title: The immunomodulation mediated by a delta-opioid receptor for [Met(5)]-enkephalin in oyster Crassostrea gigas.
abstract: Opioid receptors (OR) are a group of G protein-coupled receptors with opioids as ligands, which play an important role in triggering the second messengers to modulate immune response in vertebrate immunocytes. In the present study, the full length cDNA of a homologue of δ-opioid receptor (DOR) for [Met(5)]-enkaphalin was cloned from oyster Crassostrea gigas (designated as CgDOR), which was 1104 bp encoding a peptide of 367 amino acids containing a conserved 7tm_1 domain. After the stimulation of [Met(5)]-enkephalin, the concentration of second messengers Ca(2+) and cAMP in the HEK293T cells decreased significantly (p <0.05) with the expression of CgDOR. However, this trend was reverted with the addition of DOR antagonist BNTX. The CgDOR transcripts were ubiquitously detected in the tested tissues including haemocytes, gonad, mantle, kidney, gill, adductor muscle and hepatopancreas, with the highest expression level in the hepatopancreas. After LPS stimulation, the expression level of CgDOR mRNA began to increase (4.05-fold, p <0.05) at 6 h, and reached the highest level (5.00-fold, p <0.05) at 12 h. Haemocyte phagocytic and antibacterial activities increased significantly after [Met(5)]-enkephalin stimulation, whereas the increase was repressed with the addition of DOR antagonist BNTX. These results collectively suggested that CgDOR for [Met(5)]-enkephalin could modulate the haemocyte phagocytic and antibacterial functions through the second messengers Ca(2+) and cAMP, which might be requisite for pathogen elimination and homeostasis maintenance in oyster.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zhaoqun
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China. Electronic address: wanglingling@ms.qdio.ac.cn.
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Weilin
authors.initials: W
authors.lastname: Wang
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; School of Marine Sciences, Ningbo University, Ningbo 315211, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China. Electronic address: lshsong@ms.qdio.ac.cn.
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001597:Benzylidene Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D049896:Crassostrea / Q000276:immunology*; D000242:Cyclic AMP / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004744:Enkephalin, Methionine / Q000276:immunology*; D057809:HEK293 Cells; D043143:Hepatopancreas / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides; D008969:Molecular Sequence Data; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D010587:Phagocytosis / Q000276:immunology*; D012333:RNA, Messenger / Q000096:biosynthesis; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology*; D016415:Sequence Alignment; D015398:Signal Transduction / Q000276:immunology; D014733:Vibrio / Q000276:immunology*
chemical_list: D001597:Benzylidene Compounds; D018076:DNA, Complementary; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D017465:Receptors, Opioid, delta; C077358:7-benzylidenenaltrexone; D004744:Enkephalin, Methionine; D009271:Naltrexone; D000242:Cyclic AMP; D002118:Calcium
keywords: Crassostrea gigas; Haemocyte; Immunomodulation; [Met(5)]-enkephalin; δ-opioid receptor