Molecular characterization of G-protein-coupled receptor (GPCR) and protein kinase A (PKA) cDNA in Perinereis aibuhitensis and expression during benzo(a)pyrene exposure

Abstract

Background G-protein-coupled receptors (GPCRs) are one of the most important molecules that transfer signals across the plasma membrane, and play central roles in physiological systems. The molecular architecture of GPCRs allows them to bind to diverse chemicals, including environmental contaminants. Methods To investigate the effects of benzo(a)pyrene (B(a)P) on GPCR signaling, GPCR and the protein kinase A (PKA) catalytic subunit of Perinereis aibuhitensis were cloned. The expression patterns of these two genes during B(a)P exposure were determined with real-time fluorescence quantitative PCR. The PKA content in P. aibuhitensis under B(a)P exposure was examined. Results The full-length cDNAs of PaGPCR and the PaPKA catalytic subunit were 1,514 and 2,662 nucleotides, respectively, encoding 338 and 350 amino acids, respectively. Multiple sequence alignments indicated that the deduced amino acid sequence of PaGPCR shared a low level of similarity with the orphan GPCRs of polychaetes and echinoderms, whereas PaPKA shared a high level of identify with the PKA catalytic subunits of other invertebrates. B(a)P exposure time-dependently elevated the expression of PaGPCR and PaPKA. The expression of both PaGPCR and PaPKA was also dose-dependent, except at a dose of 10 μg/L B(a)P. The PKA content in concentration group was elevated on day 4, with time prolonging the PKA content was down-regulated to control level. Discussion These results suggested that GPCR signaling in P. aibuhitensis was involved in the polychaete’s response to environmental contaminants.