The First Non-Chordates QRFP-Like Peptide Receptor Gene in the Cephalopod Sepiella japonica: Identification, Characterization and Possible Role in Food Intake

The novel identified receptor, GPR103, now renamed QRFPR (also referred to as SP9155 or AQ27), is the endogenous receptor for the neuropeptide QRFP (also referred to as 26RFa). The distribution pattern, structure, and biological actions, such as feeding behavior, bone formation, and hormone secretion of QRFPR have been largely described in chordate species, while no research on QRFPR has been reported in non-chordate species. Here, the first non-chordates QRFP-like peptide receptor gene in the cephalopod Sepiella japonica (Sj_QRFPLR) was identified and characterized. Evidence from multiple alignments, phylogenetic analysis, and in vitro subcellular localization analysis indicated that Sj_QRFPLR is a class A GPCR and it belongs to the QRFPR family. Mean-while, QRFPR is likely to be structurally conserved in cephalopod species. In situ hybridization and RT-PCR data revealed a wide-spread distribution pattern of Sj_QRFPLR in multiple function lobes of the female brain and numerous peripheral tissues in both male and female cuttlefish. Subsequently, a food deprivation and refeeding experiment showed that Sj_QRFPLR is likely to stimulate food intake in cuttlefish. Additionally, a possible link between Sj_QRFPLR and immune response was briefly detected in cuttlefish. The results will contribute to our understanding of QRFPR in the cephalopod as well as the peptidergic regulation of the QRFP/QRFPR system in non-chordates.