BNGR-A25L and -A27 are two functional G protein-coupled receptors for CAPA periviscerokinin neuropeptides in the silkworm Bombyx mori.

CAPA peptides, such as periviscerokinin (PVK), are insect neuropeptides involved in many signaling pathways controlling, for example, metabolism, behavior, and reproduction. They are present in a large number of insects and, together with their cognate receptors, are important for research into approaches for improving insect control. However, the CAPA receptors in the silkworm (Bombyx mori) insect model are unknown. Here, we cloned cDNAs of two putative CAPA peptide receptor genes, BNGR-A27 and -A25, from the brain of B. mori larvae. We found that the predicted BNGR-A27 ORF encodes 450 amino acids and that one BNGR-A25 splice variant encodes a full-length isoform (BNGR-A25L) of 418 amino acid residues and another a short isoform (BNGR-A25S) of 341 amino acids with a truncated C-terminal tail. Functional assays indicated that both BNGR-A25L and -A27 are activated by the PVK neuropeptides Bom-CAPA-PVK-1 and -PVK-2, leading to a significant increase in cAMP-response element-controlled luciferase activity and Ca2+ mobilization in a Gq inhibitor-sensitive manner. In contrast, BNGR-A25S was not significantly activated in response to the PVK peptides. Moreover, Bom-CAPA-PVK-1 directly bound to BNGR-A25L and -A27, but not BNGR-A25S. Of note, CAPA-PVK-mediated ERK1/2 phosphorylation and receptor internalization confirmed that BNGR-A25L and -A27 are two canonical receptors for Bombyx CAPA-PVKs. However, BNGR-A25S alone is a nonfunctional receptor but serves as a dominant-negative protein for BNGR-A25L. These results provide evidence that BNGR-A25L and -A27 are two functional Gq-coupled receptors for Bombyx CAPA-PVKs, enabling the further elucidation of the endocrinological roles of Bom-CAPA-PVKs and their receptors in insect biology.

Structural elucidation and in vitro antitumor activity of a novel oligosaccharide from Bombyx batryticatus.

An oligosaccharide BBPW-2 was isolated and purified from Bombyx batryticatus, its molecular weight was 2.0 × 10(3)Da, and its structure was elucidated by compositional, methylation and NMR analysis. Our results showed that BBPW-2 consisted of ß-D-(1 → 2,6)-glucopyranose and ß-D-(1 → 2,6)-mannosyl units serving as the backbone, α-D-(1 → 2)-galactopyranose and α-D-(1 → 3)-mannosyl units as branches, and α-D-Manp and ß-D-Glcp as terminals. The in vitro inhibitory activity of BBPW-2 was measured using MTT and and crystal violet assays, which suggested that BBPW-2 had direct cytotoxic effects on the cancer cell lines HeLa and HepG2 (particularly HeLa cells), and had a long-term antiproliferative effect on MCF-7 cells, respectively. Apoptosis and cellcycle analysis of HeLa cells showed that BBPW-2 induced cellcycle disruption in the G0/G1 and G2/M phases accompanied by an impressive increment of early apoptotic cells and late apoptotic and necrotic cells. These results suggest that BBPW-2 could be a potential chemotherapeutic drug and its antitumor effects deserve further study.