1
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Cheung TC, Atwell S, Bafetti L, Cuenca PD, Froning K, Hendle J, Hickey M, Ho C, Huang J, Lieu R, Lim S, Lippner D, Obungu V, Ward-Kavanagh L, Weichert K, Ware CF, Vendel AC. Epitope topography of agonist antibodies to the checkpoint inhibitory receptor BTLA. Structure 2023; 31:958-967.e3. [PMID: 37279757 DOI: 10.1016/j.str.2023.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 12/06/2022] [Revised: 03/16/2023] [Accepted: 05/11/2023] [Indexed: 06/08/2023]
Abstract
B and T lymphocyte attenuator (BTLA) is an attractive target for a new class of therapeutics that attempt to rebalance the immune system by agonizing checkpoint inhibitory receptors (CIRs). Herpesvirus entry mediator (HVEM) binds BTLA in both trans- and cis-orientations. We report here the development and structural characterization of three humanized BTLA agonist antibodies, 22B3, 25F7, and 23C8. We determined the crystal structures of the antibody-BTLA complexes, showing that these antibodies bind distinct and non-overlapping epitopes of BTLA. While all three antibodies activate BTLA, 22B3 mimics HVEM binding to BTLA and shows the strongest agonistic activity in functional cell assays and in an imiquimod-induced mouse model of psoriasis. 22B3 is also capable of modulating HVEM signaling through the BTLA-HVEM cis-interaction. The data obtained from crystal structures, biochemical assays, and functional studies provide a mechanistic model of HVEM and BTLA organization on the cell surface and informed the discovery of a highly active BTLA agonist.
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Affiliation(s)
- Timothy C Cheung
- Infectious and Inflammatory Diseases Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Shane Atwell
- Biotechnology Discovery Research, Eli Lilly and Company, Lilly Biotechnology Center, San Diego, CA 92121, USA
| | - Lisa Bafetti
- Immunology Discovery Research, Eli Lilly and Company, Lilly Biotechnology Center, San Diego, CA 92121, USA
| | - Paulina Delgado Cuenca
- Infectious and Inflammatory Diseases Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Karen Froning
- Biotechnology Discovery Research, Eli Lilly and Company, Lilly Biotechnology Center, San Diego, CA 92121, USA
| | - Jorg Hendle
- Discovery Chemistry Research and Technologies, Eli Lilly and Company, Lilly Biotechnology Center, San Diego, CA 92121, USA
| | - Michael Hickey
- Discovery Chemistry Research and Technologies, Eli Lilly and Company, Lilly Biotechnology Center, San Diego, CA 92121, USA
| | - Carolyn Ho
- Biotechnology Discovery Research, Eli Lilly and Company, Lilly Biotechnology Center, San Diego, CA 92121, USA
| | - Jiawen Huang
- Infectious and Inflammatory Diseases Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Ricky Lieu
- Biotechnology Discovery Research, Eli Lilly and Company, Lilly Biotechnology Center, San Diego, CA 92121, USA
| | - Stacie Lim
- Infectious and Inflammatory Diseases Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - David Lippner
- Biotechnology Discovery Research, Eli Lilly and Company, Indianapolis, IN 46225, USA
| | - Victor Obungu
- Biotechnology Discovery Research, Eli Lilly and Company, Indianapolis, IN 46225, USA
| | - Lindsay Ward-Kavanagh
- Infectious and Inflammatory Diseases Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Kenneth Weichert
- Discovery Chemistry Research and Technologies, Eli Lilly and Company, Lilly Biotechnology Center, San Diego, CA 92121, USA
| | - Carl F Ware
- Infectious and Inflammatory Diseases Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA.
| | - Andrew C Vendel
- Immunology Discovery Research, Eli Lilly and Company, Lilly Biotechnology Center, San Diego, CA 92121, USA.
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2
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Kunkel GR, Cheung TC, Miyake JH, Urso O, McNamara-Schroeder KJ, Stumph WE. Identification of a SPH element in the distal region of a human U6 small nuclear RNA gene promoter and characterization of the SPH binding factor in HeLa cell extracts. Gene Expr 2018; 6:59-72. [PMID: 8979085 PMCID: PMC6148301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Vertebrate small nuclear RNA (snRNA) gene promoters contain a distal, enhancer-like region that is composed of an octamer motif adjacent to at least one other element. Here we show that a human U6 snRNA distal region contains a SPH motif previously found in several chicken snRNA gene enhancers and the 5'-flanking region of vertebrate selenocysteine tRNA genes. SPH binding factor (SBF) was detected in either chicken or HeLa cell extracts that could bind SPH elements in a species-independent manner. Both human and chicken SBF required divalent cation to bind effectively to DNA. DNase I footprinting experiments indicated that human SBF specifically protected the human U6 SPH element. Furthermore, a SBF polypeptide of approximately 85 kDa was detected in both HeLa and chicken extracts following ultraviolet light-mediated cross-linking to human U6 or chicken U4 SPH elements. A part of the human U6 SPH element was quite sensitive to mutation, as demonstrated by both specific protein binding and transcription assays. From these data it is apparent that the distal regions of some RNA polymerase III- and RNA polymerase II-transcribed small RNA promoters are virtually identical in composition, and their mechanisms of transcriptional activation are possibly quite similar.
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Affiliation(s)
- G R Kunkel
- Department of Biochemistry and Biophysics, Texas A & M University, College Station 77843-2128, USA
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3
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Abstract
The tumor necrosis factor (TNF) receptor superfamily member herpesvirus entry mediator (HVEM) (TNFRSF14) regulates T-cell immune responses by activating both inflammatory and inhibitory signaling pathways. HVEM acts as both a receptor for the canonical TNF-related ligands, LIGHT [lymphotoxin-like, exhibits inducible expression, and competes with herpes simplex virus glycoprotein D for HVEM, a receptor expressed on T lymphocytes] and lymphotoxin-α, and as a ligand for the immunoglobulin superfamily proteins BTLA (B and T lymphocyte attenuator) and CD160, a feature distinguishing HVEM from other immune regulatory molecules. The ability of HVEM to interact with multiple ligands in distinct configurations creates a functionally diverse set of intrinsic and bidirectional signaling pathways that control both inflammatory and inhibitory responses. The HVEM system is integrated into the larger LTβR and TNFR network through extensive shared ligand and receptor usage. Experimental mouse models and human diseases indicate that dysregulation of HVEM network may contribute to autoimmune pathogenesis, making it an attractive target for drug intervention.
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MESH Headings
- Animals
- Antigens, CD/genetics
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Autoimmunity
- GPI-Linked Proteins/genetics
- GPI-Linked Proteins/immunology
- GPI-Linked Proteins/metabolism
- Gene Expression/immunology
- Herpes Simplex/immunology
- Herpes Simplex/metabolism
- Herpes Simplex/virology
- Herpesvirus 1, Human/immunology
- Humans
- Immunity, Innate
- Lymphocyte Activation
- Lymphotoxin beta Receptor/genetics
- Lymphotoxin beta Receptor/immunology
- Lymphotoxin beta Receptor/metabolism
- Lymphotoxin-alpha/genetics
- Lymphotoxin-alpha/immunology
- Lymphotoxin-alpha/metabolism
- Mice
- Mice, Knockout
- Protein Binding/immunology
- Receptor Cross-Talk/immunology
- Receptors, Immunologic/genetics
- Receptors, Immunologic/immunology
- Receptors, Immunologic/metabolism
- Receptors, Tumor Necrosis Factor, Member 14/genetics
- Receptors, Tumor Necrosis Factor, Member 14/immunology
- Receptors, Tumor Necrosis Factor, Member 14/metabolism
- Signal Transduction/immunology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- Tumor Necrosis Factor Ligand Superfamily Member 14/genetics
- Tumor Necrosis Factor Ligand Superfamily Member 14/immunology
- Tumor Necrosis Factor Ligand Superfamily Member 14/metabolism
- Tumor Necrosis Factor-alpha/genetics
- Tumor Necrosis Factor-alpha/immunology
- Tumor Necrosis Factor-alpha/metabolism
- Viral Envelope Proteins/immunology
- Viral Envelope Proteins/metabolism
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Affiliation(s)
| | | | - Carl F. Ware
- Laboratory of Molecular Immunology, Center for Infectious and Inflammatory Diseases, Sanford|Burnham Medical Research Institute, La Jolla, CA, USA
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4
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Cheung TC, Coppieters K, Sanjo H, Oborne LM, Norris PS, Coddington A, Granger SW, Elewaut D, Ware CF. Polymorphic variants of LIGHT (TNF superfamily-14) alter receptor avidity and bioavailability. J Immunol 2010; 185:1949-58. [PMID: 20592286 DOI: 10.4049/jimmunol.1001159] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The TNF superfamily member homologous to lymphotoxins, exhibits inducible expression, and competes with HSV glycoprotein D for herpesvirus entry mediator (HVEM), a receptor expressed by T lymphocytes (LIGHT) [TNF superfamily (SF)-14], is a key cytokine that activates T cells and dendritic cells and is implicated as a mediator of inflammatory, metabolic, and malignant diseases. LIGHT engages the lymphotoxin-beta receptor (LTbetaR) and HVEM (TNFRSF14), but is competitively limited in activating these receptors by soluble decoy receptor-3 (DcR3; TNFRSF6B). Two variants in the human LIGHT alter the protein at E214K (rs344560) in the receptor-binding domain and S32L (rs2291667) in the cytosolic domain; however, the functional impact of these polymorphisms is unknown. A neutralizing Ab failed to bind the LIGHT-214K variant, indicating this position as a part of the receptor-binding region. Relative to the predominant reference variant S32/E214, the other variants showed altered avidity with LTbetaR and less with HVEM. Heterotrimers of the LIGHT variants decreased binding avidity to DcR3 and minimized the inhibitory effect of DcR3 toward LTbetaR-induced activation of NF-kappaB. In patients with immune-mediated inflammatory diseases, such as rheumatoid arthritis, DcR3 protein levels were significantly elevated. Immunohistochemistry revealed synoviocytes as a significant source of DcR3 production, and DcR3 hyperexpression is controlled by posttranscriptional mechanisms. The increased potential for LTbetaR signaling, coupled with increased bioavailability due to lower DcR3 avidity, provides a mechanism of how polymorphic variants in LIGHT could contribute to the pathogenesis of inflammatory diseases.
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Affiliation(s)
- Timothy C Cheung
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA
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5
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Chan M, Lo CK, Cheng LS, Cheung TC, Wong YC. Evaluation of testing capabilities for the determination of melamine in milk through an interlaboratory proficiency test programme during the melamine crisis. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2010; 26:1450-8. [PMID: 19724953 DOI: 10.1080/02652030903173627] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
An interlaboratory proficiency testing programme for melamine in milk was organized for field laboratories in Hong Kong, China, during the melamine crisis in late September 2008. One blank test sample and three homogenous samples prepared by gravimetric spiking of melamine at the concentration range of zero to 4.5 mg kg(-1) were given to participants in this programme. A total of 13 participants returned the results to the organizer and they used either liquid chromatography-tandem mass spectrometry (LC-MS/MS) or gas chromatography-mass spectrometry (GC-MS) for their determinations. The performance of the participants was assessed by determining z-scores, calculated from the bias from the assigned reference values and Horwitz standard deviation. The median values of pooled data were found to be in good agreement with the reference values and the majority of the participants demonstrated their capabilities in the quantitative measurement of melamine in milk samples. However, four participants gave false-positive results for the blank test sample, probably due to cross-contamination from other samples, and they were requested to investigate the actual causes. In summary, eight participants (or 62%) demonstrated their competence for all the four test samples.
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Affiliation(s)
- M Chan
- Analytical and Advisory Services Division, Hong Kong Government Laboratory, Hong Kong, China
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6
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Cheung TC. Modulation of T cell proliferation through the LIGHT-HVEM-BTLA cosignaling pathway. ACTA ACUST UNITED AC 2009; 3:177-82. [PMID: 19702559 DOI: 10.2174/187221509789318342] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 08/13/2009] [Indexed: 11/22/2022]
Abstract
The maintenance of T cell homeostasis requires the balance of both positive and negative regulatory signals of T cell proliferation. The herpesvirus entry mediator (HVEM) is a TNF superfamily receptor member, which provides a stimulatory signal following engagement with LIGHT (TNFSF14) on T cells. In contrast, HVEM can also provide an inhibitory signal to T cells when it binds the B and T lymphocyte attenuator (BTLA), a ligand member of the Immunoglobulin (Ig) superfamily. Thus, HVEM may be viewed as a molecular switch, capable of facilitating both stimulatory and inhibitory cosignaling in T cells. Substantial evidence from both human disease and from experimental mouse models has indicated that dysregulation of the LIGHT-HVEM-BTLA cosignaling pathway can cause inflammation in the lung and in mucosal tissues. Moreover, the discovery that two different viruses, human cytomegalovirus (HCMV) and herpes simplex virus (HSV) both target the LIGHT-HVEM-BTLA system as part of their immune evasion strategies suggests that this cosignaling pathway may prove useful in manipulating host immunity. Indeed, the LIGHT-HVEM-BTLA system may constitute an important molecular target for biopharmaceutical intervention as it holds the key for controlling both costimulatory and coinhibitory signals. Thus, the rational manipulation of this pathway should aid in the development of safer and more effective drugs for a wide range of autoimmune-related inflammatory disorders. To this end, this review provides a summary on several recent patents associated with the LIGHT-HVEM-BTLA cosignaling system.
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Affiliation(s)
- Timothy C Cheung
- Mycobacterial Research Division, Centenary Institute of Cancer Medicine and Cell Biology, Locked Bag 6, Newtown, NSW 2042, Australia.
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7
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Cheung TC, Oborne LM, Steinberg MW, Macauley MG, Fukuyama S, Sanjo H, D'Souza C, Norris PS, Pfeffer K, Murphy KM, Kronenberg M, Spear PG, Ware CF. T cell intrinsic heterodimeric complexes between HVEM and BTLA determine receptivity to the surrounding microenvironment. J Immunol 2009; 183:7286-96. [PMID: 19915044 DOI: 10.4049/jimmunol.0902490] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The inhibitory cosignaling pathway formed between the TNF receptor herpesvirus entry mediator (HVEM, TNFRSF14) and the Ig superfamily members, B and T lymphocyte attenuator (BTLA) and CD160, limits the activation of T cells. However, BTLA and CD160 can also serve as activating ligands for HVEM when presented in trans by adjacent cells, thus forming a bidirectional signaling pathway. BTLA and CD160 can directly activate the HVEM-dependent NF-kappaB RelA transcriptional complex raising the question of how NF-kappaB activation is repressed in naive T cells. In this study, we show BTLA interacts with HVEM in cis, forming a heterodimeric complex in naive T cells that inhibits HVEM-dependent NF-kappaB activation. The cis-interaction between HVEM and BTLA is the predominant form expressed on the surface of naive human and mouse T cells. The BTLA ectodomain acts as a competitive inhibitor blocking BTLA and CD160 from binding in trans to HVEM and initiating NF-kappaB activation. The TNF-related ligand, LIGHT (homologous to lymphotoxins, exhibits inducible expression, and competes with HSV glycoprotein D for HVEM, a receptor expressed by T lymphocytes, or TNFSF14) binds HVEM in the cis-complex, but NF-kappaB activation was attenuated, suggesting BTLA prevents oligomerization of HVEM in the cis-complex. Genetic deletion of BTLA or pharmacologic disruption of the HVEM-BTLA cis-complex in T cells promoted HVEM activation in trans. Interestingly, herpes simplex virus envelope glycoprotein D formed a cis-complex with HVEM, yet surprisingly, promoted the activation NF-kappaB RelA. We suggest that the HVEM-BTLA cis-complex competitively inhibits HVEM activation by ligands expressed in the surrounding microenvironment, thus helping maintain T cells in the naive state.
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Affiliation(s)
- Timothy C Cheung
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
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8
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Dhawan P, Su Y, Thu YM, Yu Y, Baugher P, Ellis DL, Sobolik-Delmaire T, Kelley M, Cheung TC, Ware CF, Richmond A. The lymphotoxin-beta receptor is an upstream activator of NF-kappaB-mediated transcription in melanoma cells. J Biol Chem 2008; 283:15399-408. [PMID: 18347013 PMCID: PMC2397477 DOI: 10.1074/jbc.m708272200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [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] [Received: 10/04/2007] [Revised: 03/04/2008] [Indexed: 12/11/2022] Open
Abstract
The pleiotropic transcription factor nuclear factor-kappaB (NF-kappaB (p50/p65)) regulates the transcription of genes involved in the modulation of cell proliferation, apoptosis, and oncogenesis. Furthermore, a host of solid and hematopoietic tumor types exhibit constitutive activation of NF-kappaB (Basseres, D. S., and Baldwin, A. S. (2006) 25, 6817-6830). However, the mechanism for this constitutive activation of NF-kappaB has not been elucidated in the tumors. We have previously shown that NF-kappaB-inducing kinase (NIK) protein and its association with Inhibitor of kappaB kinase alphabeta are elevated in melanoma cells compared with their normal counterpart, leading to constitutive activation of NF-kappaB. Moreover, expression of dominant negative NIK blocked this base-line NF-kappaB activity in melanoma cells. Of the three receptors that require NIK for activation of NF-kappaB, only the lymphotoxin-beta receptor (LTbeta-R) is expressed in melanoma. We show in this manuscript that for melanoma there is a strong relationship between expression of the LTbeta-R and constitutive NF-kappaB transcriptional activity. Moreover, we show that activation of the LTbeta-R can drive NF-kappaB activity to regulate gene expression that leads to enhanced cell growth. The inhibition by LTbeta-R shRNA resulted in decreased NF-kappaB promoter activity, decreased growth, and decreased invasiveness as compared with control. These results indicate that the LTbeta-R constitutively induces NF-kappaB activation, and this event may be associated with autonomous growth of melanoma cells.
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Affiliation(s)
- Punita Dhawan
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Yingjun Su
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Yee Mon Thu
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Yingchun Yu
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Paige Baugher
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Darrel L. Ellis
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Tammy Sobolik-Delmaire
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Mark Kelley
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Timothy C. Cheung
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Carl F. Ware
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
| | - Ann Richmond
- Department of Veterans Affairs, Nashville, Tennessee 37212,Department of Cancer Biology, Surgical Oncology Research Laboratories, Department of Surgery, and Division of Dermatology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, and Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121
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9
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Cheung TC, Hearn JP. Dimerizations of the wallaby gonadotropin-releasing hormone receptor and its splice variants. Gen Comp Endocrinol 2005; 144:280-8. [PMID: 16102759 DOI: 10.1016/j.ygcen.2005.06.008] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Revised: 06/04/2005] [Accepted: 06/15/2005] [Indexed: 11/18/2022]
Abstract
Dimerization between wallaby GnRH-R and its splice variants was examined. A baculovirus-based fluorescence resonance energy transfer (Bv-FRET) assay was used to assess protein-protein interaction between wild type wallaby GnRH-R and splice variants (GnRH-RDelta1 and GnRH-RDelta2). FRET analysis demonstrated that GnRH-R, GnRH-RDelta1 or GnRH-RDelta2 are capable of assembling as homodimers. When GnRH-R is co-expressed with GnRH-RDelta1 or GnRH-RDelta2 splice variants, GnRH-R can form heterodimers with GnRH-RDelta1 and GnRH-RDelta2. GnRH agonist is not required for the initiation of dimerization. However, the addition of a GnRH agonist enhances the FRET signal in the GnRH-R homodimers, indicating that the GnRH agonist may be involved in modulating the extent of dimerization. In addition, this study reveals that dimerization of GnRH-R may be mediated by two or more protein interaction domains. One of them is probably located between amino acid residues 74 and 174, and the other one between residues 175 and 328. This is the first study to show dimerization between a wild type mammalian GnRH-R and its splice variants. It provides additional support for the potential involvement of splice variants in GnRH-R signaling.
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Affiliation(s)
- Timothy C Cheung
- Developmental Biology Research Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, Canberra ACT 2601, Australia.
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10
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Cheung TC, Humphreys IR, Potter KG, Norris PS, Shumway HM, Tran BR, Patterson G, Jean-Jacques R, Yoon M, Spear PG, Murphy KM, Lurain NS, Benedict CA, Ware CF. Evolutionarily divergent herpesviruses modulate T cell activation by targeting the herpesvirus entry mediator cosignaling pathway. Proc Natl Acad Sci U S A 2005; 102:13218-23. [PMID: 16131544 PMCID: PMC1201609 DOI: 10.1073/pnas.0506172102] [Citation(s) in RCA: 162] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The herpesvirus entry mediator (HVEM), a member of the TNF receptor (TNFR) superfamily, can act as a molecular switch that modulates T cell activation by propagating positive signals from the TNF-related ligand LIGHT (TNFR superfamily 14), or inhibitory signals through the Ig superfamily member B and T lymphocyte attenuator (BTLA). Competitive binding analysis and mutagenesis reveals a unique BTLA binding site centered on a critical lysine residue in cysteine-rich domain 1 of HVEM. The BTLA binding site on HVEM overlaps with the binding site for the herpes simplex virus 1 envelope glycoprotein D, but is distinct from where LIGHT binds, yet glycoprotein D inhibits the binding of both ligands, potentially nullifying the pathway. The binding site on HVEM for BTLA is conserved in the orphan TNFR, UL144, present in human CMV. UL144 binds BTLA, but not LIGHT, and inhibits T cell proliferation, selectively mimicking the inhibitory cosignaling function of HVEM. The demonstration that distinct herpesviruses target the HVEM-BTLA cosignaling pathway suggests the importance of this pathway in regulating T cell activation during host defenses.
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MESH Headings
- Base Sequence
- Binding Sites
- Binding, Competitive
- Cytomegalovirus/immunology
- Cytomegalovirus/physiology
- Herpesviridae/immunology
- Herpesviridae/physiology
- Herpesvirus 1, Human/immunology
- Herpesvirus 1, Human/physiology
- Humans
- Lymphocyte Activation/immunology
- Membrane Glycoproteins/metabolism
- Membrane Proteins/metabolism
- Molecular Sequence Data
- Phylogeny
- Receptors, Immunologic/metabolism
- Receptors, Tumor Necrosis Factor/immunology
- Receptors, Tumor Necrosis Factor/metabolism
- Receptors, Tumor Necrosis Factor/physiology
- Receptors, Tumor Necrosis Factor, Member 14
- Receptors, Virus/immunology
- Receptors, Virus/metabolism
- Receptors, Virus/physiology
- Signal Transduction
- T-Lymphocytes/immunology
- T-Lymphocytes/virology
- Tumor Necrosis Factor Ligand Superfamily Member 14
- Tumor Necrosis Factor-alpha/metabolism
- Viral Envelope Proteins/metabolism
- Viral Proteins/metabolism
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Affiliation(s)
- Timothy C Cheung
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, 10355 Science Center Drive, San Diego, CA 92121, USA
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11
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Abstract
A new baculovirus-based fluorescence resonance energy transfer (Bv-FRET) assay for measuring multimerization of cell surface molecules in living cells is described. It has been demonstrated that gonadotropin-releasing hormone receptor (GnRH-R) was capable of forming oligomeric complexes in the plasma membrane under normal physiological conditions. The mouse gonadotropin-releasing hormone receptor GnRH-R was used to evaluate the efficiency and potential applications of this assay. Two chimeric constructs of GnRH-R were made, one with green fluorescent protein as a donor fluorophore and the other with enhanced yellow fluorescent protein as an acceptor fluorophore. These chimeric constructs were coexpressed in an insect cell line (BTI Tn5 B1-4) using recombinant baculoviruses. Energy transfer occurred from the excited donor to the acceptor when they were in close proximity. The association of GnRH-R was demonstrated through FRET and the fluorescence observed using a Leica TSC-SPII confocal microscope. FRET was enhanced by the addition of a GnRH agonist but not by an antagonist. The Bv-FRET assay constitutes a highly efficient, reliable and convenient method for measuring protein-protein interaction as the baculovirus expression system is superior to other transfection-based methods. Additionally, the same insect cell line can be used routinely for expressing any recombinant proteins of interest, allowing various combinations of molecules to be tested in a rapid fashion for protein-protein interactions. The assay is a valuable tool not only for the screening of new molecules that interact with known bait molecules, but also for confirming interactions between other known molecules.
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Affiliation(s)
- Timothy C Cheung
- Developmental Biology Research Group, Research School of Biological Sciences, The Australian National University, Canberra, Australia.
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12
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Abstract
The developmental expression of gonadotropin-releasing hormone receptor (GnRH-R) and its splice variants was examined in the gonads of tammar wallaby pouch young in order to elucidate the functional role of GnRH-R in the developing testis and ovary. Wallaby GnRH-R, like eutherian GnRH-Rs, contains three exons and two introns. In the present study, the transcripts of two splice variants (GnRH-R Delta 1 and GnRH-R Delta 2) were cloned from the pituitary. GnRH-R Delta 1 contained a 291 bp deletion from nucleotide positions 232 to 522 within exon 1. This transcript appears to be distinctive in the wallaby and has not been reported in other species. GnRH-R Delta 2 contained a 220 bp deletion from nucleotide positions 523 to 742, corresponding to exon 2. We examined the subcellular localization of the wild type GnRH-R and its splice variants with confocal microscopy, showing that both the wild type receptor and the splice variants were membrane-associated molecules. The different pattern of expression of the wild type receptor and the variants transcripts found in adult and neonatal tissues suggests a specific developmental regulation of the GnRH-R Delta 2 transcript. In addition, the developmental expression of the GnRH-R and GnRH-R Delta 1 transcripts showed a possible association with key physiological events during gonadal development in the wallaby pouch young, suggesting that GnRH-R may be involved in the regulation of early development in the testis and ovary.
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Affiliation(s)
- Timothy C Cheung
- Developmental Biology Research Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, Canberra, ACT 2601, Australia.
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13
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Cheung TC, Hearn JP. Molecular cloning and tissue expression of the gonadotrophin-releasing hormone receptor in the tammar wallaby (Macropus eugenii). Reprod Fertil Dev 2003; 14:157-64. [PMID: 12219937 DOI: 10.1071/rd01124] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [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: 11/23/2022] Open
Abstract
Gonadotrophin-releasing hormone (GnRH) plays a pivotal role in the endocrine control of both reproduction and embryonic development. This first study of the marsupial GnRH receptor (GnRH-R) gene in the tammar wallaby provides information on the complex molecular events that regulate hypothalamic-pituitary-gonadal function in marsupials, and allows a comparison with eutherian mammals. Two identical wallaby GnRH-R cDNA clones were obtained, one isolated from cDNA generated from the testis of a 79-day-old pouch young and the other from the pituitary of an adult. Wallaby GnRH-R is composed of 328 amino acid residues. Sequence analysis showed that wallaby GnRH-R contains 7 transmembrane domains and is a member of the G protein-coupled receptor family. A putative protein kinase A phosphorylation site and a putative protein kinase C (PKC) phosphorylation site were found in the first intracellular loop, and an additional PKC phosphorylation site was located in the third intracellular loop. Comparisons with the eutherian GnRH-Rs show a greater diversity in the N-terminal extracellular domain. Wallaby GnRH-R has approximately 80% amino acid sequence homology with eutherian GnRH-Rs and 93% homology with the brush-tail possum, another member of the Diprotodontia semiorder.
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Affiliation(s)
- Timothy C Cheung
- Developmental Biology Research Group, Research School of Biological Sciences, The Australian National University, Canberra, ACT.
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14
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Abstract
Behçet's disease, as initially described, is a triad of recurrent oral and genital ulcers and relapsing uveitis. The incomplete form, in which there is no ocular involvement, has been described in Japan and Korea, but this is not commonly recognized in the southern Chinese. We reported herein a rare case of repeated intestinal perforations caused by an incomplete form of Behçet's syndrome in a southern Chinese man.
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Affiliation(s)
- F H Ng
- Department of Medicine, Ruttonjee Hospital, Wan Chai, Hong Kong, China.
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15
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Abstract
Green tea catechins (GTCs) including (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG) and (-)-epicatechin (EC) were shown to suppress cell growth and induce apoptosis in various cell systems in addition to their chemo-preventive effect. In this study, except EC which was inactive, green tea extract (TE) and other 3 GTCs were found to suppress the growth and induce apoptosis in human prostate cancer DU145 cells largely through an increase in reactive oxygen species formation and mitochondrial depolarization. The conclusion was supported by the fact that the profiles for different GTCs in growth suppression, apoptosis induction, ROS formation and mitochondrial depolarization are in a similar order, i.e. ECG > EGCG > EGC > EC. Although the molecular mechanisms are still not clear, apoptosis induced by GTCs is not related to the members of BCL-2 family as EGCG did not alter the expression of BCL-2, BCL-X(L) and BAD in DU145 cells.
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Affiliation(s)
- L Y Chung
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin
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16
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Force WR, Glass AA, Benedict CA, Cheung TC, Lama J, Ware CF. Discrete signaling regions in the lymphotoxin-beta receptor for tumor necrosis factor receptor-associated factor binding, subcellular localization, and activation of cell death and NF-kappaB pathways. J Biol Chem 2000; 275:11121-9. [PMID: 10753918 DOI: 10.1074/jbc.275.15.11121] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Lymphotoxin-beta receptor (LTbetaR), a member of the tumor necrosis factor receptor superfamily, is essential for the development and organization of secondary lymphoid tissue. Wild type and mutant LTbetaR containing successive truncations of the cytoplasmic domain were investigated by retrovirus-mediated gene transfer into HT29.14s and in 293T cells by transfection. Wild type receptors accumulated in perinuclear compartments and enhanced responsiveness to ligand-induced cell death and ligand-independent activation of NFkappaB p50 dimers. Coimmunoprecipitation and confocal microscopy mapped the TRAF3 binding site to amino acids PEEGDPG at position 389. However, LTbetaR truncated at position Pro(379) acted as a dominant positive mutant that down-modulated surface expression and recruited TRAF3 to endogenous LTbetaR. This mutant exhibited ligand-independent cell death and activated NF-kappaB p50 dimers. By contrast, truncation at Gly(359) created a dominant-negative mutant that inhibited ligand-induced cell death and activation of NF-kappaB p50/p65 heterodimers. This mutant also blocked accumulation of wild type receptor into perinuclear compartments, suggesting subcellular localization may be crucial for signal transduction. A cryptic TRAF-independent NF-kappaB activating region was identified. These mutants define discrete subregions of a novel proline-rich domain that is required for subcellular localization and signal transduction by the LTbetaR.
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Affiliation(s)
- W R Force
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA
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17
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Lai SW, Cheung TC, Chan MC, Cheung KK, Peng SM, Che CM. Luminescent mononuclear and binuclear cyclometalated palladium(II) complexes of 6-phenyl-2,2 bipyridines: spectroscopic and structural comparisons with platinum(II) analogues. Inorg Chem 2000; 39:255-62. [PMID: 11272533 DOI: 10.1021/ic991089g] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mononuclear cyclometalated Pd(II) complexes [Pd(L1)X] (HL1 = 6-phenyl-2,2'-bipyridine; X = Cl, la; Br, 1b; I, 1c), [Pd(L1)PPh3]+ (1d), [Pd(L2-5)Cl] [2a-5a, HL2-5 = 4-(aryl)-6-phenyl-2,2'-bipyridine; aryl = phenyl (2), 4-chlorophenyl (3), 4-tolyl (4), 4-methoxyphenyl (5)] and the binuclear derivatives [Pd2(L1-5)2(mu-dppm)]2+ (1e-5e, dppm = bis(diphenylphosphino)methane) and [Pd2(L1)2(mu-dppCs)]2+, (1f, dppC5 = 1,5-bis(diphenylphosphino)pentane) were prepared. The crystal structures of 1d(ClO4), 1e(ClO4)2 x DMF, and 2e(ClO4)2 have been determined by X-ray crystallography. The magnitude of the Pd-Pd distances in le and 2e (3.230(1) and 3.320(2) A, respectively) suggest minimal metal-metal interaction, although pi-stacking of the aromatic ligands (interplanar separations 3.34 and 3.35 A, respectively) is evident. All complexes display low-energy UV absorptions at lambda approximately 390 nm, which are tentatively assigned to 1MLCT transitions; red shifts resulting from Pd-Pd interactions in the binuclear species are not apparent. The complexes in this work are non-emissive at 298 K, but the cationic derivatives exhibit intense luminescence at 77 K. The structured emissions of 1d and 1f in MeOH/EtOH glass (lambdamax 467-586 nm) and all cationic species in the solid state (lambdamax 493-578 nm) are assigned to intraligand excited states. Complexes le-5e display dual emissions in MeOH/EtOH glass at 77 K, and the broad structureless bands at lambdamax 626-658 nm are attributed to pi-pi excimeric IL transitions. A comparison between the photophysical properties of Pd(II) and Pt(II) congeners is presented.
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Affiliation(s)
- S W Lai
- Department of Chemistry, The University of Hong Kong, Hong Kong
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18
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Ng FH, Chau TN, Cheung TC, Kng C, Wong SY, Ng WF, Lee KC, Chan E, Lai ST, Yuen WC, Chang CM. Cytomegalovirus colitis in individuals without apparent cause of immunodeficiency. Dig Dis Sci 1999; 44:945-52. [PMID: 10235602 DOI: 10.1023/a:1026604529393] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cytomegalovirus infection is usually reported in immunocompromised patients. In this study, apparently immunocompetent patients with cytomegaloviral colitis were reviewed. Records with a diagnosis of cytomegaloviral colitis from January 1989 to June 1996 were retrieved for analysis. Ten patients were included (median age 70 yr). The major presenting symptoms were diarrhea and hematochezia. Ulceration was the main macroscopic finding. Rectal bleeding was mostly self-limiting. Three patients developed local complications (rectovaginal fistula in two; rectal stricture in one). In the two patients with rectovaginal fistula, lymphocytes subsets and proliferative response were entirely normal. In the other patient, low B lymphocyte count and low response to mitogen were demonstrated. However, the immunoglobulins were not suppressed and rectal biopsies revealed noncaseating granulomas, suggesting activated cell-mediated immunity. In conclusion, a high index of suspicion is crucial for early diagnosis of cytomegaloviral colitis in patients with bloody diarrhea, even though obvious evidence of immunodeficiency is lacking.
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Affiliation(s)
- F H Ng
- Department of Medicine, Ruttonjee Hospital, Hong Kong, China
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19
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Mauri DN, Ebner R, Montgomery RI, Kochel KD, Cheung TC, Yu GL, Ruben S, Murphy M, Eisenberg RJ, Cohen GH, Spear PG, Ware CF. LIGHT, a new member of the TNF superfamily, and lymphotoxin alpha are ligands for herpesvirus entry mediator. Immunity 1998; 8:21-30. [PMID: 9462508 DOI: 10.1016/s1074-7613(00)80455-0] [Citation(s) in RCA: 599] [Impact Index Per Article: 23.0] [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: 02/06/2023]
Abstract
Herpes simplex virus (HSV) 1 and 2 infect activated T lymphocytes by attachment of the HSV envelope glycoprotein D (gD) to the cellular herpesvirus entry mediator (HVEM), an orphan member of the tumor necrosis factor receptor superfamily. Here, we demonstrate that HVEM binds two cellular ligands, secreted lymphotoxin alpha (LTalpha) and LIGHT, a new member of the TNF superfamily. LIGHT is a 29 kDa type II transmembrane protein produced by activated T cells that also engages the receptor for the LTalphabeta heterotrimer but does not form complexes with either LTalpha or LTbeta. HSV1 gD inhibits the interaction of HVEM with LIGHT, and LIGHT and gD interfere with HVEM-dependent cell entry by HSV1. This characterizes herpesvirus gD as a membrane-bound viokine and establishes LIGHT-HVEM as integral components of the lymphotoxin cytokine-receptor system.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Herpesvirus 1, Human/immunology
- Herpesvirus 1, Human/metabolism
- Herpesvirus 2, Human/immunology
- Herpesvirus 2, Human/metabolism
- Humans
- Ligands
- Lymphocyte Activation
- Lymphotoxin-alpha/genetics
- Lymphotoxin-alpha/metabolism
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Molecular Sequence Data
- Receptors, Tumor Necrosis Factor
- Receptors, Tumor Necrosis Factor, Member 14
- Receptors, Virus/genetics
- Receptors, Virus/metabolism
- Sensitivity and Specificity
- Sequence Homology, Amino Acid
- T-Lymphocytes/metabolism
- T-Lymphocytes/ultrastructure
- Tumor Necrosis Factor Ligand Superfamily Member 14
- Tumor Necrosis Factor-alpha/genetics
- Tumor Necrosis Factor-alpha/metabolism
- Viral Envelope Proteins/metabolism
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Affiliation(s)
- D N Mauri
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA
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20
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Force WR, Cheung TC, Ware CF. Dominant negative mutants of TRAF3 reveal an important role for the coiled coil domains in cell death signaling by the lymphotoxin-beta receptor. J Biol Chem 1997; 272:30835-40. [PMID: 9388227 DOI: 10.1074/jbc.272.49.30835] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Ligation of the lymphotoxin-beta receptor (LTbetaR) recruits tumor necrosis factor receptor-associated factor-3 (TRAF3) and initiates cell death in HT29 adenocarcinoma cells. The minimal receptor binding domain (TRAF-C) defined by two hybrid analyses is not sufficient for direct recruitment to the ligated receptor. A series of TRAF3 deletion mutants reveal that a subregion of the coiled coil motif is required for efficient recruitment to the LTbetaR. Furthermore, the ability of TRAF3 to self-associate maps to an adjacent subregion. A TRAF3 deletion mutant that lacks the N-terminal zinc RING and zinc finger motifs, but retains the coiled coil and TRAF-C motifs, competitively displaces endogenous TRAF3 from the LTbetaR. A second TRAF3 mutant that lacks the receptor binding domain, yet contains the TRAF3 self-association domain, prevents TRAF3 homodimers from being recruited to the LTbetaR. Both of these mutants have a dominant negative effect on cell death and demonstrate that the recruitment of TRAF3 oligomers is necessary to initiate signal transduction that activates the cell death pathway.
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Affiliation(s)
- W R Force
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA
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21
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Williams-Abbott L, Walter BN, Cheung TC, Goh CR, Porter AG, Ware CF. The lymphotoxin-alpha (LTalpha) subunit is essential for the assembly, but not for the receptor specificity, of the membrane-anchored LTalpha1beta2 heterotrimeric ligand. J Biol Chem 1997; 272:19451-6. [PMID: 9235946 DOI: 10.1074/jbc.272.31.19451] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The lymphotoxins (LT) alpha and beta, members of the tumor necrosis factor (TNF) cytokine superfamily, are implicated as important regulators and developmental factors for the immune system. LTalpha is secreted as a homotrimer and signals through two TNF receptors of 55-60 kDa (TNFR60) or 75-80 kDa (TNFR80). LTalpha also assembles with LTbeta into a membrane-anchored, heterotrimeric LTalpha1beta2 complex that engages a distinct cognate receptor, the LTbeta receptor (LTbetaR). To investigate the role of the LTalpha subunit in the function of the membrane LTalpha1beta2 complex, gene transfer via baculovirus was used to assemble LTalpha and -beta complexes in insect cells. LTalpha containing mutations at D50N or Y108F are secreted as homotrimers that fail to bind either TNF receptor and are functionally inactive in triggering cell death of the HT29 adenocarcinoma cell line. In contrast, these mutant LTalpha proteins retain the ability to co-assemble with LTbeta into membrane-anchored LTalpha1beta2 complexes that engage the LTbetaR and trigger the death of HT29 cells. Membrane-anchored LTbeta expressed on the cell surface in absence of the LTalpha subunit binds the LTbetaR but is functionally inactive in the cell death assay. These results indicate that the TNF receptor-binding regions of the LTalpha subunit are not necessary for engagement of the LTbetaR, but the LTalpha subunit is required for the assembly of LTbeta into a functional heteromeric ligand.
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Affiliation(s)
- L Williams-Abbott
- Department of Biochemistry, University of California, Riverside, California 92021, USA
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22
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Cheung TC, Ng FH, Chow KC, Maw CK, Ng WF. Occult gastric cancer presenting as cor pulmonale resulting from tumor cell microembolism. Am J Gastroenterol 1997; 92:1057-9. [PMID: 9177536] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cor pulmonale resulting from tumor emboli is a rare presentation of gastric cancer, and only six similar cases have been reported in the English literature. We report the case of a 37-yr-old woman presenting with dyspnea who died of cor pulmonale. Autopsy revealed signet cell carcinoma of te stomach with intra-abdominal metastasis and right ventricular hypertrophy. There were no macroscopic pulmonary emboli or parenchymal lesions, but more than 60% of the small pulmonary arteries and arterioles were occluded. In most vessels, fibrocellular intimal proliferation was the major finding with only a few entrapped tumor cells.
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Affiliation(s)
- T C Cheung
- Department of Medicine, Ruttonjee Hospital, Hong Kong
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23
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Nolan EM, Cheung TC, Burton DW, Deftos LJ. Transcriptional regulation of the human chromogranin A gene by its 5' distal regulatory element: novel effects of orientation, structure, flanking sequences, and position on expression. Mol Cell Endocrinol 1996; 124:51-62. [PMID: 9027324 DOI: 10.1016/s0303-7207(96)03927-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In previous studies of human chromogranin A (hCgA) gene expression, we had identified a 27 bp distal regulatory element (DRE) located between -576 and -550 bp that interacts with a CRE-containing promoter to enhance gene transcription specifically in neuroendocrine (NE) cells. To characterize the DRE we have now mutated its various parts and assessed the effects on protein binding by electrophoretic mobility shift assays (EMSAs) and hCgA transcription within BEN cells. We found that the sequence TGACTAA, an AP-1 binding site that we refer to as DRE-AP-1, was necessary but not sufficient to produce the DRE's enhancer effect. Moreover, while AP-1 (Jun/Fos) bound this site, binding was not correlated with transcriptional effects. Protein binding by the DRE-AP-1 could be attenuated by mutations of its flanking sequences, and transcriptional enhancement by the DRE was dependent on its orientation and spatial relationship to the hCgA proximal promoter. Mutation of the DRE-AP-1 to a consensus AP-1 did not produce greater transcriptional activity, even though it increased binding of nuclear factors. Co-transfection with c-jun and/or c-fos expression plasmids showed that the DRE was unresponsive to the over-expressed AP-1 proteins. Co-transfection with wild-type DRE oligonucleotides competitively inhibited DRE-mediated transcription, while co-transfection with mutant DRE oligonucleotides had a lesser effect. Our studies indicate that transcriptional enhancement of hCgA by the DRE is dependent on a unique NE-specific DRE-binding factor, which we refer to as DBF, that specifically and directionally binds the DRE to assemble and synergize a functional transcription complex.
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Affiliation(s)
- E M Nolan
- Department of Medicine, University of California, San Diego, USA
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Hastings RH, Summers-Torres D, Cheung TC, Ditmer LS, Petrin EM, Burton DW, Spragg RG, Li J, Deftos LJ. Parathyroid hormone-related protein, an autocrine regulatory factor in alveolar epithelial cells. Am J Physiol 1996; 270:L353-61. [PMID: 8638727 DOI: 10.1152/ajplung.1996.270.3.l353] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Alveolar epithelial cells in vivo, primary cultures of adult rat type II cells, and human A549 alveolar carcinoma cells express parathyroid hormone-related protein (PTHrP). Here we demonstrated that type II cells and A549 cells also express the PTHrP receptor and that they exhibit differentiation-related responses to the amino-terminal PTHrP fragment, PTHrP-(1-34). PTHrP receptor expression in A549 cells was shown by detection of a 0.3-kb reverse transcriptase polymerase chain reaction product formed by primers specific for PTHrP receptor. In situ hybridization studies localized the site of production of PTHrP and PTHrP receptor mRNA in rat lung cells with morphology and location typical of type II cells. Primary cultures of such type II cells also expressed PTHrP receptor mRNA. Incubation with PTHrP-(1-34) stimulated disaturated phosphatidylcholine (DSPC) synthesis in A549 cells and increased the release of newly synthesized DSPC by cultured type II cells and A549 cells. In addition, PTHrP-(1-34) increased the number of lamellar bodies per type II cell and increased their expression of alkaline phosphatase in a dose-dependent manner. Thus PTHrP-(1-34) promoted a differentiated type II cell phenotype. Since cultured type II cells, alveolar epithelial cells in vivo, and A549 cells express PTHrP and the PTHrP receptor, PTHrP-(1-34) may be an autocrine regulatory factor in type II cells and lung cancer cells.
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Affiliation(s)
- R H Hastings
- Department of Veterans Affairs Medical Center, 92161-5085, San Diego, California 92103-8770, USA
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25
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Abstract
Chromogranin A (CgA) expression is specific to cells of endocrine and neuroendocrine (NE) tissues. Our transfection studies with CgA have identified two DNA regions 5' of the transcription start site that regulate CgA gene transcription: a distal regulatory region (DRR) located between -726 and -455, and a proximal regulatory region (PRR) between -60 and -26. In studies of the DRR using four human NE and six human non-NE cell lines, we demonstrated enhanced transcription of DRR-containing CgA-GH plasmids by the NE cells as a group compared to the non-NE cells. DNase I footprinting identified a protected area in the DRR from -570 to -555 base pairs (bp) composed of the sequence TAATGATGACTAAACA. Centered in this sequence is the simian virus 40 version of the activator protein-1-binding site, TGACTAA. Electrophoretic mobility shift assays (EMSAs) with an oligonucleotide containing the 27 bp of the DRR between -576 and -550, which we refer to as the distal regulatory element (DRE), produced a specific complex with the NE BEN and non-NE COS-1 cell nuclear extracts. The addition of c-Jun and c-Fos antibodies produced strong supershifts of the complex generated by COS-1 extract, but very weak supershifts of the complex formed by BEN extract. These EMSA studies suggest that NE cells such as BEN contain unique nuclear factors distinguishable from activator protein-1 that interact with the DRE. The enhancer effect of the 271-bp DRR could be replaced by the 27-bp DRE in both CgA and calcitonin promoter constructs in BEN cells. Replacement of the DRR with the DRE resulted in a further increase in expression from these plasmids, suggesting the presence of suppressor sequences in the DRR. In transfection studies of the PRR, deletion of its cAMP response element (CRE) dramatically lowered transcription. In addition to demonstrating that its CRE can bind CRE-binding protein, EMSAs with the PRR demonstrated that an intervening sequence between the CRE and the TATA box formed a complex with BEN cell nuclear extract. Our studies demonstrate that both the PRR and DRR are important for high level transcription of the CgA gene in NE cells. The presence of both distal and proximal 5'-regulatory regions in the human CgA gene indicates a complex mechanism of transcriptional regulation. Although the PRR is important for the formation of a functional transcription complex at the TATA region, the DRR is important for the enhancement of CgA gene expression in NE cells.
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Affiliation(s)
- E M Nolan
- Department of Medicine, University of California, San Diego, USA
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26
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Teng RJ, Wen HH, Cheung TC, Ho MM. Late metabolic acidosis in low-birth-weight babies: report of four cases. Zhonghua Min Guo Xiao Er Ke Yi Xue Hui Za Zhi 1991; 32:233-8. [PMID: 1663687] [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: 12/28/2022]
Abstract
Four low-birth-weight babies, though fed an adequate amount of formula, failed to regain their birth weight within ten days. Blood gas studies revealed metabolic acidosis in all. Their body weight gain improved dramatically after adding sodium bicarbonate to the milk. Late metabolic acidosis was presented, even using special premature formula, in three of them.
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Affiliation(s)
- R J Teng
- Department of Pediatrics, National Taiwan University Hospital, Taipei, R.O.C
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