Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
Fish Shellfish Immunol. 2012 Aug;33(2):286-93. doi: 10.1016/j.fsi.2012.05.011. Epub 2012 May 18.
Iodothyronine deiodinase is responsible for the deiodination of thyroxine T4 to T3, and involved in the complex neuroendocrine-immune regulatory network to optimize the immune response in vertebrate. In this study, the full-length cDNA of an iodothyronine deiodinase (designated as CfDx) was cloned from scallop Chlamys farreri. The complete cDNA sequence of CfDx was of 1404 bp and contained an open reading frame of 900 bp encoding a polypeptide of 299 amino acids. The deduced amino acid sequence of CfDx contained an in-frame TGA stop codon probably encoding an essential selenocysteine (SeC), and there was a conserved region of about 15 amino acids surrounding the SeC residue. The CfDx mRNA transcripts were detected in all the tested tissues, including haemocytes, hepatopancreas, kidney, adductor muscle, gonad, gill and mantle, with the higher expression level in hepatopancreas and kidney. After LPS stimulation, the CfDx mRNA expression level in haemocytes increased significantly at 12 h (25.35-fold, P < 0.05) and 24 h (7.62-fold, P < 0.05), and the concentration of T3 in haemolymph increased significantly at 12 h (3.62 ng dL(-1), P < 0.05) even the concentration of T4 did not change significantly. After scallop received an injection of 50 μg CfDx dsRNA, the expression level of CfDx mRNA in haemocytes began to decrease significantly at 36 h and maintained the relative low level (about 0.3-fold of the PBS control group) from 36 to72 h, but the ratio of T4/T3 in haemolymph began to increase at 36 h (2.31-fold, P < 0.05) and kept increasing from 36 to 72 h comparing with that in the PBS control group. These results indicated that CfDx was a homologue of iodothyronine deiodinase in scallop C. farreri, and it might be involved in the immunomodulation via regulating the concentration of thyroid hormones T3 and T4 in the haemolymph of scallop.
甲状腺素脱碘酶负责将甲状腺素 T4 脱碘为 T3，并参与脊椎动物复杂的神经内分泌-免疫调节网络，以优化免疫反应。在这项研究中，从扇贝 Chlamys farreri 中克隆了甲状腺素脱碘酶（命名为 CfDx）的全长 cDNA。CfDx 的完整 cDNA 序列为 1404 bp，包含一个 900 bp 的开放阅读框，编码一个 299 个氨基酸的多肽。CfDx 的推导氨基酸序列包含一个框架内的 TGA 终止密码子，可能编码一个必需的硒代半胱氨酸（SeC），并且在 SeC 残基周围有一个约 15 个氨基酸的保守区域。CfDx mRNA 转录本在所有测试的组织中均有检测到，包括血细胞、肝胰腺、肾脏、闭壳肌、性腺、鳃和套膜，在肝胰腺和肾脏中的表达水平较高。在 LPS 刺激后，血细胞中 CfDx mRNA 的表达水平在 12 h（25.35 倍，P < 0.05）和 24 h（7.62 倍，P < 0.05）显著增加，并且在 12 h 时血液中 T3 的浓度显著增加（3.62 ng dL(-1)，P < 0.05），即使 T4 的浓度没有显著变化。在扇贝接受 50 μg CfDx dsRNA 注射后，血细胞中 CfDx mRNA 的表达水平在 36 h 时开始显著下降，并且从 36 到 72 h 保持相对较低的水平（约为 PBS 对照组的 0.3 倍），但血液中 T4/T3 的比例在 36 h 时开始增加（2.31 倍，P < 0.05），并且从 36 到 72 h 与 PBS 对照组相比持续增加。这些结果表明，CfDx 是扇贝 C. farreri 中甲状腺素脱碘酶的同源物，它可能通过调节扇贝血液中甲状腺激素 T3 和 T4 的浓度参与免疫调节。
