Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, Dalian, 116023, China.
Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, Dalian, 116023, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Dalian Key Laboratory of Aquatic Animal Diseases Prevention and Control, Dalian Ocean University, Dalian, 116023, China.
Fish Shellfish Immunol. 2020 Apr;99:594-602. doi: 10.1016/j.fsi.2020.02.038. Epub 2020 Feb 25.
The programmed cell death protein 4 (PDCD4) is a newly defined transcriptional and translational inhibitor, which plays a key role in regulating the synthesis of inflammatory cytokines in vertebrates species. In the present study, the full-length cDNA of PDCD4 from oyster Crassostrea gigas (designed as CgPDCD4) was identified to explore its possible involvement in immune response. The open reading frame of pdcd4 gene was of 1344 bp encoding a polypeptide of 447 amino acids with two conserved MA-3 domains. The deduced amino acid sequence of CgPDCD4 shared 60.18% similarity with PDCD4 from Mizuhopecten yessoensis. The mRNA transcripts of CgPDCD4 could be detected in all the tested tissues with a higher expression level in adductor muscle and hemocytes. The mRNA expression of CgPDCD4 in hemocytes was significantly down-regulated at 3 h and 6 h (0.61-fold and 0.42-fold of that in PBS group, p < 0.01, respectively) after LPS stimulation. In hemocytes, CgPDCD4 protein was found to be mainly located in the cytoplasm. After the mRNA expression of CgPDCD4 in hemocytes was knocked down (0.40-fold of that in EGFP-RNAi group) by CgPDCD4 dsRNA (dsCgPDCD4) injection, the CgIL17-5 transcripts were up-regulated (20.11-fold of that in PBS group, p < 0.01) post LPS stimulation, which was significantly higher than that in dsEGFP-injected oysters (7.06-fold of that in PBS group, p < 0.01). Meanwhile, the nuclear translocation of CgRel (homologue of Rel/NF-κB) was significantly enhanced (about 1.36-fold of that in PBS group, p < 0.01), but it was similar as that in EGFP-RNAi group (about 1.52-fold of that in PBS group, p < 0.01) after LPS stimulation. All the results suggested that CgPDCD4 in oysters played the same role as PDCD4 of vertebrates in negatively regulating the production of interleukin in immune response, but the underpinning signal pathway was not conserved during evolution.
程序性细胞死亡蛋白 4（PDCD4）是一种新定义的转录和翻译抑制剂，在脊椎动物物种中，它在调节炎症细胞因子的合成中起着关键作用。本研究从牡蛎（Crassostrea gigas）中鉴定出 PDCD4 的全长 cDNA（命名为 CgPDCD4），以探讨其在免疫反应中的可能作用。pdcd4 基因的开放阅读框长 1344bp，编码一个 447 个氨基酸的多肽，含有两个保守的 MA-3 结构域。CgPDCD4 的推导氨基酸序列与来自日本真牡蛎（Mizuhopecten yessoensis）的 PDCD4 具有 60.18%的相似性。CgPDCD4 的 mRNA 转录本可在所有测试组织中检测到，在肌肉和血细胞中表达水平较高。LPS 刺激后 3h 和 6h，血细胞中 CgPDCD4 的 mRNA 表达水平显著下调（分别为 PBS 组的 0.61 倍和 0.42 倍，p<0.01）。在血细胞中，CgPDCD4 蛋白主要位于细胞质中。用 CgPDCD4 dsRNA（dsCgPDCD4）注射敲低血细胞中 CgPDCD4 的 mRNA 表达（dsCgPDCD4 组为 EGFP-RNAi 组的 0.40 倍）后，LPS 刺激后 CgIL17-5 转录本上调（PBS 组的 20.11 倍，p<0.01），显著高于 dsEGFP 注射牡蛎（PBS 组的 7.06 倍，p<0.01）。同时，CgRel（Rel/NF-κB 同源物）的核转位明显增强（PBS 组约 1.36 倍，p<0.01），但与 EGFP-RNAi 组相似（PBS 组约 1.52 倍，p<0.01）。所有结果表明，牡蛎中的 CgPDCD4 在负调控免疫反应中白细胞介素的产生方面发挥着与脊椎动物 PDCD4 相同的作用，但在进化过程中信号通路并不保守。
