A serotonin receptor (Cg5-HTR-1) mediating immune response in oyster Crassostrea gigas. (May 2018)

• Record Type: Journal Article
• Authors: Jia, Yunke; Yang, Bin; Dong, Wenjing; Liu, Zhaoqun; Lv, Zhao; Jia, Zhihao; Qiu, Limei; Wang, Lingling; Song, Linsheng
• Is Part Of: Developmental and comparative immunology. Volume 82(2018)
• Page Start: 83
• Page End: 93
• Publication Date: 2018-05
• Subjects: Serotonin -- Serotonin receptor 1A -- Cellular immune response -- Humoral immune response -- Crassostrea gigas; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2017.12.029
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Serotonin receptors, including ligand-gated ion channel (LGICs) and G protein-coupled receptors (GPCR), play vital roles in modulating physiological processes and immunoreaction. In the present study, a homologue of serotonin (5-HT) receptor was identified from oyster Crassostrea gigas (designated Cg 5-HTR-1). Its open reading frame (ORF) was of 1239 bp, encoding a polypeptide of 412 amino acids with a seven transmembrane region. Cg 5-HTR-1 shared high similarity with the 5-HTRs from other animals. The cAMP contents in HEK293T cells decreased significantly after Cg 5-HTR-1 transfection and 5-HT incubation ( p < .05), while blocking Cg 5-HTR-1 with specific receptor antagonist reversed this downtrend. The intracellular Ca 2+ concentrations increased significantly ( p < .05) after cell transfection and 5-HT incubation, and the antagonist treatment also arrested this process. Cg 5-HTR-1 transcripts were widely distributed in various tissues, with the highest level in hepatopancreas and lowest level in mantle and gill. The mRNA expression of Cg 5-HTR-1 in hemocyte increased significantly after lipopolysaccharide (LPS) stimulation and reached the peak level (6.47-fold, p < .05) at 6 h post treatment. The inhibition of Cg 5-HTR-1 significantly reduced the expression of tumor necrosis factor (TNF) mRNA in hemocyte, down-regulated the superoxide dismutase (SOD) activity in serum, and induced the apoptosis of hemocyte ( p < .05). These results suggested that Cg 5-HTR-1 was a novel member of 5-HT1 receptor family and it mediated serotonergic immunomodulation on both cellular and humoral immune responses. Highlights: A G protein-coupled serotonin receptor (Cg5-HTR1) was identified from pacific oyster Crassostrea gigas. The Cg5-HTR1 mRNA expression in oyster hemocytes could be induced by LPS stimulation. cAMP contents in HEK293T cells decreased significantly after Cg5-HTR-1 transfection and 5-HT incubation. CgTNF expression in hemocyte and SOD activity in serum was down-regulated after blockage of Cg5-HTR-1. Apoptosis index of hemocytes towards LPS increased after blockage of Cg5-HTR-1.