1
|
Malia TJ, Teplyakov A, Ernst R, Wu SJ, Lacy ER, Liu X, Vandermeeren M, Mercken M, Luo J, Sweet RW, Gilliland GL. Epitope mapping and structural basis for the recognition of phosphorylated tau by the anti-tau antibody AT8. Proteins 2016; 84:427-34. [PMID: 26800003 PMCID: PMC5067699 DOI: 10.1002/prot.24988] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 12/14/2015] [Accepted: 12/19/2015] [Indexed: 11/09/2022]
Abstract
Microtubule‐associated protein tau becomes abnormally phosphorylated in Alzheimer's disease and other tauopathies and forms aggregates of paired helical filaments (PHF‐tau). AT8 is a PHF‐tau‐specific monoclonal antibody that is a commonly used marker of neuropathology because of its recognition of abnormally phosphorylated tau. Previous reports described the AT8 epitope to include pS202/pT205. Our studies support and extend previous findings by also identifying pS208 as part of the binding epitope. We characterized the phosphoepitope of AT8 through both peptide binding studies and costructures with phosphopeptides. From the cocrystal structure of AT8 Fab with the diphosphorylated (pS202/pT205) peptide, it appeared that an additional phosphorylation at S208 would also be accommodated by AT8. Phosphopeptide binding studies showed that AT8 bound to the triply phosphorylated tau peptide (pS202/pT205/pS208) 30‐fold stronger than to the pS202/pT205 peptide, supporting the role of pS208 in AT8 recognition. We also show that the binding kinetics of the triply phosphorylated peptide pS202/pT205/pS208 was remarkably similar to that of PHF‐tau. The costructure of AT8 Fab with a pS202/pT205/pS208 peptide shows that the interaction interface involves all six CDRs and tau residues 202–209. All three phosphorylation sites are recognized by AT8, with pT205 acting as the anchor. Crystallization of the Fab/peptide complex under acidic conditions shows that CDR‐L2 is prone to unfolding and precludes peptide binding, and may suggest a general instability in the antibody. Proteins 2016; 84:427–434. © 2016 The Authors. Proteins: Structure, Function, and Bioinformatics Published by Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Thomas J Malia
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Alexey Teplyakov
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Robin Ernst
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Sheng-Jiun Wu
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Eilyn R Lacy
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Xuesong Liu
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Marc Vandermeeren
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Marc Mercken
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Jinquan Luo
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Raymond W Sweet
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| | - Gary L Gilliland
- Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Pennsylvania, 19477
| |
Collapse
|
2
|
Obmolova G, Malia TJ, Teplyakov A, Sweet RW, Gilliland GL. Protein crystallization with microseed matrix screening: application to human germline antibody Fabs. Acta Crystallogr F Struct Biol Commun 2014; 70:1107-15. [PMID: 25084393 PMCID: PMC4118815 DOI: 10.1107/s2053230x14012552] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 05/30/2014] [Indexed: 11/10/2022] Open
Abstract
The crystallization of 16 human antibody Fab fragments constructed from all pairs of four different heavy chains and four different light chains was enabled by employing microseed matrix screening (MMS). In initial screening, diffraction-quality crystals were obtained for only three Fabs, while many Fabs produced hits that required optimization. Application of MMS, using the initial screens and/or refinement screens, resulted in diffraction-quality crystals of these Fabs. Five Fabs that failed to give hits in the initial screen were crystallized by cross-seeding MMS followed by MMS optimization. The crystallization protocols and strategies that resulted in structure determination of all 16 Fabs are presented. These results illustrate the power of MMS and provide a basis for developing future strategies for macromolecular crystallization.
Collapse
Affiliation(s)
- Galina Obmolova
- Janssen Research and Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - Thomas J. Malia
- Janssen Research and Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - Alexey Teplyakov
- Janssen Research and Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - Raymond W. Sweet
- Janssen Research and Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - Gary L. Gilliland
- Janssen Research and Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| |
Collapse
|
3
|
Almagro JC, Teplyakov A, Luo J, Sweet RW, Kodangattil S, Hernandez-Guzman F, Gilliland GL. Second antibody modeling assessment (AMA-II). Proteins 2014; 82:1553-62. [PMID: 24668560 DOI: 10.1002/prot.24567] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [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: 12/17/2013] [Revised: 03/18/2014] [Accepted: 03/19/2014] [Indexed: 01/07/2023]
Abstract
To assess the state of the art in antibody 3D modeling, 11 unpublished high-resolution x-ray Fab crystal structures from diverse species and covering a wide range of antigen-binding site conformations were used as a benchmark to compare Fv models generated by seven structure prediction methodologies. The participants included: Accerlys Inc, Chemical Computer Group (CCG), Schrodinger, Jeff Gray's lab at John Hopkins University, Macromoltek, Astellas Pharma/Osaka University and Prediction of ImmunoGlobulin Structure (PIGS). The sequences of benchmark structures were submitted to the modelers and PIGS, and a set of models were generated for each structure. We provide here an overview of the organization, participants and main results of this second antibody modeling assessment (AMA-II). Also, we compare the results with the first antibody assessment published in this journal (Almagro et al., 2011;79:3050).
Collapse
Affiliation(s)
- Juan C Almagro
- CTI Boston, Pfizer Inc., 3 Blackfan Circle, 18 Floor, Boston, MA, 02115
| | | | | | | | | | | | | |
Collapse
|
4
|
Malia TJ, Teplyakov A, Brezski RJ, Luo J, Kinder M, Sweet RW, Almagro JC, Jordan RE, Gilliland GL. Structure and specificity of an antibody targeting a proteolytically cleaved IgG hinge. Proteins 2014; 82:1656-67. [PMID: 24638881 DOI: 10.1002/prot.24545] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [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: 12/20/2013] [Revised: 02/13/2014] [Accepted: 02/20/2014] [Indexed: 11/09/2022]
Abstract
The functional role of human antihinge (HAH) autoantibodies in normal health and disease remains elusive, but recent evidence supports their role in the host response to IgG cleavage by proteases that are prevalent in certain disorders. Characterization and potential exploitation of these HAH antibodies has been hindered by the absence of monoclonal reagents. 2095-2 is a rabbit monoclonal antibody targeting the IdeS-cleaved hinge of human IgG1. We have determined the crystal structure of the Fab of 2095-2 and its complex with a hinge analog peptide. The antibody is selective for the C-terminally cleaved hinge ending in G236 and this interaction involves an uncommon disulfide in VL CDR3. We probed the importance of the disulfide in VL CDR3 through engineering variants. We identified one variant, QAA, which does not require the disulfide for biological activity or peptide binding. The structure of this variant offers a starting point for further engineering of 2095-2 with the same specificity, but lacking the potential manufacturing liability of an additional disulfide. Proteins 2014; 82:1656-1667. © 2014 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Thomas J Malia
- Biologics Research, Janssen Research and Development, LLC, Spring House, Pennsylvania
| | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Luo J, Obmolova G, Malia TJ, Wu SJ, Duffy KE, Marion JD, Bell JK, Ge P, Zhou ZH, Teplyakov A, Zhao Y, Lamb RJ, Jordan JL, San Mateo LR, Sweet RW, Gilliland GL. Lateral clustering of TLR3:dsRNA signaling units revealed by TLR3ecd:3Fabs quaternary structure. J Mol Biol 2012; 421:112-24. [PMID: 22579623 PMCID: PMC3920545 DOI: 10.1016/j.jmb.2012.05.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 04/27/2012] [Accepted: 05/03/2012] [Indexed: 12/19/2022]
Abstract
Toll-like receptor 3 (TLR3) recognizes dsRNA and initiates an innate immune response through the formation of a signaling unit (SU) composed of one double-stranded RNA (dsRNA) and two TLR3 molecules. We report the crystal structure of human TLR3 ectodomain (TLR3ecd) in a quaternary complex with three neutralizing Fab fragments. Fab15 binds an epitope that overlaps the C-terminal dsRNA binding site and, in biochemical assays, blocks the interaction of TLR3ecd with dsRNA, thus directly antagonizing TLR3 signaling through inhibition of SU formation. In contrast, Fab12 and Fab1068 bind TLR3ecd at sites distinct from the N- and C-terminal regions that interact with dsRNA and do not inhibit minimal SU formation with short dsRNA. Molecular modeling based on the co-structure rationalizes these observations by showing that both Fab12 and Fab1068 prevent lateral clustering of SUs along the length of the dsRNA ligand. This model is further supported by cell-based assay results using dsRNA ligands of lengths that support single and multiple SUs. Thus, their antagonism of TLR3 signaling indicates that lateral clustering of SUs is required for TLR3 signal transduction.
Collapse
Affiliation(s)
- Jinquan Luo
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Galina Obmolova
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Thomas J. Malia
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Sheng-Jiun Wu
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Karen E. Duffy
- Immunology Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - James D. Marion
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Jessica K. Bell
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Peng Ge
- Electron Imaging Center for Nanomachines (EICN), UCLA, Los Angeles, CA 90095, USA
| | - Z. Hong Zhou
- Electron Imaging Center for Nanomachines (EICN), UCLA, Los Angeles, CA 90095, USA
| | - Alexey Teplyakov
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Yonghong Zhao
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Roberta J. Lamb
- Immunology Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Jarrat L. Jordan
- Immunology Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Lani R. San Mateo
- Immunology Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Raymond W. Sweet
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Gary L. Gilliland
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| |
Collapse
|
6
|
Shi L, Wheeler JC, Sweet RW, Lu J, Luo J, Tornetta M, Whitaker B, Reddy R, Brittingham R, Borozdina L, Chen Q, Amegadzie B, Knight DM, Almagro JC, Tsui P. De novo selection of high-affinity antibodies from synthetic fab libraries displayed on phage as pIX fusion proteins. J Mol Biol 2010; 397:385-96. [PMID: 20114051 DOI: 10.1016/j.jmb.2010.01.034] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 01/06/2010] [Accepted: 01/14/2010] [Indexed: 10/19/2022]
Abstract
Filamentous phage was the first display platform employed to isolate antibodies in vitro and is still the most broadly used. The success of phage display is due to its robustness, ease of use, and comprehensive technology development, as well as a broad range of selection methods developed during the last two decades. We report here the first combinatorial synthetic Fab libraries displayed on pIX, a fusion partner different from the widely used pIII. The libraries were constructed on four V(L) and three V(H) domains encoded by IGV and IGJ germ-line genes frequently used in human antibodies, which were diversified to mirror the variability observed in the germ-line genes and antibodies isolated from natural sources. Two sets of libraries were built, one with diversity focused on V(H) by keeping V(L) in the germ-line gene configuration and the other with diversity in both V domains. After selection on a diverse panel of proteins, numerous specific Fabs with affinities ranging from 0.2 nM to 20 nM were isolated. V(H) diversity was sufficient for isolating Fabs to most antigens, whereas variability in V(L) was required for isolation of antibodies to some targets. After the application of an integrated maturation process consisting of reshuffling V(L) diversity, the affinity of selected antibodies was improved up to 100-fold to the low picomolar range, suitable for in vivo studies. The results demonstrate the feasibility of displaying complex Fab libraries as pIX fusion proteins for antibody discovery and optimization and lay the foundation for studies on the structure-function relationships of antibodies.
Collapse
Affiliation(s)
- Lei Shi
- Centocor R&D, Inc., 145 King of Prussia Road, Radnor, PA 19087, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Costello RT, Mallet F, Barbarat B, Schiano De Colella JM, Sainty D, Sweet RW, Truneh A, Olive D. Stimulation of non-Hodgkin's lymphoma via HVEM: an alternate and safe way to increase Fas-induced apoptosis and improve tumor immunogenicity. Leukemia 2003; 17:2500-7. [PMID: 14562115 DOI: 10.1038/sj.leu.2403175] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Stimulation by CD40 ligand (L) improves B-cell malignancy immunogenicity, and also induces proliferative signals. To avoid these tumorigenic effects, we studied an alternate way of tumor-cell stimulation by homologous to lymphotoxin, inducible expression, competing for GpD of herpesvirus, which binds to the herpesvirus entry mediator (HVEM), and is expressed on T-lymphocytes (LIGHT), the ligand for HVEM, a new member of the tumor necrosis factor (TNF)/TNF-receptor (-R) family. HVEM is constitutively expressed on the surface of tumor B cells. We focused our attention on mantle cell lymphoma, a subtype of B-cell malignancy of poor prognosis. Triggering by LIGHT, in contrast to CD40L stimulation, did not increase lymphoma proliferation nor decrease chemotherapy entrance. We observed an upregulation of the TNFR apoptosis-inducing ligand Fas, and in contrast to CD40L-induced protection, an enhancement of lymphoma sensitivity to Fas-induced apoptosis. LIGHT triggering increased lymphoma cell recognition in a mixed lymphocyte response. In conclusion, LIGHT-mediated triggering renders B-cell lymphomas more immunogenic and sensitive to apoptosis, without inducing proliferation. Since LIGHT triggering also enhances the functions of T-lymphocytes and dendritic cells, it could be a unique way to restore an efficient cancer control by its pleiotropic effects on immune effectors and tumor cells.
Collapse
|
8
|
Tsui P, Tornetta MA, Ames RS, Silverman C, Porter T, Weston C, Griego S, Sweet RW. Progressive epitope-blocked panning of a phage library for isolation of human RSV antibodies. J Immunol Methods 2002; 263:123-32. [PMID: 12009209 DOI: 10.1016/s0022-1759(02)00032-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Epitope-blocked panning is an approach to mining antigen-specific diversity from phage display antibody libraries. Previously, we developed and used this method to recover a neutralizing antibody to respiratory syncytial virus (RSV) by blocking a dominant response to a nonneutralizing epitope on a recombinant derivative of the viral F antigen. We have extended this approach to the blocking of multiple epitopes simultaneously, which led to the recovery of new antibodies of different specificity, including one new neutralizing activity. A phage display Fab library was selected on recombinant F antigen in the presence of three representative antibodies recovered in the unblocked and subsequent single-blocked panning procedures. Restriction endonuclease fingerprinting of 13 F+ clones revealed seven unique Fabs. DNA sequence analysis of five of these clones revealed five new light chains in combination with different heavy chains, three of which were very similar or identical to Fabs previously isolated from this library. The blocking antibodies did not compete with the new Fabs, demonstrating effective masking of their binding sites in the panning procedure. Conversely, these Fabs did show variable inhibition of two of the blocking antibodies suggesting a close proximity or interdependence of their epitopes. One of the antibodies did inhibit virus infection, albeit with modest potency. These results demonstrate that epitope-blocked panning is a self-progressing approach to retrieving diverse antibodies from phage libraries.
Collapse
Affiliation(s)
- Ping Tsui
- Department of Molecular Biology, GlaxoSmithKline Pharmaceuticals, 709 Swedeland Road, P.O. Box 1539, King of Prussia, PA 19406, USA.
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Fishman-Lobell J, Tsui P, Reddy M, DiPrinzio R, Eichman C, Sweet RW, Truneh A. CD4 mAb induced apoptosis of peripheral T cells: multiparameter subpopulation analysis by flow cytometry using Attractors. J Immunol Methods 2001; 257:71-82. [PMID: 11687240 DOI: 10.1016/s0022-1759(01)00447-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Studies describing the induction of apoptosis for CD4 mAbs do not delineate between epitope-dependent and Fc-driven epitope cross-linking induced cell death. Keliximab and clenoliximab are two CD4 mAbs that differ only in their heavy chain isotypes, being an IgG1 and a modified IgG4, respectively. These antibodies suppress CD4 T cell responses in vitro and in vivo and have been in human clinical trials for the treatment of RA and asthma. Here we compared the apoptotic activity of these mAbs to differentiate between the contributions of epitope-dependent vs. Fc-driven epitope cross-linking induced cell death in vitro as a link to differential CD4 cell depletion in vivo. We developed a simple flow cytometry procedure that measures apoptosis within intact and compromised subpopulations of PBMCs within a few hours of culture. Attractors software was used to quantitate the percentage of apoptotic CD4 T cells, which generate reactive oxygen species (ROS), express external phosphatidyl serine (PS) and cleaved fluorescein diacetate (FDA), within the intact and compromised lymphocyte populations. Treatment of freshly isolated PBMCs with keliximab resulted in the appearance of characteristic apoptotic condensed CD4 T cells that contained reactive oxygen species, were annexin V positive and had intact esterase activity. Apoptosis was evident within 3 h and continued throughout the 72-h culture period. In contrast, clenoliximab alone did not induce apoptosis. The use of multiparameter flow cytometry and Attractors to analyze subpopulations based on scatter properties and biochemical processes during apoptosis provides a sensitive assay in which to quantitate and characterize the induction of cell death. Depletion of CD4 T cells in vivo by keliximab may reflect, in part, antibody-mediated apoptosis of these cells that is dependent on Fcgamma receptors.
Collapse
Affiliation(s)
- J Fishman-Lobell
- Department of Oncology Research, SmithKline Beecham Pharmaceuticals, UW2101, 709 Swedeland Road, King of Prussia, PA 19406 USA.
| | | | | | | | | | | | | |
Collapse
|
10
|
Morel Y, Truneh A, Sweet RW, Olive D, Costello RT. The TNF superfamily members LIGHT and CD154 (CD40 ligand) costimulate induction of dendritic cell maturation and elicit specific CTL activity. J Immunol 2001; 167:2479-86. [PMID: 11509586 DOI: 10.4049/jimmunol.167.5.2479] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
LIGHT is a recently identified member of the TNF superfamily that is up-regulated upon activation of T cells. Herpesvirus entry mediator, one of its receptors, is constitutively expressed on immature dendritic cells (DCs). In this report, we demonstrate that LIGHT induces partial DC maturation as demonstrated by Ag presentation and up-regulation of adhesion and costimulatory molecules. LIGHT-stimulated DCs show reduced macropinocytosis and enhanced allogeneic stimulatory capacity but fail to produce significant amounts of IL-12, IL-6, IL-1beta, or TNF-alpha compared with unstimulated DCs. However, LIGHT cooperates with CD154 (CD40 ligand) in DC maturation, with particular potentiation of allogeneic T cell proliferation and cytokine secretion of IL-12, IL-6, and TNF-alpha. Moreover, LIGHT costimulation allows DCs to prime in vitro-enhanced specific CTL responses. Our results suggest that LIGHT plays an important role in DC-mediated immune responses by regulating CD154 signals and represents a potential tool for DC-based cancer immunotherapy.
Collapse
Affiliation(s)
- Y Morel
- Laboratoire d'Immunologie des Tumeurs and Département d'Hématologie, Institut Paoli-Calmettes, Université de la Méditerranée, Marseille, France
| | | | | | | | | |
Collapse
|
11
|
Doyle ML, Brigham-Burke M, Blackburn MN, Brooks IS, Smith TM, Newman R, Reff M, Stafford WF, Sweet RW, Truneh A, Hensley P, O'Shannessy DJ. Measurement of protein interaction bioenergetics: application to structural variants of anti-sCD4 antibody. Methods Enzymol 2001; 323:207-30. [PMID: 10944754 DOI: 10.1016/s0076-6879(00)23368-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This chapter has described a bioenergetic analysis of the interaction of sCD4 with an IgG1 and two IgG4 derivatives of an anti-sCD4 MAb. The MAbs have identical VH and VL domains but differ markedly in their CH and CL domains, raising the question of whether their antigen-binding chemistries are altered. We find the sCD4-binding kinetics and thermodynamics of the MAbs are indistinguishable, which indicates rigorously that the molecular details of the binding interactions are the same. We also showed the importance of using multiple biophysical methods to define the binding model before the bioenergetics can be appropriately interpreted. Analysis of the binding thermodynamics and kinetics suggests conformational changes that might be coupled to sCD4 binding by these MAbs are small or absent.
Collapse
Affiliation(s)
- M L Doyle
- Department of Structural Biology, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406-0939, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Newman R, Hariharan K, Reff M, Anderson DR, Braslawsky G, Santoro D, Hanna N, Bugelski PJ, Brigham-Burke M, Crysler C, Gagnon RC, Dal Monte P, Doyle ML, Hensley PC, Reddy MP, Sweet RW, Truneh A. Modification of the Fc region of a primatized IgG antibody to human CD4 retains its ability to modulate CD4 receptors but does not deplete CD4(+) T cells in chimpanzees. Clin Immunol 2001; 98:164-74. [PMID: 11161972 DOI: 10.1006/clim.2000.4975] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Keliximab, a Primatized IgG1 CD4 mAb, was reconfigured to an IgG4 antibody. The gamma4 constant region was further modified by substituting glutamic acid for serine at position 235 in the CH2 domain (IgG4-E), to remove residual binding to Fcgamma receptors, and substitution of serine with proline at position 228 in the hinge region (IgG4-PE) for greater stability. Pharmacokinetic analysis in rats gave a t(1/2) of approximately 4 days for IgG4-E and 9 days for IgG4-PE, consistent with a greater stability of the IgG4-PE molecule. The effects on T cell subsets were assessed in chimpanzees given escalating doses of IgG4-PE: 0.05 mg/kg on Day 16, 1.5 mg/kg dose on Day 43, and 15 mg/kg on Day 85. Receptor modulation was observed at the two highest doses, but no depletion of T cells at any dose. The in vitro and in vivo results demonstrate the potential of this IgG4-PE mAb for use in human trials.
Collapse
MESH Headings
- Amino Acid Substitution
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/genetics
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacokinetics
- Antibody Affinity
- Arthritis, Rheumatoid/therapy
- Binding Sites
- CD4 Antigens/immunology
- CD4-Positive T-Lymphocytes/drug effects
- CD4-Positive T-Lymphocytes/immunology
- Cloning, Molecular
- Genes, Immunoglobulin
- Humans
- Immunoglobulin Constant Regions/genetics
- Immunoglobulin Fc Fragments/chemistry
- Immunoglobulin Fc Fragments/genetics
- Immunoglobulin Fc Fragments/immunology
- Immunoglobulin G/chemistry
- Immunoglobulin G/genetics
- Immunoglobulin G/immunology
- Immunoglobulin Heavy Chains/genetics
- Immunosuppression Therapy/methods
- Lymphocyte Depletion
- Macaca fascicularis
- Male
- Mutagenesis, Site-Directed
- Pan troglodytes/immunology
- Polymerase Chain Reaction
- Protein Denaturation
- Rats
- Rats, Sprague-Dawley
- Receptors, IgG/metabolism
- Structure-Activity Relationship
Collapse
Affiliation(s)
- R Newman
- IDEC Pharmaceuticals Corporation, 11011 Torreyana Road, San Diego, California, 92121, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Kwong PD, Wyatt R, Majeed S, Robinson J, Sweet RW, Sodroski J, Hendrickson WA. Structures of HIV-1 gp120 Envelope Glycoproteins from Laboratory-Adapted and Primary Isolates. Structure 2001. [DOI: 10.1016/s0969-2126(01)00574-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
14
|
Kwong PD, Wyatt R, Majeed S, Robinson J, Sweet RW, Sodroski J, Hendrickson WA. Structures of HIV-1 gp120 envelope glycoproteins from laboratory-adapted and primary isolates. Structure 2000; 8:1329-39. [PMID: 11188697 DOI: 10.1016/s0969-2126(00)00547-5] [Citation(s) in RCA: 331] [Impact Index Per Article: 13.8] [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: 10/18/2022]
Abstract
BACKGROUND The gp120 exterior envelope glycoprotein of HIV-1 binds sequentially to CD4 and chemokine receptors on cells to initiate virus entry. During natural infection, gp120 is a primary target of the humoral immune response, and it has evolved to resist antibody-mediated neutralization. We previously reported the structure at 2.5 A of a gp120 core from the HXBc2 laboratory-adapted isolate in complex with a 2 domain fragment of CD4 and the antigen binding fragment of a human antibody. This revealed atomic details of gp120-receptor interactions and suggested multiple mechanisms of immune evasion. RESULTS We have now extended the HXBc2 structure in P222, crystals to 2.2 A. The enhanced resolution enabled a more accurate modeling of less-well-ordered regions and provided conclusive identification of the density in the central cavity at the crux of the gp120-CD4 interaction as isopropanol from the crystallization medium. We have also determined the structure of a gp120 core from the primary clinical HIV-1 isolate, YU2, in the same ternary complex but in a C2 crystal lattice. Comparisons of HXBc2 and YU2 showed that while CD4 binding was rigid, portions of the gp120 core were conformationally flexible; overall differences were minor, with sequence changes concentrated on a surface expected to be exposed on the envelope oligomer. CONCLUSIONS Despite dramatic antigenic differences between primary and laboratory-adapted HIV-1, the gp120 cores from these isolates are remarkably similar. Taken together with chimeric substitution and sequence analysis, this indicates that neutralization resistance is specified by quaternary interactions involving the major variable loops and thus affords a mechanism for viral adaptation. Conservation of the central cavity suggests the possibility of therapeutic inhibitors. The structures reported here extend in detail and generality our understanding of the biology of the gp120 envelope glycoprotein.
Collapse
Affiliation(s)
- P D Kwong
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA
| | | | | | | | | | | | | |
Collapse
|
15
|
Morel Y, Schiano de Colella JM, Harrop J, Deen KC, Holmes SD, Wattam TA, Khandekar SS, Truneh A, Sweet RW, Gastaut JA, Olive D, Costello RT. Reciprocal expression of the TNF family receptor herpes virus entry mediator and its ligand LIGHT on activated T cells: LIGHT down-regulates its own receptor. J Immunol 2000; 165:4397-404. [PMID: 11035077 DOI: 10.4049/jimmunol.165.8.4397] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The TNF receptor (TNFR) family plays a central role in the development of the immune response. Here we describe the reciprocal regulation of the recently identified TNFR superfamily member herpes virus entry mediator (HVEM) (TR2) and its ligand LIGHT (TL4) on T cells following activation and the mechanism of this process. T cell activation resulted in down-regulation of HVEM and up-regulation of LIGHT, which were both more pronounced in CD8(+) than CD4(+) T lymphocytes. The analysis of HVEM and LIGHT mRNA showed an increase in the steady state level of both mRNAs following stimulation. LIGHT, which was present in cytoplasm of resting T cells, was induced both in cytoplasm and at the cell surface. For HVEM, activation resulted in cellular redistribution, with its disappearance from cell surface. HVEM down-regulation did not rely on de novo protein synthesis, in contrast to the partial dependence of LIGHT induction. Matrix metalloproteinase inhibitors did not modify HVEM expression, but did enhance LIGHT accumulation at the cell surface. However, HVEM down-regulation was partially blocked by a neutralizing mAb to LIGHT or an HVEM-Fc fusion protein during activation. As a model, we propose that following stimulation, membrane or secreted LIGHT binds to HVEM and induces receptor down-regulation. Degradation or release of LIGHT by matrix metalloproteinases then contributes to the return to baseline levels for both LIGHT and HVEM. These results reveal a self-regulating ligand/receptor system that contributes to T cell activation through the interaction of T cells with each other and probably with other cells of the immune system.
Collapse
MESH Headings
- CD4-Positive T-Lymphocytes/drug effects
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD4-Positive T-Lymphocytes/virology
- CD8-Positive T-Lymphocytes/drug effects
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- CD8-Positive T-Lymphocytes/virology
- Cell Separation
- Cells, Cultured
- Cycloheximide/pharmacology
- Down-Regulation/immunology
- Enzyme Inhibitors/pharmacology
- Humans
- Ligands
- Lymphocyte Activation
- Membrane Proteins/biosynthesis
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Membrane Proteins/physiology
- Metalloendopeptidases/antagonists & inhibitors
- Metalloendopeptidases/physiology
- Microscopy, Confocal
- Protein Synthesis Inhibitors/pharmacology
- RNA, Messenger/metabolism
- Receptors, Tumor Necrosis Factor/antagonists & inhibitors
- Receptors, Tumor Necrosis Factor/biosynthesis
- Receptors, Tumor Necrosis Factor/genetics
- Receptors, Tumor Necrosis Factor/metabolism
- Receptors, Tumor Necrosis Factor, Member 14
- Receptors, Virus/antagonists & inhibitors
- Receptors, Virus/biosynthesis
- Receptors, Virus/genetics
- Receptors, Virus/metabolism
- Simplexvirus/immunology
- T-Lymphocyte Subsets/drug effects
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocyte Subsets/virology
- Tumor Necrosis Factor Ligand Superfamily Member 14
- Tumor Necrosis Factor-alpha/biosynthesis
- Tumor Necrosis Factor-alpha/genetics
- Tumor Necrosis Factor-alpha/metabolism
- Tumor Necrosis Factor-alpha/physiology
- Up-Regulation/immunology
Collapse
Affiliation(s)
- Y Morel
- Laboratoire d'Immunologie des Tumeurs, Département d'Hématologie, Institut Paoli Calmettes, Université de la Méditerranée, Marseille, France
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Myszka DG, Sweet RW, Hensley P, Brigham-Burke M, Kwong PD, Hendrickson WA, Wyatt R, Sodroski J, Doyle ML. Energetics of the HIV gp120-CD4 binding reaction. Proc Natl Acad Sci U S A 2000; 97:9026-31. [PMID: 10922058 PMCID: PMC16815 DOI: 10.1073/pnas.97.16.9026] [Citation(s) in RCA: 336] [Impact Index Per Article: 14.0] [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: 11/18/2022] Open
Abstract
HIV infection is initiated by the selective interaction between the cellular receptor CD4 and gp120, the external envelope glycoprotein of the virus. We used analytical ultracentrifugation, titration calorimetry, and surface plasmon resonance biosensor analysis to characterize the assembly state, thermodynamics, and kinetics of the CD4-gp120 interaction. The binding thermodynamics were of unexpected magnitude; changes in enthalpy, entropy, and heat capacity greatly exceeded those described for typical protein-protein interactions. These unusual thermodynamic properties were observed with both intact gp120 and a deglycosylated and truncated form of gp120 protein that lacked hypervariable loops V1, V2, and V3 and segments of its N and C termini. Together with previous crystallographic studies, the large changes in heat capacity and entropy reveal that extensive structural rearrangements occur within the core of gp120 upon CD4 binding. CD spectral studies and slow kinetics of binding support this conclusion. These results indicate considerable conformational flexibility within gp120, which may relate to viral mechanisms for triggering infection and disguising conserved receptor-binding sites from the immune system.
Collapse
Affiliation(s)
- D G Myszka
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Reddy MP, Kinney CA, Chaikin MA, Payne A, Fishman-Lobell J, Tsui P, Dal Monte PR, Doyle ML, Brigham-Burke MR, Anderson D, Reff M, Newman R, Hanna N, Sweet RW, Truneh A. Elimination of Fc receptor-dependent effector functions of a modified IgG4 monoclonal antibody to human CD4. J Immunol 2000; 164:1925-33. [PMID: 10657642 DOI: 10.4049/jimmunol.164.4.1925] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Several CD4 mAbs have entered the clinic for the treatment of autoimmune diseases or transplant rejection. Most of these mAbs caused CD4 cell depletion, and some were murine mAbs which were further hampered by human anti-mouse Ab responses. To obviate these concerns, a primatized CD4 mAb, clenoliximab, was generated by fusing the V domains of a cynomolgus macaque mAb to human constant regions. The heavy chain constant region is a modified IgG4 containing two single residue substitutions designed to ablate residual Fc receptor binding activity and to stabilize heavy chain dimer formation. This study compares and contrasts the in vitro properties of clenoliximab with its matched IgG1 derivative, keliximab, which shares the same variable regions. Both mAbs show potent inhibition of in vitro T cell responses, lack of binding to complement component C1q, and inability to mediate complement-dependent cytotoxicity. However, clenoliximab shows markedly reduced binding to Fc receptors and therefore does not mediate Ab-dependent cell-mediated cytotoxicity or modulation/loss of CD4 from the surface of T cells, except in the presence of rheumatoid factor or activated monocytes. Thus, clenoliximab retains the key immunomodulatory attributes of keliximab without the liability of strong Fcgamma receptor binding. In initial clinical trials, these properties have translated to a reduced incidence of CD4+ T cell depletion.
Collapse
Affiliation(s)
- M P Reddy
- Department of Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Kwong PD, Wyatt R, Desjardins E, Robinson J, Culp JS, Hellmig BD, Sweet RW, Sodroski J, Hendrickson WA. Probability analysis of variational crystallization and its application to gp120, the exterior envelope glycoprotein of type 1 human immunodeficiency virus (HIV-1). J Biol Chem 1999; 274:4115-23. [PMID: 9933605 DOI: 10.1074/jbc.274.7.4115] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The extensive glycosylation and conformational mobility of gp120, the envelope glycoprotein of type 1 human immunodeficiency virus (HIV-1), pose formidable barriers for crystallization. To surmount these difficulties, we used probability analysis to determine the most effective crystallization approach and derive equations which show that a strategy, which we term variational crystallization, substantially enhances the overall probability of crystallization for gp120. Variational crystallization focuses on protein modification as opposed to crystallization screening. Multiple variants of gp120 were analyzed with an iterative cycle involving a limited set of crystallization conditions and biochemical feedback on protease sensitivity, glycosylation status, and monoclonal antibody binding. Sources of likely conformational heterogeneity such as N-linked carbohydrates, flexible or mobile N and C termini, and variable internal loops were reduced or eliminated, and ligands such as CD4 and antigen-binding fragments (Fabs) of monoclonal antibodies were used to restrict conformational mobility as well as to alter the crystallization surface. Through successive cycles of manipulation involving 18 different variants, we succeeded in growing six different types of gp120 crystals. One of these, a ternary complex composed of gp120, its receptor CD4, and the Fab of the human neutralizing monoclonal antibody 17b, diffracts to a minimum Bragg spacing of at least 2.2 A and is suitable for structural analysis.
Collapse
Affiliation(s)
- P D Kwong
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Kwong PD, Wyatt R, Robinson J, Sweet RW, Sodroski J, Hendrickson WA. Structure of an HIV gp120 envelope glycoprotein in complex with the CD4 receptor and a neutralizing human antibody. Nature 1998; 393:648-59. [PMID: 9641677 PMCID: PMC5629912 DOI: 10.1038/31405] [Citation(s) in RCA: 2234] [Impact Index Per Article: 85.9] [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: 02/07/2023]
Abstract
The entry of human immunodeficiency virus (HIV) into cells requires the sequential interaction of the viral exterior envelope glycoprotein, gp120, with the CD4 glycoprotein and a chemokine receptor on the cell surface. These interactions initiate a fusion of the viral and cellular membranes. Although gp120 can elicit virus-neutralizing antibodies, HIV eludes the immune system. We have solved the X-ray crystal structure at 2.5 A resolution of an HIV-1 gp120 core complexed with a two-domain fragment of human CD4 and an antigen-binding fragment of a neutralizing antibody that blocks chemokine-receptor binding. The structure reveals a cavity-laden CD4-gp120 interface, a conserved binding site for the chemokine receptor, evidence for a conformational change upon CD4 binding, the nature of a CD4-induced antibody epitope, and specific mechanisms for immune evasion. Our results provide a framework for understanding the complex biology of HIV entry into cells and should guide efforts to intervene.
Collapse
Affiliation(s)
- P D Kwong
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA
| | | | | | | | | | | |
Collapse
|
20
|
Wyatt R, Kwong PD, Desjardins E, Sweet RW, Robinson J, Hendrickson WA, Sodroski JG. The antigenic structure of the HIV gp120 envelope glycoprotein. Nature 1998; 393:705-11. [PMID: 9641684 DOI: 10.1038/31514] [Citation(s) in RCA: 953] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The human immunodeficiency virus HIV-1 establishes persistent infections in humans which lead to acquired immunodeficiency syndrome (AIDS). The HIV-1 envelope glycoproteins, gp120 and gp41, are assembled into a trimeric complex that mediates virus entry into target cells. HIV-1 entry depends on the sequential interaction of the gp120 exterior envelope glycoprotein with the receptors on the cell, CD4 and members of the chemokine receptor family. The gp120 glycoprotein, which can be shed from the envelope complex, elicits both virus-neutralizing and non-neutralizing antibodies during natural infection. Antibodies that lack neutralizing activity are often directed against the gp120 regions that are occluded on the assembled trimer and which are exposed only upon shedding. Neutralizing antibodies, by contrast, must access the functional envelope glycoprotein complex and typically recognize conserved or variable epitopes near the receptor-binding regions. Here we describe the spatial organization of conserved neutralization epitopes on gp120, using epitope maps in conjunction with the X-ray crystal structure of a ternary complex that includes a gp120 core, CD4 and a neutralizing antibody. A large fraction of the predicted accessible surface of gp120 in the trimer is composed of variable, heavily glycosylated core and loop structures that surround the receptor-binding regions. Understanding the structural basis for the ability of HIV-1 to evade the humoral immune response should assist in the design of a vaccine.
Collapse
Affiliation(s)
- R Wyatt
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | | | | | | | | | | |
Collapse
|
21
|
Wu H, Myszka DG, Tendian SW, Brouillette CG, Sweet RW, Chaiken IM, Hendrickson WA. Kinetic and structural analysis of mutant CD4 receptors that are defective in HIV gp120 binding. Proc Natl Acad Sci U S A 1996; 93:15030-5. [PMID: 8986758 PMCID: PMC26350 DOI: 10.1073/pnas.93.26.15030] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The T-cell antigen coreceptor CD4 also serves as the receptor for the envelope glycoprotein gp120 of HIV. Extensive mutational analysis of CD4 has implicated residues from a portion of the extracellular amino-terminal domain (D1) in gp120 binding. However, none of these proteins has been fully characterized biophysically, and thus the precise effects on molecular structure and binding interactions are unknown. In the present study, we produced soluble versions of three mutant CD4 molecules (F43V, G47S, and A55F) and characterized their structural properties, thermostability, and ability to bind gp120. Crystallographic and thermodynamic analysis showed minimal structural alterations in the F43V and G47S mutant proteins, which have solvent-exposed mutant side chains. In contrast, some degree of disorder appears to exist in the folded state of A55F, as a result of mutating a buried side chain. Real time kinetic measurements of the interaction of the mutant proteins with gp120 showed affinity decreases of 5-fold for G47S, 50-fold for A55F, and 200-fold for F43V. Although both rate constants for the binding reaction were affected by these mutations, the loss in affinity was mainly due to a decrease in on rates, with less drastic changes occurring in the off rates. These observations suggest the involvement of conformational adaptation in the CD4-gp120 interaction. Together, the structural and kinetic data confirm that F43V is a critical residue in gp120 recognition site, which may also include main chain interactions at residue Gly-47.
Collapse
Affiliation(s)
- H Wu
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | | | | | | | | | | | | |
Collapse
|
22
|
Tsui P, Tornetta MA, Ames RS, Bankosky BC, Griego S, Silverman C, Porter T, Moore G, Sweet RW. Isolation of a neutralizing human RSV antibody from a dominant, non-neutralizing immune repertoire by epitope-blocked panning. The Journal of Immunology 1996. [DOI: 10.4049/jimmunol.157.2.772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
We isolated a large panel of human Abs directed against the respiratory syncytial virus (RSV) Ag from combinatorial phage display libraries. Following initial differentiation of the Fabs by BstNI restriction patterns, DNA sequence analysis revealed 10 different classes of VH paired with more than 35 different VL genes. All the Fabs bound with high affinity to the F Ag. However, most Fabs competed with the binding of a representative member of this group, suggesting that the Fabs recognized a common epitope on the F Ag, and none of them neutralized virus in vitro. To suppress repetitive isolation of these non-neutralizing Abs, a representative Fab was included during panning to block this common epitope on the F Ag. By this "epitope-blocked panning" approach, two novel Fabs, encoded by unique VH and VL genes, were isolated from a previously screened library. Competition binding analysis confirmed that the Fabs recognized epitopes distinct from that of the previously isolated Fabs. One of these Fabs, 516, neutralized RSV in cell culture. These activities of Fab-516 were retained upon its genetic conversion to a mAb (IgG1) and expression in mammalian cells. Our results suggest that the RSV F glycoprotein presents a dominant, non-neutralizing epitope to the human immune system, which may serve in evasion of host defenses. However, less prevalent, fusion-inhibiting Abs were revealed by blockade of this epitope during the panning process.
Collapse
Affiliation(s)
- P Tsui
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - M A Tornetta
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - R S Ames
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - B C Bankosky
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - S Griego
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - C Silverman
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - T Porter
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - G Moore
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - R W Sweet
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| |
Collapse
|
23
|
Tsui P, Tornetta MA, Ames RS, Bankosky BC, Griego S, Silverman C, Porter T, Moore G, Sweet RW. Isolation of a neutralizing human RSV antibody from a dominant, non-neutralizing immune repertoire by epitope-blocked panning. J Immunol 1996; 157:772-80. [PMID: 8752928] [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] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We isolated a large panel of human Abs directed against the respiratory syncytial virus (RSV) Ag from combinatorial phage display libraries. Following initial differentiation of the Fabs by BstNI restriction patterns, DNA sequence analysis revealed 10 different classes of VH paired with more than 35 different VL genes. All the Fabs bound with high affinity to the F Ag. However, most Fabs competed with the binding of a representative member of this group, suggesting that the Fabs recognized a common epitope on the F Ag, and none of them neutralized virus in vitro. To suppress repetitive isolation of these non-neutralizing Abs, a representative Fab was included during panning to block this common epitope on the F Ag. By this "epitope-blocked panning" approach, two novel Fabs, encoded by unique VH and VL genes, were isolated from a previously screened library. Competition binding analysis confirmed that the Fabs recognized epitopes distinct from that of the previously isolated Fabs. One of these Fabs, 516, neutralized RSV in cell culture. These activities of Fab-516 were retained upon its genetic conversion to a mAb (IgG1) and expression in mammalian cells. Our results suggest that the RSV F glycoprotein presents a dominant, non-neutralizing epitope to the human immune system, which may serve in evasion of host defenses. However, less prevalent, fusion-inhibiting Abs were revealed by blockade of this epitope during the panning process.
Collapse
Affiliation(s)
- P Tsui
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Kariv I, Truneh A, Sweet RW. Analysis of the site of interaction of CD28 with its counter-receptors CD80 and CD86 and correlation with function. J Immunol 1996; 157:29-38. [PMID: 8683128] [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] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
CD28 and CTLA-4 are homologue members of the Ig superfamily of molecules, containing a single V-like domain, transmembrane, and cytoplasmic regions. Both receptors associate with the counter-receptors CD80 and CD86, but the avidity of interaction for CD28 is about 20-fold lower than for CTLA-4. The interaction between CD28 and its cognate receptors provides a costimulatory signal for optimal T cell activation. Our previous mutational analysis of CD28 defined the highly conserved "MYPPPY" motif in the CDR3-region of the V-like domain as a key site of common and selective recognition. We have extended our analysis to cover all residues in the membrane distal loops of the V region, examining their effect on association with CD80/CD86 in cell adhesion and novel protein-based binding assays, and determining correlation between binding and functional response. Conservative F substitutions at either Y residue in the MYPPPY motif selectively reduced binding to CD86, but mutation of the three amino acids immediately C-terminal to Y 104 equivalently reduced binding to both co-receptors. The conservative F substitution of Y 26 in the CDR1-like region also reduced binding to CD80 and CD86. Other substitutions in the CDR1 loop and mutations spanning the CDR2 and DE loops had no effect. We conclude that the CDR1 and CDR3 regions contribute to a common binding site for CD80/CD86, and that the CDR3 region also carries determinants for selective recognition of these counter-receptors within the MYPPPY motif. Furthermore, for CD28, the strength of functional response, as measured by IL-2 production, directly correlates with binding avidity.
Collapse
Affiliation(s)
- I Kariv
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | | | | |
Collapse
|
25
|
Kariv I, Truneh A, Sweet RW. Analysis of the site of interaction of CD28 with its counter-receptors CD80 and CD86 and correlation with function. The Journal of Immunology 1996. [DOI: 10.4049/jimmunol.157.1.29] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
CD28 and CTLA-4 are homologue members of the Ig superfamily of molecules, containing a single V-like domain, transmembrane, and cytoplasmic regions. Both receptors associate with the counter-receptors CD80 and CD86, but the avidity of interaction for CD28 is about 20-fold lower than for CTLA-4. The interaction between CD28 and its cognate receptors provides a costimulatory signal for optimal T cell activation. Our previous mutational analysis of CD28 defined the highly conserved "MYPPPY" motif in the CDR3-region of the V-like domain as a key site of common and selective recognition. We have extended our analysis to cover all residues in the membrane distal loops of the V region, examining their effect on association with CD80/CD86 in cell adhesion and novel protein-based binding assays, and determining correlation between binding and functional response. Conservative F substitutions at either Y residue in the MYPPPY motif selectively reduced binding to CD86, but mutation of the three amino acids immediately C-terminal to Y 104 equivalently reduced binding to both co-receptors. The conservative F substitution of Y 26 in the CDR1-like region also reduced binding to CD80 and CD86. Other substitutions in the CDR1 loop and mutations spanning the CDR2 and DE loops had no effect. We conclude that the CDR1 and CDR3 regions contribute to a common binding site for CD80/CD86, and that the CDR3 region also carries determinants for selective recognition of these counter-receptors within the MYPPPY motif. Furthermore, for CD28, the strength of functional response, as measured by IL-2 production, directly correlates with binding avidity.
Collapse
Affiliation(s)
- I Kariv
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - A Truneh
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| | - R W Sweet
- Department of Molecular Immunology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406, USA
| |
Collapse
|
26
|
Tendian SW, Myszka DG, Sweet RW, Chaiken IM, Brouillette CG. Interdomain communication of T-cell CD4 studied by absorbance and fluorescence difference spectroscopy measurements of urea-induced unfolding. Biochemistry 1995; 34:6464-74. [PMID: 7756278 DOI: 10.1021/bi00019a028] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [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: 01/27/2023]
Abstract
CD4 is a transmembrane glycoprotein expressed on T-lymphocytes. It is a receptor for class II major histocompatibility complex (MHC) molecules and for the HIV envelope glycoprotein gp120. The extracellular portion of CD4 (sCD4) is a rod-shaped molecule consisting of four domains designated D1 through D4. Denaturant-induced unfolding of sCD4 and of isolated CD4 domains, D1D2 and D3D4, was measured using both ultraviolet absorbance and fluorescence difference spectroscopy. Though both absorbance and fluorescence changes arise from changes in the solvent exposure of the intrinsic tryptophan chromophores, the unfolding curves obtained with the two techniques looked very different for sCD4 and D3D4. This dissimilarity is indicative of a greater than two-state unfolding mechanism. The global three-state fit for sCD4, which simultaneously fit both absorbance and emission data to a model with one thermodynamically stable unfolding intermediate, was significantly better than the best two-state fit, suggesting that there are two unfolding regions. Unfolding of isolated D3D4 also fit a three-state model while unfolding of isolated D1D2 fit satisfactorily to a two-state model. The unfolding of these two isolated fragments could not be summed to yield the unfolding profile of sCD4, implying that an interaction between D2 and D3 is lost by splitting sCD4 between these domains. The unfolding data of isolated D1D2 and D3D4 were used with the solvent-accessible surface area of tryptophans calculated from atomic crystal structure coordinates of human D1D2 and rat D3D4 to assign the unfolding steps. The data are consistent with a model for sCD4 unfolding wherein the one stable intermediate appears to contain only the D4 domain unfolded. The remaining three domains apparently unfold as a unit. Furthermore, interactions between domains D1, D2, and D3 appear to stabilize D4, suggesting that stabilizing interactions exist between D3 and D4 even though the unfolding of the D3D4 fragment is best fit by a three-state model. This report is the first to describe a thermodynamic basis for a wide range of biological properties implicated for CD4.
Collapse
Affiliation(s)
- S W Tendian
- Southern Research Institute, Birmingham, Alabama 35205, USA
| | | | | | | | | |
Collapse
|
27
|
Abstract
BACKGROUND The T-cell surface glycoprotein CD4 interacts with class II molecules of the major histocompatibility complex (MHC) enhancing the signal for T-cell activation. Human CD4 also interacts, at high affinity, with the HIV envelope glycoprotein, gp120, to mediate T-cell infection by HIV. Crystal structures of amino-terminal two-domain (D1D2) fragments of human CD4, which contain the residues implicated in HIV and MHC interactions, have been reported earlier. RESULTS We have determined the crystal structure of a new D1D2 construct by molecular replacement from a previously described crystal structure of D1D2. This structure has more uniform lattice contacts than are in the first. This gives an improved image of domain D2, which in turn has permitted further refinement of the initial structure at 2.3 A resolution against a more complete data set. The structure of the second crystal form was also refined at 2.9 A resolution. In both models, all residues from 1 to 178 are now well defined, including the loop regions in D2. CONCLUSIONS Similarities of the molecular structure in the two lattices suggest that the D1D2 fragment works as a unit, with segmental flexibility largely restricted to the junction between domains D2 and D3. Variability of conformation in loops, including those implicated in MHC and HIV binding, requires an 'induced fit' in these interactions. Well defined density for the exposed side chain of Phe43 in both crystals confirms a prominent role for this residue in gp120 binding.
Collapse
Affiliation(s)
- S E Ryu
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032
| | | | | | | |
Collapse
|
28
|
Jarvest RL, Breen AL, Edge CM, Chaikin MA, John Jennings L, Truneh A, Sweet RW, Hertzberg RP. Structure-directed discovery of an inhibitor of the binding of HIV GP120 to the CD4 receptor. Bioorg Med Chem Lett 1993. [DOI: 10.1016/s0960-894x(01)80778-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
29
|
Tsui P, Sweet RW, Sathe G, Rosenberg M. An efficient phage plaque screen for the random mutational analysis of the interaction of HIV-1 gp120 with human CD4. J Biol Chem 1992; 267:9361-7. [PMID: 1533631] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A lambda phage expression methodology was adapted to dissect protein/ligand interactions efficiently through the creation and rapid screening of large numbers of mutants. Here we describe the method and its specific application to the interaction between the external envelope glycoprotein of the human immunodeficiency virus (HIV-1), gp120, and the human cell surface protein CD4. Random substitutions were introduced throughout the gp120 binding region (amino acids 38-62) in the amino-terminal domain of CD4 by oligonucleotide mutagenesis. These mutations were expressed within phage plaques and directly screened for their effect on binding of gp120 using a modified phage plaque lift procedure. Plaques showing increased, decreased, and no effect on binding were identified and mutations were verified by sequence analysis. In this manner, 25 unique mutations were identified that altered CD4 binding to gp120. A new site was identified at which mutations reduced binding to gp120 and several novel amino acid substitutions were defined at sites previously implicated in binding. Of particular interest, this in vitro genetic approach identified a mutation which significantly increased binding to gp120. The phenotypes of several of these mutants were further characterized by quantitative measurement of their binding affinity. The results confirmed the accuracy of the phenotypic selection and demonstrated that the sensitivity of the system allowed detection of a 3-4-fold increase or decrease in affinity. In the context of the recently determined atomic structure of CD4, these results further implicate residues in the CDR2-like region and in an adjacent loop in recognition of gp120. This methodology should be generally applicable to other high affinity protein/ligand interactions that are compatible with expression in Escherichia coli.
Collapse
Affiliation(s)
- P Tsui
- Biopharmaceuticals Research and Development, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406
| | | | | | | |
Collapse
|
30
|
Mulligan MJ, Ritter GD, Chaikin MA, Yamshchikov GV, Kumar P, Hahn BH, Sweet RW, Compans RW. Human immunodeficiency virus type 2 envelope glycoprotein: differential CD4 interactions of soluble gp120 versus the assembled envelope complex. Virology 1992; 187:233-41. [PMID: 1736526 DOI: 10.1016/0042-6822(92)90311-c] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [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: 12/28/2022]
Abstract
Utilizing a recombinant vaccinia expression system, we investigated the biological properties and CD4 receptor interactions of the envelope glycoproteins of a noncytopathic human immunodeficiency virus type 2 strain, termed HIV-2/ST, and a highly cytopathic variant derived from it. The efficiency and host cell range of syncytium formation by the recombinant glycoproteins of both viruses were highly restricted compared to those of prototypic strains of HIV (HIV-2/ROD or HIV-1/IIIB). However, the glycoprotein of cytopathic but not wild-type ST generated numerous large syncytia in the human T-cell line Sup T1 from which it was derived. A single cell line (Molt 4 clone 8) was permissive to fusion by both wild-type and cytopathic ST envelopes, but only the glycoprotein of cytopathic ST could be inhibited with a soluble form of the viral receptor CD4 (sCD4). While these results indicated major differences in the envelope glycoprotein-CD4 receptor interactions of wild-type versus cytopathic ST, direct and competition binding assays utilizing soluble external glycoprotein (SU) and sCD4 surprisingly revealed equivalent low binding affinity for both viruses. From these experiments we conclude that relevant biological properties (e.g., CD4 binding, cytopathic potential, and sCD4 neutralization) of HIV viruses which differ in their pathogenic potential are reflected in the sCD4 interactions of the assembled native envelope complex (as on cell or virion surfaces) but not the soluble SU glycoprotein.
Collapse
Affiliation(s)
- M J Mulligan
- Department of Medicine, University of Alabama, Birmingham 35294
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Gonzales JM, O'Donnell JK, Stadel JM, Sweet RW, Molinoff PB. Down-regulation of beta-adrenergic receptors by pindolol in Gs alpha-transfected S49 cyc- murine lymphoma cells. J Neurochem 1992; 58:1093-1103. [PMID: 1310718 DOI: 10.1111/j.1471-4159.1992.tb09367.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [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: 12/26/2022]
Abstract
The role of the alpha subunit of the guanine nucleotide-binding regulatory protein that stimulates adenylyl cyclase (GS alpha) in the down-regulation of beta-adrenergic receptors by pindolol was studied in S49 cyc- cells (normally GS alpha-deficient) transfected to express functional recombinant rat GS alpha. An inducible cell line (S49 GS alpha IND) was derived from S49 cyc- cells transfected with a vector containing the full-length coding sequence of GS alpha under the inducible control of the mouse mammary tumor virus long-terminal repeat promoter. GS alpha was not detectable in S49 GS alpha IND cells by immunoblot or by ADP-ribosylation in the presence of cholera toxin and [alpha-32P]NAD. When cells were grown in 100 nM dexamethasone, isoproterenol-stimulated cyclic AMP accumulation increased within 3 h. After 15 h, GS alpha was present at a level 40-50% of that found in S49 wild-type (WT) cells as measured either by immunoblot analysis or by [alpha-32P]ADP-ribosylation. Membranes prepared from GS alpha IND cells grown in the presence of dexamethasone bound agonist with high affinity, and this binding was sensitive to guanine nucleotides. A second vector, DzbGS alpha +, contained the coding sequence of GS alpha under the constitutive regulatory control of the SV40 early promoter. This vector was introduced into cyc- cells, and the resulting cells, S49 GS alpha CST cells, expressed GS alpha at a level comparable to that found in S49 WT cells as measured by immunoblot analysis. Isoproterenol-stimulated cyclic AMP accumulation in S49 GS alpha CST cells was at least as great as in S49 WT cells. When cells were grown in the presence of dexamethasone, exposure to 50 nM pindolol for 12 h down-regulated the density of beta-adrenergic receptors in S49 WT cells to 60% of that in cells grown in the absence of pindolol, but pindolol had no effect on the density of receptors on cyc- or GS alpha IND cells. When GS alpha CST cells were exposed to 50 nM pindolol for 12 h, the density of beta-adrenergic receptors was down-regulated by the same amount as in S49 WT cells. These results suggest that GS alpha is necessary to restore the ability of pindolol to down-regulate beta-adrenergic receptors in S49 cyc- cells and that the protein must be expressed at a level comparable to that found in S49 WT cells.
Collapse
Affiliation(s)
- J M Gonzales
- Department of Anesthesia, University of Pennsylvania, Philadelphia 19104-4283
| | | | | | | | | |
Collapse
|
32
|
Cassatt DR, Sweet RW, Arthos JA, Truneh A. Immunization with soluble murine CD4 induces an anti-self antibody response without causing impairment of immune function. The Journal of Immunology 1991. [DOI: 10.4049/jimmunol.147.5.1470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The T cell surface molecule CD4 (L3T4 in mouse) is important in the T lymphocyte response to Ag presented in association with MHC class II molecules. To examine the role of CD4 in immune function, we expressed a soluble form of murine CD4 by deleting the transmembrane and cytoplasmic regions of the L3T4 gene and transfecting the altered gene into Chinese hamster ovary cells. The recombinant soluble mouse CD4 (smCD4) retained the native conformation of the external portion, as indicated by the binding of L3T4 mAb. In vitro, smCD4 did not inhibit class II-dependent, Ag-specific, T cell proliferation or MLR, even at concentrations 300-fold greater, on a molar basis, than that of anti-CD4 mAb. Immunization of mice with smCD4 induced a strong anti-CD4 response. These antibodies showed some binding to native cell surface CD4, indicating that immunization with smCD4 generated an anti-self response. Analysis of lymphoid cells from spleen, lymph node, and thymus of smCD4-treated mice revealed no alteration in subset phenotypes. Also, Th cell function, as measured by response to soluble Ag, was not compromised. Thus, smCD4 did not inhibit T cell activity in vitro, and the autoimmune response arising from immunization with smCD4 had no apparent consequences for normal immune function.
Collapse
Affiliation(s)
- D R Cassatt
- Department of Cellular Biochemistry and Immunology, Smith Kline Beecham Pharmaceuticals, King of Prussia, PA 19406
| | - R W Sweet
- Department of Cellular Biochemistry and Immunology, Smith Kline Beecham Pharmaceuticals, King of Prussia, PA 19406
| | - J A Arthos
- Department of Cellular Biochemistry and Immunology, Smith Kline Beecham Pharmaceuticals, King of Prussia, PA 19406
| | - A Truneh
- Department of Cellular Biochemistry and Immunology, Smith Kline Beecham Pharmaceuticals, King of Prussia, PA 19406
| |
Collapse
|
33
|
Cassatt DR, Sweet RW, Arthos JA, Truneh A. Immunization with soluble murine CD4 induces an anti-self antibody response without causing impairment of immune function. J Immunol 1991; 147:1470-6. [PMID: 1880414] [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] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The T cell surface molecule CD4 (L3T4 in mouse) is important in the T lymphocyte response to Ag presented in association with MHC class II molecules. To examine the role of CD4 in immune function, we expressed a soluble form of murine CD4 by deleting the transmembrane and cytoplasmic regions of the L3T4 gene and transfecting the altered gene into Chinese hamster ovary cells. The recombinant soluble mouse CD4 (smCD4) retained the native conformation of the external portion, as indicated by the binding of L3T4 mAb. In vitro, smCD4 did not inhibit class II-dependent, Ag-specific, T cell proliferation or MLR, even at concentrations 300-fold greater, on a molar basis, than that of anti-CD4 mAb. Immunization of mice with smCD4 induced a strong anti-CD4 response. These antibodies showed some binding to native cell surface CD4, indicating that immunization with smCD4 generated an anti-self response. Analysis of lymphoid cells from spleen, lymph node, and thymus of smCD4-treated mice revealed no alteration in subset phenotypes. Also, Th cell function, as measured by response to soluble Ag, was not compromised. Thus, smCD4 did not inhibit T cell activity in vitro, and the autoimmune response arising from immunization with smCD4 had no apparent consequences for normal immune function.
Collapse
Affiliation(s)
- D R Cassatt
- Department of Cellular Biochemistry and Immunology, Smith Kline Beecham Pharmaceuticals, King of Prussia, PA 19406
| | | | | | | |
Collapse
|
34
|
Abstract
PCR-amplification cloning of the cDNA encoding the human high-affinity receptor for IgG (Fc gamma RI) revealed two splice variants which coincide with domain boundaries predicted by amino acid sequence comparison. Both splice variants maintain the open reading frame.
Collapse
Affiliation(s)
- M A Chaikin
- SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406-0939
| | | | | | | |
Collapse
|
35
|
Sweet RW, Truneh A, Hendrickson WA. CD4: Its structure, role in immune function and AIDS pathogenesis, and potential as a pharmacological target. Curr Opin Biotechnol 1991; 2:622-33. [PMID: 1367682 DOI: 10.1016/0958-1669(91)90089-n] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
CD4 is critical for the development and function of the CD4+ subset of T cells and also subserves as the receptor for the human immunodeficiency viruses. Reports in the past year clarify the role and the molecular interactions of CD4 in these events. Determination of the structure of an extracellular fragment of CD4 reveals novel variations of the immunoglobulin fold and provides an atomic framework for interpretation of its interactions with MHC class II molecules and with gp120, the external envelope glycoprotein of the human immunodeficiency virus.
Collapse
Affiliation(s)
- R W Sweet
- SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania
| | | | | |
Collapse
|
36
|
O'Donnell JK, Sweet RW, Stadel JM. Expression and characterization of the long and short splice variants of GS alpha in S49 cyc- cells. Mol Pharmacol 1991; 39:702-10. [PMID: 1646945] [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: 12/28/2022] Open
Abstract
The alpha subunit of the guanine nucleotide-binding regulatory protein GS mediates stimulation of adenylyl cyclase activity. This subunit, GS alpha, exists as two molecular weight forms, termed long and short, that differ by 14 or 15 amino acids. A physiological distinction between these two forms has yet to be defined. To compare the activities of these GS alpha isoforms, long and short forms of rat GS alpha were expressed in the cyc- variant of S49 murine lymphoma cells, which is deficient in endogenous GS alpha expression. By immunoblot analysis, the level of recombinant proteins in the clones expressing the long form of GS alpha was about twice that present in the clones expressing the short form of GS alpha or in the S49 wild-type cells. Both recombinant GS alpha proteins were sensitive to cholera toxin-catalyzed ADP-ribosylation, although the short form was labeled preferentially in both recombinant and S49 wild-type cell lines. In whole-cell assays, the clones expressing the long and short forms of GS alpha and the S49 wild-type cells gave comparable responses for stimulation of cAMP accumulation after challenge with (-)-isoproterenol, cholera toxin, or forskolin. In adenylyl cyclase assays with partially purified membranes, clones expressing the long form of GS alpha gave approximately twice the levels of cAMP in response to isoproterenol, guanosine-5'-O-(3-thio)triphosphate, NaF, or forskolin, compared with membranes from the clones expressing the short form of GS alpha or the S49 wild-type cells. However, when maximal adenylyl cyclase activity was normalized to the level of GS alpha protein in S49 wild-type cells, the cAMP productions were similar between all of the cell lines. In other membrane-based assays, the long and short forms of GS alpha were also equivalent in their dose response to isoproterenol and GTP, their kinetics of guanine nucleotide exchange and GTPase activity, and the induced high and low affinity states of the beta-adrenergic receptor in response to isoproterenol. In the latter radioligand binding analysis, membranes from the two clones expressing the long form of GS alpha consistently gave a greater proportion of the agonist high affinity state; however, this variation likely reflects the greater expression levels of GS alpha in these membranes. Thus, we conclude that the long and short forms of GS alpha expressed in S49 cyc- cells are very similar in their ability to stimulate adenylyl cyclase activity and to couple to beta-adrenergic receptors.
Collapse
Affiliation(s)
- J K O'Donnell
- Department of Molecular Genetics, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406-0939
| | | | | |
Collapse
|
37
|
Hart TK, Kirsh R, Ellens H, Sweet RW, Lambert DM, Petteway SR, Leary J, Bugelski PJ. Binding of soluble CD4 proteins to human immunodeficiency virus type 1 and infected cells induces release of envelope glycoprotein gp120. Proc Natl Acad Sci U S A 1991; 88:2189-93. [PMID: 2006155 PMCID: PMC51195 DOI: 10.1073/pnas.88.6.2189] [Citation(s) in RCA: 163] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Human immunodeficiency virus (HIV) infects cells after binding of the viral envelope glycoprotein gp120 to the cell surface recognition marker CD4. gp120 is noncovalently associated with the HIV transmembrane envelope glycoprotein gp41, and this complex is believed responsible for the initial stages of HIV infection and cytopathic events in infected cells. Soluble constructs of CD4 that contain the gp120 binding site inhibit HIV infection in vitro. This is believed to occur by competitive inhibition of viral binding to cellular CD4. Here we suggest an alternative mechanism of viral inhibition by soluble CD4 proteins. We demonstrate biochemically and morphologically that following binding, the soluble CD4 proteins sT4, V1V2,DT, and V1[106] (amino acids 1-369, 1-183, and -2 to 106 of mature CD4) induced the release of gp120 from HIV-1 and HIV-1-infected cells. gp120 release was concentration-, time-, and temperature-dependent. The reaction was biphasic at 37 degrees C and did not take place at 4 degrees C, indicating that binding of soluble CD4 was not sufficient to release gp120. The appearance of free gp120 in the medium after incubation with sT4 correlated with a decrease in envelope glycoprotein spikes on virions and exposure of a previously cryptic epitope near the amino terminus of gp41 on virions and infected cells. The concentration of soluble CD4 proteins needed to induce the release of gp120 from virally infected cells also correlated with those required to inhibit HIV-mediated syncytium formation. These results suggest that soluble CD4 constructs may inactivate HIV by inducing the release of gp120. We propose that HIV envelope-mediated fusion is initiated following rearrangement and/or dissociation of gp120 from the gp120-gp41 complex upon binding to cellular CD4, thus exposing the fusion domain of gp41.
Collapse
Affiliation(s)
- T K Hart
- Department of Experimental Pathology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Ivey-Hoyle M, Culp JS, Chaikin MA, Hellmig BD, Matthews TJ, Sweet RW, Rosenberg M. Envelope glycoproteins from biologically diverse isolates of immunodeficiency viruses have widely different affinities for CD4. Proc Natl Acad Sci U S A 1991; 88:512-6. [PMID: 1899141 PMCID: PMC50841 DOI: 10.1073/pnas.88.2.512] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.2] [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: 12/29/2022] Open
Abstract
The envelope glycoprotein gp120 of primate immunodeficiency viruses initiates viral attachment to CD4+ cells by binding to the CD4 antigen on host cell surfaces. However, among different CD4+ cell types, different viruses display distinct host cell ranges and cytopathicities. Determinants for both of these biological properties have been mapped to the env gene. We have quantitatively compared the CD4 binding affinities of gp120 proteins from viruses exhibiting different host cell tropisms and cytopathicities. The viral proteins were produced by using a Drosophila cell expression system and were purified to greater than 90% homogeneity. Drosophila-produced gp120 from T-cell tropic human immunodeficiency virus type 1 (HIV-1) BH10 exhibits binding to soluble recombinant CD4 (sCD4) and syncytia inhibition potency identical to that of pure authentic viral gp120. Relative to the affinity of HIV-1 BH10 gp120 for sCD4, that of dual tropic HIV-1 Ba-L is 6-fold lower, that of restricted T-cell tropic simian immunodeficiency virus mac is 70-fold lower, and that of noncytopathic HIV-2 ST is greater than 280-fold lower. Thus, viruses that utilize CD4 for infection do so by using a remarkably wide range of envelope affinities. These differences in affinity may play a role in determining cell tropism and cytopathicity.
Collapse
Affiliation(s)
- M Ivey-Hoyle
- Department of Gene Expression Sciences, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406
| | | | | | | | | | | | | |
Collapse
|
39
|
Abstract
Through mutagenesis, we identified a single high-affinity binding site for gp120 on the human CD4 protein. This site is localized in the V1 domain within residues 41 to 55. The collection of mutants was also used to define the epitopes for 55 anti-CD4 monoclonal antibodies. The locations of these epitopes are consistent with a V kappa-like structure for the V1 domain. In the context of this structure, the gp120 binding site encompasses the small CDR2 loop. Through deletion mutagenesis at the termini of the V1 domain, we further defined the minimal region required to retain high-affinity binding to gp120. Short deletions at both termini disrupt binding to gp120 and recognition by conformation-sensitive anti-CD4 monoclonal antibodies. We conclude that amino acids at both the amino and carboxy termini are critical to the conformation of the V1 domain and, in particular, to the integrity of the gp120 binding site.
Collapse
Affiliation(s)
- J Arthos
- SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19479
| | | | | | | | | | | |
Collapse
|
40
|
Ryu SE, Kwong PD, Truneh A, Porter TG, Arthos J, Rosenberg M, Dai XP, Xuong NH, Axel R, Sweet RW. Crystal structure of an HIV-binding recombinant fragment of human CD4. Nature 1990; 348:419-26. [PMID: 2247146 PMCID: PMC5638305 DOI: 10.1038/348419a0] [Citation(s) in RCA: 431] [Impact Index Per Article: 12.7] [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: 12/31/2022]
Abstract
CD4 glycoprotein on the surface of T cells helps in the immune response and is the receptor for HIV infection. The structure of a soluble fragment of CD4 determined at 2.3 A resolution reveals that the molecule has two intimately associated immunoglobulin-like domains. Residues implicated in HIV recognition by analysis of mutants and antibody binding are salient features in domain D1. Domain D2 is distinguished by a variation on the beta-strand topologies of antibody domains and by an intra-sheet disulphide bridge.
Collapse
Affiliation(s)
- S E Ryu
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032
| | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Kwong PD, Ryu SE, Hendrickson WA, Axel R, Sweet RM, Folena-Wasserman G, Hensley P, Sweet RW. Molecular characteristics of recombinant human CD4 as deduced from polymorphic crystals. Proc Natl Acad Sci U S A 1990; 87:6423-7. [PMID: 2385600 PMCID: PMC54546 DOI: 10.1073/pnas.87.16.6423] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We have grown crystals of a soluble recombinant form of human CD4, a transmembrane glycoprotein found predominantly on the surface of helper T cells. Crystals composed of the entire extracellular portion of CD4 exhibit extensive polymorphism. Of the five crystal types that have been grown, the best diffracts to Bragg spacings of 4.9 A. Symmetry considerations and characterization of the asymmetric unit by volume-specific amino acid analysis lead to the suggestion that a tetramer is the fundamental unit of crystallization. The characterization also showed that several of the crystal types have unusually high solvent contents. Because high solvent content and weak diffraction are indicative of an extended flexible structure, we examined the molecular shape of the recombinant CD4 with ultracentrifugation and found that it has an axial ratio of roughly 6, when modeled as a prolate ellipsoid. These results, combined with crystal packing constraints, suggest dimensions of approximately 25 x 25 x 125 A for a monomer. The structural features deduced here may be relevant to the biological function of CD4 as a receptor mediating cell-cell and cell-virus interactions.
Collapse
Affiliation(s)
- P D Kwong
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Rosenberg M, Bugelski PJ, Fong KL, Drutz DJ, Sweet RW, Webb DD. Soluble recombinant CD4--a potential therapeutic agent for HIV infection. Biotherapy 1990; 2:107-18. [PMID: 2205260 DOI: 10.1007/bf02173451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M Rosenberg
- Department of Molecular Genetics, Smith Kline & French Laboratories, King of Prussia, PA 19406-0939
| | | | | | | | | | | |
Collapse
|
43
|
Carr SA, Hemling ME, Folena-Wasserman G, Sweet RW, Anumula K, Barr JR, Huddleston MJ, Taylor P. Protein and carbohydrate structural analysis of a recombinant soluble CD4 receptor by mass spectrometry. J Biol Chem 1989; 264:21286-95. [PMID: 2592374] [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: 01/01/2023] Open
Abstract
The primary structure of a soluble form of the CD4 receptor (sCD4) expressed in Chinese hamster ovary cells has been confirmed by mass spectrometric peptide mapping and and tandem mass spectrometry. These studies corroborated 95% of the 369-amino acid-long sequence and established the fidelity of translation of the NH2 and COOH terminal including the absence of "ragged ends." The arrangement of the three disulfide bonds in recombinant sCD4 was also established by mass spectrometry and comparative high performance liquid chromatography mapping and shown to be identical to that expected from previous studies of intrachain disulfide bonding in T4 antigens derived from sheep and mouse. No other arrangements of disulfides were detected. Carbohydrate mapping by mass spectrometry was used to establish that both potential Asn-linked glycosylation sites in sCD4 (Asn271 and Asn300) have oligosaccharides attached. Structural characterization by mass spectrometry and methylation analysis of the heterogeneous family of oligosaccharides at each of the specific attachment sites indicates that the major components of both families of oligosaccharides have the following biantennary structures: (Formula, see text) where m + n = 0-2, and x = 0,1. Minor carbohydrate components having three N-acetylneuraminic acid (NeuAc) groups and an additional hexose-hexosamine unit were detected by high performance anion-exchange chromatography.
Collapse
Affiliation(s)
- S A Carr
- Department of Physical and Structural Chemistry, Smith Kline and French Laboratories, King of Prussia, Pennsylvania 19406
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Carr SA, Hemling ME, Folena-Wasserman G, Sweet RW, Anumula K, Barr JR, Huddleston MJ, Taylor P. Protein and carbohydrate structural analysis of a recombinant soluble CD4 receptor by mass spectrometry. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)30077-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
45
|
Ibegbu CC, Kennedy MS, Maddon PJ, Deen KC, Hicks D, Sweet RW, McDougal JS. Structural features of CD4 required for binding to HIV. J Immunol 1989; 142:2250-6. [PMID: 2538505] [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] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A soluble form of the human CD4 glycoprotein (sCD4), the cellular receptor for human HIV, was treated with various physical, chemical, and enzymic regimens and tested over a range of concentrations for its capacity to inhibit the binding of HIV to CD4+ T cells. Reduction of disulfide bonds and alkylation in denaturing buffer (8 M urea) destroyed the inhibitory activity of sCD4, whereas reduction and alkylation in PBS had no effect. Derivatization or digestion of carbohydrate groups by periodate oxidation or by glycolytic enzyme digestion did not affect sCD4 inhibitory capacity. Digestion with trypsin or endoproteinase Glu-C destroyed activity. A limited digestion of sCD4 with endoproteinase Glu-C resulted in a mixture of fragments, however, and the mixture had inhibitory activity equivalent to that of intact sCD4. Within this mixture, a fragment of 23 kDa was identified that binds to HIV. Although sCD4 can be digested to yield fully active fragments, the requirement for intrachain disulfide bonding indicates that the minimum sized portion of CD4 that will retain full affinity for HIV will have to be formulated with a proper tertiary structure.
Collapse
Affiliation(s)
- C C Ibegbu
- Division of Host Factors, Centers for Disease Control, Atlanta, GA 30333
| | | | | | | | | | | | | |
Collapse
|
46
|
Ibegbu CC, Kennedy MS, Maddon PJ, Deen KC, Hicks D, Sweet RW, McDougal JS. Structural features of CD4 required for binding to HIV. The Journal of Immunology 1989. [DOI: 10.4049/jimmunol.142.7.2250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
A soluble form of the human CD4 glycoprotein (sCD4), the cellular receptor for human HIV, was treated with various physical, chemical, and enzymic regimens and tested over a range of concentrations for its capacity to inhibit the binding of HIV to CD4+ T cells. Reduction of disulfide bonds and alkylation in denaturing buffer (8 M urea) destroyed the inhibitory activity of sCD4, whereas reduction and alkylation in PBS had no effect. Derivatization or digestion of carbohydrate groups by periodate oxidation or by glycolytic enzyme digestion did not affect sCD4 inhibitory capacity. Digestion with trypsin or endoproteinase Glu-C destroyed activity. A limited digestion of sCD4 with endoproteinase Glu-C resulted in a mixture of fragments, however, and the mixture had inhibitory activity equivalent to that of intact sCD4. Within this mixture, a fragment of 23 kDa was identified that binds to HIV. Although sCD4 can be digested to yield fully active fragments, the requirement for intrachain disulfide bonding indicates that the minimum sized portion of CD4 that will retain full affinity for HIV will have to be formulated with a proper tertiary structure.
Collapse
Affiliation(s)
- C C Ibegbu
- Division of Host Factors, Centers for Disease Control, Atlanta, GA 30333
| | - M S Kennedy
- Division of Host Factors, Centers for Disease Control, Atlanta, GA 30333
| | - P J Maddon
- Division of Host Factors, Centers for Disease Control, Atlanta, GA 30333
| | - K C Deen
- Division of Host Factors, Centers for Disease Control, Atlanta, GA 30333
| | - D Hicks
- Division of Host Factors, Centers for Disease Control, Atlanta, GA 30333
| | - R W Sweet
- Division of Host Factors, Centers for Disease Control, Atlanta, GA 30333
| | - J S McDougal
- Division of Host Factors, Centers for Disease Control, Atlanta, GA 30333
| |
Collapse
|
47
|
Clapham PR, Weber JN, Whitby D, McIntosh K, Dalgleish AG, Maddon PJ, Deen KC, Sweet RW, Weiss RA. Soluble CD4 blocks the infectivity of diverse strains of HIV and SIV for T cells and monocytes but not for brain and muscle cells. Nature 1989; 337:368-70. [PMID: 2536142 DOI: 10.1038/337368a0] [Citation(s) in RCA: 323] [Impact Index Per Article: 9.2] [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: 01/01/2023]
Abstract
The CD4 antigen has been subverted as a receptor by the human and simian immunodeficiency viruses (HIV-1, HIV-2 and SIV). Several groups have reported that recombinant, soluble forms of the CD4 molecule (sCD4) block the infection of T lymphocytes by HIV-1, as CD4 binds the HIV envelope glycoprotein, gp120, with high affinity. We now report that sCD4 blocks diverse strains of HIV-1, HIV-2 and SIV, but is less effective for HIV-2. The blocking effect is apparent even after adsorption of virions to CD4 cells. Soluble CD4 prevents HIV infection of T-lymphocytic and myelomonocytic cell lines, but neither sCD4 nor anti-CD4 antibodies inhibit infection of glioma and rhabdomyosarcoma cell lines.
Collapse
Affiliation(s)
- P R Clapham
- Chester Beatty Laboratories, Institute of Cancer Research, London, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Connors RW, Sweet RW, Noveral JP, Pfarr DS, Trill JJ, Shebuski RJ, Berkowitz BA, Williams D, Franklin S, Reff ME. DHFR coamplification of t-PA in DHFR+ bovine endothelial cells: in vitro characterization of the purified serine protease. DNA 1988; 7:651-61. [PMID: 3147883 DOI: 10.1089/dna.1988.7.651] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
High-level expression of human tissue-type plasminogen activator was accomplished in endothelial cells by a novel approach to dihydrofolate reductase (DHFR) coamplification in DHFR+ cells. A tripartite mammalian expression vector coding for DHFR, neomycin phosphotransferase, and the t-PA gene was introduced into bovine endothelial cells by transfection and selection for G418 resistance. Upon methotrexate selection of these transformants, we obtained endothelial cells that had amplified the plasmid-encoded DHFR and t-PA genes. As a result, cell lines were isolated that efficiently produced t-PA (greater than 4 pg/cell.day). This t-PA was purified and compared with recombinant t-PA produced in Chinese hamster ovary cells. These two t-PA samples differed in carbohydrate composition, and amounts of 530 and 527 amino acid forms but had similar in vitro activity.
Collapse
Affiliation(s)
- R W Connors
- Department of Molecular Genetics, Smith Kline and French Laboratories, King of Prussia, PA 19406-0939
| | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Khillan JS, Deen KC, Yu SH, Sweet RW, Rosenberg M, Westphal H. Gene transactivation mediated by the TAT gene of human immunodeficiency virus in transgenic mice. Nucleic Acids Res 1988; 16:1423-30. [PMID: 3258064 PMCID: PMC336325 DOI: 10.1093/nar/16.4.1423] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Transgenic mice were generated carrying either the long terminal repeat of Human Immunodeficiency Virus fused to the bacterial chloramphenicol acetyl transferase reporter gene or a control element of the murine alpha A crystallin gene fused to the tat gene of human immunodeficiency virus. By crossing these two strains, progeny were obtained which carried both transgenes. The bacterial reporter gene was specifically transactivated in the eyes of these animals.
Collapse
Affiliation(s)
- J S Khillan
- Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, MD 20892
| | | | | | | | | | | |
Collapse
|
50
|
Deen KC, McDougal JS, Inacker R, Folena-Wasserman G, Arthos J, Rosenberg J, Maddon PJ, Axel R, Sweet RW. A soluble form of CD4 (T4) protein inhibits AIDS virus infection. Nature 1988; 331:82-4. [PMID: 3257544 DOI: 10.1038/331082a0] [Citation(s) in RCA: 458] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
CD4 (T4) is a glycoprotein of relative molecular mass 55,000 (Mr 55K) on the surface of T lymphocytes which is thought to interact with class II MHC (major histocompatibility complex) molecules, mediating efficient association of helper T cells with antigen-bearing targets. The CD4 protein is also the receptor for HIV, a T-lymphotropic RNA virus responsible for the human acquired immune deficiency syndrome (AIDS) (refs 4-7). To define the mechanisms of interaction of CD4 with the surface of antigen-presenting cells and with HIV, we have isolated the CD4 gene and expressed this gene in several different cellular environments. Here we describe an efficient expression system in which a recombinant, soluble form of CD4 (sCD4) is secreted into tissue culture supernatants. This sCD4 retains the structural and biological properties of CD4 on the cell surface, binds to the envelope glycoprotein (gp110) of HIV and inhibits the binding of virus to CD4+ lymphocytes, resulting in a striking inhibition of virus infectivity.
Collapse
Affiliation(s)
- K C Deen
- Smith Kline and French Laboratories, King of Prussia, Pennsylvania 19406
| | | | | | | | | | | | | | | | | |
Collapse
|