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

• Published in: Developmental & Comparative Immunology
• Main Authors: Jia, Yunke, Yang, Bin, Dong, Wenjing, Liu, Zhaoqun, Lv, Zhao, Jia, Zhihao, Qiu, Limei, Wang, Lingling, Song, Linsheng
• Format: Report
• Language: English
• Published: ELSEVIER SCI LTD 2018
• Subjects: Serotonin; Serotonin receptor 1A; Cellular immune response; Humoral immune response; Crassostrea gigas; Fisheries; Immunology; Zoology
• Online Access: http://ir.qdio.ac.cn/handle/337002/158366; http://ir.qdio.ac.cn/handle/337002/158367; https://doi.org/10.1016/j.dci.2017.12.029

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 Cg5-HTR1). Its open reading frame (ORF) was of 1239 bp, encoding-a polypeptide of 412 amino acids with a seven transmembrane region. Cg5-HTR-1 shared high similarity with the 5-HTRs from other animals. The cAMP contents in HEK293T cells decreased significantly after Cg5-HTR-1 transfection and 5-HT incubation (p < .05), while blocking Cg5-HTR-1 with specific receptor antagonist reversed this downtrend. The intracellular Ca2+ concentrations increased significantly (p < .05) after cell transfection and 5-HT incubation, and the antagonist treatment also arrested this process. Cg5-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 Cg5-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 Cg5-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 Cg5-HTR-1 was a novel member of 5-HT1 receptor family and it mediated serotonergic immunomodulation on both cellular and humoral immune responses. (C) 2018 Elsevier Ltd. All rights reserved.