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Lam LKM, Reilly JP, Rux AH, Murphy SJ, Kuri-Cervantes L, Weisman AR, Ittner CAG, Pampena MB, Betts MR, Wherry EJ, Song WC, Lambris JD, Meyer NJ, Cines DB, Mangalmurti NS. Erythrocytes identify complement activation in patients with COVID-19. Am J Physiol Lung Cell Mol Physiol 2021; 321:L485-L489. [PMID: 34231390 PMCID: PMC8384475 DOI: 10.1152/ajplung.00231.2021] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
COVID-19, the disease caused by the SARS-CoV-2 virus, can progress to multisystem organ failure and viral sepsis characterized by respiratory failure, arrhythmias, thromboembolic complications, and shock with high mortality. Autopsy and preclinical evidence implicate aberrant complement activation in endothelial injury and organ failure. Erythrocytes express complement receptors and are capable of binding immune complexes; therefore, we investigated complement activation in patients with COVID-19 using erythrocytes as a tool to diagnose complement activation. We discovered enhanced C3b and C4d deposition on erythrocytes in COVID-19 sepsis patients and non-COVID sepsis patients compared with healthy controls, supporting the role of complement in sepsis-associated organ injury. Our data suggest that erythrocytes may contribute to a precision medicine approach to sepsis and have diagnostic value in monitoring complement dysregulation in COVID-19-sepsis and non-COVID sepsis and identifying patients who may benefit from complement targeted therapies.
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Affiliation(s)
- L K Metthew Lam
- Division of Pulmonary, Allergy and Critical Care, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - John P Reilly
- Division of Pulmonary, Allergy and Critical Care, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ann H Rux
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sophia J Murphy
- Division of Pulmonary, Allergy and Critical Care, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Leticia Kuri-Cervantes
- Department of Microbiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Penn Institute for Immunology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ariel R Weisman
- Division of Pulmonary, Allergy and Critical Care, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Caroline A G Ittner
- Division of Pulmonary, Allergy and Critical Care, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - M Betina Pampena
- Department of Microbiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Penn Institute for Immunology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Michael R Betts
- Department of Microbiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Penn Institute for Immunology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - E John Wherry
- Penn Institute for Immunology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Parker Institute for Cancer Immunotherapy at University of Pennsylvania, Philadelphia, Pennsylvania
| | - Wen-Chao Song
- Penn Institute for Immunology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - John D Lambris
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Nuala J Meyer
- Division of Pulmonary, Allergy and Critical Care, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Penn Institute for Immunology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Lung Biology Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Douglas B Cines
- Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Penn Institute for Immunology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Nilam S Mangalmurti
- Division of Pulmonary, Allergy and Critical Care, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Penn Institute for Immunology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.,Lung Biology Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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2
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Parker ZF, Rux AH, Riblett AM, Lee FH, Rauova L, Cines DB, Poncz M, Sachais BS, Doms RW. Platelet Factor 4 Inhibits and Enhances HIV-1 Infection in a Concentration-Dependent Manner by Modulating Viral Attachment. AIDS Res Hum Retroviruses 2016; 32:705-17. [PMID: 26847431 DOI: 10.1089/aid.2015.0344] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Platelet factor 4 (PF4) has been recently shown to inhibit infection by a broad range of human immunodeficiency virus type 1 (HIV-1) isolates in vitro. We found that the inhibitory effects of PF4 are limited to a defined concentration range where PF4 exists largely in a monomeric state. Under these conditions, PF4 bound the HIV-1 envelope protein and inhibited HIV-1 attachment to the cell surface. However, as concentrations increased to the point where PF4 exists largely in tetrameric or higher-order forms, viral infection in vitro was enhanced. Enhancement could be inhibited by mutations in PF4 that shift the oligomeric equilibrium toward the monomeric state, or by using soluble glycosaminoglycans (GAGs) to which tetrameric PF4 avidly binds. We conclude that at physiologically relevant concentrations, oligomeric PF4 enhances infection by HIV-1 by interacting with the viral envelope protein as well as cell surface GAGs, enhancing virus attachment to the cell surface. This effect was not specific to HIV-1, as enhancement was seen with some but not all other viruses tested. The biphasic effects of PF4 on HIV-1 infection suggest that native PF4 will not be a useful antiviral agent and that PF4 could contribute to the hematologic abnormalities commonly seen in HIV-infected individuals by enhancing virus infection in the bone marrow.
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Affiliation(s)
- Zahra F. Parker
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Ann H. Rux
- Department of Pathology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Amber M. Riblett
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Fang-Hua Lee
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Lubica Rauova
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- Department of Hematology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Douglas B. Cines
- Department of Pathology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Mortimer Poncz
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- Department of Hematology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Bruce S. Sachais
- Department of Pathology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- New York Blood Center, New York, New York
| | - Robert W. Doms
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
- Departments of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
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3
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Cho MJ, Lo ASY, Mao X, Nagler AR, Ellebrecht CT, Mukherjee EM, Hammers CM, Choi EJ, Sharma PM, Uduman M, Li H, Rux AH, Farber SA, Rubin CB, Kleinstein SH, Sachais BS, Posner MR, Cavacini LA, Payne AS. Shared VH1-46 gene usage by pemphigus vulgaris autoantibodies indicates common humoral immune responses among patients. Nat Commun 2014; 5:4167. [PMID: 24942562 PMCID: PMC4120239 DOI: 10.1038/ncomms5167] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/20/2014] [Indexed: 12/13/2022] Open
Abstract
Pemphigus vulgaris (PV) is a potentially fatal blistering disease caused by autoantibodies (autoAbs) against desmoglein 3 (Dsg3). Here, we clone anti-Dsg3 antibodies (Abs) from four PV patients and identify pathogenic VH1-46 autoAbs from all four patients. Unexpectedly, VH1-46 autoAbs had relatively few replacement mutations. We reverted antibody somatic mutations to their germline sequences to determine the requirement of mutations for autoreactivity. Three of five VH1-46 germline-reverted Abs maintain Dsg3 binding, compared with zero of five non-VH1-46 germline-reverted Abs. Site-directed mutagenesis of VH1-46 Abs demonstrates that acidic amino-acid residues introduced by somatic mutation or heavy chain VDJ recombination are necessary and sufficient for Dsg3 binding. Our data suggest that VH1-46 autoantibody gene usage is commonly found in PV because VH1-46 Abs require few to no mutations to acquire Dsg3 autoreactivity, which may favour their early selection. Common VH gene usage indicates common humoral immune responses, even among unrelated patients.
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Affiliation(s)
- Michael Jeffrey Cho
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Agnes S Y Lo
- Division of Hematology-Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA
| | - Xuming Mao
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Arielle R Nagler
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Christoph T Ellebrecht
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Eric M Mukherjee
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Christoph M Hammers
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Eun-Jung Choi
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Preety M Sharma
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Mohamed Uduman
- Interdepartmental Program in Computational Biology and Bioinformatics, Yale University, and Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06511, USA
| | - Hong Li
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Ann H Rux
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Sara A Farber
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Courtney B Rubin
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Steven H Kleinstein
- Interdepartmental Program in Computational Biology and Bioinformatics, Yale University, and Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06511, USA
| | - Bruce S Sachais
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Marshall R Posner
- The Tisch Cancer Institute, Mount Sinai Medical Center, New York, New York 10029, USA
| | - Lisa A Cavacini
- The Tisch Cancer Institute, Mount Sinai Medical Center, New York, New York 10029, USA
| | - Aimee S Payne
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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4
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Litvinov RI, Yarovoi SV, Rauova L, Barsegov V, Sachais BS, Rux AH, Hinds JL, Arepally GM, Cines DB, Weisel JW. Distinct specificity and single-molecule kinetics characterize the interaction of pathogenic and non-pathogenic antibodies against platelet factor 4-heparin complexes with platelet factor 4. J Biol Chem 2013; 288:33060-70. [PMID: 24097975 DOI: 10.1074/jbc.m113.481598] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a thrombotic complication of heparin therapy mediated by antibodies to complexes between platelet factor 4 (PF4) and heparin or cellular glycosaminoglycans. However, only a fraction of patients with anti-PF4-heparin antibodies develop HIT, implying that only a subset of these antibodies is pathogenic. The basis for the pathogenic potential of anti-PF4-heparin antibodies remains unclear. To elucidate the intrinsic PF4-binding properties of HIT-like monoclonal antibody (KKO) versus non-pathogenic antibody (RTO) at the single-molecule level, we utilized optical trap-based force spectroscopy to measure the strength and probability of binding of surface-attached antibodies with oligomeric PF4 to simulate interactions on cells. To mimic the effect of heparin in bringing PF4 complexes into proximity, we chemically cross-linked PF4 tetramers using glutaraldehyde. Analysis of the force histograms revealed that KKO-PF4 interactions had ∼10-fold faster on-rates than RTO-PF4, and apparent equilibrium dissociation constants differed ∼10-fold with similar force-free off-rates (k(off) = 0.0031 and 0.0029 s(-1)). Qualitatively similar results were obtained for KKO and RTO interacting with PF4-heparin complexes. In contrast to WT PF4, KKO and RTO showed lower and similar binding probabilities to cross-linked PF4(K50E), which forms few if any oligomers. Thus, formation of stable PF4 polymers results in much stronger interactions with the pathogenic antibody without a significant effect on the binding of the non-pathogenic antibody. These results suggest a fundamental difference in the antigen-binding mechanisms between model pathogenic and non-pathogenic anti-PF4 antibodies that might underlie their distinct pathophysiological behaviors.
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5
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Callan MB, Patel RT, Rux AH, Bandyopadhyay S, Sireci AN, O'Donnell PA, Ruane T, Sikora T, Marryott K, Sachais BS, Hod EA. Transfusion of 28-day-old leucoreduced or non-leucoreduced stored red blood cells induces an inflammatory response in healthy dogs. Vox Sang 2013; 105:319-27. [PMID: 23763639 DOI: 10.1111/vox.12058] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/16/2013] [Accepted: 04/26/2013] [Indexed: 01/24/2023]
Abstract
BACKGROUND AND OBJECTIVES Studies in mice suggest that rapid transfusions of red blood cells (RBCs), refrigerator stored for longer durations, induce a pro-inflammatory cytokine response. Studies in human neonates confirm these findings; however, to date, adult human studies have failed to replicate these findings. We used healthy research dogs to begin to examine the factors affecting the cytokine response to transfusion. MATERIALS AND METHODS In a prospective study, healthy dogs were randomized for two autologous packed RBC transfusions after 7 (i.e. 'fresh') and 28 (i.e. 'old') days of storage, or after 28 and 7 days of storage, with or without prestorage leucoreduction (LR). RESULTS No significant differences were observed between LR and non-LR transfusions for all circulating analytes measured following transfusion. A pro-inflammatory cytokine response, exemplified by monocyte chemoattractant protein-1, was observed 6 h after only old RBC transfusions, irrespective of infusion rate (P < 0·001). This response was accompanied by increased neutrophil counts (P < 0·001) and decreased platelet counts (P < 0·001). CONCLUSION In healthy dogs, old RBC transfusions induce inflammation, which is unaffected by infusion rate.
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Affiliation(s)
- M B Callan
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
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6
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Tanhehco YC, Rux AH, Sachais BS. Low-density lipoprotein apheresis reduces platelet factor 4 on the surface of platelets: a possible protective mechanism against heparin-induced thrombocytopenia and thrombosis. Transfusion 2010; 51:1022-9. [PMID: 20977482 DOI: 10.1111/j.1537-2995.2010.02911.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Heparin-induced thrombocytopenia and thrombosis (HITT) is characterized by thrombocytopenia due to the formation of antibodies against heparin : platelet factor 4 (PF4) complexes. Despite the exposure to heparin during treatment and predisposition of patients with atherosclerosis to HITT, HITT in patients undergoing low-density lipoprotein (LDL) apheresis is rare. We investigated the possibility that LDL apheresis decreases PF4 on platelet (PLT) surfaces and/or plasma HITT antibody levels, either of which would disfavor HITT. STUDY DESIGN AND METHODS We enrolled 25 patients undergoing LDL apheresis at the Hospital of the University of Pennsylvania. Blood samples were drawn before and after treatment. Plasma samples were drawn proximal and distal to the LA-15 treatment column. PF4, HITT antibodies, heparin levels, and P-selectin were measured. RESULTS No patient had clinical symptoms of HITT. The LA-15 column was found to efficiently remove PF4. PF4 levels in peripheral blood plasma did not change significantly after LDL apheresis. However, PLT surface PF4 significantly decreased after treatment. HITT antibodies were found in only two patients and were nonfunctional. PLT surface P-selectin did not change during treatment. CONCLUSIONS We have demonstrated that LDL apheresis via dextran sulfate absorption removes plasma PF4 and reduces the amount of PF4 on the surface of circulating PLTs. Reduced surface PF4 may decrease antibody formation and/or recognition by HITT antibodies. These data provide a potential explanation for the near lack of HITT in hypercholesterolemic patients undergoing LDL apheresis. They also suggest the possibility that LDL apheresis using dextran sulfate adsorption may have therapeutic value in the treatment of HITT.
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Affiliation(s)
- Yvette C Tanhehco
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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7
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Sachais BS, Turrentine T, Dawicki McKenna JM, Rux AH, Rader D, Kowalska MA. Elimination of platelet factor 4 (PF4) from platelets reduces atherosclerosis in C57Bl/6 and apoE-/- mice. Thromb Haemost 2007; 98:1108-1113. [PMID: 18000617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Activated platelets, which release platelet factor 4 (PF4) are present in patients with atherosclerosis. To date, no direct in-vivo evidence exists for the involvement of PF4 in atherogenesis. In the current study, we tested the hypothesis that PF4 is atherogenic, and that genetic elimination of PF4 would protect mice from atherosclerosis. We have bred PF4(-/-) mice onto two athero-susceptible backgrounds, WT-C57Bl/6(WT) and apoE(-/-) to examine the importance of PF4 in atherogenesis. In order to induce atherosclerosis, WT and PF4(-/-) mice were fed an atherogenic diet for 30 weeks, while apoE(-/-) and apoE(-/-) PF4(-/-) mice were fed a high-fat Western-style diet for 10 weeks. Examination of lesions in the aortic roots of atherogenic diet fed mice demonstrated reduced atherosclerosis in PF4(-/-) (20% compared to WT). Examination of apoE(-/-) mice demonstrated similar changes, with apoE(-/-) PF4(-/-) mice demonstrating 37% of the aortic atherosclerotic burden compared to apoE(-/-) mice. Although we found similar levels of total and non-HDL cholesterol in WT and PF4(-/-) mice, HDL-cholesterol levels were increased in PF4(-/-) on both backgrounds. These data demonstrate, for the first time, that the platelet specific chemokine PF4 promotes atherosclerotic lesion development in vivo.
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Affiliation(s)
- Bruce S Sachais
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
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8
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Zhang P, Pan W, Rux AH, Sachais BS, Zheng XL. The cooperative activity between the carboxyl-terminal TSP1 repeats and the CUB domains of ADAMTS13 is crucial for recognition of von Willebrand factor under flow. Blood 2007; 110:1887-94. [PMID: 17540842 PMCID: PMC1976376 DOI: 10.1182/blood-2007-04-083329] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
ADAMTS13 cleaves von Willebrand factor (VWF) between Tyr(1605) and Met(1606) residues at the central A2 subunit. The amino-terminus of ADAMTS13 protease appears to be sufficient to bind and cleave VWF under static and denatured condition. However, the role of the carboxyl-terminus of ADAMTS13 in substrate recognition remains controversial. Present study demonstrates that ADAMTS13 cleaves VWF in a rotation speed- and protease concentration-dependent manner on a mini vortexer. Removal of the CUB domains (delCUB) or truncation after the spacer domain (MDTCS) significantly impairs its ability to cleave VWF under the same condition. ADAMTS13 and delCUB (but not MDTCS) bind VWF under flow with dissociation constants (K(D)) of about 50 nM and about 274 nM, respectively. The isolated CUB domains are neither sufficient to bind VWF detectably nor capable of inhibiting proteolytic cleavage of VWF by ADAMTS13 under flow. Addition of the TSP1 5-8 (T5-8CUB) or TSP1 2-8 repeats (T2-8CUB) to the CUB domains restores the binding affinity toward VWF and the inhibitory effect on cleavage of VWF by ADAMTS13 under flow. These data demonstrate directly and quantitatively that the cooperative activity between the middle carboxyl-terminal TSP1 repeats and the distal carboxyl-terminal CUB domains may be crucial for recognition and cleavage of VWF under flow.
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Affiliation(s)
- Ping Zhang
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
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9
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Yu G, Rux AH, Ma P, Bdeir K, Sachais BS. Endothelial expression of E-selectin is induced by the platelet-specific chemokine platelet factor 4 through LRP in an NF-kappaB-dependent manner. Blood 2004; 105:3545-51. [PMID: 15591119 PMCID: PMC1895024 DOI: 10.1182/blood-2004-07-2617] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The involvement of platelets in the pathogenesis of atherosclerosis has recently gained much attention. Platelet factor 4 (PF4), a platelet-specific chemokine released on platelet activation, has been localized to atherosclerotic lesions, including macrophages and endothelium. In this report, we demonstrate that E-selectin, an adhesion molecule involved in atherogenesis, is up-regulated in human umbilical vein endothelial cells exposed to PF4. Induction of E-selectin RNA is time and dose dependent. Surface expression of E-selectin, as measured by flow cytometry, is also increased by PF4. PF4 induces E-selectin expression by activation of transcriptional activity. Activation of nuclear factor-kappaB is critical for PF4-induced E-selectin expression, as demonstrated by promoter activation studies and electrophoretic mobility shift assays. Further, we have identified the low-density lipoprotein receptor-related protein as the cell surface receptor mediating this effect. These results demonstrate that PF4 is able to increase expression of E-selectin by endothelial cells and represents another potential mechanism by which platelets may participate in atherosclerotic lesion progression.
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Affiliation(s)
- Guangyao Yu
- University of Pennsylvania, 207 John Morgan, Philadelphia, PA 19104, USA
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10
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Abstract
The structural basis of the interaction between single-chain urokinase-type plasminogen activator (scuPA) and its receptor (uPAR) is incompletely defined. Several observations indicated the kringle facilitates the binding of uPA to uPAR. A scuPA variant lacking the kringle (Delta K-scuPA) bound to soluble uPAR (suPAR) with the similar "on-rate" but with a faster "off-rate" than wild-type (WT)-scuPA. Binding of Delta K-scuPA, but not WT-scuPA, to suPAR was comparably inhibited by its growth factor domain (GFD) and amino-terminal fragment (ATF). ATF and WT-scuPA, but not GFD, scuPA lacking the GFD (Delta GFD-scuPA), or Delta K-scuPA reconstituted the isolated domains of uPAR. ATF completely inhibited the enzymatic activity of WT-scuPA-suPAR unlike comparable concentrations of GFD. Variants containing mutations that alter the charge, length, or flexibility of linker sequence (residues 43-49) between the GFD and the kringle displayed a lower affinity for uPAR, were unable to reconstitute uPAR domains, and their binding to uPAR was inhibited by GFD in the same manner as Delta K-scuPA. A scuPA variant in which the charged amino acids in the heparin binding site (HBS) in the kringle domain were mutated to alanines behaved like Delta K-scuPA, indicating that that the structure of the kringle as well as its interaction with the GFD govern receptor binding. These data demonstrate an important role for the kringle in stabilizing the binding of scuPA to uPAR.
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Affiliation(s)
- Khalil Bdeir
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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11
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Milne RSB, Hanna SL, Rux AH, Willis SH, Cohen GH, Eisenberg RJ. Function of herpes simplex virus type 1 gD mutants with different receptor-binding affinities in virus entry and fusion. J Virol 2003; 77:8962-72. [PMID: 12885913 PMCID: PMC167229 DOI: 10.1128/jvi.77.16.8962-8972.2003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have studied the receptor-specific function of four linker-insertion mutants of herpes simplex virus type 1 glycoprotein D (gD) representing each of the functional regions of gD. We used biosensor analysis to measure binding of the gD mutants to the receptors HVEM (HveA) and nectin-1 (HveC). One of the mutants, gD(inverted Delta 34t), failed to bind HVEMt but showed essentially wild-type (WT) affinity for nectin-1t. The receptor-binding kinetics and affinities of the other three gD mutants varied over a 1,000-fold range, but each mutant had the same affinity for both receptors. All of the mutants were functionally impaired in virus entry and cell fusion, and the levels of activity were strikingly similar in these two assays. gD(inverted Delta 34)-containing virus was defective on HVEM-expressing cells but did enter nectin-1-expressing cells to about 60% of WT levels. This showed that the defect of this form of gD on HVEM-expressing cells was primarily one of binding and that this was separable from its later function in virus entry. gD(inverted Delta 243t) showed WT binding affinity for both receptors, but virus containing this form of gD had a markedly reduced rate of entry, suggesting that gD(inverted Delta 243) is impaired in a postbinding step in the entry process. There was no correlation between gD mutant activity in fusion or virus entry and receptor-binding affinity. We conclude that gD functions in virus entry and cell fusion regardless of its receptor-binding kinetics and that as long as binding to a functional receptor occurs, entry will progress.
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Affiliation(s)
- Richard S B Milne
- Department of Microbiology and Center for Oral Health Research, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6002, USA.
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12
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Rux AH, Lou H, Lambris JD, Friedman HM, Eisenberg RJ, Cohen GH. Kinetic analysis of glycoprotein C of herpes simplex virus types 1 and 2 binding to heparin, heparan sulfate, and complement component C3b. Virology 2002; 294:324-32. [PMID: 12009874 DOI: 10.1006/viro.2001.1326] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glycoprotein C (gC) from herpes simplex virus (HSV) facilitates virus entry by attaching the virion to host cell-surface heparan sulfate (HS). Although gC from HSV-1 (gC1) and from HSV-2 (gC2) bind to heparin, gC2 is believed to play a less significant role than gC1 in attachment of virus to cells. This attachment step is followed by the binding of gD to one of several cellular receptors. gC also plays an important role in immune evasion by binding to the C3b fragment of the third component of the host complement system. Yet, although both gC1 and gC2 protect HSV against complement-mediated neutralization, only gC on HSV-1-infected cells acts as a receptor for C3b. We used optical biosensor technology to quantitate the affinities (K(D)) and the stabilities (k(off)) between both serotypes of gC with heparin, HS, and C3b to address three questions concerning gC interactions. First, can differences in affinity or stability account for differences between the contributions of HSV-1 and HSV-2 gC in attachment? Our data show that the gC2-HS complex is highly unstable (k(off) = 0.2 s(-1)) compared to the gC1-HS complex (k(off) = 0.003 s(-1)), suggesting why gC2 may not play an important role in attachment of virus to cells as does gC1. Second, does gC2 have a lower affinity for C3b than does gC1, thereby explaining the lack of C3b-receptor activity on HSV-2 infected cells? Surprisingly, gC2 had a 10-fold higher affinity for C3b compared to gC1, so this functional difference in serotypes cannot be accounted for by affinity. Third, do differences in gC-HS and gD-receptor affinities support a model of HSV entry in which the gC-HS interaction is of lower affinity than the gD-receptor interaction? Our biosensor results indicate that gC has a higher affinity for HS than gD does for cellular receptors HveA (HVEM) and HveC (nectin-1).
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Affiliation(s)
- Ann H Rux
- Department of Microbiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Connolly SA, Whitbeck JJ, Rux AH, Krummenacher C, van Drunen Littel-van den Hurk S, Cohen GH, Eisenberg RJ. Glycoprotein D homologs in herpes simplex virus type 1, pseudorabies virus, and bovine herpes virus type 1 bind directly to human HveC(nectin-1) with different affinities. Virology 2001; 280:7-18. [PMID: 11162814 DOI: 10.1006/viro.2000.0747] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Distinct subsets of human receptors for alphaherpesviruses mediate the entry of herpes simplex virus (HSV), pseudorabies virus (PrV), or bovine herpes virus type 1 (BHV-1) into cells. Glycoprotein D (gD) is essential for receptor-mediated entry of all three viruses into cells. However, the gD homologs of these viruses share only 22-33% amino acid identity. Several entry receptors for HSV have been identified. Two of these, HveA (HVEM) and HveC (nectin-1), mediate entry of most HSV-1 and HSV-2 strains and are bound directly by HSV gD. A third receptor, HveB (nectin-2), mediates entry of HSV-2 and only a limited number of HSV-1 strains. HveB and HveC can also serve as entry receptors for PrV, whereas only HveC can serve this function for BHV-1. We show here that gD from PrV and BHV-1 binds directly to the human receptors that mediate PrV and BHV-1 entry. We expressed soluble forms of PrV gD and BHV-1 gD using recombinant baculoviruses and purified each protein. Using ELISA, we detected direct binding of PrV gD to HveB and HveC and direct binding of BHV-1 gD to HveC. Biosensor analysis revealed that PrV gD had a 10-fold higher affinity than HSV-1 gD for human HveC. In contrast, the binding of BHV-1 gD to HveC was weak. PrV gD and HSV-1 gD competed for binding to the V domain of HveC and both inhibited entry of the homologous and heterologous viruses. These data suggest that the two forms of gD bind to a common region on human HveC despite their low amino acid similarity. Based on affinities for human HveC, we predict a porcine HveC homolog may be important for PrV infection in its natural host, whereas a BHV-1 infection in its natural host may be mediated by a receptor other than a bovine HveC homolog.
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Affiliation(s)
- S A Connolly
- Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia 19104, USA.
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14
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Abstract
To study the kinetics and equilibrium of poliovirus binding to the poliovirus receptor, we used surface plasmon resonance to examine the interaction of a soluble form of the receptor with poliovirus. Soluble receptor purified from mammalian cells is able to bind poliovirus, neutralize viral infectivity, and induce structural changes in the virus particle. Binding studies revealed that there are two binding sites for the receptor on the poliovirus type 1 capsid, with affinity constants at 20 degrees C of K(D)(1) = 0.67 microm and K(D)(2) = 0.11 microm. The relative abundance of the two binding sites varies with temperature. At 20 degrees C, the K(D)(2) site constitutes approximately 46% of the total binding sites on the sensor chip, and its relative abundance decreased with decreasing temperature such that at 5 degrees C, the relative abundance of the K(D)(2) site is only 12% of the total binding sites. Absolute levels of the K(D)(1) site remained relatively constant at all temperatures tested. The two binding sites may correspond to docking sites for domain 1 of the receptor on the viral capsid, as predicted by a model of the poliovirus-receptor complex. Alternatively, the binding sites may be a consequence of structural breathing, or could result from receptor-induced conformational changes in the virus.
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Affiliation(s)
- B M McDermott
- Department of Microbiology, Columbia University College of Physicians & Surgeons, New York, New York 10032, USA
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15
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Whitbeck JC, Muggeridge MI, Rux AH, Hou W, Krummenacher C, Lou H, van Geelen A, Eisenberg RJ, Cohen GH. The major neutralizing antigenic site on herpes simplex virus glycoprotein D overlaps a receptor-binding domain. J Virol 1999; 73:9879-90. [PMID: 10559300 PMCID: PMC113037 DOI: 10.1128/jvi.73.12.9879-9890.1999] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Herpes simplex virus (HSV) entry is dependent on the interaction of virion glycoprotein D (gD) with one of several cellular receptors. We previously showed that gD binds specifically to two structurally dissimilar receptors, HveA and HveC. We have continued our studies by using (i) a panel of baculovirus-produced gD molecules with various C-terminal truncations and (ii) a series of gD mutants with nonoverlapping 3-amino-acid deletions between residues 222 and 254. Binding of the potent neutralizing monoclonal antibody (MAb) DL11 (group Ib) was unaffected in forms of gD containing residues 1 to 250 but was greatly diminished in molecules truncated at residue 240 or 234. Both receptor binding and blocking of HSV infection were also affected by these C-terminal truncations. gD-1(234t) bound weakly to both HveA and HveC as determined by enzyme-linked immunosorbent assay (ELISA) and failed to block infection. Interestingly, gD-1(240t) bound well to both receptors but blocked infection poorly, indicating that receptor binding as measured by ELISA is not the only gD function required for blocking. Optical biosensor studies showed that while gD-1(240t) bound HveC with an affinity similar to that of gD-1(306t), the rates of complex formation and dissociation were significantly faster than for gD-1(306t). Complementation analysis showed that any 3-amino-acid deletion between residues 222 and 251 of gD resulted in a nonfunctional protein. Among this set of proteins, three had lost DL11 reactivity (those with deletions between residues 222 and 230). One of these proteins (deletion 222-224) was expressed as a soluble form in the baculovirus system. This protein did not react with DL11, bound to both HveA and HveC poorly as shown by ELISA, and failed to block HSV infection. Since this protein was bound by several other MAbs that recognize discontinuous epitopes, we conclude that residues 222 to 224 are critical for gD function. We propose that the potent virus-neutralizing activity of DL11 (and other group Ib MAbs) likely reflects an overlap between its epitope and a receptor-binding domain of gD.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Viral/genetics
- Antigens, Viral/immunology
- Baculoviridae
- Binding Sites
- Biosensing Techniques
- Cell Line
- Chlorocebus aethiops
- Epitopes, B-Lymphocyte/genetics
- Epitopes, B-Lymphocyte/immunology
- Gene Expression
- Genes, Overlapping
- Genetic Complementation Test
- Genetic Vectors
- HeLa Cells
- Herpesvirus 1, Human/genetics
- Herpesvirus 1, Human/immunology
- Herpesvirus 1, Human/metabolism
- Herpesvirus 1, Human/physiology
- Humans
- Molecular Sequence Data
- Mutagenesis
- Neutralization Tests
- Receptors, Tumor Necrosis Factor
- Receptors, Tumor Necrosis Factor, Member 14
- Receptors, Virus/metabolism
- Sequence Deletion
- Solubility
- Spodoptera/cytology
- Vero Cells
- Viral Envelope Proteins/genetics
- Viral Envelope Proteins/immunology
- Viral Envelope Proteins/metabolism
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Affiliation(s)
- J C Whitbeck
- School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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16
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Krummenacher C, Rux AH, Whitbeck JC, Ponce-de-Leon M, Lou H, Baribaud I, Hou W, Zou C, Geraghty RJ, Spear PG, Eisenberg RJ, Cohen GH. The first immunoglobulin-like domain of HveC is sufficient to bind herpes simplex virus gD with full affinity, while the third domain is involved in oligomerization of HveC. J Virol 1999; 73:8127-37. [PMID: 10482562 PMCID: PMC112829 DOI: 10.1128/jvi.73.10.8127-8137.1999] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human herpesvirus entry mediator C (HveC/PRR1) is a member of the immunoglobulin family used as a cellular receptor by the alphaherpesviruses herpes simplex virus (HSV), pseudorabies virus, and bovine herpesvirus type 1. We previously demonstrated direct binding of the purified HveC ectodomain to purified HSV type 1 (HSV-1) and HSV-2 glycoprotein D (gD). Here, using a baculovirus expression system, we constructed and purified truncated forms of the receptor containing one [HveC(143t)], two [HveC(245t)], or all three immunoglobulin-like domains [HveC(346t)] of the extracellular region. All three constructs were equally able to compete with HveC(346t) for gD binding. The variable domain bound to virions and blocked HSV infection as well as HveC(346t). Thus, all of the binding to the receptor occurs within the first immunoglobulin-like domain, or V-domain, of HveC. These data confirm and extend those of Cocchi et al. (F. Cocchi, M. Lopez, L. Menotti, M. Aoubala, P. Dubreuil, and G. Campadelli-Fiume, Proc. Natl. Acad. Sci. USA 95:15700, 1998). Using biosensor analysis, we measured the affinity of binding of gD from HSV strains KOS and rid1 to two forms of HveC. Soluble gDs from the KOS strain of HSV-1 had the same affinity for HveC(346t) and HveC(143t). The mutant gD(rid1t) had an increased affinity for HveC(346t) and HveC(143t) due to a faster rate of complex formation. Interestingly, we found that HveC(346t) was a tetramer in solution, whereas HveC(143t) and HveC(245t) formed dimers, suggesting a role for the third immunoglobulin-like domain of HveC in oligomerization. In addition, the stoichiometry between gD and HveC appeared to be influenced by the level of HveC oligomerization.
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Affiliation(s)
- C Krummenacher
- Department of Microbiology, School of Dental Medicine, Philadelphia, Pennsylvania 19104, USA.
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17
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Pond AE, Roach MP, Sono M, Rux AH, Franzen S, Hu R, Thomas MR, Wilks A, Dou Y, Ikeda-Saito M, Ortiz de Montellano PR, Woodruff WH, Boxer SG, Dawson JH. Assignment of the heme axial ligand(s) for the ferric myoglobin (H93G) and heme oxygenase (H25A) cavity mutants as oxygen donors using magnetic circular dichroism. Biochemistry 1999; 38:7601-8. [PMID: 10360958 DOI: 10.1021/bi9825448] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UV-visible absorption and magnetic circular dichroism (MCD) data are reported for the cavity mutants of sperm whale H93G myoglobin and human H25A heme oxygenase in their ferric states at 4 degreesC. Detailed spectral analyses of H93G myoglobin reveal that its heme coordination structure has a single water ligand at pH 5.0, a single hydroxide ligand at pH 10.0, and a mixture of species at pH 7.0 including five-coordinate hydroxide-bound, and six-coordinate structures. The five-coordinate aquo structure at pH 5 is supported by spectral similarity to acidic horseradish peroxidase (pH 3.1), whose MCD data are reported herein for the first time, and acidic myoglobin (pH 3.4), whose structures have been previously assigned by resonance Raman spectroscopy. The five-coordinate hydroxide structure at pH 10.0 is supported by MCD and resonance Raman data obtained here and by comparison with those of other known five-coordinate oxygen donor complexes. In particular, the MCD spectrum of alkaline ferric H93G myoglobin is strikingly similar to that of ferric tyrosinate-ligated human H93Y myoglobin, whose MCD data are reported herein for the first time, and that of the methoxide adduct of ferric protoporphyrin IX dimethyl ester (FeIIIPPIXDME). Analysis of the spectral data for ferric H25A heme oxygenase at neutral pH in the context of the spectra of other five-coordinate ferric heme complexes with proximal oxygen donor ligands, in particular the p-nitrophenolate and acetate adducts of FeIIIPPIXDME, is most consistent with ligation by a carboxylate group of a nearby glutamyl (or aspartic) acid residue.
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Affiliation(s)
- A E Pond
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia 29208, USA
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18
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Rux AH, Willis SH, Nicola AV, Hou W, Peng C, Lou H, Cohen GH, Eisenberg RJ. Functional region IV of glycoprotein D from herpes simplex virus modulates glycoprotein binding to the herpesvirus entry mediator. J Virol 1998; 72:7091-8. [PMID: 9696802 PMCID: PMC109930 DOI: 10.1128/jvi.72.9.7091-7098.1998] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/1998] [Accepted: 06/03/1998] [Indexed: 11/20/2022] Open
Abstract
Glycoprotein D (gD) of herpes simplex virus (HSV) is essential for virus entry and has four functional regions (I to IV) important for this process. We previously showed that a truncated form of a functional region IV variant, gD1(Delta290-299t), had an enhanced ability to block virus entry and to bind to the herpesvirus entry mediator (HveAt; formerly HVEMt), a cellular receptor for HSV. To explore this phenotype further, we examined other forms of gD, especially ones with mutations in region IV. Variant proteins with deletions of amino acids between 277 and 300 (region IV), as well as truncated forms lacking C-terminal residues up to amino acid 275 of gD, were able to block HSV entry into Vero cells 1 to 2 logs better than wild-type gD1(306t). In contrast, gD truncated at residue 234 did not block virus entry into Vero cells. Using optical biosensor technology, we recently showed that gD1(Delta290-299t) had a 100-fold-higher affinity for HveAt than gD1(306t) (3.3 x 10(-8) M versus 3.2 x 10(-6) M). Here we found that the affinities of other region IV variants for HveAt were similar to that of gD1(Delta290-299t). Thus, the affinity data follow the same hierarchy as the blocking data. In each case, the higher affinity was due primarily to a faster kon rather than to a slower koff. Therefore, once the gDt-HveAt complex formed, its stability was unaffected by mutations in or near region IV. gD truncated at residue 234 bound to HveAt with a lower affinity (2.0 x 10(-5) M) than did gD1(306t) due to a more rapid koff. These data suggest that residues between 234 and 275 are important for maintaining stability of the gDt-HveAt complex and that functional region IV is important for modulating the binding of gD to HveA. The binding properties of any gD1(234t)-receptor complex could account for the inability of this form of gDt to block HSV infection.
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Affiliation(s)
- A H Rux
- Department of Microbiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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19
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Willis SH, Rux AH, Peng C, Whitbeck JC, Nicola AV, Lou H, Hou W, Salvador L, Eisenberg RJ, Cohen GH. Examination of the kinetics of herpes simplex virus glycoprotein D binding to the herpesvirus entry mediator, using surface plasmon resonance. J Virol 1998; 72:5937-47. [PMID: 9621056 PMCID: PMC110398 DOI: 10.1128/jvi.72.7.5937-5947.1998] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Previously, we showed that truncated soluble forms of herpes simplex virus (HSV) glycoprotein D (gDt) bound directly to a truncated soluble form of the herpesvirus entry mediator (HveAt, formerly HVEMt), a cellular receptor for HSV. The purpose of the present study was to determine the affinity of gDt for HveAt by surface plasmon resonance and to compare and contrast the kinetics of an expanded panel of gDt variants in binding to HveAt in an effort to better understand the mechanism of receptor binding and virus entry. Both HveAt and gDt are dimers in solution and interact with a 2:1 stoichiometry. With HveAt, gD1(306t) (from the KOS strain of HSV-1) had a dissociation constant (KD) of 3.2 x 10(-6) M and gD2(306t) had a KD of 1.5 x 10(-6) M. The interaction between gDt and HveAt fits a 1:1 Langmuir binding model, i.e., two dimers of HveAt may act as one binding unit to interact with one dimer of gDt as the second binding unit. A gD variant lacking all signals for N-linked oligosaccharides had an affinity for HveAt similar to that of gD1(306t). A variant lacking the bond from cysteine 1 to cysteine 5 had an affinity for HveAt that did not differ from that of the wild type. However, variants with double cysteine mutations that eliminated either of the other two disulfide bonds showed decreased affinity for HveAt. This result suggests that two of the three disulfide bonds of gD are important for receptor binding. Four nonfunctional gDt variants, each representing one functional domain of gD, were also studied. Mutations in functional regions I and II drastically decreased the affinity of gDt for HveAt. Surprisingly, a variant with an insertion in functional region III had a wild-type level of affinity for HveAt, suggesting that this domain may function in virus entry at a step other than receptor binding. A variant with a deletion in functional region IV [gD1(Delta290-299t)] exhibited a 100-fold enhancement in affinity for HveAt (KD = 3.3 x 10(-8) M) due mainly to a 40-fold increase in its kinetic on rate. This agrees with the results of other studies showing the enhanced ability of gD1(Delta290-299t) to block infection. Interestingly, all the variants with decreased affinities for HveAt exhibited decreased kinetic on rates but only minor changes in their kinetic off rates. The results suggest that once the complex between gDt and HveAt forms, its stability is unaffected by a variety of changes in gD.
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Affiliation(s)
- S H Willis
- School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Willis SH, Peng C, Leon MP, Nicola AV, Rux AH, Cohen GH, Eisenberg RJ. Expression and Purification of Secreted Forms of HSV Glycoproteins from Baculovirus-Infected Insect Cells. Methods Mol Med 1998; 10:131-156. [PMID: 21374226 DOI: 10.1385/0-89603-347-3:131] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Herpes simplex virus (HSV) remains a major human pathogen worldwide (25 causing cold sores, eye and genital infections, blindness, encephalitis, and neonatal infections. Most adults have antibodies against the oral form of the virus HSV-1 (9), and a significant number are infected with the genital form, HSV-2. Both serotypes establish lifelong latent infections and reactivate periodically to produce recurrent disease (25). After infection, virus-encoded glycoproteins are expressed on all cellular membranes and are major targets of the host's immune response. The virion envelope contains 10 glycoproteins that are important for infection and pathogenesis of HSV-1 and HSV-2. Because HSV contains so many glycoproteins, sorting out their functions in virus entry remains a difficult task. Our approach has focused on establishing structure-function relationships of the individual glycoproteins with particular emphasis on gC and gD. After many years of studying the properties of these proteins in HSV-infected and plasmid-transfected mammalian cells, we have now begun to overexpress the proteins using a baculovirus expression system.
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Affiliation(s)
- S H Willis
- Department of Microbiology, University of Pennsylvania, Philadelphia, PA
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Rux AH, Moore WT, Lambris JD, Abrams WR, Peng C, Friedman HM, Cohen GH, Eisenberg RJ. Disulfide bond structure determination and biochemical analysis of glycoprotein C from herpes simplex virus. J Virol 1996; 70:5455-65. [PMID: 8764057 PMCID: PMC190503 DOI: 10.1128/jvi.70.8.5455-5465.1996] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A biochemical analysis of glycoprotein C (gC of herpes simplex virus was undertaken to further characterize the structure of the glycoprotein and to determine its disulfide bond arrangement. We used three recombinant forms of gC, gC1(457t), gC1(delta33-123t), and gC2(426t), each truncated prior to the transmembrane region. The proteins were expressed and secreted by using a baculovirus expression system and have been shown to bind to monoclonal antibodies which recognize discontinuous epitopes and to complement component C3b in a dose-dependent manner. We confirmed the N-terminal residues of each mature protein by Edman degradation and confirmed the internal deletion in gC1(delta33-123t). The molecular weight and extent of glycosylation of gC1 (457t), gC1(delta33-123t), and gC2(426t) were determined by treating each protein with endoglycosidases and then subjecting it to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometric analysis. The data indicate that eight to nine of the predicted N-linked oligosaccharide sites on gC1(457t) are occupied by glycans of approximately 1,000 Da. In addition, O-linked oligosaccharides are present on gC1(457t), primarily localized to the N-terminal region (amino acids [aa] 33 to 123) of the protein. gC2(426t) contains N-linked oligosaccharides, but no O-linked oligosaccharides were detected. To determine the disulfide bond arrangement of the eight cysteines of gC1(457t),the protein was cleaved with cyanogen bromide. SDS-PAGE analysis followed by Edman degradation identified three cysteine-containing fragments which are not connected by disulfide linkages. Chemical modification of cysteines combined with matrix-assisted laser desorption ionization mass spectrometry identified disulfide bonds between cysteine 1 (aa 127) and cysteine 2 (aa 144) and between cysteine 3 (aa 286) and cysteine 4 (aa 347). Further proteolysis of the cyanogen bromide-generated fragment containing cysteine 5 through cysteine 8, combined with mass spectrometry and Edman degradation, showed that disulfide bonds link cysteine 5 (aa 386) to cysteine 8 (aa 442) and cysteine 6 (aa 390) to cysteine 7 (aa 419). A similar disulfide bond arrangement is postulated to exist in gC homologs from other herpesviruses.
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Affiliation(s)
- A H Rux
- Department of Microbiology, University of Pennsylvania, Philadelphia 19104, USA
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