Precursor polyprotein for multiple neuropeptides secreted from the suboesophageal ganglion of the silkworm Bombyx mori: characterization of the cDNA encoding the diapause hormone precursor and identification of additional peptides.

Abstract

Peptidergic neurons, which serve as source of various endocrine neuropeptides, were identified in the suboesophageal ganglion (SG) and brain of insects. In the silkworm Bombyx mori, SG is known to secrete two neuropeptides, diapause hormone (DH) responsible for induction ofembryonic diapause and pheromone biosynthesis-activating neuropeptide, which share a pentapeptide amide, Phe-Xaa-Pro-Arg-Leu-NH2 (Xaa = Gly or Ser), at the C terminus. We have isolated cDNA clones for DH from the cDNA library of SG by using oligonucleotide probes. The molecular characterization of the cDNA reveals that the mRNA encodes an open reading frame consisting of 192 aa residues in which the 24-aa DH peptide is localized at the N-terminal region just after the signal peptide. A homology search proposed that the cDNA encodes pheromone biosynthesis-activating neuropeptide and three other neuropeptides [a-, (3-, and y-SG neuropeptide (SGNP)] in the region following DH, all of which are flanked by possible tryptic cleavage sites and share the Phe-Xaa-Pro-Arg-Leu-Gly sequence at the C terminus. Northern hybridization analysis clearly showed that the gene expression was limited to SG. We chemically synthesized a-, p-, and y-SGNP and used them to identify components in extracts of SG and to examine biological functions. a-and y-SGNP were identified in extracts of SG, and the synthetic P-and y-SGNP expressed weak DH activity.These results indicate that DH, along with four other neuropeptides, is generated from a common precursor polyprotein that is encoded by a single mRNA transcribed in neurosecretory cells of SG.

The pheromone biosynthesis activating neuropeptide (PBAN) receptor of Heliothis virescens: Identification, functional expression, and structure–activity relationships of ligand analogs

“…In some butterfly and moth species, synthesis and release of pheromones are regulated by pheromone biosynthesis activating neuropeptides (PBANs). The first PBANs identified from brain and subesophageal ganglia contain 33 or 34 amino acids, amidated at the C-terminus [5,14,16,24,27]. Despite significant advances over the last decades [4,10], many questions regarding the precise functional roles of PBANs remain.…”

The hormonal and circadian basis for insect photoperiodic timing

“…In B. mori, the DH precursor peptide can give rise to DH and other four additional FXPRL neuropeptides, the pheromone biosynthesis activating neuropeptide (PBAN) and the suboesophageal ganglion neuropeptides (a-, b-, c-SGNPs) [91,92]. DH, synthesized at the level of SOG of the silkworm, is released via the CC/CA complex in the haemolymph and it signals directly to egg chambers during vitellogenesis to elicit embryonic diapause (Fig.…”

“…The maternal SOG regulates embryonic state by producing diapause hormone (DH), which is a 24-amino acid peptide with a FXPRL motif at the C-terminus (X = G, T, V, S, I). The silkworm DH is encoded by the DH-PBAN gene that is expressed in neurosecretory cells (DHPCs) of the SOG, under the positive control of B. mori Pitx, a bicoid-like homeobox transcription factor that binds a cis-regulatory element in the promoter region of DH-PBAN [90][91][92]. Mammalian Pitx1 encodes an activator of pituitary-specific promoters such as those of genes encoding growth hormone (GH), prolactin (PRL), pro-opiomelanocortin (POMC), luteinizing hormone b-subunit (LHb), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) [93].…”

Molecular Cloning of a New Type of cDNA for Pheromone Biosynthesis Activating Neuropeptide in the Silkworm,Bombyx mori

“…5) Recently, we cloned the cDNA for the Bomhyx PBAN, designated Type-A, from adult female moths (heterozygous Bombyx strain 11 06 x Daizo) usually used for the bioassay. b) The nucleotide sequence showed that the gene encodes, in addition to PBAN, diapause hormone, and three other putative amidated peptides structurally related to PBAN, and the sequence of the coding region is completely matched with that obtained by Sato et al 7) During the previous study, we found a partial cDNA the nucleotide sequence of which differs from Type-A cDNA's.…”