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Belhaouane I, Hoffmann E, Chamaillard M, Brodin P, Machelart A. Paradoxical Roles of the MAL/Tirap Adaptor in Pathologies. Front Immunol 2020; 11:569127. [PMID: 33072109 PMCID: PMC7544743 DOI: 10.3389/fimmu.2020.569127] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 08/24/2020] [Indexed: 12/14/2022] Open
Abstract
Toll-like receptors (TLRs) are at the forefront of pathogen recognition ensuring host fitness and eliciting protective cellular and humoral responses. Signaling pathways downstream of TLRs are tightly regulated for preventing collateral damage and loss of tolerance toward commensals. To trigger effective intracellular signaling, these receptors require the involvement of adaptor proteins. Among these, Toll/Interleukin-1 receptor domain containing adaptor protein (Tirap or MAL) plays an important role in establishing immune responses. Loss of function of MAL was associated with either disease susceptibility or resistance. These opposite effects reveal paradoxical functions of MAL and their importance in containing infectious or non-infectious diseases. In this review, we summarize the current knowledge on the signaling pathways involving MAL in different pathologies and their impact on inducing protective or non-protective responses.
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Affiliation(s)
- Imène Belhaouane
- Univ. Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Eik Hoffmann
- Univ. Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Mathias Chamaillard
- Laboratory of Cell Physiology, INSERM U1003, University of Lille, Lille, France
| | - Priscille Brodin
- Univ. Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Arnaud Machelart
- Univ. Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
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Han R, Zeng YL, Ni LY, Luo XC, Li AX, Dan XM, Li YW. Grouper (Epinephelus coioides) MyD88 adaptor-like (Mal): Molecular cloning, expression, and functionality. FISH & SHELLFISH IMMUNOLOGY 2019; 93:308-312. [PMID: 31352113 DOI: 10.1016/j.fsi.2019.07.065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/14/2019] [Accepted: 07/24/2019] [Indexed: 06/10/2023]
Abstract
Initiation of the innate immune response requires recognition of pathogen-associated molecular patterns by pathogen recognition receptors such as Toll-like receptors (TLRs). MyD88 adaptor-like (Mal) is an adaptor that responds to TLR activation and acts as a bridging adaptor for MyD88. In the present study, the open reading frame of Mal was identified in orange-spotted grouper (Epinephelus coioides), and named EcMal. It contained 831 bp encoding 276 aa, and was encoded by a 1299 bp DNA sequence with three exons and two introns. EcMal and the Mal sequence of other species shared different degrees of sequence identity, and clustered into the same group. EcMal was distributed in all tissues tested in healthy grouper, with the highest expression level in the head kidney. After infection with Cryptocaryon irritans, the expression level of EcMal was up-regulated in the gill and spleen. In addition, EcMal exhibited global cytosolic and nucleus localization, and could significantly activate NF-κB activity in grouper spleen cells.
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Affiliation(s)
- Rui Han
- Joint Laboratory of Guangdong Province and Hong Kong Regions on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China, Agricultural University, Guangzhou, 510642, China
| | - Yu-Long Zeng
- Joint Laboratory of Guangdong Province and Hong Kong Regions on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China, Agricultural University, Guangzhou, 510642, China
| | - Lu-Yun Ni
- Joint Laboratory of Guangdong Province and Hong Kong Regions on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China, Agricultural University, Guangzhou, 510642, China
| | - Xiao-Chun Luo
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China
| | - An-Xing Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Lab for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, Guangdong Province, China
| | - Xue-Ming Dan
- Joint Laboratory of Guangdong Province and Hong Kong Regions on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China, Agricultural University, Guangzhou, 510642, China.
| | - Yan-Wei Li
- Joint Laboratory of Guangdong Province and Hong Kong Regions on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China, Agricultural University, Guangzhou, 510642, China.
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Li L, Chen X, Zhang Y, Li Q, Qi C, Fei X, Zheng F, Gong F, Fang M. Toll-like receptor 2 deficiency promotes the generation of alloreactive Th17 cells after cardiac transplantation in mice. Cell Immunol 2019; 338:9-20. [DOI: 10.1016/j.cellimm.2019.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 02/11/2019] [Accepted: 02/21/2019] [Indexed: 12/11/2022]
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Ropert C. How toll-like receptors reveal monocyte plasticity: the cutting edge of antiinflammatory therapy. Cell Mol Life Sci 2019; 76:745-755. [PMID: 30413835 PMCID: PMC11105477 DOI: 10.1007/s00018-018-2959-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 10/23/2018] [Accepted: 10/29/2018] [Indexed: 12/12/2022]
Abstract
Toll-like receptors (TLR)s are central in immune response by recognizing pathogen-associated molecular patterns (PAMP)s. If they are essential to eliminate pathogens in earlier stages of infection, they also might play a role in homeostasis and tissue repair. TLR versatility parallels the plasticity of monocytes, which represent an heterogeneous population of immune cells. They are rapidly recruited to sites of infection and involved in clearance of pathogens and in tissue healing. This review underlines how TLRs have proved to be an interesting tool to study the properties of monocytes and why different therapeutic strategies exploring monocyte plasticity may be relevant in the context of chronic inflammatory disorders.
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Affiliation(s)
- Catherine Ropert
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, Pampulha, Belo Horizonte, MG, 31270-910, Brazil.
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Karaś MA, Turska-Szewczuk A, Janczarek M, Szuster-Ciesielska A. Glycoconjugates of Gram-negative bacteria and parasitic protozoa - are they similar in orchestrating the innate immune response? Innate Immun 2019; 25:73-96. [PMID: 30782045 PMCID: PMC6830889 DOI: 10.1177/1753425918821168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 12/03/2018] [Indexed: 02/06/2023] Open
Abstract
Innate immunity is an evolutionarily ancient form of host defense that serves to limit infection. The invading microorganisms are detected by the innate immune system through germline-encoded PRRs. Different classes of PRRs, including TLRs and cytoplasmic receptors, recognize distinct microbial components known collectively as PAMPs. Ligation of PAMPs with receptors triggers intracellular signaling cascades, activating defense mechanisms. Despite the fact that Gram-negative bacteria and parasitic protozoa are phylogenetically distant organisms, they express glycoconjugates, namely bacterial LPS and protozoan GPI-anchored glycolipids, which share many structural and functional similarities. By activating/deactivating MAPK signaling and NF-κB, these ligands trigger general pro-/anti-inflammatory responses depending on the related patterns. They also use conservative strategies to subvert cell-autonomous defense systems of specialized immune cells. Signals triggered by Gram-negative bacteria and parasitic protozoa can interfere with host homeostasis and, depending on the type of microorganism, lead to hypersensitivity or silencing of the immune response. Activation of professional immune cells, through a ligand which triggers the opposite effect (antagonist versus agonist) appears to be a promising solution to restoring the immune balance.
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Affiliation(s)
- Magdalena A Karaś
- Department of Genetics and Microbiology, Maria Curie–Skłodowska
University, Lublin, Poland
| | - Anna Turska-Szewczuk
- Department of Genetics and Microbiology, Maria Curie–Skłodowska
University, Lublin, Poland
| | - Monika Janczarek
- Department of Genetics and Microbiology, Maria Curie–Skłodowska
University, Lublin, Poland
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Balka KR, De Nardo D. Understanding early TLR signaling through the Myddosome. J Leukoc Biol 2018; 105:339-351. [PMID: 30256449 DOI: 10.1002/jlb.mr0318-096r] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/27/2018] [Accepted: 09/06/2018] [Indexed: 12/27/2022] Open
Abstract
TLRs are expressed on the plasma and endosomal membranes of innate immune cells acting as sensors of foreign and inherent danger signals that threaten the host. Upon activation, TLRs facilitate the assembly of large intracellular oligomeric signaling complexes, termed Myddosomes, which initiate key signal transduction pathways to elicit critical inflammatory immune responses. The formation of the Myddosome is integral for TLR signaling; however, the molecular mechanisms controlling its formation, disassembly, and the subsequent proximal signaling events remain to be clearly defined. In this review, we present a brief overview of TLR signal transduction pathways, summarize the current understanding of the Myddosome and the proteins that comprise its structure, including MyD88 and members of the IL-1 receptor-associated kinase (IRAK) family. Finally, we will discuss recent advances and open questions regarding early TLR signaling in the context of the Myddosome complex.
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Affiliation(s)
- Katherine R Balka
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Dominic De Nardo
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
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Patra MC, Choi S. Insight into Phosphatidylinositol-Dependent Membrane Localization of the Innate Immune Adaptor Protein Toll/Interleukin 1 Receptor Domain-Containing Adaptor Protein. Front Immunol 2018; 9:75. [PMID: 29434596 PMCID: PMC5796906 DOI: 10.3389/fimmu.2018.00075] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 01/11/2018] [Indexed: 01/23/2023] Open
Abstract
The toll/interleukin 1 receptor (TIR) domain-containing adaptor protein (TIRAP) plays an important role in the toll-like receptor (TLR) 2, TLR4, TLR7, and TLR9 signaling pathways. TIRAP anchors to phosphatidylinositol (PI) 4,5-bisphosphate (PIP2) on the plasma membrane and PI (3,4,5)-trisphosphate (PIP3) on the endosomal membrane and assists in recruitment of the myeloid differentiation primary response 88 protein to activated TLRs. To date, the structure and mechanism of TIRAP’s membrane association are only partially understood. Here, we modeled an all-residue TIRAP dimer using homology modeling, threading, and protein–protein docking strategies. Molecular dynamics simulations revealed that PIP2 creates a stable microdomain in a dipalmitoylphosphatidylcholine bilayer, providing TIRAP with its physiologically relevant orientation. Computed binding free energy values suggest that the affinity of PI-binding domain (PBD) for PIP2 is stronger than that of TIRAP as a whole for PIP2 and that the short PI-binding motif (PBM) contributes to the affinity between PBD and PIP2. Four PIP2 molecules can be accommodated by distinct lysine-rich surfaces on the dimeric PBM. Along with the known PI-binding residues (K15, K16, K31, and K32), additional positively charged residues (K34, K35, and R36) showed strong affinity toward PIP2. Lysine-to-alanine mutations at the PI-binding residues abolished TIRAP’s affinity for PIP2; however, K34, K35, and R36 consistently interacted with PIP2 headgroups through hydrogen bond (H-bond) and electrostatic interactions. TIRAP exhibited a PIP2-analogous intermolecular contact and binding affinity toward PIP3, aided by an H-bond network involving K34, K35, and R36. The present study extends our understanding of TIRAP’s membrane association, which could be helpful in designing peptide decoys to block TLR2-, TLR4-, TLR7-, and TLR9-mediated autoimmune diseases.
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Affiliation(s)
- Mahesh Chandra Patra
- Department of Molecular Science and Technology, Ajou University, Suwon, South Korea
| | - Sangdun Choi
- Department of Molecular Science and Technology, Ajou University, Suwon, South Korea
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