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He L, Liang Y, Yu X, Zhao Y, Zou Z, Dai Q, Wu J, Gan S, Lin H, Zhang Y, Lu D. UNC93B1 facilitates the localization and signaling of TLR5M in Epinephelus coioides. Int J Biol Macromol 2024; 258:128729. [PMID: 38086430 DOI: 10.1016/j.ijbiomac.2023.128729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 11/02/2023] [Accepted: 12/08/2023] [Indexed: 12/29/2023]
Abstract
Toll-like receptor 5 (TLR5), serving as a sensor of bacterial flagellin, mediates the innate immune response to actively engage in the host's immune processes against pathogen invasion. However, the mechanism underlying TLR5-mediated immune response in fish remains unclear. Despite the presumed cell surface expression of TLR5 member form (TLR5M), its trafficking dynamics remain elusive. Here, we have identified Epinephelus coioides TLR5M as a crucial mediator of Vibrio flagellin-induced cytokine expression in grouper cells. EcTLR5M facilitated the activation of NF-κB signaling pathway in response to flagellin stimulation and exerted a modest influence on the mitogen-activated protein kinase (MAPK)-extracellular regulated kinase (ERK) signaling. The trafficking chaperone Unc-93 homolog B1 (EcUNC93B1) participated in EcTLR5M-mediated NF-κB signaling activation and downstream cytokine expression. In addition, EcUNC93B1 combined with EcTLR5M to mediate its exit from the endoplasmic reticulum, and also affected its post-translational maturation. Collectively, these findings first discovered that EcTLR5M mediated the flagellin-induced cytokine expression primarily by regulating the NF-κB signaling pathway, and EcUNC93B1 mediated EcTLR5M function through regulating its trafficking and post-translational maturation. This research expanded the understanding of fish innate immunity and provided a novel concept for the advancement of anti-vibrio immunity technology.
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Affiliation(s)
- Liangge He
- State Key Laboratory of Biocontrol and School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Yaosi Liang
- State Key Laboratory of Biocontrol and School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Xue Yu
- State Key Laboratory of Biocontrol and School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Yulin Zhao
- State Key Laboratory of Biocontrol and School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Zhenjiang Zou
- State Key Laboratory of Biocontrol and School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Qinxi Dai
- State Key Laboratory of Biocontrol and School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Jinhui Wu
- Agro-Tech Extension Center of Guangdong Province, Guangzhou 510145, PR China
| | - Songyong Gan
- Agro-Tech Extension Center of Guangdong Province, Guangzhou 510145, PR China
| | - Haoran Lin
- State Key Laboratory of Biocontrol and School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, Sun Yat-Sen University, Guangzhou 510275, PR China; College of Ocean, Hainan University, Haikou 570228, PR China
| | - Yong Zhang
- State Key Laboratory of Biocontrol and School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, Sun Yat-Sen University, Guangzhou 510275, PR China; Guangdong South China Sea Key Laboratory of Aquaculture for Aquatic Economic Animals, Fisheries College, Guangdong Ocean University, Zhanjiang 524088, PR China
| | - Danqi Lu
- State Key Laboratory of Biocontrol and School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Provincial Key Laboratory for Aquatic Economic Animals, Guangdong Provincial Engineering Technology Research Center for Healthy Breeding of Important Economic Fish, Sun Yat-Sen University, Guangzhou 510275, PR China.
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2
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Kefi M, Konstantinos P, Balabanidou V, Sarafoglou C, Tsakireli D, Douris V, Monastirioti M, Maréchal JD, Feyereisen R, Vontas J. Insights into unique features of Drosophila CYP4G enzymes. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2024; 164:104041. [PMID: 38008364 DOI: 10.1016/j.ibmb.2023.104041] [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: 05/19/2023] [Revised: 11/12/2023] [Accepted: 11/19/2023] [Indexed: 11/28/2023]
Abstract
The cytochrome P450 enzymes of the CYP4G subfamily are some of the most intriguing insect P450s in terms of structure and function. In Drosophila, CYP4G1 is highly expressed in the oenocytes and is the last enzyme in the biosynthesis of cuticular hydrocarbons, while CYP4G15 is expressed in the brain and is of unknown function. Both proteins have a CYP4G-specific and characteristic amino acid sequence insertion corresponding to a loop between the G and H helices whose function is unclear. Here we address these enigmatic structural and functional features of Drosophila CYP4Gs. First, we used reverse genetics to generate D. melanogaster strains in which all or part of the CYP4G-specific loop was removed from CYP4G1. We showed that the full loop was not needed for proper folding of the P450, but it is essential for function, and that just a short stretch of six amino acids is required for the enzyme's ability to make hydrocarbons. Second, we confirmed by immunocytochemistry that CYP4G15 is expressed in the brain and showed that it is specifically associated with the cortex glia cell subtype. We then expressed CYP4G15 ectopically in oenocytes, revealing that it can produce of a blend of hydrocarbons, albeit to quantitatively lower levels resulting in only a partial rescue of CYP4G1 knockdown flies. The CYP4G1 structural variants studied here should facilitate the biochemical characterization of CYP4G enzymes. Our results also raise the question of the putative role of hydrocarbons and their synthesis by cortex glial cells.
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Affiliation(s)
- Mary Kefi
- Department of Biology, University of Crete, Vassilika Vouton, 70013, Heraklion, Greece; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira Street 100, 70013, Heraklion, Greece
| | - Parasyris Konstantinos
- Department of Biology, University of Crete, Vassilika Vouton, 70013, Heraklion, Greece; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira Street 100, 70013, Heraklion, Greece
| | - Vasileia Balabanidou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira Street 100, 70013, Heraklion, Greece
| | - Chara Sarafoglou
- Department of Biology, University of Crete, Vassilika Vouton, 70013, Heraklion, Greece; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira Street 100, 70013, Heraklion, Greece
| | - Dimitra Tsakireli
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira Street 100, 70013, Heraklion, Greece; Pesticide Science Laboratory, Department of Crop Science, Agricultural University of Athens, Greece
| | - Vassilis Douris
- Department of Biological Applications and Technology, University of Ioannina, 45110, Ioannina, Greece; Biomedical Research Institute (BRI), Foundation for Research and Technology (FORTH), University Campus, 451 10, Ioannina, Greece
| | - Maria Monastirioti
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira Street 100, 70013, Heraklion, Greece
| | - Jean-Didier Maréchal
- Departament de Química, Universitat Autònoma de Barcelona, Edifici C.n., Cerdanyola del Vallès, 08193, Barcelona, Spain
| | - René Feyereisen
- Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Belgium.
| | - John Vontas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira Street 100, 70013, Heraklion, Greece; Pesticide Science Laboratory, Department of Crop Science, Agricultural University of Athens, Greece.
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3
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Yang J, Rong SJ, Zhou HF, Yang C, Sun F, Li JY. Lysosomal control of dendritic cell function. J Leukoc Biol 2023; 114:518-531. [PMID: 37774493 DOI: 10.1093/jleuko/qiad117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 06/22/2023] [Accepted: 09/08/2023] [Indexed: 10/01/2023] Open
Abstract
Lysosomal compartments undergo extensive remodeling during dendritic cell (DC) activation to meet the dynamic functional requirements of DCs. Instead of being regarded as stationary and digestive organelles, recent studies have increasingly appreciated the versatile roles of lysosomes in regulating key aspects of DC biology. Lysosomes actively control DC motility by linking calcium efflux to the actomyosin contraction, while enhanced DC lysosomal membrane permeability contributes to the inflammasome activation. Besides, lysosomes provide a platform for the transduction of innate immune signaling and the intricate host-pathogen interplay. Lysosomes and lysosome-associated structures are also critically engaged in antigen presentation and cross-presentation processes, which are pivotal for the induction of antigen-specific adaptive immune response. Through the current review, we emphasize that lysosome targeting strategies serve as vital DC-based immunotherapies in fighting against tumor, infectious diseases, and autoinflammatory disorders.
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Affiliation(s)
- Jia Yang
- Department of Integrated Traditional Chinese and Western Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Avenue No.1277, 430000, Wuhan, China
| | - Shan-Jie Rong
- Department of Respiratory and Critical Care Medicine, Center for Biomedical Research, NHC Key Laboratory of Respiratory Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, Jiefang Avenue No.1095, 430000, Wuhan, China
| | - Hai-Feng Zhou
- Department of Integrated Traditional Chinese and Western Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Avenue No.1277, 430000, Wuhan, China
| | - Chao Yang
- Department of Gerontology, Hubei Provincial Hospital of Integrated Chinese and Western Medicine, Ling Jiaohu Road No.11, 430000, Wuhan, China
| | - Fei Sun
- Department of Respiratory and Critical Care Medicine, Center for Biomedical Research, NHC Key Laboratory of Respiratory Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, Jiefang Avenue No.1095, 430000, Wuhan, China
| | - Jun-Yi Li
- Department of Integrated Traditional Chinese and Western Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Avenue No.1277, 430000, Wuhan, China
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Nguyen TP, Nguyen BT, Dao TNL, Ho TH, Lee PT. Investigation of the functional role of UNC93B1 in Nile tilapia (Oreochromis niloticus): mRNA expression, subcellular localization, and physical interaction with fish-specific TLRs. FISH & SHELLFISH IMMUNOLOGY 2023; 139:108902. [PMID: 37330026 DOI: 10.1016/j.fsi.2023.108902] [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: 05/05/2023] [Revised: 06/13/2023] [Accepted: 06/15/2023] [Indexed: 06/19/2023]
Abstract
Nile tilapia (Oreochromis niloticus) is one of the major food fish worldwide. The farming business, on the other hand, has faced considerable obstacles, such as disease infestations. Toll-like receptors (TLRs) play an important function in the activation of the innate immune system in response to infections. Unc-93 homolog B1 (UNC93B1) is a key regulator of nucleic acid (NA)-sensing TLRs. Here the UNC93B1 gene, which was cloned from Nile tilapia tissue for this investigation, had the same genetic structure as a homologous gene in humans and mice. Phylogenetic analysis revealed that Nile tilapia UNC93B1 clustered with UNC93B1 from other species and separately from the UNC93A clade. The gene structure of the Nile tilapia UNC93B1 was found to be identical to that of human UNC93B1. Our gene expression studies revealed that Nile tilapia UNC93B1 was highly expressed in the spleen, followed by other immune-related tissues such as the head kidney, gills, and intestine. Moreover, Nile tilapia UNC93B1 mRNA transcripts were up-regulated in vivo in the head kidney and spleen tissues from poly I:C and Streptococcus agalactiae injected Nile tilapia, as well as in vitro in LPS stimulated Tilapia head kidney (THK) cells. The Nile tilapia UNC93B1-GFP protein signal was detected in the cytosol of THK cells and was co-localized with endoplasmic reticulum and lysosome but not with mitochondria. Moreover, the results of a co-immunoprecipitation and immunostaining analysis showed that Nile tilapia UNC93B1 can be pulled down with fish-specific TLRs such as TLR18 and TLR25 from Nile tilapia, and was found to be co-localized with these fish-specific TLRs in the THK cells. Overall, our findings highlight the potential role of UNC93B1 as an accessory protein in fish-specific TLR signaling.
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Affiliation(s)
- Tan Phat Nguyen
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan
| | - Bao Trung Nguyen
- College of Aquaculture and Fisheries, Can Tho University, Viet Nam
| | - Thi Ngoc Linh Dao
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan
| | - Thi Hang Ho
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan
| | - Po-Tsang Lee
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan.
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5
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Song HS, Park S, Huh JW, Lee YR, Jung DJ, Yang C, Kim SH, Kim HM, Kim YM. N-glycosylation of UNC93B1 at a Specific Asparagine Residue Is Required for TLR9 Signaling. Front Immunol 2022; 13:875083. [PMID: 35874766 PMCID: PMC9301129 DOI: 10.3389/fimmu.2022.875083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 05/27/2022] [Indexed: 11/29/2022] Open
Abstract
Toll-like receptors (TLRs) play critical roles in the first line of host defense against pathogens through recognition of pathogen-associated molecular patterns and initiation of the innate immune responses. The proper localization of TLRs in specific subcellular compartments is crucial for their ligand recognition and downstream signaling to ensure appropriate responses against pathogens while avoiding erroneous or excessive activation. Several TLRs, including TLR7 and TLR9 but not TLR4, depend on UNC93B1 for their proper intracellular localization and signaling. Accumulating evidence suggest that UNC93B1 differentially regulates its various client TLRs, but the specific mechanisms by which UNC93B1 controls individual TLRs are not well understood. Protein N-glycosylation is one of the most frequent and important post-translational modification that occurs in membrane-localized or secreted proteins. UNC93B1 was previously shown to be glycosylated at Asn251 and Asn272 residues. In this study, we investigated whether N-glycosylation of UNC93B1 affects its function by comparing wild type and glycosylation-defective mutant UNC93B1 proteins. It was found that glycosylation of Asn251 and Asn272 residues can occur independently of each other and mutation of neither N251Q or N272Q in UNC93B1 altered expression and localization of UNC93B1 and TLR9. In contrast, CpG DNA-stimulated TLR9 signaling was severely inhibited in cells expressing UNC93B1(N272Q), but not in cells with UNC93B1(N251Q). Further, it was found that glycosylation at Asn272 of UNC93B1 is essential for the recruitment of MyD88 to TLR9 and the subsequent downstream signaling. On the other hand, the defective glycosylation at Asn272 did not affect TLR7 signaling. Collectively, these data demonstrate that the glycosylation at a specific asparagine residue of UNC93B1 is required for TLR9 signaling and the glycosylation status of UNC93B1 differently affects activation of TLR7 and TLR9.
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Affiliation(s)
- Hyun-Sup Song
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Soeun Park
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Ji-Won Huh
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Yu-Ran Lee
- Division of Integrative Biosciences and Bioengineering, Pohang University of Science and Technology (POSTECH), Pohang, South Korea
| | - Da-Jung Jung
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Chorong Yang
- Division of Integrative Biosciences and Bioengineering, Pohang University of Science and Technology (POSTECH), Pohang, South Korea
| | - So Hyun Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
- Center for Biomolecular & Cellular Structure, Institute for Basic Science (IBS), Daejeon, South Korea
| | - Ho Min Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
- Center for Biomolecular & Cellular Structure, Institute for Basic Science (IBS), Daejeon, South Korea
| | - You-Me Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
- *Correspondence: You-Me Kim,
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6
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McElroy AN, Invernizzi R, Laskowska JW, O'Neill A, Doroudian M, Moghoofei M, Mostafaei S, Li F, Przybylski AA, O'Dwyer DN, Bowie AG, Fallon PG, Maher TM, Hogaboam CM, Molyneaux PL, Hirani N, Armstrong ME, Donnelly SC. Candidate Role for Toll-like Receptor 3 L412F Polymorphism and Infection in Acute Exacerbation of Idiopathic Pulmonary Fibrosis. Am J Respir Crit Care Med 2022; 205:550-562. [DOI: 10.1164/rccm.202010-3880oc] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
| | - Rachele Invernizzi
- Imperial College London, National Heart and Lung Institute, London, United Kingdom of Great Britain and Northern Ireland
| | - Joanna W. Laskowska
- Trinity College Dublin School of Medicine, 155276, Clinical Medicine, Dublin, Ireland
| | - Andrew O'Neill
- University of Dublin Trinity College, 8809, Medicine, Dublin, Ireland
| | | | - Mohsen Moghoofei
- Kermanshah University of Medical Sciences, 48464, Department of Microbiology, Faculty of Medicine, Kermanshah, Iran (the Islamic Republic of)
| | - Shayan Mostafaei
- Kermanshah University of Medical Sciences, 48464, Department of Biostatistics, Kermanshah, Iran (the Islamic Republic of)
| | - Feng Li
- University of Edinburgh MRC Centre for Inflammation Research, 47954, Edinburgh, United Kingdom of Great Britain and Northern Ireland
| | - Alexander A. Przybylski
- University of Edinburgh MRC Centre for Inflammation Research, 47954, Edinburgh, United Kingdom of Great Britain and Northern Ireland
| | - David N O'Dwyer
- University of Michigan Hospital, 166144, Internal Medicine, Ann Arbor, Michigan, United States
| | - Andrew G. Bowie
- University of Dublin Trinity College, 8809, School of Biochemistry and Immunology, Dublin 2, Ireland
| | | | - Toby M. Maher
- Imperial College London - Royal Brompton Campus, 152930, London, United Kingdom of Great Britain and Northern Ireland
| | - Cory M Hogaboam
- Cedars Sinai Medical Center, Department of Medicine, Los Angeles, California, United States
| | - Philip L Molyneaux
- Imperial College London, National Heart and Lung Institute, London, United Kingdom of Great Britain and Northern Ireland
| | - Nik Hirani
- The University of Edinburgh, 3124, Center for Inflammation Research, Edinburgh, United Kingdom of Great Britain and Northern Ireland
- NHS Lothian, 3129, Respiratory Medicine, Edinburgh, United Kingdom of Great Britain and Northern Ireland
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7
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Toll-Like Receptors: General Molecular and Structural Biology. J Immunol Res 2021; 2021:9914854. [PMID: 34195298 PMCID: PMC8181103 DOI: 10.1155/2021/9914854] [Citation(s) in RCA: 97] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 05/19/2021] [Indexed: 12/11/2022] Open
Abstract
Background/Aim Toll-like receptors (TLRs) are pivotal biomolecules in the immune system. Today, we are all aware of the importance of TLRs in bridging innate and adaptive immune system to each other. The TLRs are activated through binding to damage/danger-associated molecular patterns (DAMPs), microbial/microbe-associated molecular patterns (MAMPs), pathogen-associated molecular patterns (PAMPs), and xenobiotic-associated molecular patterns (XAMPs). The immunogenetic molecules of TLRs have their own functions, structures, coreceptors, and ligands which make them unique. These properties of TLRs give us an opportunity to find out how we can employ this knowledge for ligand-drug discovery strategies to control TLRs functions and contribution, signaling pathways, and indirect activities. Hence, the authors of this paper have a deep observation on the molecular and structural biology of human TLRs (hTLRs). Methods and Materials To prepare this paper and fulfill our goals, different search engines (e.g., GOOGLE SCHOLAR), Databases (e.g., MEDLINE), and websites (e.g., SCOPUS) were recruited to search and find effective papers and investigations. To reach this purpose, we tried with papers published in the English language with no limitation in time. The iCite bibliometrics was exploited to check the quality of the collected publications. Results Each TLR molecule has its own molecular and structural biology, coreceptor(s), and abilities which make them unique or a complementary portion of the others. These immunogenetic molecules have remarkable roles and are much more important in different sections of immune and nonimmune systems rather than that we understand to date. Conclusion TLRs are suitable targets for ligand-drug discovery strategies to establish new therapeutics in the fields of infectious and autoimmune diseases, cancers, and other inflammatory diseases and disorders.
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9
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Cryo-EM structures of Toll-like receptors in complex with UNC93B1. Nat Struct Mol Biol 2021; 28:173-180. [PMID: 33432245 DOI: 10.1038/s41594-020-00542-w] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 11/19/2020] [Indexed: 11/09/2022]
Abstract
Nucleic acid-sensing Toll-like receptors (TLRs) play a pivotal role in innate immunity by recognizing foreign DNA and RNA. Compartmentalization of these TLRs in the endosome limits their activation by self-derived nucleic acids and reduces the possibility of autoimmune reactions. Although chaperone Unc-93 homolog B1, TLR signaling regulator (UNC93B1) is indispensable for the trafficking of TLRs from the endoplasmic reticulum to the endosome, mechanisms of UNC93B1-mediated TLR regulation remain largely unknown. Here, we report two cryo-EM structures of human and mouse TLR3-UNC93B1 complexes and a human TLR7-UNC93B1 complex. UNC93B1 exhibits structural similarity to the major facilitator superfamily transporters. Both TLRs interact with the UNC93B1 amino-terminal six-helix bundle through their transmembrane and luminal juxtamembrane regions, but the complexes of TLR3 and TLR7 with UNC93B1 differ in their oligomerization state. The structural information provided here should aid in designing compounds to combat autoimmune diseases.
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10
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Kang W, Park A, Huh JW, You G, Jung DJ, Song M, Lee HK, Kim YM. Flagellin-Stimulated Production of Interferon-β Promotes Anti-Flagellin IgG2c and IgA Responses. Mol Cells 2020; 43:251-263. [PMID: 32131150 PMCID: PMC7103879 DOI: 10.14348/molcells.2020.2300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/25/2019] [Accepted: 12/30/2019] [Indexed: 12/14/2022] Open
Abstract
Flagellin, a major structural protein of the flagellum found in all motile bacteria, activates the TLR5- or NLRC4 inflammasomedependent signaling pathway to induce innate immune responses. Flagellin can also serve as a specific antigen for the adaptive immune system and stimulate anti-flagellin antibody responses. Failure to recognize commensal-derived flagellin in TLR5-deficient mice leads to the reduction in antiflagellin IgA antibodies at steady state and causes microbial dysbiosis and mucosal barrier breach by flagellated bacteria to promote chronic intestinal inflammation. Despite the important role of anti-flagellin antibodies in maintaining the intestinal homeostasis, regulatory mechanisms underlying the flagellin-specific antibody responses are not well understood. In this study, we show that flagellin induces interferon-β (IFN-β) production and subsequently activates type I IFN receptor signaling in a TLR5- and MyD88-dependent manner in vitro and in vivo . Internalization of TLR5 from the plasma membrane to the acidic environment of endolysosomes was required for the production of IFN-β, but not for other proinflammatory cytokines. In addition, we found that antiflagellin IgG2c and IgA responses were severely impaired in interferon-alpha receptor 1 (IFNAR1)-deficient mice, suggesting that IFN-β produced by the flagellin stimulation regulates anti-flagellin antibody class switching. Our findings shed a new light on the regulation of flagellin-mediated immune activation and may help find new strategies to promote the intestinal health and develop mucosal vaccines.
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Affiliation(s)
- Wondae Kang
- Division of Integrative Biosciences & Biotechnology, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Areum Park
- Division of Integrative Biosciences & Biotechnology, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Ji-Won Huh
- Division of Integrative Biosciences & Biotechnology, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Gihoon You
- Division of Integrative Biosciences & Biotechnology, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Da-Jung Jung
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Manki Song
- International Vaccine Institute, Seoul 08826, Korea
| | - Heung Kyu Lee
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - You-Me Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
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11
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Parekh NJ, Krouse TE, Reider IE, Hobbs RP, Ward BM, Norbury CC. Type I interferon-dependent CCL4 is induced by a cGAS/STING pathway that bypasses viral inhibition and protects infected tissue, independent of viral burden. PLoS Pathog 2019; 15:e1007778. [PMID: 31603920 PMCID: PMC6808495 DOI: 10.1371/journal.ppat.1007778] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 10/23/2019] [Accepted: 09/16/2019] [Indexed: 11/18/2022] Open
Abstract
Type I interferons (T1-IFN) are critical in the innate immune response, acting upon infected and uninfected cells to initiate an antiviral state by expressing genes that inhibit multiple stages of the lifecycle of many viruses. T1-IFN triggers the production of Interferon-Stimulated Genes (ISGs), activating an antiviral program that reduces virus replication. The importance of the T1-IFN response is highlighted by the evolution of viral evasion strategies to inhibit the production or action of T1-IFN in virus-infected cells. T1-IFN is produced via activation of pathogen sensors within infected cells, a process that is targeted by virus-encoded immunomodulatory molecules. This is probably best exemplified by the prototypic poxvirus, Vaccinia virus (VACV), which uses at least 6 different mechanisms to completely block the production of T1-IFN within infected cells in vitro. Yet, mice lacking aspects of T1-IFN signaling are often more susceptible to infection with many viruses, including VACV, than wild-type mice. How can these opposing findings be rationalized? The cytosolic DNA sensor cGAS has been implicated in immunity to VACV, but has yet to be linked to the production of T1-IFN in response to VACV infection. Indeed, there are two VACV-encoded proteins that effectively prevent cGAS-mediated activation of T1-IFN. We find that the majority of VACV-infected cells in vivo do not produce T1-IFN, but that a small subset of VACV-infected cells in vivo utilize cGAS to sense VACV and produce T1-IFN to protect infected mice. The protective effect of T1-IFN is not mediated via ISG-mediated control of virus replication. Rather, T1-IFN drives increased expression of CCL4, which recruits inflammatory monocytes that constrain the VACV lesion in a virus replication-independent manner by limiting spread within the tissue. Our findings have broad implications in our understanding of pathogen detection and viral evasion in vivo, and highlight a novel immune strategy to protect infected tissue.
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Affiliation(s)
- Nikhil J. Parekh
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Tracy E. Krouse
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Irene E. Reider
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Ryan P. Hobbs
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
- Department of Dermatology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Brian M. Ward
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Christopher C. Norbury
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
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12
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Zhao J, Xue Y, Pan Y, Yao A, Wang G, Li D, Wang T, Zhao S, Hou Y. Toll-like receptor 3 agonist poly I:C reinforces the potency of cytotoxic chemotherapy via the TLR3-UNC93B1-IFN-β signaling axis in paclitaxel-resistant colon cancer. J Cell Physiol 2018; 234:7051-7061. [PMID: 30387134 DOI: 10.1002/jcp.27459] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Accepted: 08/29/2018] [Indexed: 12/19/2022]
Abstract
Type I interferon (IFN) signaling in neoplastic cells has a chemo-sensitizing effect in cancer therapy. Toll-like receptor 3 (TLR3) activation promotes IFN-β production, which induces apoptosis and impairs proliferation in some cancer cells. Herein, we tested whether the TLR3 agonist polyinosinic: polycytidylic acid (poly I:C) can improve chemotherapeutic efficacy in paclitaxel (PTX) resistant cell lines. Human colon cancer cell lines HCT116, SW620, HCT-8 (sensitive to PTX), and HCT-8/PTX (resistant to PTX) were treated with poly I:C and the cell viability was measured. Results showed that poly I:C specifically impaired the cell viability of HCT-8/PTX by simultaneously promoting cell apoptosis and inhibiting cell proliferation. In addition, when TLR3 was overexpressed in HCT-8/PTX cells, we found that TLR3 contributed to the production of IFN-β that reduced cell viability, and poly I:C preferentially activated the TLR3-UNC93B1 signaling pathway to mediate this effect. Moreover, cotreatment of poly I:C and PTX acted synergistically to induce cell apoptosis of HCT-8/PTX via upregulating the expression of TLR3 and its molecular chaperone UNC93B1, assisting in the secretion of IFN-β. Notably, a combination of poly I:C and PTX synergistically inhibited the PTX-resistant tumor growth in vivo without side effects. In conclusion, our studies demonstrate that poly I:C reinforces the potency of cytotoxic chemotherapeutics in PTX-resistant cell line through the TLR3-UNC93B1-IFN-β signaling pathway, which supplies a novel mechanism of poly I:C for the chemotherapy sensitizing effect in a PTX-resistant tumor.
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Affiliation(s)
- Jiaojiao Zhao
- Division of Immunology, The State Key Laboratory of Pharmaceutical Biotechnology, Medical School, Nanjing University, Nanjing, China
| | - Yaxian Xue
- Division of Immunology, The State Key Laboratory of Pharmaceutical Biotechnology, Medical School, Nanjing University, Nanjing, China
| | - Yuchen Pan
- Division of Immunology, The State Key Laboratory of Pharmaceutical Biotechnology, Medical School, Nanjing University, Nanjing, China
| | - Anran Yao
- Division of Immunology, The State Key Laboratory of Pharmaceutical Biotechnology, Medical School, Nanjing University, Nanjing, China
| | - Guoqun Wang
- Department of Oncology, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Dan Li
- Division of Immunology, The State Key Laboratory of Pharmaceutical Biotechnology, Medical School, Nanjing University, Nanjing, China
| | - Tingting Wang
- Division of Immunology, The State Key Laboratory of Pharmaceutical Biotechnology, Medical School, Nanjing University, Nanjing, China
| | - Shuli Zhao
- General Clinical Research Center, Nanjing First hospital, Nanjing Medical University, Nanjing, China
| | - Yayi Hou
- Division of Immunology, The State Key Laboratory of Pharmaceutical Biotechnology, Medical School, Nanjing University, Nanjing, China.,Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, China
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13
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Faber E, Tedin K, Speidel Y, Brinkmann MM, Josenhans C. Functional expression of TLR5 of different vertebrate species and diversification in intestinal pathogen recognition. Sci Rep 2018; 8:11287. [PMID: 30050158 PMCID: PMC6062626 DOI: 10.1038/s41598-018-29371-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 07/10/2018] [Indexed: 12/12/2022] Open
Abstract
Toll-like receptor 5 (TLR5) is activated by bacterial flagellins and plays a crucial role in the first-line defence against pathogenic bacteria and in immune homeostasis, and is highly conserved in vertebrate species. However, little comparative information is available on TLR5 functionality. In this study, we compared TLR5 activation using full-length and chimeric TLR5 of various vertebrate species (human, chicken, mouse, pig, cattle). Chimeric TLR5 receptors, consisting of human transmembrane and intracellular domains, linked to extracellular domains of animal origin, were generated and expressed. The comparison of chimeric TLR5s and their full-length counterparts revealed significant functional disparities. While porcine and chicken full-length TLR5s showed a strongly reduced functionality in human cells, all chimeric receptors were functional when challenged with TLR5 ligand Salmonella FliC. Using chimeric receptors as a tool allowed for the identification of ectodomain-dependent activation potential and partially host species-specific differences in response to various enteric bacterial strains and their purified flagellins. We conclude that both the extra- and intracellular determinants of TLR5 receptors are crucial for compatibility with the species expression background and hence for proper receptor functionality. TLR5 receptors with a common intracellular domain provide a useful system to investigate bacteria- and host-specific differences in receptor activation.
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Affiliation(s)
- Eugenia Faber
- Medizinische Hochschule Hannover, Institute for Medical Microbiology, Carl-Neuberg-Strasse 1, 30625, Hannover, Germany.,DZIF-German Center for Infection Research, Partner site Hannover-Braunschweig, Hannover, Germany
| | - Karsten Tedin
- Institute of Microbiology and Epizootics, Free University Berlin, Robert-von-Ostertag-Strasse 7-13, 14163, Berlin, Germany
| | - Yvonne Speidel
- Medizinische Hochschule Hannover, Institute for Medical Microbiology, Carl-Neuberg-Strasse 1, 30625, Hannover, Germany.,DZIF-German Center for Infection Research, Partner site Hannover-Braunschweig, Hannover, Germany
| | - Melanie M Brinkmann
- Helmholtz Center for Infection Research, Inhoffenstrasse 7, 38124, Braunschweig, Germany
| | - Christine Josenhans
- Medizinische Hochschule Hannover, Institute for Medical Microbiology, Carl-Neuberg-Strasse 1, 30625, Hannover, Germany. .,DZIF-German Center for Infection Research, Partner site Hannover-Braunschweig, Hannover, Germany. .,Max von Pettenkofer Institute, Ludwig Maximilians University Munich, Pettenkoferstrasse 9a, 80336, Munich, Germany.
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14
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Martínez-García EA, Zavala-Cerna MG, Lujano-Benítez AV, Sánchez-Hernández PE, Martín-Márquez BT, Sandoval-García F, Vázquez-Del Mercado M. Potential Chronotherapeutic Optimization of Antimalarials in Systemic Lupus Erythematosus: Is Toll-Like Receptor 9 Expression Dependent on the Circadian Cycle in Humans? Front Immunol 2018; 9:1497. [PMID: 30034390 PMCID: PMC6043638 DOI: 10.3389/fimmu.2018.01497] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 06/15/2018] [Indexed: 12/13/2022] Open
Abstract
Toll-like receptor 9 (TLR9) belongs to the group of endosomal receptors of the innate immune system with the ability to recognize hypomethylated CpG sequences from DNA. There is scarce information about TLR9 expression and its association with the circadian cycle (CC). Different patterns of TLR9 expression are regulated by the CC in mice, with an elevated expression at Zeitgeber time 19 (1:00 a.m.); nevertheless, we still need to corroborate this in humans. In systemic lupus erythematosus (SLE), the inhibitory effect of chloroquine (CQ) on TLR9 is limited. TLR9 activation has been associated with the presence of some autoantibodies: anti-Sm/RNP, anti-histone, anti-Ro, anti-La, and anti-double-stranded DNA. Treatment with CQ for SLE has been proven to be useful, in part by interfering with HLA-antigen coupling and with TLR9 ligand recognition. Studies have shown that TLR9 inhibitors such as antimalarial drugs are able to mask TLR9-binding sites on nucleic acids. The data presented here provide the basic information that could be useful for other clinical researchers to design studies that will have an impact in achieving a chronotherapeutic effect by defining the ideal time for CQ administration in SLE patients, consequently reducing the pathological effects that follow the activation of TLR9.
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Affiliation(s)
- Erika Aurora Martínez-García
- Instituto de Investigación en Reumatología y del Sistema Músculo Esquelético, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
- Departamento de Fisiología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
- UDG-CA-703, Inmunología y Reumatología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
| | - Maria Guadalupe Zavala-Cerna
- Immunology Research Laboratory, Programa Internacional de Medicina, Universidad Autonoma de Guadalajara, Guadalajara, Mexico
| | - Andrea Verónica Lujano-Benítez
- Instituto de Investigación en Reumatología y del Sistema Músculo Esquelético, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
| | - Pedro Ernesto Sánchez-Hernández
- Departamento de Fisiología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
- Laboratorio de Inmunología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
| | - Beatriz Teresita Martín-Márquez
- Instituto de Investigación en Reumatología y del Sistema Músculo Esquelético, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
- UDG-CA-703, Inmunología y Reumatología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
| | - Flavio Sandoval-García
- Instituto de Investigación en Reumatología y del Sistema Músculo Esquelético, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
- Departamento de Clínicas Médicas, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
- UDG CA-701, Inmunometabolismo en Enfermedades Emergentes (GIIEE), Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
| | - Mónica Vázquez-Del Mercado
- Instituto de Investigación en Reumatología y del Sistema Músculo Esquelético, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
- UDG-CA-703, Inmunología y Reumatología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Mexico
- Hospital Civil de Guadalajara “Juan I. Menchaca”, Servicio de Reumatología, Programa Nacional de Posgrados de Calidad (PNPC), Consejo Nacional de Ciencia y Tecnología (CONACYT), Guadalajara, Mexico
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15
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Liang Y, Wang Y, He L, He J, Peng W, Zhou L, Zhang Y, Zhang H, Shi H, Lin H, Lu D. Unc93b1 is essential for cytokine activation of five PAMPs in the orange-spotted grouper (Epinephelus coioides). DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 81:8-18. [PMID: 29097235 DOI: 10.1016/j.dci.2017.10.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/26/2017] [Accepted: 10/26/2017] [Indexed: 06/07/2023]
Abstract
Toll-like receptors (TLRs) are important innate immune receptors that recognize multiple pathogen-associated molecular patterns (PAMPs) and activate the immune responses to resist the invasion of pathogens. Many TLRs need assistance from trafficking chaperones to transport to the specific cell compartments and then are processed before they are activated. In this study, we identified an important trafficking chaperone, Unc-93 homolog B1 (unc93b1), from the Epinephelus coioides (orange-spotted grouper). The deduced protein sequence of Eco.unc93b1 was 632 amino acids, containing 12 transmembrane domains, consistent with other UNC93B1 proteins from other species. Phylogenetic analysis showed that Eco.Unc93b1 was clustered with teleost Unc93b1 and had the closest relationship with Larimichthys crocea (large yellow croaker) Unc93b1. Eco.unc93b1 was expressed the highest in the spleen, and its protein was co-localized with the endoplasmic reticulum and early endosomes in both human embryonic kidney 293T cells and grouper spleen cells (GS cells). Moreover, the stimulation of lipopolysaccharide (LPS), high-molecular-weight poly (I:C) (HMW), imidazoquinoline (R848), polyadenylic-polyuridylic acid (poly AU), and 19-mer Staphylococcus aureus 23S rRNA-derived oligoribonucleotide (ORN Sa 19) promoted the mRNA expression of unc93b1 in GS cells with different patterns. Furthermore, the cytokine expression induced by these PAMPs was suppressed, while Eco.unc93b1 was knocked down, by small interfering RNA. In conclusion, these results suggest that Eco.unc93b1 plays an essential role in several PAMP-induced immune responses.
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Affiliation(s)
- Yaosi Liang
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Yu Wang
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Sun Yat-Sen University, Guangzhou, China
| | - Liangge He
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Jianan He
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Wan Peng
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Libin Zhou
- School of Life Science, Huizhou University, Huizhou 516007, China
| | - Yong Zhang
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Haifa Zhang
- Marine Fisheries Development Center of Guangdong Province, Huizhou, China
| | - Herong Shi
- Marine Fisheries Development Center of Guangdong Province, Huizhou, China
| | - Haoran Lin
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China; South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Sun Yat-Sen University, Guangzhou, China.
| | - Danqi Lu
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China.
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16
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Abstract
Toll-like receptor 5 (TLR5) of mammals, birds, and reptiles detects bacterial flagellin and signals as a homodimeric complex. Structural studies using truncated TLR5b of zebrafish confirm the homodimeric TLR5-flagellin interaction. Here we provide evidence that zebrafish (Danio rerio) TLR5 unexpectedly signals as a heterodimer composed of the duplicated gene products drTLR5b and drTLR5a. Flagellin-induced signaling by the zebrafish TLR5 heterodimer increased in the presence of the TLR trafficking chaperone UNC93B1. Targeted exchange of drTLR5b and drTLR5a regions revealed that TLR5 activation needs a heterodimeric configuration of the receptor ectodomain and cytoplasmic domain, consistent with ligand-induced changes in receptor conformation. Structure-guided substitution of the presumed principal flagellin-binding site in human TLR5 with corresponding zebrafish TLR5 residues abrogated human TLR5 activation, indicating a species-specific TLR5-flagellin interaction. Our findings indicate that the duplicated TLR5 of zebrafish underwent subfunctionalization through concerted coevolution to form a unique heterodimeric flagellin receptor that operates fundamentally differently from TLR5 of other species.
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17
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Pelka K, Shibata T, Miyake K, Latz E. Nucleic acid-sensing TLRs and autoimmunity: novel insights from structural and cell biology. Immunol Rev 2016; 269:60-75. [PMID: 26683145 DOI: 10.1111/imr.12375] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Invasion of pathogenic microorganisms or tissue damage activates innate immune signaling receptors that sample subcellular locations for foreign molecular structures, altered host molecules, or signs of compartment breaches. Upon engagement of innate immune receptors an acute but transient inflammatory response is initiated, aimed at the clearance of pathogens and cellular debris. Among the molecules that are sensed are nucleic acids, which activate several members of the transmembrane Toll-like receptor (TLR) family. Inappropriate recognition of nucleic acids by TLRs can cause inflammatory pathologies and autoimmunity. Here, we review the mechanisms involved in triggering nucleic acid-sensing TLRs and indicate checkpoints that restrict their activation to endolysosomal compartments. These mechanisms are crucial to sample the content of endosomes for nucleic acids in the context of infection or tissue damage, yet prevent accidental activation by host nucleic acids under physiological conditions. Decoding the molecular mechanisms that regulate nucleic acid recognition by TLRs is central to understand pathologies linked to unrestricted nucleic acid sensing and to develop novel therapeutic strategies.
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Affiliation(s)
- Karin Pelka
- Institute of Innate Immunity, University Hospitals Bonn, Bonn, Germany
| | - Takuma Shibata
- Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.,Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo, Japan
| | - Kensuke Miyake
- Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Eicke Latz
- Institute of Innate Immunity, University Hospitals Bonn, Bonn, Germany.,German Center for Neurodegenerative Diseases, Bonn, Germany.,Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA
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18
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Leifer CA, Medvedev AE. Molecular mechanisms of regulation of Toll-like receptor signaling. J Leukoc Biol 2016; 100:927-941. [PMID: 27343013 DOI: 10.1189/jlb.2mr0316-117rr] [Citation(s) in RCA: 183] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 06/01/2016] [Indexed: 01/22/2023] Open
Abstract
TLRs play a critical role in the detection of microbes and endogenous "alarmins" to initiate host defense, yet they can also contribute to the development and progression of inflammatory and autoimmune diseases. To avoid pathogenic inflammation, TLR signaling is subject to multilayer regulatory control mechanisms, including cooperation with coreceptors, post-translational modifications, cleavage, cellular trafficking, and interactions with negative regulators. Nucleic acid-sensing TLRs are particularly interesting in this regard, as they can both recognize host-derived structures and require internalization of their ligand as a result of intracellular sequestration of the nucleic acid-sensing TLRs. This review summarizes the regulatory mechanisms of TLRs, including regulation of their access to ligands, receptor folding, intracellular trafficking, and post-translational modifications, as well as how altered control mechanism could contribute to inflammatory and autoimmune disorders.
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Affiliation(s)
- Cynthia A Leifer
- Department of Microbiology and Immunology, Cornell University, Ithaca, New York, USA; and
| | - Andrei E Medvedev
- Department of Immunology, University of Connecticut Heath Center, Farmington, Connecticut, USA
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19
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Sheng R, Jung DJ, Silkov A, Kim H, Singaram I, Wang ZG, Xin Y, Kim E, Park MJ, Thiagarajan-Rosenkranz P, Smrt S, Honig B, Baek K, Ryu S, Lorieau J, Kim YM, Cho W. Lipids Regulate Lck Protein Activity through Their Interactions with the Lck Src Homology 2 Domain. J Biol Chem 2016; 291:17639-50. [PMID: 27334919 DOI: 10.1074/jbc.m116.720284] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Indexed: 11/06/2022] Open
Abstract
Lymphocyte-specific protein-tyrosine kinase (Lck) plays an essential role in T cell receptor (TCR) signaling and T cell development, but its activation mechanism is not fully understood. To explore the possibility that plasma membrane (PM) lipids control TCR signaling activities of Lck, we measured the membrane binding properties of its regulatory Src homology 2 (SH2) and Src homology 3 domains. The Lck SH2 domain binds anionic PM lipids with high affinity but with low specificity. Electrostatic potential calculation, NMR analysis, and mutational studies identified the lipid-binding site of the Lck SH2 domain that includes surface-exposed basic, aromatic, and hydrophobic residues but not the phospho-Tyr binding pocket. Mutation of lipid binding residues greatly reduced the interaction of Lck with the ζ chain in the activated TCR signaling complex and its overall TCR signaling activities. These results suggest that PM lipids, including phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate, modulate interaction of Lck with its binding partners in the TCR signaling complex and its TCR signaling activities in a spatiotemporally specific manner via its SH2 domain.
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Affiliation(s)
- Ren Sheng
- From the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Da-Jung Jung
- the Division of Integrative Biosciences and Biotechnology and
| | - Antonina Silkov
- the Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York, New York 11032, and
| | - Hyunjin Kim
- From the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Indira Singaram
- From the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Zhi-Gang Wang
- From the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Yao Xin
- From the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Eui Kim
- the Division of Integrative Biosciences and Biotechnology and
| | - Mi-Jeong Park
- the Division of Integrative Biosciences and Biotechnology and
| | | | - Sean Smrt
- From the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Barry Honig
- the Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York, New York 11032, and
| | - Kwanghee Baek
- the Department of Genetic Engineering, Kyung Hee University, Yongin 446-701, Korea
| | - Sungho Ryu
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Justin Lorieau
- From the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | - You-Me Kim
- the Division of Integrative Biosciences and Biotechnology and Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea,
| | - Wonhwa Cho
- From the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, the Department of Genetic Engineering, Kyung Hee University, Yongin 446-701, Korea
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20
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SH2 Domains Serve as Lipid-Binding Modules for pTyr-Signaling Proteins. Mol Cell 2016; 62:7-20. [PMID: 27052731 DOI: 10.1016/j.molcel.2016.01.027] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 12/21/2015] [Accepted: 01/26/2016] [Indexed: 01/26/2023]
Abstract
The Src-homology 2 (SH2) domain is a protein interaction domain that directs myriad phosphotyrosine (pY)-signaling pathways. Genome-wide screening of human SH2 domains reveals that ∼90% of SH2 domains bind plasma membrane lipids and many have high phosphoinositide specificity. They bind lipids using surface cationic patches separate from pY-binding pockets, thus binding lipids and the pY motif independently. The patches form grooves for specific lipid headgroup recognition or flat surfaces for non-specific membrane binding and both types of interaction are important for cellular function and regulation of SH2 domain-containing proteins. Cellular studies with ZAP70 showed that multiple lipids bind its C-terminal SH2 domain in a spatiotemporally specific manner and thereby exert exquisite spatiotemporal control over its protein binding and signaling activities in T cells. Collectively, this study reveals how lipids control SH2 domain-mediated cellular protein-protein interaction networks and suggest a new strategy for therapeutic modulation of pY-signaling pathways.
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21
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Lee YR, Kang W, Kim YM. Detection of Interaction Between Toll-Like Receptors and Other Transmembrane Proteins by Co-immunoprecipitation Assay. Methods Mol Biol 2016; 1390:107-120. [PMID: 26803625 DOI: 10.1007/978-1-4939-3335-8_7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Toll-like receptors are type I membrane proteins and bind other membrane proteins often via a specific interaction between transmembrane domains. The co-immunoprecipitation assay is a widely used biochemical technique for assessing interactions among proteins in cell lysates or tissue extracts. By isolating a native protein complex with a specific antibody against a protein of interest, followed by western blotting with an antibody for a binding partner, the co-immunoprecipitation assay can be used to confirm a putative interaction between two proteins. The co-immunoprecipitation assay can also be combined with a proteomics approach such as protein mass spectrometry to build an interactome of a target protein. Despite its usefulness and popularity to probe protein interactions within complex biological samples, the co-immunoprecipitation assay of membrane proteins is rather tricky, often resulting in false data. Here, we describe a co-immunoprecipitation method for analyzing interactions between toll-like receptors and other membrane proteins, using the interaction between TLR9 and UNC93B1 as an example. Especially, we describe an optimal cell lysis and sample preparation method to preserve protein interactions mediated by transmembrane domains.
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Affiliation(s)
- Yu-Ran Lee
- Division of Integrative Biosciences and Biotechnologies, Department of Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea
| | - Wondae Kang
- Division of Integrative Biosciences and Biotechnologies, Department of Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea
| | - You-Me Kim
- Division of Integrative Biosciences and Biotechnologies, Department of Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea.
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22
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Tatematsu M, Funami K, Ishii N, Seya T, Obuse C, Matsumoto M. LRRC59 Regulates Trafficking of Nucleic Acid-Sensing TLRs from the Endoplasmic Reticulum via Association with UNC93B1. THE JOURNAL OF IMMUNOLOGY 2015; 195:4933-42. [PMID: 26466955 DOI: 10.4049/jimmunol.1501305] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 09/11/2015] [Indexed: 01/18/2023]
Abstract
Compartmentalization of nucleic acid (NA)-sensing TLR3, 7, 8, and 9 is strictly regulated to direct optimal response against microbial infection and evade recognition of host-derived NAs. Uncoordinated 93 homolog B1 (UNC93B1) is indispensable for trafficking of NA-sensing TLRs from the endoplasmic reticulum (ER) to endosomes/lysosomes. UNC93B1 controls loading of the TLRs into COPII vesicles to exit from the ER and traffics with the TLRs in the steady state. Ligand-induced translocation also happens on NA-sensing TLRs. However, the molecular mechanism for ligand-dependent trafficking of TLRs from the ER to endosomes/lysosomes remains unclear. In this study, we demonstrated that leucine-rich repeat containing protein (LRRC) 59, an ER membrane protein, participated in trafficking of NA-sensing TLRs from the ER. Knockdown of LRRC59 reduced TLR3-, 8-, and 9-mediated, but not TLR4-mediated, signaling. Upon ligand stimulation, LRRC59 associated with UNC93B1 in a TLR-independent manner, which required signals induced by ligand internalization. Endosomal localization of endogenous TLR3 was decreased by silencing of LRRC59, suggesting that LRRC59 promotes UNC93B1-mediated translocation of NA-sensing TLRs from the ER upon infection. These findings help us understand how NA-sensing TLRs control their proper distribution in the infection/inflammatory state.
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Affiliation(s)
- Megumi Tatematsu
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan; and
| | - Kenji Funami
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan; and
| | - Noriko Ishii
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan; and
| | - Tsukasa Seya
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan; and
| | - Chikashi Obuse
- Division of Molecular Life Science, Graduate School of Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Misako Matsumoto
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan; and
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23
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Yu S, Gao N. Compartmentalizing intestinal epithelial cell toll-like receptors for immune surveillance. Cell Mol Life Sci 2015; 72:3343-53. [PMID: 26001904 DOI: 10.1007/s00018-015-1931-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 05/13/2015] [Accepted: 05/18/2015] [Indexed: 02/08/2023]
Abstract
Toll-like receptors (TLRs) are membrane-bound microbial sensors that mediate important host-to-microbe responses. Cell biology aspects of TLR function have been intensively studied in professional immune cells, in particular the macrophages and dendritic cells, but not well explored in other specialized epithelial cell types. The adult intestinal epithelial cells are in close contact with trillions of enteric microbes and engage in lifelong immune surveillance. Mature intestinal epithelial cells, in contrast to immune cells, are highly polarized. Recent studies suggest that distinct mechanisms may govern TLR traffic and compartmentalization in these specialized epithelial cells to establish and maintain precise signaling of individual TLRs. We, using immune cells as references, discuss here the shared and/or unique molecular machineries used by intestinal epithelial cells to control TLR transport, localization, processing, activation, and signaling. A better understanding of these mechanisms will certainly generate important insights into both the mechanism and potential intervention of leading digestive disorders, in particular inflammatory bowel diseases.
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Affiliation(s)
- Shiyan Yu
- Department of Biological Sciences, Rutgers University, Room 206, 195 University Ave., Newark, NJ, 07102, USA
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24
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Lee PT, Zou J, Holland JW, Martin SAM, Scott CJW, Kanellos T, Secombes CJ. Functional characterisation of a TLR accessory protein, UNC93B1, in Atlantic salmon (Salmo salar). DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2015; 50:38-48. [PMID: 25576824 DOI: 10.1016/j.dci.2014.12.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 12/22/2014] [Accepted: 12/22/2014] [Indexed: 06/04/2023]
Abstract
Toll-like receptors (TLRs) are indispensable components of the innate immune system, which recognise conserved pathogen associated molecular patterns (PAMPs) and induce a series of defensive immune responses to protect the host. Biosynthesis, localisation and activation of TLRs are dependent on TLR accessory proteins. In this study, we identified the accessory protein, UNC93B1, from Atlantic salmon (Salmo salar) whole-genome shotgun (WGS) contigs aided by the conserved gene synteny of genes flanking UNC93B1 in fish, birds and mammals. Phylogenetic analysis showed that salmon UNC93B1 grouped with other vertebrate UNC93B1 molecules, and had highest amino acid identity and similarity to zebrafish UNC93B1. The salmon UNC93B1 gene organisation was also similar in structure to mammalian UNC93B1. Our gene expression studies revealed that salmon UNC93B1 was more highly expressed in spleen, liver and gill tissues but was expressed at a lower level in head kidney tissue in post-smolts relative to parr. Moreover, salmon UNC93B1 mRNA transcripts were up-regulated in vivo in spleen tissue from polyI:C treated salmon and in vitro in polyI:C or IFNγ stimulated Salmon Head Kidney-1 (SHK-1) cells. Initial studies into the functional role of salmon UNC93B1 in fish TLR signalling found that both wild type salmon UNC93B1 and a molecule with a site-directed mutation (H424R) co-immunoprecipitated with salmon TLR19, TLR20a and TLR20d. Overall, these data illustrate the potential importance of UNC93B1 as an accessory protein in fish TLR signalling.
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Affiliation(s)
- P T Lee
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom
| | - J Zou
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom
| | - J W Holland
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom
| | - S A M Martin
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom
| | - C J W Scott
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom
| | - T Kanellos
- Animal Health Division, Zoetis, 23-25 avenue du Dr. Lannelongue, Paris Cedex 14 75668, France
| | - C J Secombes
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom.
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25
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Kagan JC, Barton GM. Emerging principles governing signal transduction by pattern-recognition receptors. Cold Spring Harb Perspect Biol 2014; 7:a016253. [PMID: 25395297 PMCID: PMC4355268 DOI: 10.1101/cshperspect.a016253] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The problem of recognizing and disposing of non-self-organisms, whether for nutrients or defense, predates the evolution of multicellularity. Accordingly, the function of the innate immune system is often intimately associated with fundamental aspects of cell biology. Here, we review our current understanding of the links between cell biology and pattern-recognition receptors of the innate immune system. We highlight the importance of receptor localization for the detection of microbes and for the initiation of antimicrobial signaling pathways. We discuss examples that illustrate how pattern-recognition receptors influence, and are influenced by, the general membrane trafficking machinery of mammalian cells. In the future, cell biological analysis likely will rival pure genetic analysis as a tool to uncover fundamental principles that govern host-microbe interactions.
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Affiliation(s)
- Jonathan C Kagan
- Harvard Medical School and Division of Gastroenterology, Boston Children's Hospital, Boston, Massachusetts 02115
| | - Gregory M Barton
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, California 94720-3200
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26
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UNC93B1 is essential for the plasma membrane localization and signaling of Toll-like receptor 5. Proc Natl Acad Sci U S A 2014; 111:7072-7. [PMID: 24778236 DOI: 10.1073/pnas.1322838111] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The proper trafficking and localization of Toll-like receptors (TLRs) are important for specific ligand recognition and efficient signal transduction. The TLRs sensing bacterial membrane components are expressed on the cell surface and recruit signaling adaptors to the plasma membrane upon stimulation. On the contrary, the nucleotide-sensing TLRs are mostly found inside cells and signal from the endolysosomes in an acidic pH-dependent manner. Trafficking of the nucleotide-sensing TLRs from the endoplasmic reticulum to the endolysosomes strictly depends on UNC93B1, and their signaling is completely abolished in the 3d mutant mice bearing the H412R mutation of UNC93B1. In contrast, UNC93B1 was considered to have no role for the cell surface-localized TLRs and signaling via TLR1, TLR2, TLR4, and TLR6 is normal in the 3d mice. Unexpectedly, we discovered that TLR5, a cell surface receptor for bacterial protein flagellin, also requires UNC93B1 for plasma membrane localization and signaling. TLR5 physically interacts with UNC93B1, and the cells from the 3d or UNC93B1-deficient mice not only lack TLR5 at the plasma membrane but also fail to secret cytokines and to up-regulate costimulatory molecules upon flagellin stimulation, demonstrating the essential role of UNC93B1 in TLR5 signaling. Our study reveals that the role of UNC93B1 is not limited to the TLRs signaling from the endolysosomes and compels the further probing of the mechanisms underlying the UNC93B1-assisted differential targeting of TLRs.
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27
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The ectodomain of TLR3 receptor is required for its plasma membrane translocation. PLoS One 2014; 9:e92391. [PMID: 24651829 PMCID: PMC3961339 DOI: 10.1371/journal.pone.0092391] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 02/21/2014] [Indexed: 12/26/2022] Open
Abstract
Toll-like receptor 3 (TLR3) is a dsRNA sensing receptor that is localized in the cellular compartments but also at the plasma membrane. Overexpression of UNC93B1 promoted localization of TLR3, but not other nucleic acid sensing TLRs, to the plasma membrane. Here we show that UNC93B1 itself is localized at the plasma membrane. We investigated the role of different domains of TLR3 on cell signaling by preparing chimeric receptors between TLR3 and TLR9 where each of the transmembrane segments or cytosolic domains has been exchanged. While the ectodomain completely governs ligand specificity and the cytosolic TIR domain determines the engagement of the signaling adapters as well as the potentiation of receptor activation by UNC93B1, the ectodomain but not transmembrane segment or cytosolic domain determines plasma membrane localization of TLR3. Nevertheless, TLR3 receptor and ligand endocytosis as well as endosomal acidification are important for the robust signaling of TLR3.
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28
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Lee BL, Barton GM. Trafficking of endosomal Toll-like receptors. Trends Cell Biol 2014; 24:360-9. [PMID: 24439965 DOI: 10.1016/j.tcb.2013.12.002] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/14/2013] [Accepted: 12/19/2013] [Indexed: 02/08/2023]
Abstract
Over the past decade we have learned much about nucleic acid recognition by the innate immune system and in particular by Toll-like receptors (TLRs). These receptors localize to endosomal compartments where they are poised to recognize microbial nucleic acids. Multiple regulatory mechanisms function to limit responses to self DNA or RNA, and breakdowns in these mechanisms can contribute to autoimmune or inflammatory disorders. In this review we discuss our current understanding of the cell biology of TLRs involved in nucleic acid recognition and how localization and trafficking of these receptors regulates their function.
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Affiliation(s)
- Bettina L Lee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
| | - Gregory M Barton
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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29
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Deguine J, Lee BL, Newman ZR, Barton GM. No antigen-presentation defect in Unc93b1(3d/3d) (3d) mice. Nat Immunol 2013; 14:1101-2. [PMID: 24145778 DOI: 10.1038/ni.2733] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jacques Deguine
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
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30
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Toll-like receptor 9 and 21 have different ligand recognition profiles and cooperatively mediate activity of CpG-oligodeoxynucleotides in zebrafish. Proc Natl Acad Sci U S A 2013; 110:20711-6. [PMID: 24282308 DOI: 10.1073/pnas.1305273110] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
CpG-oligodeoxynucleotides (CpG-ODNs) are potent immune stimuli currently under investigation as antimicrobial agents for different species. Toll-like receptor (TLR) 9 and TLR21 are the cellular receptors of CpG-ODN in mammals and chickens, respectively. The avian genomes lack TLR9, whereas mammalian genomes lack TLR21. Although fish contain both of these genes, the biological functions of fish TLR9 and TLR21 have not been investigated previously. In this study, we comparatively investigated zebrafish TLR9 (zebTLR9) and TLR21 (zebTLR21). The two TLRs have similar expression profiles in zebrafish. They are expressed during early development stages and are preferentially expressed in innate immune function-related organs in adult fish. Results from cell-based activation assays indicate that these two zebrafish TLRs are functional, responding to CpG-ODN but not to other TLR ligands. zebTLR9 broadly recognized CpG-ODN with different CpG motifs, but CpG-ODN with GACGTT or AACGTT had better activity to this TLR. In contrast, zebTLR21 responded preferentially to CpG-ODN with GTCGTT motifs. The distinctive ligand recognition profiles of these two TLRs were determined by their ectodomains. Activation of these two TLRs by CpG-ODN occurred inside the cells and was modulated by UNC93B1. The biological functions of these two TLRs were further investigated. The CpG-ODNs that activate both zebTLR9 and zebTLR21 were more potent than others that activate only zebTLR9 in the activation of cytokine productions and were more bactericidal in zebrafish. These results suggest that zebTLR9 and zebTLR21 cooperatively mediate the antimicrobial activities of CpG-ODN. Overall, this study provides a molecular basis for the activities of CpG-ODN in fish.
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