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Abstract
Viruses are obligate intracellular parasites. Despite their dependence on host cells, viruses are evolutionarily autonomous, with their own genomes and evolutionary trajectories locked in arms races with the hosts. Here, we discuss a simple functional logic to explain virus macroevolution that appears to define the course of virus evolution. A small core of virus hallmark genes that are responsible for genome replication apparently descended from primordial replicators, whereas most virus genes, starting with those encoding capsid proteins, were subsequently acquired from hosts. The oldest of these acquisitions antedate the last universal cellular ancestor (LUCA). Host gene capture followed two major routes: convergent recruitment of genes with functions that directly benefit virus reproduction and exaptation when host proteins are repurposed for unique virus functions. These forms of host protein recruitment by viruses result in different levels of similarity between virus and host homologs, with the exapted ones often changing beyond easy recognition.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA.
| | - Valerian V Dolja
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA; Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, F-75015 Paris, France.
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Möckel T, Basta F, Weinmann-Menke J, Schwarting A. B cell activating factor (BAFF): Structure, functions, autoimmunity and clinical implications in Systemic Lupus Erythematosus (SLE). Autoimmun Rev 2020; 20:102736. [PMID: 33333233 DOI: 10.1016/j.autrev.2020.102736] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 08/28/2020] [Indexed: 12/30/2022]
Abstract
The B cell activating factor (BAFF), or B lymphocyte stimulator (BLyS), is a B cell survival factor which supports autoreactive B cells and prevents their deletion. BAFF expression is closely linked with autoimmunity and is enhanced by genetic alterations and viral infections. Furthermore, BAFF seems to be involved in adipogenesis, atherosclerosis, neuro-inflammatory processes and ischemia reperfusion (I/R) injury. BAFF is commonly overexpressed in Systemic Lupus Erythematosus (SLE) and strongly involved in the pathogenesis of the disease. The relationship between BAFF levels, disease activity and damage accrual in SLE is controversial, but growing evidence is emerging on its role in renal involvement. Belimumab, a biologic BAFF inhibitor, has been the first biologic agent licensed for SLE therapy so far. As Rituximab (RTX) has been shown to increase BAFF levels following B cell depletion, the combination therapy of RTX plus belimumab (being evaluated in two RCT) seems to be a valuable option for several clinical scenarios. In this review we will highlight the growing body of evidence of immune and non-immune related BAFF expression in experimental and clinical settings.
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Affiliation(s)
- Tamara Möckel
- Department of Internal Medicine I, Division of Rheumatology and Clinical Immunology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
| | - Fabio Basta
- Acura Rheumatology Center Rhineland Palatinate, Bad Kreuznach, Germany
| | - Julia Weinmann-Menke
- Department of Internal Medicine I, Division of Nephrology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Andreas Schwarting
- Department of Internal Medicine I, Division of Rheumatology and Clinical Immunology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany; Acura Rheumatology Center Rhineland Palatinate, Bad Kreuznach, Germany
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3
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Eslami M, Meinl E, Eibel H, Willen L, Donzé O, Distl O, Schneider H, Speiser DE, Tsiantoulas D, Yalkinoglu Ö, Samy E, Schneider P. BAFF 60-mer, and Differential BAFF 60-mer Dissociating Activities in Human Serum, Cord Blood and Cerebrospinal Fluid. Front Cell Dev Biol 2020; 8:577662. [PMID: 33240880 PMCID: PMC7677505 DOI: 10.3389/fcell.2020.577662] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/15/2020] [Indexed: 12/12/2022] Open
Abstract
B cell activation factor of the TNF family (BAFF/BLyS), an essential B cell survival factor of which circulating levels are elevated in several autoimmune disorders, is targeted in the clinic for the treatment of systemic lupus erythematosus (SLE). The soluble form of BAFF can exist as 3-mer, or as 60-mer that results from the ordered assembly of twenty 3-mers and that can be obtained from naturally cleaved membrane-bound BAFF or made as a recombinant protein. However, which forms of soluble BAFF exist and act in humans is unclear. In this study, BAFF 3-mer and 60-mer in biological fluids were characterized for size, activity and response to specific stimulators or inhibitors of BAFF. Human cerebrospinal fluids (CSF) from patients with multiple sclerosis and adult human sera contained exclusively BAFF 3-mer in these assays, also when BAFF concentrations were moderately SLE or highly (BAFFR-deficient individual) increased. Human sera, but not CSF, contained a high molecular weight, saturable activity that dissociated preformed recombinant BAFF 60-mer into 3-mer. This activity was lower in cord blood. Cord blood displayed BAFF levels 10-fold higher than in adults and consistently contained a fair proportion of active high molecular weight BAFF able to dissociate into 3-mer but not endowed with all properties of recombinant BAFF 60-mer. If BAFF 60-mer is produced in humans, it is dissociated, or at least attenuated in the circulation.
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Affiliation(s)
- Mahya Eslami
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | - Edgar Meinl
- Institute of Clinical Neuroimmunology, University Hospital of the Ludwig-Maximilians-Universität München, Munich, Germany
| | - Hermann Eibel
- Faculty of Medicine, Center for Chronic Immunodeficiency, Medical Center - University of Freiburg, Freiburg, Germany
| | - Laure Willen
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
| | | | - Ottmar Distl
- Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Holm Schneider
- Department of Pediatrics, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Daniel E Speiser
- Department of Oncology, University of Lausanne, Lausanne, Switzerland
| | | | - Özkan Yalkinoglu
- Clinical Pharmacology, Quantitative Pharmacology, Translational Medicine, Merck KGaA, Darmstadt, Germany
| | - Eileen Samy
- Business of Merck KGaA, EMD Serono Research & Development Institute, Inc., Billerica, MA, United States
| | - Pascal Schneider
- Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
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Samy E, Wax S, Huard B, Hess H, Schneider P. Targeting BAFF and APRIL in systemic lupus erythematosus and other antibody-associated diseases. Int Rev Immunol 2017; 36:3-19. [PMID: 28215100 DOI: 10.1080/08830185.2016.1276903] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The B cell-stimulating molecules, BAFF (B cell activating factor) and APRIL (a proliferation-inducing ligand), are critical factors in the maintenance of the B cell pool and humoral immunity. In addition, BAFF and APRIL are involved in the pathogenesis of a number of human autoimmune diseases, with elevated levels of these cytokines detected in the sera of patients with systemic lupus erythematosus (SLE), IgA nephropathy, Sjögren's syndrome, and rheumatoid arthritis. As such, both molecules are rational targets for new therapies in B cell-driven autoimmune diseases, and several inhibitors of BAFF or BAFF and APRIL together have been investigated in clinical trials. These include the BAFF/APRIL dual inhibitor, atacicept, and the BAFF inhibitor, belimumab, which is approved as an add-on therapy for patients with active SLE. Post hoc analyses of these trials indicate that baseline serum levels of BAFF and BAFF/APRIL correlate with treatment response to belimumab and atacicept, respectively, suggesting a role for the two molecules as predictive biomarkers. It will, however, be important to refine future testing to identify active forms of BAFF and APRIL in the circulation, as well as to distinguish between homotrimer and heteromer configurations. In this review, we discuss the rationale for dual BAFF/APRIL inhibition versus single BAFF inhibition in autoimmune disease, by focusing on the similarities and differences between the physiological and pathogenic roles of the two molecules. A summary of the preclinical and clinical data currently available is also presented.
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Affiliation(s)
- Eileen Samy
- a EMD Serono Research & Development Institute, Inc. , Billerica , Massachusetts , USA
| | - Stephen Wax
- a EMD Serono Research & Development Institute, Inc. , Billerica , Massachusetts , USA
| | - Bertrand Huard
- b Institute for Advanced Biosciences , University Grenoble Alpes , INSERM U1209, Grenoble , France
| | | | - Pascal Schneider
- d Department of Biochemistry , University of Lausanne , Lausanne , Switzerland
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5
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Nicoletti AM, Kenny CH, Khalil AM, Pan Q, Ralph KLM, Ritchie J, Venkataramani S, Presky DH, DeWire SM, Brodeur SR. Unexpected Potency Differences between B-Cell-Activating Factor (BAFF) Antagonist Antibodies against Various Forms of BAFF: Trimer, 60-Mer, and Membrane-Bound. ACTA ACUST UNITED AC 2016; 359:37-44. [DOI: 10.1124/jpet.116.236075] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 07/18/2016] [Indexed: 02/01/2023]
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6
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Stohl W. Therapeutic targeting of the BAFF/APRIL axis in systemic lupus erythematosus. Expert Opin Ther Targets 2014; 18:473-89. [DOI: 10.1517/14728222.2014.888415] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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7
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Increased adsorption of histidine-tagged proteins onto tissue culture polystyrene. Colloids Surf B Biointerfaces 2012; 92:286-92. [DOI: 10.1016/j.colsurfb.2011.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 12/02/2011] [Accepted: 12/02/2011] [Indexed: 11/20/2022]
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8
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Kreuzaler M, Rauch M, Salzer U, Birmelin J, Rizzi M, Grimbacher B, Plebani A, Lougaris V, Quinti I, Thon V, Litzman J, Schlesier M, Warnatz K, Thiel J, Rolink AG, Eibel H. Soluble BAFF levels inversely correlate with peripheral B cell numbers and the expression of BAFF receptors. THE JOURNAL OF IMMUNOLOGY 2011; 188:497-503. [PMID: 22124120 DOI: 10.4049/jimmunol.1102321] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The TNF family member protein BAFF/BLyS is essential for B cell survival and plays an important role in regulating class switch recombination as well as in the selection of autoreactive B cells. In humans, increased concentrations of soluble BAFF are found in different pathological conditions, which may be as diverse as autoimmune diseases, B cell malignancies, and primary Ab deficiencies (PAD). Because the mechanisms that regulate BAFF levels are not well understood, we newly developed a set of mAbs against human BAFF to study the parameters that determine the concentrations of soluble BAFF in circulation. Patients with PAD, including severe functional B cell defects such as BTK, BAFF-R, or TACI deficiency, were found to have higher BAFF levels than asplenic individuals, patients after anti-CD20 B cell depletion, chronic lymphocytic leukemia patients, or healthy donors. In a comparable manner, mice constitutively expressing human BAFF were found to have higher concentrations of BAFF in the absence than in the presence of B cells. Therefore, our data strongly suggest that BAFF steady-state concentrations mainly depend on the number of B cells as well as on the expression of BAFF-binding receptors. Because most patients with PAD have high levels of circulating BAFF, the increase in BAFF concentrations cannot compensate defects in B cell development and function.
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Zhu ZC, Gupta KK, Slabbekoorn AR, Paulson BA, Folker ES, Goodson HV. Interactions between EB1 and microtubules: dramatic effect of affinity tags and evidence for cooperative behavior. J Biol Chem 2009; 284:32651-61. [PMID: 19778897 DOI: 10.1074/jbc.m109.013466] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Plus end tracking proteins (+TIPs) are a unique group of microtubule binding proteins that dynamically track microtubule (MT) plus ends. EB1 is a highly conserved +TIP with a fundamental role in MT dynamics, but it remains poorly understood in part because reported EB1 activities have differed considerably. One reason for this inconsistency could be the variable presence of affinity tags used for EB1 purification. To address this question and establish the activity of native EB1, we have measured the MT binding and tubulin polymerization activities of untagged EB1 and EB1 fragments and compared them with those of His-tagged EB1 proteins. We found that N-terminal His tags directly influence the interaction between EB1 and MTs, significantly increasing both affinity and activity, and that small amounts of His-tagged proteins act synergistically with larger amounts of untagged proteins. Moreover, the binding ratio between EB1 and tubulin can exceed 1:1, and EB1-MT binding curves do not fit simple binding models. These observations demonstrate that EB1 binding is not limited to the MT seam, and they suggest that EB1 binds cooperatively to MTs. Finally, we found that removal of tubulin C-terminal tails significantly reduces EB1 binding, indicating that EB1-tubulin interactions are mediated in part by the same tubulin acidic tails utilized by other MAPs. These binding relationships are important for helping to elucidate the complex of proteins at the MT tip.
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Affiliation(s)
- Zhiqing C Zhu
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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10
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Masoudi R, Ioannou MS, Coughlin MD, Pagadala P, Neet KE, Clewes O, Allen SJ, Dawbarn D, Fahnestock M. Biological activity of nerve growth factor precursor is dependent upon relative levels of its receptors. J Biol Chem 2009; 284:18424-33. [PMID: 19389705 PMCID: PMC2709390 DOI: 10.1074/jbc.m109.007104] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Indexed: 01/19/2023] Open
Abstract
Nerve growth factor (NGF) is produced as a precursor called pro-nerve growth factor (proNGF), which is secreted by many tissues and is the predominant form of NGF in the central nervous system. In Alzheimer disease brain, cholinergic neurons degenerate and can no longer transport NGF as efficiently, leading to an increase in untransported NGF in the target tissue. The protein that accumulates in the target tissue is proNGF, not the mature form. The role of this precursor is controversial, and both neurotrophic and apoptotic activities have been reported for recombinant proNGFs. Differences in the protein structures, protein expression systems, methods used for protein purification, and methods used for bioassay may affect the activity of these proteins. Here, we show that proNGF is neurotrophic regardless of mutations or tags, and no matter how it is purified or in which system it is expressed. However, although proNGF is neurotrophic under our assay conditions for primary sympathetic neurons and for pheochromocytoma (PC12) cells, it is apoptotic for unprimed PC12 cells when they are deprived of serum. The ratio of tropomyosin-related kinase A to p75 neurotrophin receptor is low in unprimed PC12 cells compared with primed PC12 cells and sympathetic neurons, altering the balance of proNGF-induced signaling to favor apoptosis. We conclude that the relative level of proNGF receptors determines whether this precursor exhibits neurotrophic or apoptotic activity.
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Affiliation(s)
| | | | - Michael D. Coughlin
- Department of Psychiatry & Behavioural Neurosciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - Promila Pagadala
- the Rosalind Franklin University of Medicine & Science, North Chicago, Illinois 60064, and
| | - Kenneth E. Neet
- the Rosalind Franklin University of Medicine & Science, North Chicago, Illinois 60064, and
| | - Oliver Clewes
- the University of Bristol, Bristol BS1 3NY, United Kingdom
| | | | - David Dawbarn
- the University of Bristol, Bristol BS1 3NY, United Kingdom
| | - Margaret Fahnestock
- From the Department of Biology
- Graduate Program in Neuroscience, and
- Department of Psychiatry & Behavioural Neurosciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
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11
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Jin T, Guo F, Kim S, Howard A, Zhang YZ. X-ray crystal structure of TNF ligand family member TL1A at 2.1A. Biochem Biophys Res Commun 2007; 364:1-6. [PMID: 17935696 DOI: 10.1016/j.bbrc.2007.09.097] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 09/20/2007] [Indexed: 10/22/2022]
Abstract
The TNF family has been one of the most intensively studied protein families in the past two decades and it has rapidly expanded through the era of genomics and bioinformatics. However, the structural basis of the functional and interactional similarities and differences of this family is poorly understood. TL1A is a recently identified TNF family member that has received increasing attention. Here, the crystal structure of human TL1A is reported. TL1A forms a homotrimer with each monomer assuming a jellyroll beta-sandwich fold. The CD loop in TL1A is the longest among the TNF ligand members with known structure and the AA' loop in TL1A is the second longest after that in TRAIL, where part of it is disordered. Both these loops are known to participate in receptor binding in TNFbeta/LTalpha. The AA' loop may be very different in other TL1A variants if the overall fold is to be preserved.
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Affiliation(s)
- Tengchuan Jin
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
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Maita N, Aoyagi H, Osanai M, Shirakawa M, Fujiwara H. Characterization of the sequence specificity of the R1Bm endonuclease domain by structural and biochemical studies. Nucleic Acids Res 2007; 35:3918-27. [PMID: 17537809 PMCID: PMC1919474 DOI: 10.1093/nar/gkm397] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 04/25/2007] [Accepted: 05/01/2007] [Indexed: 11/30/2022] Open
Abstract
R1Bm is a long interspersed element (LINE) inserted into a specific sequence within 28S rDNA of the silkworm genome. Of two open reading frames (ORFs) of R1Bm, ORF2 encodes a reverse transcriptase (RT) and an endonuclease (EN) domain which digests specifically both top and bottom strand of the target sequence in 28S rDNA. To elucidate the sequence specificity of EN domain of R1Bm (R1Bm EN), we examined the cleavage tendency for the target sequences, and found that 5'-A(G/C)(A/T)!(A/G)T-3' is the consensus sequence (! = cleavage site). We also determined the crystal structure of R1Bm EN at 2.0 A resolution. Its structure was basically similar to AP endonuclease family, but had a special beta-hairpin at the edge of the DNA binding surface, which is a common feature among EN of LINEs. Point-mutations on the DNA binding surface of R1Bm EN significantly decreased the cleavage activities, but did not affect the sequence recognition in most residues. However, two mutants Y98A and N180A had altered cleavage patterns, suggesting an important role of these residues (Y98 and N180) for the sequence recognition of R1Bm EN. In addition, Y98A mutant showed another cleavage pattern, that implies de novo design of novel sequence-specific EN.
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Affiliation(s)
- Nobuo Maita
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka 812-8582, Japan, Graduate School of Integrated Science, Yokohama City University, Yokohama 230-0045, Japan, Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 501, Kashiwa, Chiba 277-8562, Japan, Graduate School of Engineering Kyoto University, Kyoto 615-8510, Japan and CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012, Japan
| | - Hideyuki Aoyagi
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka 812-8582, Japan, Graduate School of Integrated Science, Yokohama City University, Yokohama 230-0045, Japan, Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 501, Kashiwa, Chiba 277-8562, Japan, Graduate School of Engineering Kyoto University, Kyoto 615-8510, Japan and CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012, Japan
| | - Mizuko Osanai
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka 812-8582, Japan, Graduate School of Integrated Science, Yokohama City University, Yokohama 230-0045, Japan, Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 501, Kashiwa, Chiba 277-8562, Japan, Graduate School of Engineering Kyoto University, Kyoto 615-8510, Japan and CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012, Japan
| | - Masahiro Shirakawa
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka 812-8582, Japan, Graduate School of Integrated Science, Yokohama City University, Yokohama 230-0045, Japan, Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 501, Kashiwa, Chiba 277-8562, Japan, Graduate School of Engineering Kyoto University, Kyoto 615-8510, Japan and CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012, Japan
| | - Haruhiko Fujiwara
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka 812-8582, Japan, Graduate School of Integrated Science, Yokohama City University, Yokohama 230-0045, Japan, Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 501, Kashiwa, Chiba 277-8562, Japan, Graduate School of Engineering Kyoto University, Kyoto 615-8510, Japan and CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama 332-0012, Japan
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Agarwal S, Gopal K, Upadhyaya T, Dixit A. Biochemical and functional characterization of UDP-galactose 4-epimerase from Aeromonas hydrophila. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:828-37. [PMID: 17553760 DOI: 10.1016/j.bbapap.2007.04.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 04/08/2007] [Accepted: 04/17/2007] [Indexed: 11/21/2022]
Abstract
Bacteria of genus Aeromonas, responsible for a variety of pathological conditions in humans and fish, are ubiquitous waterborne bacteria. Aeromonas produces several virulent factors including a complex of lipopolysaccharide and surface array protein, involved in colonization. UDP-galactose 4-epimerase (GalE) catalyzes the production of UDP-galactose, a precursor for lipopolysaccharide biosynthesis, and thus is an important drug target. GalE exhibits interspecies variation and heterogeneity at its structural and functional level and therefore, the differences between the GalE of the host and the pathogen can be exploited for drug designing. In the present study, we report biochemical and functional characterization of the recombinant GalE of Aeromonas hydrophila. Unlike GalE reported from all other species, the purified recombinant GalE of A. hydrophila was found to exist as a monomer. This is the first report of UDP-galactose 4-epimerase from any species being a monomer. The molecular mass of the 6xHis-rGalE was determined to be 38271.477 (m/z). The 6xHis-rGalE with a K(m) of 0.5 mM for UDP-galactose exhibited optimum activity at 37 degrees C and pH 8-9. Spectrofluorimetric and CD analysis confirmed that the thermal inactivation was due to structural changes and not due to the NAD-dissociation. A relatively more ordered structure of the enzyme at pH 8 and 9 as compared to that at pH 6 or 7 suggests a key role of the electrostatic interactions in maintaining its native tertiary structure.
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Affiliation(s)
- Shivani Agarwal
- Gene Regulation Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
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Grivennikov SI, Kuprash DV, Liu ZG, Nedospasov SA. Intracellular signals and events activated by cytokines of the tumor necrosis factor superfamily: From simple paradigms to complex mechanisms. ACTA ACUST UNITED AC 2007; 252:129-61. [PMID: 16984817 DOI: 10.1016/s0074-7696(06)52002-9] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Tumor necrosis factor (TNF) and several related cytokines can induce opposite effects such as cell activation and proliferation or cell death. How the cell maintains the balance between these seemingly mutually exclusive pathways has long remained a mystery. TNF receptor I (TNFRI) initially emerged as a potent activator of NFkappaB and AP-1 transcription factors, while the related CD95 (Fas, Apo-1) was recognized as a prototype death receptor. Advances in research have uncovered critical molecular players in these intracellular processes. They have also revealed a much more complex picture than originally thought. Several new signaling pathways, including the alternative NFkappaB activation cascade, have been uncovered, and previously unknown modes of cross-talk between intracellular signaling molecules were revealed. It also turned out that signaling mechanisms mediated by the TNF receptor superfamily members can operate not only in the immune system but also in organ development.
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Affiliation(s)
- Sergei I Grivennikov
- Laboratory of Molecular Immunology, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
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15
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Ludwig LB, Ambrus JL, Krawczyk KA, Sharma S, Brooks S, Hsiao CB, Schwartz SA. Human Immunodeficiency Virus-Type 1 LTR DNA contains an intrinsic gene producing antisense RNA and protein products. Retrovirology 2006; 3:80. [PMID: 17090330 PMCID: PMC1654176 DOI: 10.1186/1742-4690-3-80] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Accepted: 11/08/2006] [Indexed: 11/27/2022] Open
Abstract
Background While viruses have long been shown to capitalize on their limited genomic size by utilizing both strands of DNA or complementary DNA/RNA intermediates to code for viral proteins, it has been assumed that human retroviruses have all their major proteins translated only from the plus or sense strand of RNA, despite their requirement for a dsDNA proviral intermediate. Several studies, however, have suggested the presence of antisense transcription for both HIV-1 and HTLV-1. More recently an antisense transcript responsible for the HTLV-1 bZIP factor (HBZ) protein has been described. In this study we investigated the possibility of an antisense gene contained within the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR). Results Inspection of published sequences revealed a potential transcription initiator element (INR) situated downstream of, and in reverse orientation to, the usual HIV-1 promoter and transcription start site. This antisense initiator (HIVaINR) suggested the possibility of an antisense gene responsible for RNA and protein production. We show that antisense transcripts are generated, in vitro and in vivo, originating from the TAR DNA of the HIV-1 LTR. To test the possibility that protein(s) could be translated from this novel HIV-1 antisense RNA, recombinant HIV antisense gene-FLAG vectors were designed. Recombinant protein(s) were produced and isolated utilizing carboxy-terminal FLAG epitope (DYKDDDDK) sequences. In addition, affinity-purified antisera to an internal peptide derived from the HIV antisense protein (HAP) sequences identified HAPs from HIV+ human peripheral blood lymphocytes. Conclusion HIV-1 contains an antisense gene in the U3-R regions of the LTR responsible for both an antisense RNA transcript and proteins. This antisense transcript has tremendous potential for intrinsic RNA regulation because of its overlap with the beginning of all HIV-1 sense RNA transcripts by 25 nucleotides. The novel HAPs are encoded in a region of the LTR that has already been shown to be deleted in some HIV-infected long-term survivors and represent new potential targets for vaccine development.
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Affiliation(s)
- Linda B Ludwig
- Division of Allergy, Immunology and Rheumatology, Department of Medicine, School of Biomedical Science and Medicine, State University of New York at Buffalo, Buffalo, New York 14203, USA
- Present address: 2519 145th Circle, Vancouver, Washington 98686, USA
| | - Julian L Ambrus
- Division of Allergy, Immunology and Rheumatology, Department of Medicine, School of Biomedical Science and Medicine, State University of New York at Buffalo, Buffalo, New York 14203, USA
| | - Kristie A Krawczyk
- Division of Allergy, Immunology and Rheumatology, Department of Medicine, School of Biomedical Science and Medicine, State University of New York at Buffalo, Buffalo, New York 14203, USA
| | - Sanjay Sharma
- Department of Surgery, School of Biomedical Science and Medicine, State University of New York at Buffalo, Buffalo, New York 14203, USA
| | - Stephen Brooks
- Department of Surgery, School of Biomedical Science and Medicine, State University of New York at Buffalo, Buffalo, New York 14203, USA
| | - Chiu-Bin Hsiao
- Division of Infectious Disease, Department of Medicine, School of Biomedical Science and Medicine, State University of New York at Buffalo, Buffalo, New York 14203, USA
| | - Stanley A Schwartz
- Division of Allergy, Immunology and Rheumatology, Department of Medicine, School of Biomedical Science and Medicine, State University of New York at Buffalo, Buffalo, New York 14203, USA
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Bossen C, Schneider P. BAFF, APRIL and their receptors: structure, function and signaling. Semin Immunol 2006; 18:263-75. [PMID: 16914324 DOI: 10.1016/j.smim.2006.04.006] [Citation(s) in RCA: 371] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 04/03/2006] [Indexed: 12/17/2022]
Abstract
BAFF, APRIL and their receptors play important immunological roles, especially in the B cell arm of the immune system. A number of splice isoforms have been described for both ligands and receptors in this subfamily, some of which are conserved between mouse and human, while others are species-specific. Structural and mutational analyses have revealed key determinants of receptor-ligand specificity. BAFF-R has a strong selectivity for BAFF; BCMA has a higher affinity for APRIL than for BAFF, while TACI binds both ligands equally well. The molecular signaling events downstream of BAFF-R, BCMA and TACI are still incompletely characterized. Survival appears to be mediated by upregulation of Bcl-2 family members through NF-kappaB activation, degradation of the pro-apototic Bim protein, and control of subcellular localization of PCKdelta. Very little is known about other signaling events associated with receptor engagement by BAFF and APRIL that lead for example to B cell activation or to CD40L-independent Ig switch.
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Affiliation(s)
- Claudia Bossen
- Biochemistry Department, University of Lausanne, Boveresses 155, CH-1066 Epalinges, Switzerland
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17
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Hughes RK, Belfield EJ, Muthusamay M, Khan A, Rowe A, Harding SE, Fairhurst SA, Bornemann S, Ashton R, Thorneley RNF, Casey R. Characterization of Medicago truncatula (barrel medic) hydroperoxide lyase (CYP74C3), a water-soluble detergent-free cytochrome P450 monomer whose biological activity is defined by monomer-micelle association. Biochem J 2006; 395:641-52. [PMID: 16454766 PMCID: PMC1462683 DOI: 10.1042/bj20051667] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We describe the detailed biochemical characterization of CYP74C3 (cytochrome P450 subfamily 74C3), a recombinant plant cytochrome P450 enzyme with HPL (hydroperoxide lyase) activity from Medicago truncatula (barrel medic). Steady-state kinetic parameters, substrate and product specificities, RZ (Reinheitszahl or purity index), molar absorption coefficient, haem content, and new ligands for an HPL are reported. We show on the basis of gel filtration, sedimentation velocity (sedimentation coefficient distribution) and sedimentation equilibrium (molecular mass) analyses that CYP74C3 has low enzyme activity as a detergent-free, water-soluble, monomer. The enzyme activity can be completely restored by re-activation with detergent micelles, but not detergent monomers. Corresponding changes in the spin state equilibrium, and probably co-ordination of the haem iron, are novel for cytochrome P450 enzymes and suggest that detergent micelles have a subtle effect on protein conformation, rather than substrate presentation, which is sufficient to improve substrate binding and catalytic-centre activity by an order of magnitude. The kcat/K(m) of up to 1.6x10(8) M(-1) x s(-1) is among the highest recorded, which is remarkable for an enzyme whose reaction mechanism involves the scission of a C-C bond. We carried out both kinetic and biophysical studies to demonstrate that this effect is a result of the formation of a complex between a protein monomer and a single detergent micelle. Association with a detergent micelle rather than oligomeric state represents a new mechanism of activation for membrane-associated cytochrome P450 enzymes. Highly concentrated and monodispersed samples of detergent-free CYP74C3 protein may be well suited for the purposes of crystallization and structural resolution of the first plant cytochrome P450 enzyme.
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18
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Carter RH, Zhao H, Liu X, Pelletier M, Chatham W, Kimberly R, Zhou T. Expression and occupancy of BAFF-R on B cells in systemic lupus erythematosus. ACTA ACUST UNITED AC 2006; 52:3943-54. [PMID: 16320342 DOI: 10.1002/art.21489] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE To determine whether receptors for B lymphocyte stimulator (BLyS) are altered on B cells of patients with systemic lupus erythematosus (SLE). METHODS Total available receptors for BLyS were measured by analysis of binding of recombinant soluble BLyS to peripheral blood B cells in 36 SLE patients, 29 healthy controls, and 10 disease controls. Antibodies to the receptors BAFF-R, BCMA, and TACI were used to define expression of the individual BLyS receptors on subsets of B cells in blood, spleen, and tonsils. Two different antibodies to BAFF-R, which were differentially sensitive to BAFF-R occupancy, were used to compare BAFF-R on B cells in an additional 20 healthy subjects and 25 SLE patients. Assays of B cell survival after stimulation in vitro were used to determine the sensitivity of B cells to exogenous BLyS. RESULTS Total available receptors for BLyS were decreased in patients with SLE, independent of changes of subsets in the blood in these patients. The decrease correlated with changes in disease activity. Although total surface BAFF-R was not significantly different between healthy controls and SLE patients, BAFF-R was occupied in SLE patients. B cells from these patients were less responsive to exogenous BLyS. CONCLUSION BAFF-R is consistently occupied on blood B cells in SLE. Occupancy of BAFF-R on blood B cells is likely to contribute to disease mechanisms in SLE and could serve as a biomarker of disease activity. Targeting BLyS as a therapeutic strategy will require overcoming the persistent binding of BLyS to BAFF-R.
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Affiliation(s)
- Robert H Carter
- University of Alabama at Birmingham, Birmingham VA Medical Center, Alabama, USA.
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20
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Cancro MP. The BLyS family of ligands and receptors: an archetype for niche-specific homeostatic regulation. Immunol Rev 2005; 202:237-49. [PMID: 15546397 DOI: 10.1111/j.0105-2896.2004.00212.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Discovery and characterization of the tumor necrosis factor (TNF) family member B-lymphocyte stimulator (BLyS) has opened a novel chapter in the role of TNF family members in the homeostatic control of lymphocyte populations. BLyS and its sister cytokine APRIL (a proliferation-inducing ligand) act primarily as soluble trimers and serve to regulate the steady-state numbers of nearly all B-cell compartments. This homeostatic regulation is accomplished through the regulation of B-cell production rates, selection thresholds, and lifespan. Differential expression of the three BLyS receptors during differentiation and activation provides related yet distinct homeostatic niches for follicular, marginal zone, and memory B-cell subsets.
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Affiliation(s)
- Michael P Cancro
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6082, USA.
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21
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Stohl W. Targeting B lymphocyte stimulator in systemic lupus erythematosus and other autoimmune rheumatic disorders. Expert Opin Ther Targets 2005; 8:177-89. [PMID: 15161425 DOI: 10.1517/14728222.8.3.177] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
B lymphocyte stimulator (BLyS) is a vital B cell survival factor. Overexpression of BLyS in mice can lead to systemic lupus erythematosus (SLE)-like disease and to Sjögren's syndrome (SS)-like disease. Treatment of mice with established SLE with BLyS antagonists ameliorates disease progression and enhances survival. Moreover, similar treatment of mice with inflammatory arthritis ameliorates the ongoing inflammation and subsequent joint destruction. In humans, BLyS overexpression is common in patients with SLE, rheumatoid arthritis or SS. Results from a Phase I clinical trial with a BLyS antagonist in human SLE have shown the antagonist to be biologically active and safe. These features collectively point to BLyS as an attractive therapeutic target in human disease.
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Affiliation(s)
- William Stohl
- Division of Rheumatology, University of Southern California Keck School of Medicine, 2011 Zonal Avenue HMR 711, Los Angeles, CA 90033, USA.
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22
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Yousaf N, Gould DJ, Aganna E, Hammond L, Mirakian RM, Turner MD, Hitman GA, McDermott MF, Chernajovsky Y. Tumor necrosis factor receptor I from patients with tumor necrosis factor receptor-associated periodic syndrome interacts with wild-type tumor necrosis factor receptor I and induces ligand-independent NF-κB activation. ACTA ACUST UNITED AC 2005; 52:2906-16. [PMID: 16142754 DOI: 10.1002/art.21268] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE To investigate the molecular consequences of expressing mutated forms of tumor necrosis factor receptor I (TNFRI) as found in patients with TNFR-associated periodic syndrome (TRAPS). METHODS We cloned and expressed full-length wild-type (WT) and T50K and P46L variants of TNFRI using a new tightly regulated doxycycline-dependent expression system. This system enabled the study of molecular interactions between these receptors at both physiologic and pathophysiologic levels of expression. RESULTS We used chemical crosslinking on the cell surface to show that WT and mutant forms of TNFRI, derived from TRAPS patients, interact in the absence of TNF ligand. Doxycycline-controlled up-regulation of one TNFRI allele, either WT or mutant, caused down-regulation of the other allele, indicating dynamic control of cell surface assembly. We also demonstrated that increased expression of mutant TNFRI (T50K) was associated with a parallel increase in NF-kappaB p65 (RelA) subunit activation, which did not occur with increased expression of WT TNFRI. CONCLUSION The T50K TRAPS-related variant is capable of sustaining inappropriate NF-kappaB activation, resulting in persistent auto-inflammation in target organs such as skin, synovial membrane, and the central nervous system. We conclude that some of the inflammatory processes seen in TRAPS do not involve direct interaction of TNF with its receptors, but that other proinflammatory mechanisms capable of up-regulating TNFRI expression may cause cellular activation through the NF-kappaB signaling pathway.
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Affiliation(s)
- Nasim Yousaf
- Barts and The London Queen Mary's School of Medicine and Dentistry, University of London, London, UK
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Wallweber HJA, Compaan DM, Starovasnik MA, Hymowitz SG. The Crystal Structure of A Proliferation-inducing Ligand, APRIL. J Mol Biol 2004; 343:283-90. [PMID: 15451660 DOI: 10.1016/j.jmb.2004.08.040] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Revised: 07/28/2004] [Accepted: 08/09/2004] [Indexed: 11/19/2022]
Abstract
A proliferation-inducing ligand (APRIL) is a TNF-like cytokine that stimulates tumor cell growth. Within the TNF ligand superfamily, APRIL is most similar to B-cell activation factor (BAFF) with which it shares 30% sequence identity. APRIL binds the receptors B-cell maturation antigen (BCMA) and TACI with high affinity; both of these receptors have also been shown to bind BAFF, although BCMA has significantly higher affinity for APRIL than BAFF. Determination of the crystal structure of APRIL from three crystallization conditions at resolutions of 1.8-2.4A over a pH range from 5.0 to 8.5 reveals a compact trimeric ligand with a backbone fold very similar to that of BAFF (1.1A RMSD over 122 structurally equivalent Calpha atoms), with the exception of differences in the AA' and DE loop regions. Whereas BAFF has been shown to form 20-trimer assemblies under certain conditions, the molecular determinants required for BAFF-like assemblies are absent in the APRIL structure. No crystal packing suggestive of the formation of higher-order assemblies is seen in any of the crystal forms nor does the structure vary significantly between pH 5.0 and 8.5. Modeling of the APRIL-BCMA complex shows the resulting interface is in agreement with mutagenesis data.
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Affiliation(s)
- Heidi J A Wallweber
- Department of Protein Engineering, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
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