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Shi C, Jin Z, Yu Y, Tang Z, Zhang Y, Qu C, Lin TH. Identification and characterization of a TLR4 homologue in Eriocheir sinensis based on structure analysis. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 157:105192. [PMID: 38714270 DOI: 10.1016/j.dci.2024.105192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 05/03/2024] [Accepted: 05/05/2024] [Indexed: 05/09/2024]
Abstract
Toll-like receptor 4 (TLR4) plays an essential role in the activation of innate immunity by recognizing diverse pathogenic components of bacteria. Six Tolls were found in Eriocheir sinensis but have not yet been identified as mammalian TLR4 homolog. For this purpose, we predicted three-dimensional (3D) structures of EsTolls (EsToll1-6) with AlphaFold2. 3D structure of LRRs and TIR most had high accuracy (pLDDT >70). By structure analysis, 3D structures of EsToll6 had a high overlap with HsTLR4. Moreover, we also predicted potential 11 hydrogen bonds and 3 salt bridges in the 3D structure of EsToll6-EsML1 complex. 18 hydrogen bonds and 7 salt bridges were predicted in EsToll6-EsML2 complex. Co-immunoprecipitation assay showed that EsToll6 could interact with EsML1 and EsML2, respectively. Importantly, TAK242 (a mammalian TLR4-specific inhibitor) could inhibit the generation of ROS stimulated by lipopolysaccharides (LPS) in EsToll6-EsML2-overexpression Hela cells. Collectively, these results implied that EsToll6 was a mammalian TLR4 homolog and provided a new insight for researching mammalian homologs in invertebrates.
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Affiliation(s)
- Chenchen Shi
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361102, China
| | - Zhixin Jin
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Yanping Yu
- Fujian Provincial Key Laboratory of Functional and Clinical Translational Medicine, Xiamen Medical College, Xiamen, Fujian, 361023, China; Department of Basic Medical Science, Xiamen Medical College, Xiamen, Fujian, 361023, China
| | - Zhuyun Tang
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Yuguo Zhang
- Fujian Provincial Key Laboratory of Functional and Clinical Translational Medicine, Xiamen Medical College, Xiamen, Fujian, 361023, China; Department of Basic Medical Science, Xiamen Medical College, Xiamen, Fujian, 361023, China
| | - Chen Qu
- Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China.
| | - Ta-Hui Lin
- Fujian Provincial Key Laboratory of Functional and Clinical Translational Medicine, Xiamen Medical College, Xiamen, Fujian, 361023, China; State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, 361102, China; Department of Basic Medical Science, Xiamen Medical College, Xiamen, Fujian, 361023, China.
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Zhang XL, Shen GQ, Zhang XN, Zhao YH, Li WW, Wang Q. Immune functions of the Dscam extracellular variable region in Chinese mitten crab. FISH & SHELLFISH IMMUNOLOGY 2023; 138:108850. [PMID: 37244319 DOI: 10.1016/j.fsi.2023.108850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 05/29/2023]
Abstract
In arthropods, there is only a single copy of Down Syndrome Cell Adhesion Molecule (Dscam) in the genome, but it can exist as numerous splice variants. There are three hypervariable exons in the extracellular domain and one hypervariable exon in the transmembrane domain. In Chinese mitten crab (Eriocheir sinensis), exons 4, 6 and 14 can produce 25, 34 and 18 alternative splice variants, respectively. In this study, through Illumina sequencing, we identified additional splice variants for exons 6 and 14, hence there may be > 50,000 Dscam protein variants. Sequencing of exons 4, 6 and 14 showed that alternative splicing was altered after bacterial stimulation. Therefore, we expressed and purified the extracellular variable region of Dscam (EsDscam-Ig1-Ig7). Exons 4.3, 6.46 and 14.18, three variable exons of the recombinant protein, were randomly selected. The functions of EsDscam-Ig1-Ig7 in immune defences of E. sinensis were subsequently explored. EsDscam-Ig1-Ig7 was discovered to bind to both Gram-positive Staphylococcus aureus and Gram-negative Vibrio parahaemolyticus, but it did not exhibit antibacterial activity. By promoting hemocyte phagocytosis and bacterial removal, EsDscam-Ig1-Ig7 can also shield the host from bacterial infection. The findings highlight the immunological activities of Dscam alternative splicing and reveal the potential for many more Dscam isoforms than were previously predicted in E. sinensis.
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Affiliation(s)
- Xiao-Li Zhang
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Guo-Qing Shen
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Xiao-Na Zhang
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Yue-Hong Zhao
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Wei-Wei Li
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China.
| | - Qun Wang
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China.
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Zhang X, Zhang X, Zong S, Shen G, Zhao Y, Li W, Wang Q. The extracellular non-variable region of Dscam promotes bacterial clearance by promoting phagocytosis of hemocytes in Eriocheir sinensis. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2023; 138:104541. [PMID: 36108933 DOI: 10.1016/j.dci.2022.104541] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/07/2022] [Accepted: 09/07/2022] [Indexed: 06/15/2023]
Abstract
As the most typical example of mRNA variable splicing, Down Syndrome Cell Adhesion Molecule (Dscam) can produce a large number of mRNA isomers. It plays an important role not only in the nervous system, but also in the immune system. In Eriocheir sinensis, the extracellular region of Dscam has three variable domains, which can produce 25, 34 and 18 exons and encode the N-terminal region of immunoglobulin (Ig) 2 and Ig3 domains, and the entire Ig7 domain, respectively. In addition to three variable domains, the extracellular non-variable region of Dscam also includes many Ig domains and fibronectin type III (FNIII) domains. However, the role of the extracellular non-variable region function of Dscam in the immune defense of E. sinensis is unclear. In this study, we focused on the role of the extracellular non-variable region of Dscam in crab immune defense. The results indicate that the extracellular non-variable region of Dscam can bind bacteria and has bacteriostatic function. At the same time, the extracellular non-variable region of Dscam can also directly promote bacterial clearance by promoting phagocytosis of hemocytes.
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Affiliation(s)
- Xiaoli Zhang
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Xiaona Zhang
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Shibo Zong
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Guoqing Shen
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Yuehong Zhao
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Weiwei Li
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China.
| | - Qun Wang
- Laboratory of Invertebrate Immunological Defense & Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China.
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Wang Y, Yang LG, Feng GP, Yao ZL, Li SH, Zhou JF, Fang WH, Chen YH, Li XC. PvML1 suppresses bacterial infection by recognizing LPS and regulating AMP expression in shrimp. Front Immunol 2022; 13:1088862. [PMID: 36643915 PMCID: PMC9832027 DOI: 10.3389/fimmu.2022.1088862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/06/2022] [Indexed: 12/29/2022] Open
Abstract
Toll and Toll-like receptors (TLRs) play essential roles in the innate immunity of Drosophila and mammals. Recent studies have revealed the presence of Toll-mediated immune signaling pathways in shrimp. However, the recognition and activation mechanism of Toll signaling pathways in crustaceans remain poorly understood due to the absence of key recognition molecules, such as peptidoglycan recognition proteins. Here, a novel MD2-related lipid-recognition (ML) member named PvML1 was characterized in Penaeus vannamei. We found that PvML1 shared a similar 3D structure with human MD2 that could specifically recognize lipopolysaccharides (LPS) participating in LPS-mediated TLR4 signaling. PvML1 was highly expressed in hemocytes and remarkably upregulated after Vibrio parahemolyticus challenge. Furthermore, the binding and agglutinating assays showed that PvML1 possessed strong binding activities to LPS and its key portion lipid A as well as Vibrio cells, and the binding of PvML1 with bacterial cells led to the agglutination of bacteria, suggesting PvML1 may act as a potential pathogen recognition protein upon interaction with LPS. Besides, coating V. parahemolyticus with recombinant PvML1 promoted bacterial clearance in vivo and increased the survival rate of bacterium-challenged shrimp. This result was further confirmed by RNAi experiments. The knockdown of PvML1 remarkably suppressed the clearance of bacteria in hemolymph and decreased the survival rate of infected shrimp. Meanwhile, the silencing of PvML1 severely impaired the expression of a few antimicrobial peptides (AMPs). These results demonstrated the significant correlation of bacterial clearance mediated by PvML1 with the AMP expression. Interestingly, we found that PvML1 interacted with the extracellular region of PvToll2, which had been previously shown to participate in bacterial clearance by regulating AMP expression. Taken together, the proposed antibacterial model mediated by PvML1 might be described as follows. PvML1 acted as a potential recognition receptor for Gram-negative bacteria by binding to LPS, and then it activated PvToll2-mediated signaling pathway by interacting with PvToll2 to eliminate invading bacteria through producing specific AMPs. This study provided new insights into the recognition and activation mechanism of Toll signaling pathways of invertebrates and the defense functions of ML members.
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Affiliation(s)
- Yue Wang
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China,Laboratory of Marine Biological Resources and Molecular Engineering, Marine Science and Technology College, Zhejiang Ocean University, Zhoushan, China
| | - Li-Guo Yang
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Guang-Peng Feng
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Zong-Li Yao
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Shou-Hu Li
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Jun-Fang Zhou
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Wen-Hong Fang
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China
| | - Yi-Hong Chen
- Key Laboratory for Healthy and Safe Aquaculture, Institute of Modern Aquaculture Science and Engineering (IMASE), College of Life Science, South China Normal University, Guangzhou, China,Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China,*Correspondence: Yi-Hong Chen, ; Xin-Cang Li,
| | - Xin-Cang Li
- Key Laboratory of Inland Saline-alkaline Aquaculture, Ministry of Agriculture and Rural Affairs, Shanghai, China,East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, China,*Correspondence: Yi-Hong Chen, ; Xin-Cang Li,
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Qin Y, Luo Z, Zhao K, Nan X, Guo Y, Li W, Wang Q. A new SVWC protein functions as a pattern recognition protein in antibacterial responses in Chinese mitten crab (Eriocheirsinensis). FISH & SHELLFISH IMMUNOLOGY 2022; 131:1125-1135. [PMID: 36402266 DOI: 10.1016/j.fsi.2022.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/01/2022] [Accepted: 11/04/2022] [Indexed: 06/16/2023]
Abstract
Because invertebrates lack acquired immunity, they rely primarily on the innate immune system to defend themselves against viral and bacterial infections. SVWC, also called Vago, is a class of small-molecule proteins characterized by a single von Willebrand factor C-domain and appears to be restricted to arthropods. It has been reported that SVWC is involved in antiviral immunity in invertebrates, but whether it is involved in antimicrobial immunity and the mechanism of its involvement in antimicrobial immunity remains unclear. In this study, we identified a novel SVWC gene in Eriocheir sinensis and named it EsSVWC. EsSVWC was found to respond positively to bacterial stimulation and to regulate the expression of related antimicrobial peptides (AMPs). The EsSVWC protein recognized and bound to a variety of pathogen-associated molecular patterns (PAMPs) but did not exhibit direct bactericidal effects. Thus, the EsSVWC protein in crabs helps resist bacterial infection and improve survival rates. In summary, EsSVWC may regulate the innate immune system of crabs in response to microbial invasion in an indirect manner.
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Affiliation(s)
- Yukai Qin
- Laboratory of Invertebrate Immunological Defense and Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Zhi Luo
- Laboratory of Invertebrate Immunological Defense and Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Ke Zhao
- Laboratory of Invertebrate Immunological Defense and Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Xingyu Nan
- Laboratory of Invertebrate Immunological Defense and Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Yanan Guo
- Laboratory of Invertebrate Immunological Defense and Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China
| | - Weiwei Li
- Laboratory of Invertebrate Immunological Defense and Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China.
| | - Qun Wang
- Laboratory of Invertebrate Immunological Defense and Reproductive Biology, School of Life Sciences, East China Normal University, Shanghai, China.
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