites in known Drosophila neuropeptides that have been associated with the regulation of physiology and behavior (reviewed in Nässel and Winther 2010) as well as in the newly identified group classified as natalisins (Jiang et al 2013). Using the known cleavage site preferences of mammalian neprilysins and observed Drosophila Nep cleavage patterns, we identified potential Nep target sites in 56 of these 68 neuropeptides (Table S4).…”

“…Between mammals and the zebrafish, Danio rerio, the estrogendependent features of tachykinins and their receptors appear to be conserved (Biran et al 2012). In the insects Drosophila melanogaster and Tribolium castaneum, the tachykinin-like neuropeptide, natalisin, plays a role in regulating mating and reproductive outcomes (Jiang et al 2013). Finally, in both the locust Locusta migratoria and the cockroach, Leucophaea maderae, the functional cleavage of tachykinins by neprilysins in the brain is conserved (Isaac and Nässel 2003).…”