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Ávila G, Ceciliani F, Viala D, Dejean S, Sala G, Lecchi C, Bonnet M. Conjugated linoleic acid (CLA) modulates bovine peripheral blood mononuclear cells (PBMC) proteome in vitro. J Proteomics 2024; 304:105232. [PMID: 38909954 DOI: 10.1016/j.jprot.2024.105232] [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: 04/20/2024] [Revised: 06/16/2024] [Accepted: 06/20/2024] [Indexed: 06/25/2024]
Abstract
Conjugated linoleic acid (CLA) is a group of natural isomers of the n-6 polyunsaturated fatty acid (PUFA) linoleic acid, exerting biological effects on cow physiology. This study assessed the impact of the mixture 50:50 (vol:vol) of CLA isomers (cis-9, trans-11 and trans-10, cis-12) on bovine peripheral blood mononuclear cells (PBMC) proteome, identifying 1608 quantifiable proteins. A supervised multivariate statistical analysis, sparse variant partial least squares - discriminant analysis (sPLS-DA) for paired data identified 407 discriminant proteins (DP), allowing the clustering between the CLA and controls. The ProteINSIDE workflow found that DP with higher abundance in the CLA group included proteins related to innate immune defenses (PLIN2, CD36, C3, C4, and AGP), with antiapoptotic (SERPINF2 and ITIH4) and antioxidant effects (HMOX1). These results demonstrated that CLA modulates the bovine PBMC proteome, supports the antiapoptotic and immunomodulatory effects observed in previous in vitro studies on bovine PBMC, and suggests a cytoprotective role against oxidative stress. SIGNIFICANCE: In this study, we report for the first time that the mixture 50:50 (vol:vol) of cis-9, trans-11, and trans-10, cis-12-CLA isomers modulates the bovine PBMC proteome. Our results support the immunomodulatory and antiapoptotic effects observed in bovine PBMC in vitro. In addition, the present study proposes a cytoprotective role of CLA mixture against oxidative stress. We suggest a molecular signature of CLA treatment based on combining a multivariate sparse discriminant analysis and a clustering method. This demonstrates the great value of sPLS-DA as an alternative option to identify discriminant proteins with relevant biological significance.
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Affiliation(s)
- G Ávila
- Department of Veterinary Medicine and Animal Science, Università Degli Studi di Milano, Via dell'Università 6, 26900 Lodi, Italy
| | - F Ceciliani
- Department of Veterinary Medicine and Animal Science, Università Degli Studi di Milano, Via dell'Università 6, 26900 Lodi, Italy.
| | - D Viala
- INRAE, Université Clermont Auvergne, Vetagro Sup, UMRH, 63122 Saint-Genès-Champanelle, France; INRAE, Metabolomic and Proteomic Exploration Facility (PFEM), F-63122 Saint-Genès-Champanelle, France
| | - S Dejean
- Institut de Mathématiques de Toulouse, Université de Toulouse, CNRS, UPS, UMR 5219, 31062 Toulouse, France
| | - G Sala
- Department of Veterinary Medicine and Animal Science, Università Degli Studi di Milano, Via dell'Università 6, 26900 Lodi, Italy
| | - C Lecchi
- Department of Veterinary Medicine and Animal Science, Università Degli Studi di Milano, Via dell'Università 6, 26900 Lodi, Italy
| | - M Bonnet
- INRAE, Université Clermont Auvergne, Vetagro Sup, UMRH, 63122 Saint-Genès-Champanelle, France
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2
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Mishra H, Schlack-Leigers C, Lim EL, Thieck O, Magg T, Raedler J, Wolf C, Klein C, Ewers H, Lee-Kirsch MA, Meierhofer D, Hauck F, Majer O. Disrupted degradative sorting of TLR7 is associated with human lupus. Sci Immunol 2024; 9:eadi9575. [PMID: 38207015 DOI: 10.1126/sciimmunol.adi9575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 12/22/2023] [Indexed: 01/13/2024]
Abstract
Hyperactive TLR7 signaling has long been appreciated as driver of autoimmune disease in mouse models. Recently, gain-of-function mutations in TLR7 were identified as a monogenic cause of human lupus. TLR7 is an intracellular transmembrane receptor, sensing RNA breakdown products within late endosomes. Here, we show that endosome dysfunction leads to unrestricted TLR7 signaling and is associated with human lupus. The late endosomal BORC complex together with the small GTPase Arl8b controls intracellular TLR7 levels by regulating receptor turnover. This requires a direct interaction between the TLR7-associated trafficking factor Unc93b1 and Arl8b. We identified an UNC93B1 mutation in a patient with childhood-onset lupus, which results in reduced BORC interaction and endosomal TLR7 accumulation. Therefore, a failure to control TLR7 turnover is sufficient to break immunological tolerance to nucleic acids. Our results highlight the importance of an intact endomembrane system in preventing pathological TLR7 signaling and autoimmune disease.
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Affiliation(s)
- Harshita Mishra
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Claire Schlack-Leigers
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin 14195, Germany
| | - Ee Lyn Lim
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Oliver Thieck
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Thomas Magg
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich 80337, Germany
| | - Johannes Raedler
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich 80337, Germany
| | - Christine Wolf
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
| | - Christoph Klein
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich 80337, Germany
| | - Helge Ewers
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin 14195, Germany
| | - Min Ae Lee-Kirsch
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Berlin 14195, Germany
| | - Fabian Hauck
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich 80337, Germany
| | - Olivia Majer
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
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3
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Yan L, Han X, Zhang M, Fu Y, Yang F, Li Q, Cheng T. Integrative analysis of TBI data reveals Lgmn as a key player in immune cell-mediated ferroptosis. BMC Genomics 2023; 24:747. [PMID: 38057699 DOI: 10.1186/s12864-023-09842-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 11/24/2023] [Indexed: 12/08/2023] Open
Abstract
BACKGROUND Traumatic brain injury (TBI) is a central nervous system disease caused by external trauma, which has complex pathological and physiological mechanisms. The aim of this study was to explore the correlation between immune cell infiltration and ferroptosis post-TBI. METHODS This study utilized the GEO database to download TBI data and performed differentially expressed genes (DEGs) and ferroptosis-related differentially expressed genes (FRDEGs) analysis. DEGs were further analyzed for enrichment using the DAVID 6.8. Immunoinfiltration cell analysis was performed using the ssGSEA package and the Timer2.0 tool. The WGCNA analysis was then used to explore the gene modules in the data set associated with differential expression of immune cell infiltration and to identify the hub genes. The tidyverse package and corrplot package were used to calculate the correlations between hub genes and immune cell infiltration and ferroptosis-marker genes. The miRDB and TargetScan databases were used to predict complementary miRNAs for the Hub genes selected from the WGCNA analysis, and the DIANA-LncBasev3 tool was used to identify target lncRNAs for the miRNAs, constructing an mRNA-miRNA-lncRNA regulatory network. RESULTS A total of 320 DEGs and 21 FRDEGs were identified in GSE128543. GO and KEGG analyses showed that the DEGs after TBI were primarily associated with inflammation and immune response. Xcell and ssGSEA immune infiltration cell analysis showed significant infiltration of T cell CD4+ central memory, T cell CD4+ Th2, B cell memory, B cell naive, monocyte, macrophage, and myeloid dendritic cell activated. The WGCNA analysis identified two modules associated with differentially expressed immune cells and identified Lgmn as a hub gene associated with immune infiltrating cells. Lgmn showed significant correlation with immune cells and ferroptosis-marker genes, including Gpx4, Hspb1, Nfe2l2, Ptgs2, Fth1, and Tfrc. Finally, an mRNA-miRNA-lncRNA regulatory network was constructed using Lgmn. CONCLUSION Our results indicate that there is a certain correlation between ferroptosis and immune infiltrating cells in brain tissue after TBI, and that Lgmn plays an important role in this process.
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Affiliation(s)
- Liyan Yan
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, Henan, China
| | - Xiaonan Han
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, Henan, China
| | - Mingkang Zhang
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, Henan, China
| | - Yikun Fu
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, Henan, China
| | - Fei Yang
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Qian Li
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China.
| | - Tian Cheng
- Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, Henan, China.
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4
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de Lavergne M, Maisonneuve L, Podsypanina K, Manoury B. The role of the antigen processing machinery in the regulation and trafficking of intracellular -Toll-like receptor molecules. Curr Opin Immunol 2023; 84:102375. [PMID: 37562076 DOI: 10.1016/j.coi.2023.102375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 07/09/2023] [Accepted: 07/11/2023] [Indexed: 08/12/2023]
Abstract
Intracellular Toll-like receptors (TLRs) are key components of the innate immune system. Their expression in antigen-presenting cells (APCs), and in particular dendritic cells (DCs), makes them critical in the induction of the adaptive immune response. In DCs, they interact with the chaperone UNC93B1 that mediates their trafficking from the endoplasmic reticulum (ER) to endosomes where they are cleaved by proteases and activated. All these different steps are also shared by major histocompatibility complex class-II (MHCII) molecules. Here, we will discuss the tight relationship intracellular TLRs have with the antigen processing machinery in APCs for their trafficking and activation.
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Affiliation(s)
- Moïse de Lavergne
- Institut Necker Enfants Malades, INSERM U1151-CNRS UMR 8253, Université Paris Cité, Faculté de Médecine Necker, France
| | - Lucie Maisonneuve
- Institut Necker Enfants Malades, INSERM U1151-CNRS UMR 8253, Université Paris Cité, Faculté de Médecine Necker, France
| | - Katrina Podsypanina
- Institut Necker Enfants Malades, INSERM U1151-CNRS UMR 8253, Université Paris Cité, Faculté de Médecine Necker, France
| | - Bénédicte Manoury
- Institut Necker Enfants Malades, INSERM U1151-CNRS UMR 8253, Université Paris Cité, Faculté de Médecine Necker, France.
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5
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Liu J, Ke P, Guo H, Gu J, Liu Y, Tian X, Wang X, Xiao F. Activation of TLR7-mediated autophagy increases epileptic susceptibility via reduced KIF5A-dependent GABA A receptor transport in a murine model. Exp Mol Med 2023; 55:1159-1173. [PMID: 37258573 PMCID: PMC10317981 DOI: 10.1038/s12276-023-01000-5] [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: 09/02/2022] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 06/02/2023] Open
Abstract
The pathophysiological mechanisms underlying epileptogenesis are poorly understood but are considered to actively involve an imbalance between excitatory and inhibitory synaptic transmission. Excessive activation of autophagy, a cellular pathway that leads to the removal of proteins, is known to aggravate the disease. Toll-like receptor (TLR) 7 is an innate immune receptor that regulates autophagy in infectious and noninfectious diseases. However, the relationship between TLR7, autophagy, and synaptic transmission during epileptogenesis remains unclear. We found that TLR7 was activated in neurons in the early stage of epileptogenesis. TLR7 knockout significantly suppressed seizure susceptibility and neuronal excitability. Furthermore, activation of TLR7 induced autophagy and decreased the expression of kinesin family member 5 A (KIF5A), which influenced interactions with γ-aminobutyric acid type A receptor (GABAAR)-associated protein and GABAARβ2/3, thus producing abnormal GABAAR-mediated postsynaptic transmission. Our results indicated that TLR7 is an important factor in regulating epileptogenesis, suggesting a possible therapeutic target for epilepsy.
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Affiliation(s)
- Jing Liu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
- Department of Neurology, Chongqing University Three Gorges Hospital, 165 Xincheng Road, Chongqing, 404100, China
| | - Pingyang Ke
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - Haokun Guo
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - Juan Gu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - Yan Liu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - Xin Tian
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China
| | - Xuefeng Wang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China.
| | - Fei Xiao
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing, 400016, China.
- Institute for Brain Science and Disease of Chongqing Medical University, Chongqing, 400016, China.
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6
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Wilkinson IVL, Castro-Falcón G, Roda-Serrat MC, Purdy TN, Straetener J, Brauny MM, Maier L, Brötz-Oesterhelt H, Christensen LP, Sieber SA, Hughes CC. The Cyanobacterial "Nutraceutical" Phycocyanobilin Inhibits Cysteine Protease Legumain. Chembiochem 2023; 24:e202200455. [PMID: 36538283 DOI: 10.1002/cbic.202200455] [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: 08/08/2022] [Revised: 12/19/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
The blue biliprotein phycocyanin, produced by photo-autotrophic cyanobacteria including spirulina (Arthrospira) and marketed as a natural food supplement or "nutraceutical," is reported to have anti-inflammatory, antioxidant, immunomodulatory, and anticancer activity. These diverse biological activities have been specifically attributed to the phycocyanin chromophore, phycocyanobilin (PCB). However, the mechanism of action of PCB and the molecular targets responsible for the beneficial properties of PCB are not well understood. We have developed a procedure to rapidly cleave the PCB pigment from phycocyanin by ethanolysis and then characterized it as an electrophilic natural product that interacts covalently with thiol nucleophiles but lacks any appreciable cytotoxicity or antibacterial activity against common pathogens and gut microbes. We then designed alkyne-bearing PCB probes for use in chemical proteomics target deconvolution studies. Target identification and validation revealed the cysteine protease legumain (also known as asparaginyl endopeptidase, AEP) to be a target of PCB. Inhibition of this target may account for PCB's diverse reported biological activities.
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Affiliation(s)
- Isabel V L Wilkinson
- Center for Protein Assemblies (CPA), Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Str. 8, 85748, Garching, Germany
| | - Gabriel Castro-Falcón
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, CA 92093, USA
| | - Maria C Roda-Serrat
- Department of Green Technology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Trevor N Purdy
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, CA 92093, USA
| | - Jan Straetener
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
| | - Melanie M Brauny
- Cluster of Excellence EXC 2124, Controlling Microbes to Fight Infection, University of Tübingen, 72076, Tübingen, Germany
- Microbiome-Host-Interaction Lab, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
| | - Lisa Maier
- Cluster of Excellence EXC 2124, Controlling Microbes to Fight Infection, University of Tübingen, 72076, Tübingen, Germany
- Microbiome-Host-Interaction Lab, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
| | - Heike Brötz-Oesterhelt
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence EXC 2124, Controlling Microbes to Fight Infection, University of Tübingen, 72076, Tübingen, Germany
- German Center for Infection Research, Partner Site Tübingen, 72076, Tübingen, Germany
| | - Lars P Christensen
- Department of Green Technology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Stephan A Sieber
- Center for Protein Assemblies (CPA), Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Str. 8, 85748, Garching, Germany
| | - Chambers C Hughes
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, CA 92093, USA
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence EXC 2124, Controlling Microbes to Fight Infection, University of Tübingen, 72076, Tübingen, Germany
- German Center for Infection Research, Partner Site Tübingen, 72076, Tübingen, Germany
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7
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Solberg R, Lunde NN, Forbord KM, Okla M, Kassem M, Jafari A. The Mammalian Cysteine Protease Legumain in Health and Disease. Int J Mol Sci 2022; 23:ijms232415983. [PMID: 36555634 PMCID: PMC9788469 DOI: 10.3390/ijms232415983] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 12/05/2022] [Accepted: 12/10/2022] [Indexed: 12/23/2022] Open
Abstract
The cysteine protease legumain (also known as asparaginyl endopeptidase or δ-secretase) is the only known mammalian asparaginyl endopeptidase and is primarily localized to the endolysosomal system, although it is also found extracellularly as a secreted protein. Legumain is involved in the regulation of diverse biological processes and tissue homeostasis, and in the pathogenesis of various malignant and nonmalignant diseases. In addition to its proteolytic activity that leads to the degradation or activation of different substrates, legumain has also been shown to have a nonproteolytic ligase function. This review summarizes the current knowledge about legumain functions in health and disease, including kidney homeostasis, hematopoietic homeostasis, bone remodeling, cardiovascular and cerebrovascular diseases, fibrosis, aging and senescence, neurodegenerative diseases and cancer. In addition, this review addresses the effects of some marketed drugs on legumain. Expanding our knowledge on legumain will delineate the importance of this enzyme in regulating physiological processes and disease conditions.
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Affiliation(s)
- Rigmor Solberg
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, N-0316 Oslo, Norway
- Correspondence: (R.S.); (A.J.); Tel.: +47-22-857-514 (R.S.); +45-35-337-423 (A.J.)
| | - Ngoc Nguyen Lunde
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, N-0316 Oslo, Norway
| | - Karl Martin Forbord
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, N-0316 Oslo, Norway
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, DK-5000 Odense, Denmark
| | - Meshail Okla
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, DK-5000 Odense, Denmark
- Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh 12372, Saudi Arabia
| | - Moustapha Kassem
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, DK-5000 Odense, Denmark
- Department of Cellular and Molecular Medicine, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Abbas Jafari
- Department of Endocrinology and Metabolism, Odense University Hospital, University of Southern Denmark, DK-5000 Odense, Denmark
- Department of Cellular and Molecular Medicine, University of Copenhagen, DK-2200 Copenhagen, Denmark
- Correspondence: (R.S.); (A.J.); Tel.: +47-22-857-514 (R.S.); +45-35-337-423 (A.J.)
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8
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Ciaston I, Dobosz E, Potempa J, Koziel J. The subversion of toll-like receptor signaling by bacterial and viral proteases during the development of infectious diseases. Mol Aspects Med 2022; 88:101143. [PMID: 36152458 PMCID: PMC9924004 DOI: 10.1016/j.mam.2022.101143] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/29/2022] [Accepted: 09/09/2022] [Indexed: 02/05/2023]
Abstract
Toll-like receptors (TLRs) are pattern recognition receptors (PRRs) that respond to pathogen-associated molecular patterns (PAMPs). The recognition of specific microbial ligands by TLRs triggers an innate immune response and also promotes adaptive immunity, which is necessary for the efficient elimination of invading pathogens. Successful pathogens have therefore evolved strategies to subvert and/or manipulate TLR signaling. Both the impairment and uncontrolled activation of TLR signaling can harm the host, causing tissue destruction and allowing pathogens to proliferate, thus favoring disease progression. In this context, microbial proteases are key virulence factors that modify components of the TLR signaling pathway. In this review, we discuss the role of bacterial and viral proteases in the manipulation of TLR signaling, highlighting the importance of these enzymes during the development of infectious diseases.
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Affiliation(s)
- Izabela Ciaston
- Department of Microbiology Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Ewelina Dobosz
- Department of Microbiology Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Jan Potempa
- Department of Microbiology Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland; Department of Oral Health and Systemic Disease, University of Louisville School of Dentistry, University of Louisville, Louisville, KY, USA.
| | - Joanna Koziel
- Department of Microbiology Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
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9
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The Asparaginyl Endopeptidase Legumain: An Emerging Therapeutic Target and Potential Biomarker for Alzheimer’s Disease. Int J Mol Sci 2022; 23:ijms231810223. [PMID: 36142134 PMCID: PMC9499314 DOI: 10.3390/ijms231810223] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 08/30/2022] [Accepted: 09/02/2022] [Indexed: 11/21/2022] Open
Abstract
Alzheimer’s disease (AD) is incurable dementia closely associated with aging. Most cases of AD are sporadic, and very few are inherited; the pathogenesis of sporadic AD is complex and remains to be elucidated. The asparaginyl endopeptidase (AEP) or legumain is the only recognized cysteine protease that specifically hydrolyzes peptide bonds after asparagine residues in mammals. The expression level of AEPs in healthy brains is far lower than that of peripheral organs. Recently, growing evidence has indicated that aging may upregulate and overactivate brain AEPs. The overactivation of AEPs drives the onset of AD through cleaving tau and amyloid precursor proteins (APP), and SET, an inhibitor of protein phosphatase 2A (PP2A). The AEP-mediated cleavage of these peptides enhances amyloidosis, promotes tau hyperphosphorylation, and ultimately induces neurodegeneration and cognitive impairment. Upregulated AEPs and related deleterious reactions constitute upstream events of amyloid/tau toxicity in the brain, and represent early pathological changes in AD. Thus, upregulated AEPs are an emerging drug target for disease modification and a potential biomarker for predicting preclinical AD. However, the presence of the blood–brain barrier greatly hinders establishing body-fluid-based methods to measure brain AEPs. Research on AEP-activity-based imaging probes and our recent work suggest that the live brain imaging of AEPs could be used to evaluate its predictive efficacy as an AD biomarker. To advance translational research in this area, AEP imaging probes applicable to human brain and AEP inhibitors with good druggability are urgently needed.
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10
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Saucereau Y, Wilson TH, Tang MCK, Moncrieffe MC, Hardwick SW, Chirgadze DY, Soares SG, Marcaida MJ, Gay NJ, Gangloff M. Structure and dynamics of Toll immunoreceptor activation in the mosquito Aedes aegypti. Nat Commun 2022; 13:5110. [PMID: 36042238 PMCID: PMC9427763 DOI: 10.1038/s41467-022-32690-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 08/09/2022] [Indexed: 11/09/2022] Open
Abstract
Aedes aegypti has evolved to become an efficient vector for arboviruses but the mechanisms of host-pathogen tolerance are unknown. Immunoreceptor Toll and its ligand Spaetzle have undergone duplication which may allow neofunctionalization and adaptation. Here we present cryo-EM structures and biophysical characterisation of low affinity Toll5A complexes that display transient but specific interactions with Spaetzle1C, forming asymmetric complexes, with only one ligand clearly resolved. Loop structures of Spaetzle1C and Toll5A intercalate, temporarily bridging the receptor C-termini to promote signalling. By contrast unbound receptors form head-to-head homodimers that keep the juxtamembrane regions far apart in an inactive conformation. Interestingly the transcriptional signature of Spaetzle1C differs from other Spaetzle cytokines and controls genes involved in innate immunity, metabolism and tissue regeneration. Taken together our results explain how upregulation of Spaetzle1C in the midgut and Toll5A in the salivary gland shape the concomitant immune response.
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Affiliation(s)
- Yoann Saucereau
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Thomas H Wilson
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Matthew C K Tang
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Martin C Moncrieffe
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Steven W Hardwick
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Dimitri Y Chirgadze
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Sandro G Soares
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Maria Jose Marcaida
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Nicholas J Gay
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK
| | - Monique Gangloff
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK.
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11
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Meng Y, Ma J, Yao C, Ye Z, Ding H, Liu C, Li J, Li G, He Y, Li J, Yin Z, Wu L, Zhou H, Shen N. The NCF1 variant aggravates autoimmunity by facilitating the activation of plasmacytoid dendritic cells. J Clin Invest 2022; 132:153619. [PMID: 35788118 PMCID: PMC9374378 DOI: 10.1172/jci153619] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 06/28/2022] [Indexed: 11/17/2022] Open
Abstract
Plasmacytoid dendritic cells (pDCs) are a professional type I IFN producer that play critical roles in the pathogenesis of autoimmune diseases. However, both genetic regulation of the function of pDCs and their relationships with autoimmunity are largely undetermined. Here, we investigated the causality of the neutrophil cytosolic factor 1 (NCF1) missense variant, which is one of the most significant associated risk variants for lupus, and found that the substitution of arginine (R) for histidine (H) at position 90 in the NCF1 protein (NCF1 p.R90H) led to excessive activation of pDCs. A mechanism study demonstrated that p.R90H reduced the affinity of NCF1 for phospholipids, thereby impairing endosomal localization of NCF1. As NCF1 is a subunit of the NADPH oxidase 2 (NOX2) complex, this impairment led to an acidified endosomal pH and facilitated downstream TLR signaling. Consistently, the homozygous knockin mice manifested aggravated lupus progression in a pDC-dependent lupus model. More important, pharmaceutical intervention revealed that hydroxychloroquine (HCQ) could antagonize the detrimental function of NCF1 p.R90H in the lupus model and systemic lupus erythematosus samples, supporting the idea that NCF1 p.R90H could be identified as a genetic biomarker for HCQ application. Therefore, our study provides insights into the genetic control of pDC function and a paradigm for applying genetic variants to improve targeted therapy for autoimmune diseases.
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Affiliation(s)
- Yao Meng
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jianyang Ma
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chao Yao
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zhizhong Ye
- Shenzhen Futian Hospital for Rheumatic Diseases, Shenzhen, China
| | - Huihua Ding
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Can Liu
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jun Li
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Guanhua Li
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yuke He
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jia Li
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zhihua Yin
- Shenzhen Futian Hospital for Rheumatic Diseases, Shenzhen, Shenzhen, China
| | - Li Wu
- Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University School of Medicine, Beijing, China
| | - Haibo Zhou
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Nan Shen
- Shanghai Institute of Rheumatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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12
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Discovery of the anti-influenza A virus activity of SB216763 and cyclosporine A by mining infected cells and compound cellular signatures. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.09.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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13
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Wang D, Kang L, Chen C, Guo J, Du L, Zhou D, Li G, Zhang Y, Mi X, Zhang M, Liu S, Tan X. Loss of legumain induces premature senescence and mediates aging-related renal fibrosis. Aging Cell 2022; 21:e13574. [PMID: 35195326 PMCID: PMC8920435 DOI: 10.1111/acel.13574] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 01/19/2022] [Accepted: 02/05/2022] [Indexed: 12/14/2022] Open
Abstract
Aging is an independent risk factor for acute kidney injury and subsequent chronic kidney diseases, while the underlying mechanism is still elusive. Here, we found that renal tubules highly express a conserved lysosomal endopeptidase, legumain, which is significantly downregulated with the growing of age. Tubule‐specific legumain‐knockout mice exhibit spontaneous renal interstitial fibrosis from the 3rd month. In the tubule‐specific legumain‐knockout mice and the cultured legumain‐knockdown HK‐2 cells, legumain deficiency induces the activation of tubular senescence and thus increases the secretion of profibrotic senescence‐associated cytokines, which in turn accelerates the activation of fibroblasts. Blockage of senescence mitigates the fibrotic lesion caused by legumain deficiency. Mechanistically, we found that silencing down of legumain leads to the elevated lysosome pH value, enlargement of lysosome size, and increase of lysosomal voltage dependent membrane channel proteins. Either legumain downregulation or aging alone induces the activation of nuclear transcription factors EB (TFEB) while it fails to further upregulate in the elderly legumain‐knockdown tubules, accompanied with impaired mitophagy and increased mitochondrial ROS (mtROS) accumulation. Therapeutically, supplementation of exosomal legumain ameliorated fibronectin and collagen I production in an in vitro coculture system of tubular cells and fibroblasts. Altogether, our data demonstrate that loss of legumain in combined with aging dysregulates lysosomal homeostasis, although either aging or legumain deficiency alone induces lysosome adaptation via stimulating lysosomal biogenesis. Consequently, impaired mitophagy leads to mtROS accumulation and therefore activates tubular senescence and boosts the interstitial fibrosis.
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Affiliation(s)
- Dekun Wang
- Department of Pathology School of Medicine Nankai University Tianjin China
| | - Lichun Kang
- Department of Pathology School of Medicine Nankai University Tianjin China
| | - Chuan'ai Chen
- Department of Pathology School of Medicine Nankai University Tianjin China
| | - Jiasen Guo
- College of Life Science Nankai University Tianjin China
| | - Lingfang Du
- Department of Pathology School of Medicine Nankai University Tianjin China
| | - Donghui Zhou
- Department of Pathology School of Medicine Nankai University Tianjin China
| | - Gang Li
- Nephrology Division The Second Hospital of Tianjin Medical University Tianjin China
| | - Yuying Zhang
- Department of Pathology School of Medicine Nankai University Tianjin China
| | - Xue Mi
- Department of Pathology School of Medicine Nankai University Tianjin China
| | - Mianzhi Zhang
- Dongfang Hospital of Beijing University of Chinese medicine Beijing China
| | - Shuxia Liu
- Hebei Key Laboratory of Nephrology Department of Pathology Hebei Medical University Shijiazhuang China
| | - Xiaoyue Tan
- Department of Pathology School of Medicine Nankai University Tianjin China
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14
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Watts C. Lysosomes and lysosome‐related organelles in immune responses. FEBS Open Bio 2022; 12:678-693. [PMID: 35220694 PMCID: PMC8972042 DOI: 10.1002/2211-5463.13388] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 02/25/2022] [Indexed: 11/17/2022] Open
Abstract
The catabolic, degradative capacity of the endo‐lysosome system is put to good use in mammalian immune responses as is their recently established status as signaling platforms. From the ‘creative destruction’ of antigenic and ‘self’ material for antigen presentation to T cells to the re‐purposing of lysosomes as toxic exocytosable lysosome‐related organelles (granules) in leukocytes such as CD8 T cells and eosinophils, endo‐lysosomes are key players in host defense. Signaled responses to some pathogen products initiate in endo‐lysosomes and these organelles are emerging as important in distinct ways in the unique immunobiology of dendritic cells. Potential self‐inflicted toxicity from lysosomal and granule proteases is countered by expression of serpin and cystatin family members.
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Affiliation(s)
- Colin Watts
- Division of Cell Signalling & Immunology School of Life Sciences University of Dundee Dundee DD1 5EH UK
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15
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Martinez-Fabregas J, Tamargo-Azpilicueta J, Diaz-Moreno I. Lysosomes: Multifunctional compartments ruled by a complex regulatory network. FEBS Open Bio 2022; 12:758-774. [PMID: 35218162 PMCID: PMC8972048 DOI: 10.1002/2211-5463.13387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 02/08/2022] [Accepted: 02/24/2022] [Indexed: 11/23/2022] Open
Abstract
More than 50 years have passed since Nobel laureate Cristian de Duve described for the first time the presence of tiny subcellular compartments filled with hydrolytic enzymes: the lysosome. For a long time, lysosomes were deemed simple waste bags exerting a plethora of hydrolytic activities involved in the recycling of biopolymers, and lysosomal genes were considered to just be simple housekeeping genes, transcribed in a constitutive fashion. However, lysosomes are emerging as multifunctional signalling hubs involved in multiple aspects of cell biology, both under homeostatic and pathological conditions. Lysosomes are involved in the regulation of cell metabolism through the mTOR/TFEB axis. They are also key players in the regulation and onset of the immune response. Furthermore, it is becoming clear that lysosomal hydrolases can regulate several biological processes outside of the lysosome. They are also implicated in a complex communication network among subcellular compartments that involves intimate organelle‐to‐organelle contacts. Furthermore, lysosomal dysfunction is nowadays accepted as the causative event behind several human pathologies: low frequency inherited diseases, cancer, or neurodegenerative, metabolic, inflammatory, and autoimmune diseases. Recent advances in our knowledge of the complex biology of lysosomes have established them as promising therapeutic targets for the treatment of different pathologies. Although recent discoveries have started to highlight that lysosomes are controlled by a complex web of regulatory networks, which in some cases seem to be cell‐ and stimuli‐dependent, to harness the full potential of lysosomes as therapeutic targets, we need a deeper understanding of the little‐known signalling pathways regulating this subcellular compartment and its functions.
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Affiliation(s)
- Jonathan Martinez-Fabregas
- Instituto de Investigaciones Químicas (IIQ) - Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, 41092, Sevilla, Spain
| | - Joaquin Tamargo-Azpilicueta
- Instituto de Investigaciones Químicas (IIQ) - Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, 41092, Sevilla, Spain
| | - Irene Diaz-Moreno
- Instituto de Investigaciones Químicas (IIQ) - Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, 41092, Sevilla, Spain
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16
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Zhang W, Lin Y. The Mechanism of Asparagine Endopeptidase in the Progression of Malignant Tumors: A Review. Cells 2021; 10:cells10051153. [PMID: 34068767 PMCID: PMC8151911 DOI: 10.3390/cells10051153] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 04/24/2021] [Accepted: 05/07/2021] [Indexed: 12/20/2022] Open
Abstract
Asparagine endopeptidase (AEP), also called legumain, is currently the only known cysteine protease that specifically cleaves peptide bonds in asparaginyl residue in the mammalian genome. Since 2003, AEP has been reported to be widely expressed in a variety of carcinomas and is considered a potential therapeutic target. In the following years, researchers intensively investigated the substrates of AEP and the mechanism of AEP in partial tumors. With the identification of substrate proteins such as P53, integrin αvβ3, MMP-2, and MMP-9, the biochemical mechanism of AEP in carcinomas is also more precise. This review will clarify the probable mechanisms of AEP in the progression of breast carcinoma, glioblastoma, gastric carcinoma, and epithelial ovarian carcinoma. This review will also discuss the feasibility of targeted therapy with AEP inhibitor (AEPI) in these carcinomas.
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17
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Mielcarska MB, Bossowska-Nowicka M, Toka FN. Cell Surface Expression of Endosomal Toll-Like Receptors-A Necessity or a Superfluous Duplication? Front Immunol 2021; 11:620972. [PMID: 33597952 PMCID: PMC7882679 DOI: 10.3389/fimmu.2020.620972] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 12/11/2020] [Indexed: 12/28/2022] Open
Abstract
Timely and precise delivery of the endosomal Toll-like receptors (TLRs) to the ligand recognition site is a critical event in mounting an effective antimicrobial immune response, however, the same TLRs should maintain the delicate balance of avoiding recognition of self-nucleic acids. Such sensing is widely known to start from endosomal compartments, but recently enough evidence has accumulated supporting the idea that TLR-mediated signaling pathways originating in the cell membrane may be engaged in various cells due to differential expression and distribution of the endosomal TLRs. Therefore, the presence of endosomal TLRs on the cell surface could benefit the host responses in certain cell types and/or organs. Although not fully understood why, TLR3, TLR7, and TLR9 may occur both in the cell membrane and intracellularly, and it seems that activation of the immune response can be initiated concurrently from these two sites in the cell. Furthermore, various forms of endosomal TLRs may be transported to the cell membrane, indicating that this may be a normal process orchestrated by cysteine proteases-cathepsins. Among the endosomal TLRs, TLR3 belongs to the evolutionary distinct group and engages a different protein adapter in the signaling cascade. The differently glycosylated forms of TLR3 are transported by UNC93B1 to the cell membrane, unlike TLR7, TLR8, and TLR9. The aim of this review is to reconcile various views on the cell surface positioning of endosomal TLRs and add perspective to the implication of such receptor localization on their function, with special attention to TLR3. Cell membrane-localized TLR3, TLR7, and TLR9 may contribute to endosomal TLR-mediated inflammatory signaling pathways. Dissecting this signaling axis may serve to better understand mechanisms influencing endosomal TLR-mediated inflammation, thus determine whether it is a necessity for immune response or simply a circumstantial superfluous duplication, with other consequences on immune response.
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Affiliation(s)
- Matylda Barbara Mielcarska
- Division of Immunology, Institute of Veterinary Medicine, Department of Preclinical Sciences, Warsaw University of Life Sciences, Warsaw, Poland
| | - Magdalena Bossowska-Nowicka
- Division of Immunology, Institute of Veterinary Medicine, Department of Preclinical Sciences, Warsaw University of Life Sciences, Warsaw, Poland
| | - Felix Ngosa Toka
- Division of Immunology, Institute of Veterinary Medicine, Department of Preclinical Sciences, Warsaw University of Life Sciences, Warsaw, Poland.,Center for Integrative Mammalian Research, Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, Saint Kitts and Nevis
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18
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Pišlar A, Mitrović A, Sabotič J, Pečar Fonović U, Perišić Nanut M, Jakoš T, Senjor E, Kos J. The role of cysteine peptidases in coronavirus cell entry and replication: The therapeutic potential of cathepsin inhibitors. PLoS Pathog 2020; 16:e1009013. [PMID: 33137165 PMCID: PMC7605623 DOI: 10.1371/journal.ppat.1009013] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Over the last 2 decades, several coronaviruses (CoVs) have crossed the species barrier into humans, causing highly prevalent and severe respiratory diseases, often with fatal outcomes. CoVs are a large group of enveloped, single-stranded, positive-sense RNA viruses, which encode large replicase polyproteins that are processed by viral peptidases to generate the nonstructural proteins (Nsps) that mediate viral RNA synthesis. Papain-like peptidases (PLPs) and chymotrypsin-like cysteine 3C-like peptidase are essential for coronaviral replication and represent attractive antiviral drug targets. Furthermore, CoVs utilize the activation of their envelope spike glycoproteins by host cell peptidases to gain entry into cells. CoVs have evolved multiple strategies for spike protein activation, including the utilization of lysosomal cysteine cathepsins. In this review, viral and host peptidases involved in CoV cell entry and replication are discussed in depth, with an emphasis on papain-like cysteine cathepsins. Furthermore, important findings on cysteine peptidase inhibitors with regard to virus attenuation are highlighted as well as the potential of such inhibitors for future treatment strategies for CoV-related diseases.
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Affiliation(s)
- Anja Pišlar
- Department of Pharmaceutical Biology, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Ana Mitrović
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Jerica Sabotič
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Urša Pečar Fonović
- Department of Pharmaceutical Biology, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | | | - Tanja Jakoš
- Department of Pharmaceutical Biology, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Emanuela Senjor
- Department of Pharmaceutical Biology, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Janko Kos
- Department of Pharmaceutical Biology, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
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19
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Gregersen I, Michelsen AE, Lunde NN, Åkerblom A, Lakic TG, Skjelland M, Ryeng Skagen K, Becker RC, Lindbäck J, Himmelmann A, Solberg R, Johansen HT, James SK, Siegbahn A, Storey RF, Kontny F, Aukrust P, Ueland T, Wallentin L, Halvorsen B. Legumain in Acute Coronary Syndromes: A Substudy of the PLATO (Platelet Inhibition and Patient Outcomes) Trial. J Am Heart Assoc 2020; 9:e016360. [PMID: 32809893 PMCID: PMC7660754 DOI: 10.1161/jaha.120.016360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Background The cysteine protease legumain is increased in patients with atherosclerosis, but its causal role in atherogenesis and cardiovascular disease is still unclear. The aim of the study was to investigate the association of legumain with clinical outcome in a large cohort of patients with acute coronary syndrome. Methods and Results Serum levels of legumain were analyzed in 4883 patients with acute coronary syndrome from a substudy of the PLATO (Platelet Inhibition and Patient Outcomes) trial. Levels were analyzed at admission and after 1 month follow-up. Associations between legumain and a composite of cardiovascular death, spontaneous myocardial infarction or stroke, and its individual components were assessed by multivariable Cox regression analyses. At baseline, a 50% increase in legumain level was associated with a hazard ratio (HR) of 1.13 (95% CI, 1.04-1.21), P=0.0018, for the primary composite end point, adjusted for randomized treatment. The association remained significant after adjustment for important clinical and demographic variables (HR, 1.10; 95% CI, 1.02-1.19; P=0.013) but not in the fully adjusted model. Legumain levels at 1 month were not associated with the composite end point but were negatively associated with stroke (HR, 0.62; 95% CI, 0.44-0.88; P=0.0069), including in the fully adjusted model (HR, 0.57; 95% CI, 0.37-0.88; P=0.0114). Conclusions Baseline legumain was associated with the primary outcome in patients with acute coronary syndrome, but not in the fully adjusted model. The association between high levels of legumain at 1 month and decreased occurrence of stroke could be of interest from a mechanistic point of view, illustrating the potential dual role of legumain during atherogenesis and acute coronary syndrome. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00391872.
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Affiliation(s)
- Ida Gregersen
- Research Institute for Internal Medicine Oslo University Hospital Rikshospitalet Oslo Norway.,Institute of Clinical Medicine Faculty of Medicine University of Oslo Norway
| | - Annika E Michelsen
- Research Institute for Internal Medicine Oslo University Hospital Rikshospitalet Oslo Norway.,Institute of Clinical Medicine Faculty of Medicine University of Oslo Norway
| | - Ngoc Nguyen Lunde
- Section of Pharmacology and Pharmaceutical Biosciences Department of Pharmacy University of Oslo Norway
| | - Axel Åkerblom
- Department of Medical Sciences, Cardiology and Uppsala Clinical Research Center Uppsala University Uppsala Sweden
| | - Tatevik G Lakic
- Uppsala Clinical Research Center Uppsala University Uppsala Sweden
| | - Mona Skjelland
- Department of Neurology Oslo University Hospital Rikshospitalet Oslo Norway
| | | | - Richard C Becker
- Division of Cardiovascular Health and Disease Heart, Lung and Vascular Institute Academic Health Center Cincinnati OH
| | - Johan Lindbäck
- Uppsala Clinical Research Center Uppsala University Uppsala Sweden
| | | | - Rigmor Solberg
- Section of Pharmacology and Pharmaceutical Biosciences Department of Pharmacy University of Oslo Norway
| | - Harald T Johansen
- Section of Pharmacology and Pharmaceutical Biosciences Department of Pharmacy University of Oslo Norway
| | - Stefan K James
- Department of Medical Sciences, Cardiology and Uppsala Clinical Research Center Uppsala University Uppsala Sweden
| | - Agneta Siegbahn
- Uppsala Clinical Research Center Uppsala University Uppsala Sweden
| | - Robert F Storey
- Department of Infection, Immunity and Cardiovascular Disease University of Sheffield Sheffield United Kingdom
| | - Frederic Kontny
- Department of Cardiology Stavanger University Hospital Stavanger Norway.,Drammen Heart Center Drammen Norway
| | - Pål Aukrust
- Research Institute for Internal Medicine Oslo University Hospital Rikshospitalet Oslo Norway.,Institute of Clinical Medicine Faculty of Medicine University of Oslo Norway.,Section of Clinical Immunology and Infectious Diseases Oslo University Hospital Rikshospitalet Oslo Norway.,K.G. Jebsen TREC The Faculty of Health Sciences The Arctic University of Tromsø Tromsø Norway
| | - Thor Ueland
- Research Institute for Internal Medicine Oslo University Hospital Rikshospitalet Oslo Norway.,Institute of Clinical Medicine Faculty of Medicine University of Oslo Norway.,K.G. Jebsen TREC The Faculty of Health Sciences The Arctic University of Tromsø Tromsø Norway
| | - Lars Wallentin
- Department of Medical Sciences, Cardiology and Uppsala Clinical Research Center Uppsala University Uppsala Sweden
| | - Bente Halvorsen
- Research Institute for Internal Medicine Oslo University Hospital Rikshospitalet Oslo Norway.,Institute of Clinical Medicine Faculty of Medicine University of Oslo Norway
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20
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van de Graaff MJ, Oosenbrug T, Marqvorsen MHS, Nascimento CR, de Geus MAR, Manoury B, Ressing ME, van Kasteren SI. Conditionally Controlling Human TLR2 Activity via Trans-Cyclooctene Caged Ligands. Bioconjug Chem 2020; 31:1685-1692. [PMID: 32510940 PMCID: PMC7303972 DOI: 10.1021/acs.bioconjchem.0c00237] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Toll-like
receptors (TLRs) are key pathogen sensors of the immune
system. Their activation results in the production of cytokines, chemokines,
and costimulatory molecules that are crucial for innate and adaptive
immune responses. In recent years, specific (sub)-cellular location
and timing of TLR activation have emerged as parameters for defining
the signaling outcome and magnitude. To study the subtlety of this
signaling, we here report a new molecular tool to control the activation
of TLR2 via “click-to-release”-chemistry. We conjugated
a bioorthogonal trans-cyclooctene (TCO) protecting group via solid
support to a critical position within a synthetic TLR2/6 ligand to
render the compound unable to initiate signaling. The TCO-group could
then be conditionally removed upon addition of a tetrazine, resulting
in restored agonist activity and TLR2 activation. This approach was
validated on RAW264.7 macrophages and various murine primary immune
cells as well as human cell line systems, demonstrating that TCO-caging
constitutes a versatile approach for generating chemically controllable
TLR2 agonists.
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Affiliation(s)
- Michel J van de Graaff
- Department of Bio-Organic Synthesis, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, Zuid-Holland, The Netherlands
| | - Timo Oosenbrug
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, Zuid-Holland, The Netherlands
| | - Mikkel H S Marqvorsen
- Department of Bio-Organic Synthesis, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, Zuid-Holland, The Netherlands
| | - Clarissa R Nascimento
- INEM, INSERM, Unité 1151-CNRS UMR 8253, Université de Paris, Faculté de Médecine, 156 Rue de Vaugirard, 75015 Paris, France
| | - Mark A R de Geus
- Department of Bio-Organic Synthesis, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, Zuid-Holland, The Netherlands
| | - Bénédicte Manoury
- INEM, INSERM, Unité 1151-CNRS UMR 8253, Université de Paris, Faculté de Médecine, 156 Rue de Vaugirard, 75015 Paris, France
| | - Maaike E Ressing
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, Zuid-Holland, The Netherlands
| | - Sander I van Kasteren
- Department of Bio-Organic Synthesis, Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, Zuid-Holland, The Netherlands
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21
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Tohme M, Maisonneuve L, Achour K, Dussiot M, Maschalidi S, Manoury B. TLR7 trafficking and signaling in B cells is regulated by the MHCII-associated invariant chain. J Cell Sci 2020; 133:jcs.236711. [PMID: 32079661 DOI: 10.1242/jcs.236711] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 02/04/2020] [Indexed: 11/20/2022] Open
Abstract
Toll-like receptor 7 (TLR7) is an endosomal receptor that recognizes single-stranded RNA from viruses. Its trafficking and activation is regulated by the endoplasmic reticulum (ER) chaperone UNC93B1 and lysosomal proteases. UNC93B1 also modulates major histocompatibility complex class II (MHCII) antigen presentation, and deficiency in MHCII protein diminishes TLR9 signaling. These results indicate a link between proteins that regulate both innate and adaptive responses. Here, we report that TLR7 resides in lysosomes and interacts with the MHCII-chaperone molecule, the invariant chain (Ii) or CD74, in B cells. In the absence of CD74, TLR7 displays both ER and lysosomal localization, leading to an increase in pro-inflammatory cytokine production. Furthermore, stimulation with TLR7 but not TLR9, is inefficient in boosting antigen presentation in Ii-deficient cells. In contrast, in B cells lacking TLR7 or mutated for UNC93B1, which are able to trigger TLR7 activation, antigen presentation is enhanced. This suggests that TLR7 signaling in B cells is controlled by the Ii chain.
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Affiliation(s)
- Mira Tohme
- Nkarta Therapeutics, South San Fransisco, CA 94080, USA
| | - Lucie Maisonneuve
- Institut Necker Enfant Malade, INSERM U1151-CNRS UMR 8253, 75015 Paris, France.,Université de Paris, Faculté de médecine, 75015 Paris, France
| | - Karim Achour
- Institut de recherche Servier, 3 rue de la république, 92150 Suresnes, France
| | - Michaël Dussiot
- Institut Imagine, INSERM U1163, CNRS ERL 8254, Université Paris Descartes, Sorbonne Paris-Cité, Laboratoire d'Excellence GR-Ex, 75015 Paris, France
| | - Sophia Maschalidi
- VIB-UGent Center for Inflammation Research, UGent-VIB Research Building FSVM, Technologiepark 71, 9052 Ghent, Belgium
| | - Bénédicte Manoury
- Institut Necker Enfant Malade, INSERM U1151-CNRS UMR 8253, 75015 Paris, France .,Université de Paris, Faculté de médecine, 75015 Paris, France
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22
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Dombkowski AA, Cukovic D, Bagla S, Jones M, Caruso JA, Chugani HT, Chugani DC. TLR7 activation in epilepsy of tuberous sclerosis complex. Inflamm Res 2019; 68:993-998. [PMID: 31511910 PMCID: PMC6823312 DOI: 10.1007/s00011-019-01283-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/30/2019] [Accepted: 09/05/2019] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Neuroinflammation and toll-like receptors (TLR) of the innate immune system have been implicated in epilepsy. We previously reported high levels of microRNAs miR-142-3p and miR-223-3p in epileptogenic brain tissue resected for the treatment of intractable epilepsy in children with tuberous sclerosis complex (TSC). As miR-142-3p has recently been reported to be a ligand and activator of TLR7, a detector of exogenous and endogenous single-stranded RNA, we evaluated TLR7 expression and downstream IL23A activation in surgically resected TSC brain tissue. METHODS Gene expression analysis was performed on cortical tissue obtained from surgery of TSC children with pharmacoresistent epilepsy. Expression of TLRs 2, 4 and 7 was measured using NanoString nCounter assays. Real-time quantitative PCR was used to confirm TLR7 expression and compare TLR7 activation, indicated by IL-23A levels, to levels of miR-142-3p. Protein markers characteristic for TLR7 activation were assessed using data from our existing quantitative proteomics dataset of TSC tissue. Capillary electrophoresis Western blots were used to confirm TLR7 protein expression in a subset of samples. RESULTS TLR7 transcript expression was present in all TSC specimens. The signaling competent form of TLR7 protein was detected in the membrane fraction of each sample tested. Downstream activation of TLR7 was found in epileptogenic lesions having elevated neuroinflammation indicated by clinical neuroimaging. TLR7 activity was significantly associated with tissue levels of miR-142-3p. CONCLUSION TLR7 activation by microRNAs may contribute to the neuroinflammatory cascade in epilepsy in TSC. Further characterization of this mechanism may enable the combined of use of neuroimaging and TLR7 inhibitors in a personalized approach towards the treatment of intractable epilepsy.
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Affiliation(s)
- Alan A Dombkowski
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA.
- Children's Hospital of Michigan, Clinical Pharmacology Room 3L22, 3901 Beaubien Blvd., Detroit, MI, 48201, USA.
| | - Daniela Cukovic
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA
| | - Shruti Bagla
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA
| | - McKenzie Jones
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA
| | - Joseph A Caruso
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI, 48201, USA
| | - Harry T Chugani
- Katzin Diagnostic and Research PET/MR Center, Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, USA
- Department of Neurology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Diane C Chugani
- Katzin Diagnostic and Research PET/MR Center, Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, USA
- Departments of Communication Sciences and Disorders, and Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
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23
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Martínez-Fábregas J, Prescott A, van Kasteren S, Pedrioli DL, McLean I, Moles A, Reinheckel T, Poli V, Watts C. Lysosomal protease deficiency or substrate overload induces an oxidative-stress mediated STAT3-dependent pathway of lysosomal homeostasis. Nat Commun 2018; 9:5343. [PMID: 30559339 PMCID: PMC6297226 DOI: 10.1038/s41467-018-07741-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 11/18/2018] [Indexed: 12/21/2022] Open
Abstract
Diverse cellular processes depend on the lysosomal protease system but how cells regulate lysosomal proteolytic capacity is only partly understood. We show here that cells can respond to protease/substrate imbalance in this compartment by de novo expression of multiple lysosomal hydrolases. This response, exemplified here either by loss of asparagine endopeptidase (AEP) or other lysosomal cysteine proteases, or by increased endocytic substrate load, is not dependent on the transcription factor EB (TFEB) but rather is triggered by STAT3 activation downstream of lysosomal oxidative stress. Similar lysosomal adaptations are seen in mice and cells expressing a constitutively active form of STAT3. Our results reveal how cells can increase lysosomal protease capacity under ‘fed’ rather than ‘starved’ conditions that activate the TFEB system. In addition, STAT3 activation due to lysosomal stress likely explains the hyperproliferative kidney disease and splenomegaly observed in AEP-deficient mice. How cells regulate their lysosomal proteolytic capacity is only partly understood. Here, the authors show that lysosomal protease deficiency or substrate overload induces lysosomal stress leading to activation of a STAT3-dependent, TFEB-independent pathway of lysosomal hydrolase expression.
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Affiliation(s)
- Jonathan Martínez-Fábregas
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
| | - Alan Prescott
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Sander van Kasteren
- Division of Bio-Organic Chemistry, Leiden Institute of Chemistry, Einsteinweg 55, Leiden, 2333CC, Netherlands
| | - Deena Leslie Pedrioli
- Division of Molecular Medicine, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.,Department of Molecular Mechanisms of Disease, University of Zurich, Winterthurestrasse190, 8057 Zurich, Switzerland
| | - Irwin McLean
- Division of Molecular Medicine, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Anna Moles
- Fibrosis Research Group, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.,Institute of Biomedical Research of Barcelona, Spanish Research Council, Barcelona, 08036, Spain
| | - Thomas Reinheckel
- Institute of Molecular Medicine and Cell Research, Medical Faculty, Albert-Ludwigs-University, Freiburg, D-79104, Germany
| | - Valeria Poli
- Department of Genetics, Biology and Biochemistry, University of Turin, Via Nizza 52, 10126, Turin, Italy
| | - Colin Watts
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
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24
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Tatematsu M, Funami K, Seya T, Matsumoto M. Extracellular RNA Sensing by Pattern Recognition Receptors. J Innate Immun 2018; 10:398-406. [PMID: 30404092 PMCID: PMC6784046 DOI: 10.1159/000494034] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 09/25/2018] [Accepted: 09/25/2018] [Indexed: 12/11/2022] Open
Abstract
RNA works as a genome and messenger in RNA viruses, and it sends messages in most of the creatures of the Earth, including viruses, bacteria, fungi, plants, and animals. The human innate immune system has evolved to detect single- and double-stranded RNA molecules from microbes by pattern recognition receptors and induce defense reactions against infections such as the production of type I interferons and inflammatory cytokines. To avoid cytokine toxicity causing chronic inflammation or autoimmunity by sensing self-RNA, the activation of RNA sensors is strictly regulated. All of the Toll-like receptors that recognize RNA are localized to endosomes/lysosomes, which require internalization of RNA for sensing through an endocytic pathway. RIG-I-like receptors sense RNA in cytosol. These receptors are expressed in a cell type-specific fashion, enabling sensing of RNA for a wide range of microbial invasions. At the same time, both endosomal and cytoplasmic receptors have strategies to respond only to RNA of pathogenic microorganisms or dying cells. RNA are potential vaccine adjuvants for immune enhancement against cancer and provide a benefit for vaccinations. Understanding the detailed molecular mechanisms of the RNA-sensing system will help us to broaden the clinical utility of RNA adjuvants for patients with incurable diseases.
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Affiliation(s)
- Megumi Tatematsu
- Department of Vaccine Immunology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
- Dr. von Hauner Children's Hospital, Department of Pediatrics, University Hospital, LMU Munich, Munich, Germany
| | - Kenji Funami
- Department of Vaccine Immunology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Tsukasa Seya
- Department of Vaccine Immunology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Misako Matsumoto
- Department of Vaccine Immunology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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25
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Shen ZJ, Hu J, Kashi V, Bochkov YA, Gern JE, Malter JS. TLR-7 Stress Signaling in Differentiating and Mature Eosinophils Is Mediated by the Prolyl Isomerase Pin1. THE JOURNAL OF IMMUNOLOGY 2018; 201:3503-3513. [PMID: 30397031 DOI: 10.4049/jimmunol.1800881] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 10/01/2018] [Indexed: 12/30/2022]
Abstract
The response of eosinophils (Eos) to respiratory virus has emerged as an important link between pulmonary infection and allergic asthmatic exacerbations. Eos activate innate immune responses through TLR signaling. In this study, using mouse and human Eos and mice lacking the prolyl isomerase Pin1 selectively in Eos, we show that Pin1 is indispensable for eosinophilopoiesis in the bone marrow (BM) and mature cell function in the presence of TLR7 activation. Unbiased in vivo analysis of mouse models of allergic airway inflammation revealed that TLR7 activation in knockout mice resulted in systemic loss of Eos, reduced IFN production, and an inability to clear respiratory viruses. Consistent with this finding, BM mouse Eos progenitors lacking Pin1 showed markedly reduced cell proliferation and survival after TLR7 activation. Mechanistically, unlike wild-type cells, Pin1 null mouse Eos were defective in the activation of the endoplasmic reticulum stress-induced unfolded protein response. We observed significant reductions in the expression of unfolded protein response components and target genes, aberrant TLR7 cleavage and trafficking, and reduced granule protein production in knockout Eos. Our data strongly suggest that Pin1 is required for BM Eos generation and function during concurrent allergen challenge and viral infection.
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Affiliation(s)
- Zhong-Jian Shen
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390;
| | - Jie Hu
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Venkatesh Kashi
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Yury A Bochkov
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI; and
| | - James E Gern
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI; and.,Department of Medicine, University of Wisconsin-Madison, Madison, WI 53792
| | - James S Malter
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390;
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26
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Tan X, Sun L, Chen J, Chen ZJ. Detection of Microbial Infections Through Innate Immune Sensing of Nucleic Acids. Annu Rev Microbiol 2018; 72:447-478. [DOI: 10.1146/annurev-micro-102215-095605] [Citation(s) in RCA: 221] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microbial infections are recognized by the innate immune system through germline-encoded pattern recognition receptors (PRRs). As most microbial pathogens contain DNA and/or RNA during their life cycle, nucleic acid sensing has evolved as an essential strategy for host innate immune defense. Pathogen-derived nucleic acids with distinct features are recognized by specific host PRRs localized in endolysosomes and the cytosol. Activation of these PRRs triggers signaling cascades that culminate in the production of type I interferons and proinflammatory cytokines, leading to induction of an antimicrobial state, activation of adaptive immunity, and eventual clearance of the infection. Here, we review recent progress in innate immune recognition of nucleic acids upon microbial infection, including pathways involving endosomal Toll-like receptors, cytosolic RNA sensors, and cytosolic DNA sensors. We also discuss the mechanisms by which infectious microbes counteract host nucleic acid sensing to evade immune surveillance.
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Affiliation(s)
- Xiaojun Tan
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA;, , , ,
- Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Lijun Sun
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA;, , , ,
- Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA
| | - Jueqi Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA;, , , ,
- Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Zhijian J. Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA;, , , ,
- Center for Inflammation Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA
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27
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Abstract
Microbial nucleic acids are major signatures of invading pathogens, and their recognition by various host pattern recognition receptors (PRRs) represents the first step toward an efficient innate immune response to clear the pathogens. The nucleic acid-sensing PRRs are localized at the plasma membrane, the cytosol, and/or various cellular organelles. Sensing of nucleic acids and signaling by PRRs involve recruitment of distinct signaling components, and PRRs are intensively regulated by cellular organelle trafficking. PRR-mediated innate immune responses are also heavily regulated by posttranslational modifications, including phosphorylation, polyubiquitination, sumoylation, and glutamylation. In this review, we focus on our current understanding of recognition of microbial nucleic acid by PRRs, particularly on their regulation by organelle trafficking and posttranslational modifications. We also discuss how sensing of self nucleic acids and dysregulation of PRR-mediated signaling lead to serious human diseases.
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Affiliation(s)
- Ming-Ming Hu
- Medical Research Institute, School of Medicine, Wuhan University, Wuhan 430071, China; ,
| | - Hong-Bing Shu
- Medical Research Institute, School of Medicine, Wuhan University, Wuhan 430071, China; ,
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28
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Ascough S, Paterson S, Chiu C. Induction and Subversion of Human Protective Immunity: Contrasting Influenza and Respiratory Syncytial Virus. Front Immunol 2018; 9:323. [PMID: 29552008 PMCID: PMC5840263 DOI: 10.3389/fimmu.2018.00323] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 02/06/2018] [Indexed: 12/15/2022] Open
Abstract
Respiratory syncytial virus (RSV) and influenza are among the most important causes of severe respiratory disease worldwide. Despite the clinical need, barriers to developing reliably effective vaccines against these viruses have remained firmly in place for decades. Overcoming these hurdles requires better understanding of human immunity and the strategies by which these pathogens evade it. Although superficially similar, the virology and host response to RSV and influenza are strikingly distinct. Influenza induces robust strain-specific immunity following natural infection, although protection by current vaccines is short-lived. In contrast, even strain-specific protection is incomplete after RSV and there are currently no licensed RSV vaccines. Although animal models have been critical for developing a fundamental understanding of antiviral immunity, extrapolating to human disease has been problematic. It is only with recent translational advances (such as controlled human infection models and high-dimensional technologies) that the mechanisms responsible for differences in protection against RSV compared to influenza have begun to be elucidated in the human context. Influenza infection elicits high-affinity IgA in the respiratory tract and virus-specific IgG, which correlates with protection. Long-lived influenza-specific T cells have also been shown to ameliorate disease. This robust immunity promotes rapid emergence of antigenic variants leading to immune escape. RSV differs markedly, as reinfection with similar strains occurs despite natural infection inducing high levels of antibody against conserved antigens. The immunomodulatory mechanisms of RSV are thus highly effective in inhibiting long-term protection, with disturbance of type I interferon signaling, antigen presentation and chemokine-induced inflammation possibly all contributing. These lead to widespread effects on adaptive immunity with impaired B cell memory and reduced T cell generation and functionality. Here, we discuss the differences in clinical outcome and immune response following influenza and RSV. Specifically, we focus on differences in their recognition by innate immunity; the strategies used by each virus to evade these early immune responses; and effects across the innate-adaptive interface that may prevent long-lived memory generation. Thus, by comparing these globally important pathogens, we highlight mechanisms by which optimal antiviral immunity may be better induced and discuss the potential for these insights to inform novel vaccines.
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Affiliation(s)
- Stephanie Ascough
- Section of Infectious Diseases and Immunity, Imperial College London, London, United Kingdom
| | - Suzanna Paterson
- Section of Infectious Diseases and Immunity, Imperial College London, London, United Kingdom
| | - Christopher Chiu
- Section of Infectious Diseases and Immunity, Imperial College London, London, United Kingdom
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29
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Gentile F, Deriu MA, Barakat K, Danani A, Tuszynski J. A Novel Interaction Between the TLR7 and a Colchicine Derivative Revealed Through a Computational and Experimental Study. Pharmaceuticals (Basel) 2018; 11:ph11010022. [PMID: 29462934 PMCID: PMC5874718 DOI: 10.3390/ph11010022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 02/01/2018] [Accepted: 02/13/2018] [Indexed: 01/05/2023] Open
Abstract
The Toll-Like Receptor 7 (TLR7) is an endosomal membrane receptor involved in the innate immune system response. Its best-known small molecule activators are imidazoquinoline derivatives such as imiquimod (R-837) and resiquimod (R-848). Recently, an interaction between R-837 and the colchicine binding site of tubulin was reported. To investigate the possibility of an interaction between structural analogues of colchicine and the TLR7, a recent computational model for the dimeric form of the TLR7 receptor was used to determine a possible interaction with a colchicine derivative called CR42-24, active as a tubulin polymerization inhibitor. The estimated values of the binding energy of this molecule with respect to the TLR7 receptor were comparable to the energies of known binders as reported in a previous study. The binding to the TLR7 was further assessed by introducing genetic transformations in the TLR7 gene in cancer cell lines and exposing them to the compound. A negative shift of the IC50 value in terms of cell growth was observed in cell lines carrying the mutated TLR7 gene. The reported study suggests a possible interaction between TLR7 and a colchicine derivative, which can be explored for rational design of new drugs acting on this receptor by using a colchicine scaffold for additional modifications.
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Affiliation(s)
- Francesco Gentile
- Department of Physics, University of Alberta, AB T6G 2E1 Edmonton, Canada.
| | - Marco A Deriu
- Istituto Dalle Molle di Studi Sull'intelligenza Artificiale (IDSIA), Scuola Universitaria Professionale della Svizzera Italiana (SUPSI), Università della Svizzera Italiana (USI), CH-6928 Manno, Switzerland.
| | - Khaled Barakat
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, AB T6G 2H1 Edmonton, Canada.
| | - Andrea Danani
- Istituto Dalle Molle di Studi Sull'intelligenza Artificiale (IDSIA), Scuola Universitaria Professionale della Svizzera Italiana (SUPSI), Università della Svizzera Italiana (USI), CH-6928 Manno, Switzerland.
| | - Jack Tuszynski
- Department of Physics, University of Alberta, AB T6G 2E1 Edmonton, Canada.
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Torino, Italy.
- Department of Oncology, University of Alberta, AB T6G 1Z2 Edmonton, Canada.
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30
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Maschalidi S, Nunes-Hasler P, Nascimento CR, Sallent I, Lannoy V, Garfa-Traore M, Cagnard N, Sepulveda FE, Vargas P, Lennon-Duménil AM, van Endert P, Capiod T, Demaurex N, Darrasse-Jèze G, Manoury B. UNC93B1 interacts with the calcium sensor STIM1 for efficient antigen cross-presentation in dendritic cells. Nat Commun 2017; 8:1640. [PMID: 29158474 PMCID: PMC5696382 DOI: 10.1038/s41467-017-01601-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 10/02/2017] [Indexed: 11/25/2022] Open
Abstract
Dendritic cells (DC) have the unique ability to present exogenous antigens via the major histocompatibility complex class I pathway to stimulate naive CD8+ T cells. In DCs with a non-functional mutation in Unc93b1 (3d mutation), endosomal acidification, phagosomal maturation, antigen degradation, antigen export to the cytosol and the function of the store-operated-Ca2+-entry regulator STIM1 are impaired. These defects result in compromised antigen cross-presentation and anti-tumor responses in 3d-mutated mice. Here, we show that UNC93B1 interacts with the calcium sensor STIM1 in the endoplasmic reticulum, a critical step for STIM1 oligomerization and activation. Expression of a constitutively active STIM1 mutant, which no longer binds UNC93B1, restores antigen degradation and cross-presentation in 3d-mutated DCs. Furthermore, ablation of STIM1 in mouse and human cells leads to a decrease in cross-presentation. Our data indicate that the UNC93B1 and STIM1 cooperation is important for calcium flux and antigen cross-presentation in DCs. STIM proteins sense Ca2+ depletion in the ER and activate store-operated Ca2+ entry in response, a process associated with dendritic cell (DC) functions. Here, the authors show that optimal antigen cross-presentation in DCs requires the association of the chaperone molecule UNC93B1 with STIM1.
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Affiliation(s)
- Sophia Maschalidi
- INSERM UMR1163, Laboratory of Normal and Pathological Homeostasis of the Immune System, Imagine Institute, 75015, Paris, France.,Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France
| | - Paula Nunes-Hasler
- Department of Cell Physiology and Metabolism, University of Geneva, CH-1211, Geneva, Switzerland
| | - Clarissa R Nascimento
- Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France.,Institut National de la Santé et de la Recherche Médicale, Unité 1151, 75015, Paris, France.,Centre National de la Recherche Scientifique, UMR 8253, 75015, Paris, France
| | - Ignacio Sallent
- Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France.,Institut National de la Santé et de la Recherche Médicale, Unité 1151, 75015, Paris, France.,Centre National de la Recherche Scientifique, UMR 8253, 75015, Paris, France
| | - Valérie Lannoy
- Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France.,Institut National de la Santé et de la Recherche Médicale, Unité 1151, 75015, Paris, France.,Centre National de la Recherche Scientifique, UMR 8253, 75015, Paris, France
| | - Meriem Garfa-Traore
- Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France.,Cell Imaging and Bioinformatic Platform, INSERM US24 Structure Federative de Recherche Necker, 75015, Paris, France
| | - Nicolas Cagnard
- Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France.,Cell Imaging and Bioinformatic Platform, INSERM US24 Structure Federative de Recherche Necker, 75015, Paris, France
| | - Fernando E Sepulveda
- INSERM UMR1163, Laboratory of Normal and Pathological Homeostasis of the Immune System, Imagine Institute, 75015, Paris, France.,Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France
| | - Pablo Vargas
- Institut Curie, PSL Research University, Centre National de la Recherche Scientifique, UMR 144, 75005, Paris, France.,Institut Pierre-Gilles de Genes, PSL Research University, 75005, Paris, France
| | - Ana-Maria Lennon-Duménil
- Institut National de la Santé et de la Recherché Médicale, Unité 932, Institut Curie, PSL Research University, 75005, Paris, France
| | - Peter van Endert
- Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France.,Institut National de la Santé et de la Recherche Médicale, Unité 1151, 75015, Paris, France.,Centre National de la Recherche Scientifique, UMR 8253, 75015, Paris, France
| | - Thierry Capiod
- Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France.,Institut National de la Santé et de la Recherche Médicale, Unité 1151, 75015, Paris, France.,Centre National de la Recherche Scientifique, UMR 8253, 75015, Paris, France
| | - Nicolas Demaurex
- Department of Cell Physiology and Metabolism, University of Geneva, CH-1211, Geneva, Switzerland
| | - Guillaume Darrasse-Jèze
- Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France.,Institut National de la Santé et de la Recherche Médicale, Unité 1151, 75015, Paris, France.,Centre National de la Recherche Scientifique, UMR 8253, 75015, Paris, France
| | - Bénédicte Manoury
- Faculté de médecine Paris Descartes, Université Paris Descartes, 75015, Paris, France. .,Institut National de la Santé et de la Recherche Médicale, Unité 1151, 75015, Paris, France. .,Centre National de la Recherche Scientifique, UMR 8253, 75015, Paris, France.
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31
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Petes C, Odoardi N, Gee K. The Toll for Trafficking: Toll-Like Receptor 7 Delivery to the Endosome. Front Immunol 2017; 8:1075. [PMID: 28928743 PMCID: PMC5591332 DOI: 10.3389/fimmu.2017.01075] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 08/18/2017] [Indexed: 01/12/2023] Open
Abstract
Toll-like receptor (TLR)-7 is an endosomal innate immune sensor capable of detecting single-stranded ribonucleic acid. TLR7-mediated induction of type I interferon and other inflammatory cytokine production is important in antiviral immune responses. Furthermore, altered TLR7 expression levels are implicated in various autoimmune disorders, indicating a key role for this receptor in modulating inflammation. This review is focused on the regulation of TLR7 expression and localization compared to that of the other endosomal TLRs: TLR3, 8, and 9. Endosomal TLR localization is a tightly controlled and intricate process with some shared components among various TLRs. However, TLR-specific mechanisms must also be in place in order to regulate the induction of pathogen- and cell-specific responses. It is known that TLR7 is shuttled from the endoplasmic reticulum to the endosome via vesicles from the Golgi. Several chaperone proteins are required for this process, most notably uncoordinated 93 homolog B1 (Caenorhabditis elegans), recently identified to also be involved in the localization of the other endosomal TLRs. Acidification of the endosome and proteolytic cleavage of TLR7 are essential for TLR7 signaling in response to ligand binding. Cleavage of TLR7 has been demonstrated to be accomplished by furin peptidases in addition to cathepsins and asparagine endopeptidases. Moreover, triggering receptor expressed on myeloid cells like 4, a protein associated with antigen presentation and apoptosis in immune cells, has been implicated in the amplification of TLR7 signaling. Understanding these and other molecular mechanisms controlling TLR7 expression and trafficking will give insight into the specific control of TLR7 activity compared to the other endosomal TLRs.
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Affiliation(s)
- Carlene Petes
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Natalya Odoardi
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Katrina Gee
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
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IRAP + endosomes restrict TLR9 activation and signaling. Nat Immunol 2017; 18:509-518. [PMID: 28319098 DOI: 10.1038/ni.3711] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 02/14/2017] [Indexed: 12/16/2022]
Abstract
The retention of intracellular Toll-like receptors (TLRs) in the endoplasmic reticulum prevents their activation under basal conditions. TLR9 is activated by sensing ligands in specific endosomal-lysosomal compartments. Here we identified IRAP+ endosomes as major cellular compartments for the early steps of TLR9 activation in dendritic cells (DCs). Both TLR9 and its ligand, the dinucleotide CpG, were present as cargo in IRAP+ endosomes. In the absence of the aminopeptidase IRAP, the trafficking of CpG and TLR9 to lysosomes and signaling via TLR9 were enhanced in DCs and in mice following bacterial infection. IRAP stabilized CpG-containing endosomes by interacting with the actin-nucleation factor FHOD4, which slowed the trafficking of TLR9 toward lysosomes. Thus, endosomal retention of TLR9 via the interaction of IRAP with the actin cytoskeleton is a mechanism that prevents hyper-activation of TLR9 in DCs.
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Zhang Z, Xie M, Ye K. Asparagine endopeptidase is an innovative therapeutic target for neurodegenerative diseases. Expert Opin Ther Targets 2016; 20:1237-45. [PMID: 27115710 DOI: 10.1080/14728222.2016.1182990] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Asparagine endopeptidase (AEP) is a pH-dependent endolysosomal cysteine protease that cleaves its substrates after asparagine residues. Our most recent study identifies that it possesses the delta-secretase activity, and that it is implicated in numerous neurological diseases such as Alzheimer's disease (AD) and stroke. Accumulating evidence supports that the inhibition of AEP exhibits beneficial effects for treating these devastating diseases. AREAS COVERED Based on recent evidence, it is clear that AEP cleaves its substrate, such as amyloid precursor protein (APP), tau and SET, and plays a critical role in neuronal cell death in various neurodegenerative diseases and stroke. In this article, the basic biology of AEP, its knockout phenotypes in mouse models, its substrates in neurodegenerative diseases, and its small peptidyl inhibitors and prodrugs are discussed. In addition, we discuss the potential of AEP as a novel therapeutic target for neurodegenerative diseases. EXPERT OPINION AEP plays a unique role in numerous biological processes, depending on both pH and context. Most striking is our most recent finding; that AEP is activated in an age-dependent manner and simultaneously cleaves both APP and tau, thereby unifying both major pathological events in AD. Thus, AEP acts as an innovative trigger for neurodegenerative diseases. Inhibition of AEP will provide a disease-modifying treatment for neurodegenerative diseases including AD.
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Affiliation(s)
- Zhentao Zhang
- a Department of Neurology , Renmin Hospital of Wuhan University , Wuhan , China.,b Department of Pathology and Laboratory Medicine , Emory University School of Medicine , Atlanta , GA , USA
| | - Manling Xie
- b Department of Pathology and Laboratory Medicine , Emory University School of Medicine , Atlanta , GA , USA
| | - Keqiang Ye
- b Department of Pathology and Laboratory Medicine , Emory University School of Medicine , Atlanta , GA , USA
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Ohto U, Shimizu T. Structural aspects of nucleic acid-sensing Toll-like receptors. Biophys Rev 2016; 8:33-43. [PMID: 28510149 DOI: 10.1007/s12551-015-0187-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 12/03/2015] [Indexed: 02/25/2023] Open
Abstract
Invading pathogens elicit potent immune responses in cells through interactions between structurally conserved molecules derived from the pathogens and specialized innate immune receptors such as the Toll-like receptors (TLRs). Nucleic acid is one of the principal TLR ligands. Nucleic acid-sensing TLRs recognize an array of nucleic acids, including double-stranded RNA, single-stranded RNA, and DNAs with specific sequence motifs. Although ligand-induced dimerization is commonly observed followed by TLR activation, both the specific recognition mechanisms and the ligand-receptor interactions vary among different TLRs. In this review, we highlight our current understanding of how these receptors recognize their cognate ligands based on the recent advances in structural biology.
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Affiliation(s)
- Umeharu Ohto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Toshiyuki Shimizu
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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Structure and function of legumain in health and disease. Biochimie 2015; 122:126-50. [PMID: 26403494 DOI: 10.1016/j.biochi.2015.09.022] [Citation(s) in RCA: 194] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 09/18/2015] [Indexed: 12/27/2022]
Abstract
The last years have seen a steady increase in our understanding of legumain biology that is driven from two largely uncoupled research arenas, the mammalian and the plant legumain field. Research on legumain, which is also referred to as asparaginyl endopeptidase (AEP) or vacuolar processing enzyme (VPE), is slivered, however. Here we summarise recent important findings and put them into a common perspective. Legumain is usually associated with its cysteine endopeptidase activity in lysosomes where it contributes to antigen processing for class II MHC presentation. However, newly recognized functions disperse previously assumed boundaries with respect to their cellular compartmentalisation and enzymatic activities. Legumain is also found extracellularly and even translocates to the cytosol and the nucleus, with seemingly incompatible pH and redox potential. These different milieus translate into changes of legumain's molecular properties, including its (auto-)activation, conformational stability and enzymatic functions. Contrasting its endopeptidase activity, legumain can develop a carboxypeptidase activity which remains stable at neutral pH. Moreover, legumain features a peptide ligase activity, with intriguing mechanistic peculiarities in plant and human isoforms. In pathological settings, such as cancer or Alzheimer's disease, the proper association of legumain activities with the corresponding cellular compartments is breached. Legumain's increasingly recognized physiological and pathological roles also indicate future research opportunities in this vibrant field.
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Abstract
The innate immune system provides the first barrier against pathogens. Intracellular Toll-like receptors (TLR3, 7 and 9) localise in endosomes and sense nucleotides from viruses and bacteria. This recognition induces their conformational changes resulting in the production of proinflammatory cytokines and MHC class II (MHCII) antigenic presentation. In the absence of stimulation, TLRs are retained in the endoplasmic reticulum. Upon stimulation, they relocate to the endo-lysosomal compartment, allowing the recruitment of the adaptor molecules, MyD88 or TRIF. Increasing evidences describe a cross talk between proteins that regulate both innate and adaptive immune responses. For example, proteolytic enzymes which are required for breaking down exogenous antigen to generate suitable peptides for MHCII molecules are also essential to activate endosomal TLRs and MHCII molecules were recently described to regulate TLR signalling. But other proteins are possibly involved and regulated differentially between cell types. We have observed that intracellular TLR trafficking and signalling in B cells are different from dendritic cells and macrophages and involved the MHCII chaperone molecule, the invariant chain (Ii).
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Hipp MM, Shepherd D, Booth S, Waithe D, Reis e Sousa C, Cerundolo V. The Processed Amino-Terminal Fragment of Human TLR7 Acts as a Chaperone To Direct Human TLR7 into Endosomes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2015; 194:5417-25. [PMID: 25917086 PMCID: PMC4432728 DOI: 10.4049/jimmunol.1402703] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 03/25/2015] [Indexed: 11/28/2022]
Abstract
TLR7 mediates innate immune responses to viral RNA in endocytic compartments. Mouse and human (h)TLR7 undergo proteolytic cleavage, resulting in the generation of a C-terminal fragment that accumulates in endosomes and associates with the signaling adaptor MyD88 upon receptor triggering by TLR7 agonists. Although mouse TLR7 is cleaved in endosomes by acidic proteases, hTLR7 processing can occur at neutral pH throughout the secretory pathway through the activity of furin-like proprotein convertases. However, the mechanisms by which cleaved hTLR7 reaches the endosomal compartment remain unclear. In this study, we demonstrate that, after hTLR7 proteolytic processing, the liberated amino (N)-terminal fragment remains bound to the C terminus through disulfide bonds and provides key trafficking information that ensures correct delivery of the complex to endosomal compartments. In the absence of the N-terminal fragment, the C-terminal fragment is redirected to the cell surface, where it is functionally inactive. Our data reveal a novel role for the N terminus of hTLR7 as a molecular chaperone that provides processed hTLR7 with the correct targeting instructions to reach the endosomal compartment, hence ensuring its biological activity and preventing inadvertent cell surface responses to self-RNA.
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Affiliation(s)
- Madeleine M Hipp
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, United Kingdom; and
| | - Dawn Shepherd
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, United Kingdom; and
| | - Sarah Booth
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, United Kingdom; and
| | - Dominic Waithe
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, United Kingdom; and
| | - Caetano Reis e Sousa
- The Francis Crick Institute, Lincoln's Inn Fields Laboratory, London WC2A 3LY, United Kingdom
| | - Vincenzo Cerundolo
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, United Kingdom; and
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Gentile F, Deriu MA, Licandro G, Prunotto A, Danani A, Tuszynski JA. Structure Based Modeling of Small Molecules Binding to the TLR7 by Atomistic Level Simulations. Molecules 2015; 20:8316-40. [PMID: 26007168 PMCID: PMC6272798 DOI: 10.3390/molecules20058316] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 04/17/2015] [Accepted: 04/30/2015] [Indexed: 12/15/2022] Open
Abstract
Toll-Like Receptors (TLR) are a large family of proteins involved in the immune system response. Both the activation and the inhibition of these receptors can have positive effects on several diseases, including viral pathologies and cancer, therefore prompting the development of new compounds. In order to provide new indications for the design of Toll-Like Receptor 7 (TLR7)-targeting drugs, the mechanism of interaction between the TLR7 and two important classes of agonists (imidazoquinoline and adenine derivatives) was investigated through docking and Molecular Dynamics simulations. To perform the computational analysis, a new model for the dimeric form of the receptors was necessary and therefore created. Qualitative and quantitative differences between agonists and inactive compounds were determined. The in silico results were compared with previous experimental observations and employed to define the ligand binding mechanism of TLR7.
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Affiliation(s)
- Francesco Gentile
- Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada.
| | - Marco A Deriu
- Institute of Computer Integrated Manufacturing for Sustainable Innovation, Department of Innovative Technologies, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Manno CH-6928, Switzerland.
| | - Ginevra Licandro
- Institute of Computer Integrated Manufacturing for Sustainable Innovation, Department of Innovative Technologies, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Manno CH-6928, Switzerland.
| | - Alessio Prunotto
- Institute of Computer Integrated Manufacturing for Sustainable Innovation, Department of Innovative Technologies, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Manno CH-6928, Switzerland.
| | - Andrea Danani
- Institute of Computer Integrated Manufacturing for Sustainable Innovation, Department of Innovative Technologies, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Manno CH-6928, Switzerland.
| | - Jack A Tuszynski
- Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada.
- Cross Cancer Institute, Department of Oncology, University of Alberta, Edmonton, AB T6G 1Z2, Canada.
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Chow J, Franz KM, Kagan JC. PRRs are watching you: Localization of innate sensing and signaling regulators. Virology 2015; 479-480:104-9. [PMID: 25800355 PMCID: PMC4424080 DOI: 10.1016/j.virol.2015.02.051] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/24/2015] [Accepted: 02/27/2015] [Indexed: 12/24/2022]
Abstract
To prevent the spread of infection, an invading pathogen must first be recognized by the innate immune system. Host pattern recognition receptors detect distinct pathogen-associated molecules and induce the transcription and release of interferon and inflammatory molecules to resolve infection. Unlike infections with pathogens that replicate autonomously from the host, viral infections blur the boundaries of self and non-self. Differentiation of host from virus is achieved by restricting localization of host nucleic acids and by placing pattern recognition receptors in specific subcellular compartments. Within this review, we discuss how several families of pattern recognition receptors act to provide a comprehensive surveillance network that has the potential to induce interferon expression in response to any viral infection.
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Affiliation(s)
- Jonathan Chow
- Division of Gastroenterology, Boston Children׳s Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Immunology, Harvard Medical School, Boston, MA 02115, USA
| | - Kate M Franz
- Division of Gastroenterology, Boston Children׳s Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Virology, Harvard Medical School, Boston, MA 02115, USA
| | - Jonathan C Kagan
- Division of Gastroenterology, Boston Children׳s Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Immunology, Harvard Medical School, Boston, MA 02115, USA; Program in Virology, Harvard Medical School, Boston, MA 02115, USA.
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40
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Rimbach K, Kaiser S, Helm M, Dalpke AH, Eigenbrod T. 2'-O-Methylation within Bacterial RNA Acts as Suppressor of TLR7/TLR8 Activation in Human Innate Immune Cells. J Innate Immun 2015; 7:482-93. [PMID: 25823462 DOI: 10.1159/000375460] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 01/23/2015] [Indexed: 12/25/2022] Open
Abstract
Microbial RNA is an important stimulator of innate immune responses. Differences in posttranscriptional RNA modification profiles enable the immune system to discriminate between self and non-self nucleic acids. This principle may be exploited by certain bacteria to circumvent immune cell activation. In this regard, 2'-O-methylation of Escherichia coli tRNATyr at position 18 (Gm18) has recently been described to inhibit TLR7-mediated IFN-α production in human plasmacytoid dendritic cells (pDCs). Extending these findings, we now demonstrate that Gm18 also potently inhibits TLR7-independent human monocyte activation by RNA derived from a variety of bacterial strains. The half minimal inhibitory concentration values were similar to those found for IFN-α inhibition in pDCs. Mechanistically, 2'-O-methylated RNA impaired upstream signalling events, including MAP kinase and NFx03BA;B activation. Our results suggest that antagonizing effects of Gm18-modified RNA are due to competition with stimulatory RNA for receptor binding. The antagonistic effect was specific for RNA because the small molecule TLR7/8 agonist R848 was not inhibited. Despite the striking phenotype in human cells, 2'-O-methylated RNA did not interfere with TLR13 activation by bacterial 23S rRNA in murine DC and BMDM. Thus, we identify here Gm18 in E. coli tRNA(Tyr) as a universal suppressor of innate immune activation in the human but not the murine system.
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Affiliation(s)
- Katharina Rimbach
- Department of Infectious Diseases, Medical Microbiology and Hygiene, University of Heidelberg, Heidelberg, Germany
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41
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Local mitochondrial-endolysosomal microfusion cleaves voltage-dependent anion channel 1 to promote survival in hypoxia. Mol Cell Biol 2015; 35:1491-505. [PMID: 25691661 DOI: 10.1128/mcb.01402-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 02/06/2015] [Indexed: 12/24/2022] Open
Abstract
The oxygen-limiting (hypoxic) microenvironment of tumors induces metabolic reprogramming and cell survival, but the underlying mechanisms involving mitochondria remain poorly understood. We previously demonstrated that hypoxia-inducible factor 1 mediates the hyperfusion of mitochondria by inducing Bcl-2/adenovirus E1B 19-kDa interacting protein 3 and posttranslational truncation of the mitochondrial ATP transporter outer membrane voltage-dependent anion channel 1 in hypoxic cells. In addition, we showed that truncation is associated with increased resistance to drug-induced apoptosis and is indicative of increased patient chemoresistance. We now show that silencing of the tumor suppressor TP53 decreases truncation and increases drug-induced apoptosis. We also show that TP53 regulates truncation through induction of the mitochondrial protein Mieap. While we found that truncation was independent of mitophagy, we observed local microfusion between mitochondria and endolysosomes in hypoxic cells in culture and in patients' tumor tissues. Since we found that the endolysosomal asparagine endopeptidase was responsible for truncation, we propose that it is a readout of mitochondrial-endolysosomal microfusion in hypoxia. These novel findings provide the framework for a better understanding of hypoxic cell metabolism and cell survival through mitochondrial-endolysosomal microfusion regulated by hypoxia-inducible factor 1 and TP53.
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42
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Dall E, Fegg JC, Briza P, Brandstetter H. Struktur und Mechanismus einer Aspartimid-abhängigen Peptidligase in humanem Legumain. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201409135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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43
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Dall E, Fegg JC, Briza P, Brandstetter H. Structure and mechanism of an aspartimide-dependent peptide ligase in human legumain. Angew Chem Int Ed Engl 2015; 54:2917-21. [PMID: 25630877 PMCID: PMC4506564 DOI: 10.1002/anie.201409135] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 11/04/2014] [Indexed: 02/01/2023]
Abstract
Peptide ligases expand the repertoire of genetically encoded protein architectures by synthesizing new peptide bonds, energetically driven by ATP or NTPs. Here, we report the discovery of a genuine ligase activity in human legumain (AEP) which has important roles in immunity and tumor progression that were believed to be due to its established cysteine protease activity. Defying dogma, the ligase reaction is independent of the catalytic cysteine but exploits an endogenous energy reservoir that results from the conversion of a conserved aspartate to a metastable aspartimide. Legumain's dual protease-ligase activities are pH- and thus localization controlled, dominating at acidic and neutral pH, respectively. Their relevance includes reversible on-off switching of cystatin inhibitors and enzyme (in)activation, and may affect the generation of three-dimensional MHC epitopes. The aspartate-aspartimide (succinimide) pair represents a new paradigm of coupling endergonic reactions in ATP-scarce environments.
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Affiliation(s)
- Elfriede Dall
- Department of Molecular Biology, University of Salzburg, 5020 Salzburg (Austria)
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44
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Ishii N, Funami K, Tatematsu M, Seya T, Matsumoto M. Endosomal localization of TLR8 confers distinctive proteolytic processing on human myeloid cells. THE JOURNAL OF IMMUNOLOGY 2014; 193:5118-28. [PMID: 25297876 DOI: 10.4049/jimmunol.1401375] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Nucleic acid-sensing TLRs are involved in both antimicrobial immune responses and autoimmune inflammation. TLR8 is phylogenetically and structurally related to TLR7 and TLR9, which undergo proteolytic processing in the endolysosomes to generate functional receptors. Recent structural analyses of human TLR8 ectodomain and its liganded form demonstrated that TLR8 is also cleaved, and both the N- and C-terminal halves contribute to ligand binding. However, the structures and ssRNA recognition mode of endogenous TLR8 in human primary cells are largely unknown. In this study, we show that proteolytic processing of TLR8 occurs in human monocytes and macrophages in a different manner compared with TLR7/9 cleavage. The insertion loop between leucine-rich repeats 14 and 15 in TLR8 is indispensable for the cleavage and stepwise processing that occurs in the N-terminal fragment. Both furin-like proprotein convertase and cathepsins contribute to TLR8 cleavage in the early/late endosomes. TLR8 recognizes viral ssRNA and endogenous RNA, such as microRNAs, resulting in the production of proinflammatory cytokines. Hence, localization sites of the receptors are crucial for the nucleic acid-sensing mode and downstream signaling.
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Affiliation(s)
- Noriko Ishii
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Kenji Funami
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Megumi Tatematsu
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Tsukasa Seya
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Misako Matsumoto
- Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
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Abstract
Macrophages are capable of assuming distinct, meta-stable, functional phenotypes in response to environmental cues-a process referred to as macrophage polarization. The identity and plasticity of polarized macrophage subsets as well as their functions in the maintenance of homeostasis and the progression of various pathologies have become areas of intense interest. Yet, the mechanisms by which they achieve subset-specific functions at the cellular level remain unclear. It is becoming apparent that phagocytosis and phagosome maturation differ depending on the polarization of macrophages. This minireview summarizes recent progress in this field, highlighting developing trends and discussing the molecular mechanisms that underlie subset-specific functions.
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Affiliation(s)
- Johnathan Canton
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
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46
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Tseng CY, Gajewski M, Danani A, Tuszynski JA. Homology and Molecular Dynamics Models of Toll-Like Receptor 7 Protein and Its Dimerization. Chem Biol Drug Des 2014; 83:656-65. [DOI: 10.1111/cbdd.12278] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 12/12/2013] [Indexed: 12/28/2022]
Affiliation(s)
- Chih-Yuan Tseng
- Department of Oncology; University of Alberta; 3-336 Cross Cancer Institute 11560 University Avenue Edmonton AB T6G 1Z2 Canada
| | - Melissa Gajewski
- DTI-Department of Innovative Technologies; PMET-Laboratory of Pharmaceutical and Medical Technologies SUPSI-University of Applied Sciences of Southern Switzerland; Lugano Switzerland
| | - Andrea Danani
- DTI-Department of Innovative Technologies; PMET-Laboratory of Pharmaceutical and Medical Technologies SUPSI-University of Applied Sciences of Southern Switzerland; Lugano Switzerland
| | - Jack A. Tuszynski
- Department of Oncology; University of Alberta; 3-336 Cross Cancer Institute 11560 University Avenue Edmonton AB T6G 1Z2 Canada
- DTI-Department of Innovative Technologies; PMET-Laboratory of Pharmaceutical and Medical Technologies SUPSI-University of Applied Sciences of Southern Switzerland; Lugano Switzerland
- Department of Physics; University of Alberta; Edmonton AB Canada
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Gene Expression Profiles Underlying Selective T-Cell-Mediated Immunity Activity of a Chinese Medicine Granule on Mice Infected with Influenza Virus H1N1. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 2014:976364. [PMID: 24527057 PMCID: PMC3910462 DOI: 10.1155/2014/976364] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 10/25/2013] [Accepted: 11/18/2013] [Indexed: 11/17/2022]
Abstract
A Chinese medicine granule, Shu-Feng-Xuan-Fei (SFXF), is critical for viral clearance in early phase of influenza virus infection. In this study, 72 ICR mice were randomly divided into six groups: normal control group, virus control group, Oseltamivir group, low-dose SFXF, medium-dose SFXF, and high-dose SFXF. Mice were anesthetized and inoculated with 4LD50 of influenza virus A (H1N1) except normal control group. Oseltamivir group received 11.375 mg·kg(-1) ·d(-1) Oseltamivir Phosphate. SFXF 3.76, 1.88 and 0.94 g·kg(-1) ·d(-1) were administrated to mice in all SFXF groups. Each group was in equal dose of 0.2ml daily for 4 consecutive days. Mice were sacrificed and then total RNA was extracted in lung tissue. Some genes involved in T-cell-mediated immunity were selected by DNA microarray. These candidate genes were verified by Real-Time PCR and western immunoblotting. Compared with virus control group, in Toll-like receptor signaling pathway, 12 virus-altered genes were significantly reduced following medium-dose SFXF treatment. Eighteen antigen processing presentation-associated genes were upregulated by medium-dose SFXF. In the process of T cell receptor signaling pathway, 19 genes were downregulated by medium-dose SFXF treatment. On exploration into effector T cells activation and cytokines, all of altered genes in virus control group were reversed by medium-dose SFXF. Real-time PCR and western immunoblotting showed that the regulation of medium-dose SFXF in IL-4, IFN-γ, TNF-α, IL-1β, TLR7, MyD88, p38, and JNK was superior to Oseltamivir and high-dose SFXF group. Therefore, SFXF granules could reduce influenza infected cells and activation of T cells.
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Intracellular Toll-Like Receptor Recruitment and Cleavage in Endosomal/Lysosomal Organelles. Methods Enzymol 2014; 535:141-7. [DOI: 10.1016/b978-0-12-397925-4.00009-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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49
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Guiducci C, Gong M, Cepika AM, Xu Z, Tripodo C, Bennett L, Crain C, Quartier P, Cush JJ, Pascual V, Coffman RL, Barrat FJ. RNA recognition by human TLR8 can lead to autoimmune inflammation. ACTA ACUST UNITED AC 2013; 210:2903-19. [PMID: 24277153 PMCID: PMC3865472 DOI: 10.1084/jem.20131044] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
High expression level of human TLR8 in mice results in spontaneous, multiorgan inflammation attributable in part to increased DC activation. Studies on the role of the RNA receptor TLR8 in inflammation have been limited by its different function in human versus rodents. We have generated multiple lines of transgenic mice expressing different levels of human TLR8. The high copy number chimeras were unable to pass germline; developed severe inflammation targeting the pancreas, salivary glands, and joints; and the severity of the specific phenotypes closely correlated with the huTLR8 expression levels. Mice with relatively low expression levels survived and bred successfully but had increased susceptibility to collagen-induced arthritis, and the levels of huTLR8 correlated with proinflammatory cytokines in the joints of the animals. At the cellular level, huTLR8 signaling exerted a DC-intrinsic effect leading to up-regulation of co-stimulatory molecules and subsequent T cell activation. A pathogenic role for TLR8 in human diseases was suggested by its increased expression in patients with systemic arthritis and the correlation of TLR8 expression with the elevation of IL-1β levels and disease status. We found that the consequence of self-recognition via TLR8 results in a constellation of diseases, strikingly distinct from those related to TLR7 signaling, and points to specific inflammatory diseases that may benefit from inhibition of TLR8 in humans.
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50
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Hipp MM, Shepherd D, Gileadi U, Aichinger MC, Kessler BM, Edelmann MJ, Essalmani R, Seidah NG, Reis e Sousa C, Cerundolo V. Processing of human toll-like receptor 7 by furin-like proprotein convertases is required for its accumulation and activity in endosomes. Immunity 2013; 39:711-21. [PMID: 24138882 PMCID: PMC4839496 DOI: 10.1016/j.immuni.2013.09.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 07/25/2013] [Indexed: 11/18/2022]
Abstract
Toll-like receptor 7 (TLR7) triggers antiviral immune responses by recognizing viral single-stranded RNA in endosomes, but the biosynthetic pathway of human TLR7 (hTLR7) remains unclear. Here, we show that hTLR7 is proteolytically processed and that the C-terminal fragment selectively accumulates in endocytic compartments. hTLR7 processing occurred at neutral pH and was dependent on furin-like proprotein convertases (PCs). Furthermore, TLR7 processing was required for its functional response to TLR7 agonists such as R837 or influenza virus. Notably, proinflammatory and differentiation stimuli increased the expression of furin-like PCs in immune cells, suggesting a positive feedback mechanism for TLR7 processing during infection. Because self-RNA can under certain conditions activate TLR7 and trigger autoimmunity, our results identify furin-like PCs as a possible target to attenuate TLR7-dependent autoimmunity and other immune pathologies.
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Affiliation(s)
- Madeleine M Hipp
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DU, UK
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