Adiponectin receptors (AdipoRs) comprise a seven-transmembrane domain-containing protein family, which specifically recognize adiponectin (APN) and play critical roles in the immunological and physiological processes in vertebrates. In the present study, a novel AdipoR is identified from oyster Crassostrea gigas (designated as CgAdipoR). The full-length cDNA of CgAdipoR is of 1209 bp encoding a polypeptide of 343 amino acids. There is an N-terminal domain, a Hly III domain, and a C-terminal domain in CgAdipoR. After the transfection of CgAdipoR, the level of intracellular Ca2+ into HEK293T cells increases significantly (1.36-fold, p < 0.05) after APN incubation. The mRNA transcripts of CgAdipoR are widely distributed in all the tested tissues, with the highest expression level in haemocytes (3.20-fold of that in hepatopancreas, p < 0.05). After lipopolysaccharide (LPS), Vibrio splendidus and polyinosinic-polycytidylic acid (poly (I:C)) stimulations, the mRNA expression of CgAdipoR in haemocytes is significantly up-regulated and reached the highest level at 24 h (15.07-fold, p < 0.01), 6 h (4.39-fold, p < 0.01) and 24 h (5.62-fold, p < 0.01) compared to control group, respectively. After CgAdipoR is interfered by specific CgAdipoR-dsRNA, the expression level of interleukins (CgIL17-1, CgIL17-2, CgIL17-3 and CgIL17-5) in haemocytes decreases significantly (p < 0.01) at 24 h post LPS stimulation, while the expression level of CgTNF-1 increases significantly (1.68-fold, p < 0.01), compared to that in the dsEGFP group. In CgAdipoR dsRNA-injected oysters, the mRNA expressions of anti-apoptotic B-cell lymphoma-2 (Bcl-2) in haemocytes significantly decreases at 24 h after LPS challenge, which is (0.58-fold, p < 0.05) of that in dsEGFP-injected oysters, while the apoptotic rate of haemocytes is significantly up-regulated (1.93-fold of that in dsEGFP group, p < 0.05). These results collectively suggest that CgAdipoR plays an important role in the immune response of oysters by regulating the expressions of inflammatory cytokines and haemocyte apoptosis.

中文翻译：

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一种新型脂联素受体 (AdipoR)，其参与调节牡蛎巨牡蛎中细胞因子的产生和血细胞的凋亡。

脂联素受体 (AdipoRs) 包括一个包含七跨膜结构域的蛋白质家族，其特异性识别脂联素 (APN) 并在脊椎动物的免疫和生理过程中发挥关键作用。在本研究中，从牡蛎Crassostrea gigas（指定为CgAdipoR）中鉴定出一种新型AdipoR。CgAdipoR 的全长 cDNA 为 1209 bp，编码 343 个氨基酸的多肽。CgAdipoR 中有一个 N 端域、一个 Hly III 域和一个 C 端域。CgAdipoR 转染后，APN 孵育后细胞内 Ca2+ 进入 HEK293T 细胞的水平显着增加（1.36 倍，p < 0.05）。CgAdipoR 的 mRNA 转录本广泛分布于所有受试组织中，在血细胞中表达水平最高（肝胰腺的 3.20 倍，p < 0.05）。脂多糖（LPS）、灿烂弧菌和聚肌苷酸（poly（I:C））刺激后，血细胞中CgAdipoR的mRNA表达显着上调，并在24小时达到最高水平（15.07倍，p < 0.01）、6 小时（4.39 倍，p < 0.01）和 24 小时（5.62 倍，p < 0.01）分别与对照组相比。CgAdipoR 受特定 CgAdipoR-dsRNA 干扰后，血细胞中白细胞介素（CgIL17-1、CgIL17-2、CgIL17-3 和 CgIL17-5）的表达水平在 LPS 刺激后 24 小时显着降低（p < 0.01），而与 dsEGFP 组相比，CgTNF-1 的表达水平显着增加（1.68 倍，p < 0.01）。在注射 CgAdipoR dsRNA 的牡蛎中，血细胞中抗凋亡 B 细胞淋巴瘤-2 (Bcl-2) 的 mRNA 表达在 LPS 攻击后 24 小时显着降低，是注射 dsEGFP 牡蛎的（0.58 倍，p < 0.05），而血细胞凋亡率显着上调（dsEGFP组的1.93倍，p < 0.05）。这些结果共同表明CgAdipoR通过调节炎性细胞因子的表达和血细胞凋亡在牡蛎的免疫反应中发挥重要作用。