Cloning of Octopus cephalotocin receptor, a member of the oxytocin/vasopressin superfamily

Abstract

We reported that the common octopus, Octopus vulgaris, in common with vertebrates, possesses two members of the oxytocin/vasopressin superfamily: octopressin (OP) and cephalotocin (CT). This was the first observation of its kind in invertebrates. As OP and CT have different biological activities, the presence of specific receptors has been proposed. We cloned the cDNA of an orphan receptor from Octopus brain and found it to encode a polypeptide of 397 amino acids that displays sequences characteristic of G-protein coupled receptors. The orphan receptor showed high homology to receptors of the oxytocin/vasopressin superfamily and seemed to conserve the agonist-binding pocket common to the oxytocin and vasopressin receptors. Xenopus oocytes that express the orphan receptor responded to the application of CT by an induction of membrane Cl currents coupled to the inositol phosphate/Ca 2+ pathway. OP and the other members of the oxytocin/vasopressin superfamily did not activate this receptor. HPLC fractionation of the Octopus brain extract combined with an oocyte assay yielded a single substance that was identical to CT. On the basis of these results, we conclude that the cloned receptor is the CT receptor (CTR). Expression of CTR mRNA in Octopus was detected in the central and the peripheral nervous systems, the pancreas, the oviduct and the ovary. This receptor may mediate physiological functions of CT in Octopus such as neurotransmission, reproduction and metabolism.

Cloning and identification of an oxytocin/vasopressin-like receptor and its ligand from insects

“…1 and 2). Furthermore, other protostomian invertebrates, more basal than arthropods, such as annelids and mollusks, do also have oxytocin/vasopressin-like neuropeptides (Table 1) and their corresponding GPCRs (37)(38)(39)(40). From these data, the following picture emerges (Fig.…”

Global map of oxytocin/vasopressin-like neuropeptide signalling in insects

“…Local and whole genome duplication and deletion events during vertebrate evolution led to different number of gene copies (two or more) of oxytocin/vasopressin receptors and precursors within distinct vertebrate species3132. Likewise among invertebrates more than one copy of receptor and/or precursor is known for nematodes19 or molluscs33343536. In some molluscs the expression pattern of three oxytocin/vasopressin-like (conopressin) receptors and two precursors in different organs is indicative for different biological functions3436.…”

“…Likewise among invertebrates more than one copy of receptor and/or precursor is known for nematodes19 or molluscs33343536. In some molluscs the expression pattern of three oxytocin/vasopressin-like (conopressin) receptors and two precursors in different organs is indicative for different biological functions3436. Thus, these Chelicerata species mentioned above could become interesting model systems to study the biological functions of multiple and different copies of inotocin-like peptides and receptors in arthropods.…”

Oxytocin/vasopressin and gonadotropin‐releasing hormone from cephalopods to vertebrates

“…Three receptor genes cloned from the octopus brain show high homologies to those of the oxytocin/vasopressin superfamily of peptide receptors 46,47 . Two of them are subtypes of the cephalotocin receptor (CTR‐1 and CTR‐2) and one is the octopressin receptor (OPR).…”