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

BackgroundG-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.MethodsTo 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.ResultsThe 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.DiscussionThese results suggested that GPCR signaling in P. aibuhitensis was involved in the polychaete’s response to environmental contaminants.

Benzo[a]pyrene disrupts LH/hCG-dependent mouse Leydig cell steroidogenesis through receptor/Gαs protein targeting

“…These results, together with the short-term nature of the BaP effect, suggest that the endocrine disruptor decreases cAMP production in mLTC1 directly targeting the LH receptor or Gαs protein, rather than decreasing the receptor expression levels. We may hypothesize that the direct action of BaP on GPCR/Gαs protein could be responsible of disrupted early signalling also of other receptors 30 – 32 . A similar mechanism of action was previously described for BaP-induced interference with the β2-adrenoreceptor (β2ADR)/Gαs protein/cAMP signalling cascade 33 .…”