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Liu CY, Ahonen CL, Brown ME, Zhou L, Welin M, Krauland EM, Pejchal R, Widboom PF, Battles MB. Structure-based engineering of a novel CD3ε-targeting antibody for reduced polyreactivity. MAbs 2023; 15:2189974. [PMID: 36991534 PMCID: PMC10072072 DOI: 10.1080/19420862.2023.2189974] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 03/06/2023] [Indexed: 03/31/2023] Open
Abstract
Bispecific antibodies continue to represent a growth area for antibody therapeutics, with roughly a third of molecules in clinical development being T-cell engagers that use an anti-CD3 binding arm. CD3 antibodies possessing cross-reactivity with cynomolgus monkey typically recognize a highly electronegative linear epitope at the extreme N-terminus of CD3 epsilon (CD3ε). Such antibodies have high isoelectric points and display problematic polyreactivity (correlated with poor pharmacokinetics for monospecific antibodies). Using insights from the crystal structure of anti-Hu/Cy CD3 antibody ADI-26906 in complex with CD3ε and antibody engineering using a yeast-based platform, we have derived high-affinity CD3 antibody variants with very low polyreactivity and significantly improved biophysical developability. Comparison of these variants with CD3 antibodies in the clinic (as part of bi- or multi-specifics) shows that affinity for CD3 is correlated with polyreactivity. Our engineered CD3 antibodies break this correlation, forming a broad affinity range with no to low polyreactivity. Such antibodies will enable bispecifics with improved pharmacokinetic and safety profiles and suggest engineering solutions that will benefit the large and growing sector of T-cell engagers.
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2
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Gosmann D, Russelli L, Weber WA, Schwaiger M, Krackhardt AM, D'Alessandria C. Promise and challenges of clinical non-invasive T-cell tracking in the era of cancer immunotherapy. EJNMMI Res 2022; 12:5. [PMID: 35099641 PMCID: PMC8804060 DOI: 10.1186/s13550-022-00877-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 01/05/2022] [Indexed: 12/12/2022] Open
Abstract
In the last decades, our understanding of the role of the immune system in cancer has significantly improved and led to the discovery of new immunotherapeutic targets and tools, which boosted the advances in cancer immunotherapy to fight a growing number of malignancies. Approved immunotherapeutic approaches are currently mainly based on immune checkpoint inhibitors, antibody-derived targeted therapies, or cell-based immunotherapies. In essence, these therapies induce or enhance the infiltration and function of tumor-reactive T cells within the tumors, ideally resulting in complete tumor eradication. While the clinical application of immunotherapies has shown great promise, these therapies are often accompanied either by a variety of side effects as well as partial or complete unresponsiveness of a number of patients. Since different stages of disease progression elicit different local and systemic immune responses, the ability to longitudinally interrogate the migration and expansion of immune cells, especially T cells, throughout the whole body might greatly facilitate disease characterization and understanding. Furthermore, it can serve as a tool to guide development as well as selection of appropriate treatment regiments. This review provides an overview about a variety of immune-imaging tools available to characterize and study T-cell responses induced by anti-cancer immunotherapy. Moreover, challenges are discussed that must be taken into account and overcome to use immune-imaging tools as predictive and surrogate markers to enhance assessment and successful application of immunotherapies.
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Affiliation(s)
- Dario Gosmann
- Klinik und Poliklinik für Innere Medizin III, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Lisa Russelli
- Klinik und Poliklinik für Nuklearmedizin, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Wolfgang A Weber
- Klinik und Poliklinik für Nuklearmedizin, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Markus Schwaiger
- Klinik und Poliklinik für Nuklearmedizin, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Angela M Krackhardt
- Klinik und Poliklinik für Innere Medizin III, Klinikum rechts der Isar, Technische Universität München, Munich, Germany. .,German Cancer Consortium (DKTK), Partner-Site Munich and German Cancer Research Center (DKFZ), Heidelberg, Germany.
| | - Calogero D'Alessandria
- Klinik und Poliklinik für Nuklearmedizin, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
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3
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Extensive proteomic and transcriptomic changes quench the TCR/CD3 activation signal of latently HIV-1 infected T cells. PLoS Pathog 2021; 17:e1008748. [PMID: 33465149 PMCID: PMC7846126 DOI: 10.1371/journal.ppat.1008748] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 01/29/2021] [Accepted: 12/01/2020] [Indexed: 12/24/2022] Open
Abstract
The biomolecular mechanisms controlling latent HIV-1 infection, despite their importance for the development of a cure for HIV-1 infection, are only partially understood. For example, ex vivo studies have recently shown that T cell activation only triggered HIV-1 reactivation in a fraction of the latently infected CD4+ T cell reservoir, but the molecular biology of this phenomenon is unclear. We demonstrate that HIV-1 infection of primary T cells and T cell lines indeed generates a substantial amount of T cell receptor (TCR)/CD3 activation-inert latently infected T cells. RNA-level analysis identified extensive transcriptomic differences between uninfected, TCR/CD3 activation-responsive and -inert T cells, but did not reveal a gene expression signature that could functionally explain TCR/CD3 signaling inertness. Network analysis suggested a largely stochastic nature of these gene expression changes (transcriptomic noise), raising the possibility that widespread gene dysregulation could provide a reactivation threshold by impairing overall signal transduction efficacy. Indeed, compounds that are known to induce genetic noise, such as HDAC inhibitors impeded the ability of TCR/CD3 activation to trigger HIV-1 reactivation. Unlike for transcriptomic data, pathway enrichment analysis based on phospho-proteomic data directly identified an altered TCR signaling motif. Network analysis of this data set identified drug targets that would promote TCR/CD3-mediated HIV-1 reactivation in the fraction of otherwise TCR/CD3-reactivation inert latently HIV-1 infected T cells, regardless of whether the latency models were based on T cell lines or primary T cells. The data emphasize that latent HIV-1 infection is largely the result of extensive, stable biomolecular changes to the signaling network of the host T cells harboring latent HIV-1 infection events. In extension, the data imply that therapeutic restoration of host cell responsiveness prior to the use of any activating stimulus will likely have to be an element of future HIV-1 cure therapies. A curative therapy for HIV-1 infection will at least require the eradication of a small pool of CD4+ helper T cells in which the virus can persist in an inactive, latent state, even after years of successful antiretroviral therapy. It has been assumed that activation of these viral reservoir T cells will also reactivate the latent virus, which is a prerequisite for the destruction of these cells. Remarkably, this is not always the case and following application of even the most potent stimuli that activate normal T cells through their T cell receptor, a large portion of the latent virus pool remains in a dormant state. Herein we demonstrate that a large part of latent HIV-1 infection events reside in T cells that have been rendered activation inert. We provide a systemwide, biomolecular description of the changes that render latently HIV-1 infected T cells activation inert and using this description, devise pharmacologic interference strategies that render initially activation inert T cells responsive to stimulation. This in turn allows for efficient triggering of HIV-1 reactivation in a large part of the otherwise unresponsive latently HIV-1 infected T cell reservoir.
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4
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Lin JJ, O'Donoghue GP, Wilhelm KB, Coyle MP, Low-Nam ST, Fay NC, Alfieri KN, Groves JT. Membrane Association Transforms an Inert Anti-TCRβ Fab' Ligand into a Potent T Cell Receptor Agonist. Biophys J 2020; 118:2879-2893. [PMID: 32407684 DOI: 10.1016/j.bpj.2020.04.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 03/09/2020] [Accepted: 04/13/2020] [Indexed: 12/27/2022] Open
Abstract
The natural peptide-major histocompatibility complex (pMHC) ligand for T cell receptors (TCRs) is inactive from solution yet capable of activating T cells at single-molecule levels when membrane-associated. This distinctive feature stems from the mechanism of TCR activation, which is thought to involve steric phosphatase exclusion as well as direct mechanical forces. It is possible to defeat this mechanism and activate T cells with solution ligands by cross-linking pMHC or using multivalent antibodies to TCR. However, these widely used strategies activate TCRs through a nonphysiological mechanism and can produce different activation profiles than natural, monovalent, membrane-associated pMHC. Here, we introduce a strictly monovalent anti-TCRβ H57 Fab' ligand that, when coupled to a supported lipid bilayer via DNA complementation, triggers TCRs and activates nuclear translocation of the transcription factor nuclear factor of activated T cells (NFAT) with a similar potency to pMHC in primary murine T cells. Importantly, like monovalent pMHC and unlike bivalent antibodies, monovalent Fab'-DNA triggers TCRs only when physically coupled to the membrane, and only around 100 individual Fab':TCR interactions are necessary to stimulate early T cell activation.
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Affiliation(s)
- Jenny J Lin
- Department of Chemistry, University of California, Berkeley, Berkeley, California
| | - Geoff P O'Donoghue
- Department of Chemistry, University of California, Berkeley, Berkeley, California.
| | - Kiera B Wilhelm
- Department of Chemistry, University of California, Berkeley, Berkeley, California
| | - Michael P Coyle
- Department of Chemistry, University of California, Berkeley, Berkeley, California.
| | - Shalini T Low-Nam
- Department of Chemistry, University of California, Berkeley, Berkeley, California
| | - Nicole C Fay
- Department of Molecular and Cellular Biology, University of California, Berkeley, Berkeley, California
| | - Katherine N Alfieri
- Department of Chemistry, University of California, Berkeley, Berkeley, California
| | - Jay T Groves
- Department of Chemistry, University of California, Berkeley, Berkeley, California.
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5
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Sukumar P, Deliorman M, Brimmo AT, Alnemari R, Elsori D, Chen W, Qasaimeh MA. Airplug-mediated isolation and centralization of single T cells in rectangular microwells for biosensing. ADVANCED THERAPEUTICS 2020; 3:1900085. [PMID: 33117882 PMCID: PMC7591138 DOI: 10.1002/adtp.201900085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Indexed: 11/09/2022]
Abstract
Sorting cells in a single cell per microwell format is of great interest to basic biology studies, biotherapeutics, and biosensing including cell phenotyping. For instance, isolation of individual immune T cells in rectangular microwells has been shown to empower the multiplex cytokine profiling at the single cell level for therapeutics applications. The present study, however, shows that there is an existing bias in temporal cytokine sensing that originates from random "unpredicted" positions of loaded cells within the rectangular microwells. To eliminate this bias, the isolated cells need to be well-aligned with each other and relative to the sensing elements. Hence, an approach that utilizes the in situ formation and release of airplugs to localize cells towards the center of the rectangular microwells is reported. The chip includes 2250 microwells (each 500 × 50 × 20 μm3) arranged in 9 rows. Results showed 20% efficiency in trapping single T cells per microwells, where cells are localized within ±3% of the center of microwells. The developed platform could provide real-time dynamic and unbiased multiplex cytokine detection from single T cells for phenotyping and biotherapeutics studies.
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Affiliation(s)
- Pavithra Sukumar
- Division of Engineering, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, UAE
| | - Muhammedin Deliorman
- Division of Engineering, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, UAE
| | - Ayoola T Brimmo
- Division of Engineering, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, UAE
| | - Roaa Alnemari
- Division of Engineering, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, UAE
| | - Deena Elsori
- Department of Applied Sciences and Mathematics, Abu Dhabi University, P.O. Box 59911, Abu Dhabi, UAE
| | - Weiqiang Chen
- Department of Biomedical Engineering, New York University, Brooklyn, NY 11201, USA
| | - Mohammad A Qasaimeh
- Division of Engineering, New York University Abu Dhabi (NYUAD), P.O. Box 129188, Abu Dhabi, UAE
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6
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Dunn ZS, Mac J, Wang P. T cell immunotherapy enhanced by designer biomaterials. Biomaterials 2019; 217:119265. [PMID: 31271861 PMCID: PMC6689323 DOI: 10.1016/j.biomaterials.2019.119265] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 12/21/2022]
Abstract
Cancer immunotherapy has recently burst onto the center stage of cancer treatment and research. T lymphocyte adoptive cellular transfer (ACT), a form of cancer immunotherapy, has spawned unprecedented complete remissions for terminal patients with certain leukemias and lymphomas. Unfortunately, the successes have been overshadowed by the disappointing clinical results of ACT administered to treat solid tumors, in addition to the toxicities associated with the treatment, a lack of efficacy in a significant proportion of the patient population, and cancer relapse following the treatment. Biomaterials hold the promise of addressing these shortcomings. ACT consists of two main stages - T lymphocyte ex vivo expansion followed by reinfusion into the patient - and biomaterials can improve the efficacy of ACT at both stages. In this review, we highlight recent advances in the use of biomaterials for T lymphocyte adoptive cellular cancer immunotherapy and discuss the challenges at each stage.
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Affiliation(s)
- Zachary S Dunn
- Mork Family Department of of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, United States
| | - John Mac
- Mork Family Department of of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, United States
| | - Pin Wang
- Mork Family Department of of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, United States; Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States; Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA, United States.
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7
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June CH. Toward synthetic biology with engineered T cells: a long journey just begun. Hum Gene Ther 2014; 25:779-84. [PMID: 25244569 PMCID: PMC4174426 DOI: 10.1089/hum.2014.2533] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 09/03/2014] [Indexed: 01/16/2023] Open
Affiliation(s)
- Carl H June
- Abramson Cancer Center; Abramson Family Cancer Research Institute; and Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA 19104-5156
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8
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Wang F, Xu Z, Zhou J, Lo WS, Lau CF, Nangle LA, Yang XL, Zhang M, Schimmel P. Regulated capture by exosomes of mRNAs for cytoplasmic tRNA synthetases. J Biol Chem 2013; 288:29223-8. [PMID: 24003230 PMCID: PMC3795223 DOI: 10.1074/jbc.c113.490599] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 08/15/2013] [Indexed: 01/08/2023] Open
Abstract
Although tRNA synthetases are enzymes that catalyze the first step of translation in the cytoplasm, surprising functions unrelated to translation have been reported. These studies, and the demonstration of novel activities of splice variants, suggest a far broader reach of tRNA synthetases into cell biology than previously recognized. Here we show that mRNAs for most tRNA synthetases can be detected in exosomes. Also detected in exosomes was an mRNA encoding a unique splice variant that others had associated with prostate cancer. The exosomal mRNAs encoding the native synthetase and its cancer-associated splice variant could be translated in vitro and in mammalian cells into stable proteins. Other results showed that selection by exosomes of the splice variant mRNA could be regulated by an external stimulus. Thus, a broad and diverse regulated pool of tRNA synthetase-derived mRNAs is packaged for genetic exchange.
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Affiliation(s)
- Feng Wang
- From the IAS HKUST–Scripps R&D Laboratory, Institute for Advanced Study and
- Pangu Biopharma, Edinburgh Tower, The Landmark, 15 Queen's Road Central, Hong Kong, China
| | - Zhiwen Xu
- From the IAS HKUST–Scripps R&D Laboratory, Institute for Advanced Study and
- Pangu Biopharma, Edinburgh Tower, The Landmark, 15 Queen's Road Central, Hong Kong, China
| | - Jie Zhou
- From the IAS HKUST–Scripps R&D Laboratory, Institute for Advanced Study and
- Pangu Biopharma, Edinburgh Tower, The Landmark, 15 Queen's Road Central, Hong Kong, China
| | - Wing-Sze Lo
- From the IAS HKUST–Scripps R&D Laboratory, Institute for Advanced Study and
- Pangu Biopharma, Edinburgh Tower, The Landmark, 15 Queen's Road Central, Hong Kong, China
| | - Ching-Fun Lau
- From the IAS HKUST–Scripps R&D Laboratory, Institute for Advanced Study and
- Pangu Biopharma, Edinburgh Tower, The Landmark, 15 Queen's Road Central, Hong Kong, China
| | | | - Xiang-Lei Yang
- From the IAS HKUST–Scripps R&D Laboratory, Institute for Advanced Study and
- The Scripps Research Institute, La Jolla, California 92037
| | - Mingjie Zhang
- From the IAS HKUST–Scripps R&D Laboratory, Institute for Advanced Study and
- the Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Paul Schimmel
- From the IAS HKUST–Scripps R&D Laboratory, Institute for Advanced Study and
- The Scripps Research Institute, La Jolla, California 92037
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9
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Rudloff I, Bachmann M, Pfeilschifter J, Mühl H. Mechanisms of rapid induction of interleukin-22 in activated T cells and its modulation by cyclosporin a. J Biol Chem 2012; 287:4531-43. [PMID: 22170067 PMCID: PMC3281663 DOI: 10.1074/jbc.m111.286492] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 12/09/2011] [Indexed: 12/30/2022] Open
Abstract
IL-22 is an immunoregulatory cytokine displaying pathological functions in models of autoimmunity like experimental psoriasis. Understanding molecular mechanisms driving IL-22, together with knowledge on the capacity of current immunosuppressive drugs to target this process, may open an avenue to novel therapeutic options. Here, we sought to characterize regulation of human IL22 gene expression with focus on the established model of Jurkat T cells. Moreover, effects of the prototypic immunosuppressant cyclosporin A (CsA) were investigated. We report that IL-22 induction by TPA/A23187 (T/A) or αCD3 is inhibited by CsA or related FK506. Similar data were obtained with peripheral blood mononuclear cells or purified CD3(+) T cells. IL22 promoter analysis (-1074 to +156 bp) revealed a role of an NF-AT (-95/-91 nt) and a CREB (-194/-190 nt) binding site for gene induction. Indeed, binding of CREB and NF-ATc2, but not c-Rel, under the influence of T/A to those elements could be proven by ChIP. Because CsA has the capability to impair IκB kinase (IKK) complex activation, the IKKα/β inhibitor IKKVII was evaluated. IKKVII likewise reduced IL-22 induction in Jurkat cells and peripheral blood mononuclear cells. Interestingly, transfection of Jurkat cells with siRNA directed against IKKα impaired IL22 gene expression. Data presented suggest that NF-AT, CREB, and IKKα contribute to rapid IL22 gene induction. In particular the crucial role of NF-AT detected herein may form the basis of direct action of CsA on IL-22 expression by T cells, which may contribute to therapeutic efficacy of the drug in autoimmunity.
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Affiliation(s)
- Ina Rudloff
- From the Pharmazentrum Frankfurt/Zentrum für Arzneimittelforschung, Entwicklung und Sicherheit, University Hospital Goethe-University Frankfurt, Frankfurt am Main 60590, Germany
| | - Malte Bachmann
- From the Pharmazentrum Frankfurt/Zentrum für Arzneimittelforschung, Entwicklung und Sicherheit, University Hospital Goethe-University Frankfurt, Frankfurt am Main 60590, Germany
| | - Josef Pfeilschifter
- From the Pharmazentrum Frankfurt/Zentrum für Arzneimittelforschung, Entwicklung und Sicherheit, University Hospital Goethe-University Frankfurt, Frankfurt am Main 60590, Germany
| | - Heiko Mühl
- From the Pharmazentrum Frankfurt/Zentrum für Arzneimittelforschung, Entwicklung und Sicherheit, University Hospital Goethe-University Frankfurt, Frankfurt am Main 60590, Germany
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10
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Borowski P, Heiland M, Kornetzky L, Medem S, Laufs R. Purification of catalytic domain of rat spleen p72syk kinase and its phosphorylation and activation by protein kinase C. Biochem J 1998; 331 ( Pt 2):649-57. [PMID: 9531509 PMCID: PMC1219400 DOI: 10.1042/bj3310649] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The catalytic domain of p72(syk) kinase (CDp72(syk)) was purified from a 30000 g particulate fraction of rat spleen. The purification procedure employed sequential chromatography on columns of DEAE-Sephacel and Superdex-200, and elution from HA-Ultrogel by chloride. The analysis of the final CDp72(syk) preparation by SDS/PAGE revealed a major silver-stained 40 kDa protein. The kinase was identified by covalent modification of its ATP-binding site with [14C]5'-fluorosulphonylbenzoyladenosine and by immunoblotting with a polyclonal antibody against the 'linker' region of p72(syk). By using poly(Glu4, Tyr1) as a substrate, the specific activity of the enzyme was determined as 18.5 nmol Pi/min per mg. Casein, histones H1 and H2B and myelin basic protein were efficiently phosphorylated by CDp72(syk). The kinase exhibited a limited ability to phosphorylate random polymers containing tyrosine residues. CDp72(syk) autophosphorylation activity was associated with an activation of the kinase towards exogenous substrates. The extent of activation was dependent on the substrates added. CDp72(syk) was phosphorylated by protein kinase C (PKC) on serine and threonine residues. With a newly developed assay method, we demonstrated that the PKC-mediated phosphorylation had a strong activating effect on the tyrosine kinase activity of CDp72(syk). Studies extended to conventional PKC isoforms revealed an isoform-dependent manner (alpha > betaI = betaII > gamma) of CDp72(syk) phosphorylation. The different phosphorylation efficiencies of the PKC isoforms closely correlated with the ability to enhance the tyrosine kinase activity.
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Affiliation(s)
- P Borowski
- Institut für Medizinishe Mikrobiologie und Immunologie, Universitätskrankenhaus Eppendorf, Martinistrasse 52, 20246 Hamburg, Federal Republic of Germany
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11
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Haffar OK, Moran PA, Smithgall MD, Diegel ML, Sridhar P, Ledbetter JA, Zarling JM, Hu SL. Inhibition of virus production in peripheral blood mononuclear cells from human immunodeficiency virus (HIV) type 1-seropositive donors by treatment with recombinant HIV-like particles. J Virol 1992; 66:4279-87. [PMID: 1602544 PMCID: PMC241233 DOI: 10.1128/jvi.66.7.4279-4287.1992] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We have previously reported on the assembly of recombinant human immunodeficiency virus (HIV)-like particles that contain gag structural proteins and present env glycoproteins gp120 and gp41 on their surfaces (O. Haffar,. J. Garriques, B. Travis, P. Moran, J. Zarling, and S.-L. Hu, J. Virol. 64:2653-2659, 1990). On the basis of their structures, we hypothesized that the recombinant particles would interfere with virus infection and tested our hypothesis in vitro by using peripheral blood mononuclear cells (PBMC) from HIV type 1-seropositive donors. Addition of the recombinant particles to PBMC concomitant with stimulation by anti-CD3 inhibited virus production, as determined by reduced levels of p24 in the culture supernatants. This inhibition of p24 production correlated with lower levels of cell-associated viral DNA. Several lines of evidence suggested that the recombinant particles exerted their antiviral effects primarily by inhibiting virus production from latently infected cells and not by inhibiting subsequent virus spread. Importantly, CD4+ T-cell stimulation by specific antigen or by anti-CD3 was not inhibited by treatment with the recombinant particles. This apparent selective inhibition of virus replication in infected PBMC represents a novel property of the recombinant HIV-like particles.
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Affiliation(s)
- O K Haffar
- Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, Washington 98121
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12
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Dallman MJ, Shiho O, Page TH, Wood KJ, Morris PJ. Peripheral tolerance to alloantigen results from altered regulation of the interleukin 2 pathway. J Exp Med 1991; 173:79-87. [PMID: 1985127 PMCID: PMC2118748 DOI: 10.1084/jem.173.1.79] [Citation(s) in RCA: 238] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Tolerance to alloantigen may be induced in rats by administration of blood followed by transplantation of a renal allograft. The mechanism of this tolerance was investigated by directly analyzing the functional activity of graft-infiltrating cells. We have previously shown cytotoxic T lymphocyte infiltration of, and major histocompatibility complex induction on, grafts of tolerant animals. We now report that cells isolated from the grafts of tolerant rats show a reduced expression of the p55 interleukin 2 receptor (IL-2R) chain on the cell surface compared with that seen on the cells of untreated animals. Scatchard analysis further reveals low expression of high affinity IL-2R. This is due to reduced transcription of both IL-2R alpha and beta chain mRNAs and results in a reduced ability of cells to proliferate in response to IL-2. Cells isolated from tolerant animals are unable to make biologically active IL-2 in culture, whereas cells from untreated animals make high levels. This is not reflected at the mRNA level as the IL-2 gene is induced in both tolerant and untreated animals to similar levels. The induction of tolerance is abrogated by administration of recombinant IL-2 to animals at the time of transplantation. Thus, we conclude that an altered regulation of the IL-2 pathway results in tolerance in these alloantigen-treated and transplanted animals.
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Affiliation(s)
- M J Dallman
- Nuffield Department of Surgery, University of Oxford, John Radcliffe Hospital, Headington, England
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13
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A major myristylated substrate of protein kinase C and protein kinase C itself are differentially regulated during murine B- and T-lymphocyte development and activation. Mol Cell Biol 1989. [PMID: 2789336 DOI: 10.1128/mcb.9.9.3727] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The regulation and expression of protein kinase C (PKC) and phosphomyristin C (PMC) (a principal substrate of PKC which is the major myristylated protein in lymphocyte and glioma lines that express it) in murine B and T lymphocytes were investigated. Both PMC and PKC are differentially regulated during T-cell development. The level of PMC expression is highest in CD4-8-, intermediate in CD4+8+, and lowest in J11d-, CD4, or CD8 single-positive thymocytes. PKC is equally expressed by all three thymic populations. In striking contrast to thymocytes, resting peripheral lymph node T cells and T-cell clones express little if any PMC and reduced levels of PKC. Neither PKC nor PMC is significantly induced upon the activation of lymph node T cells: treatment with anti-CD3 antibodies or anti-CD3 and interleukin-2 fails to induce PKC, whereas PMC is not induced by anti-CD3 alone and is only slightly induced by anti-CD3 and interleukin-2. In contrast to the situation with T cells, PMC and PKC are constitutively expressed at moderate levels in mature B cells. PMC is greatly increased in B-cell blasts generated by cross-linking the antigen receptor with anti-immunoglobulin. These results demonstrate that PMC and PKC are differentially regulated during the development and activation of B and T cells, suggesting that cellular events that rely upon PKC and PMC may differ during ontogeny and activation of different lymphocyte subsets.
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14
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Mutation of amino acids in pp60c-src that are phosphorylated by protein kinases C and A. Mol Cell Biol 1989. [PMID: 2474754 DOI: 10.1128/mcb.9.6.2453] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The product of the c-src proto-oncogene, pp60c-src, is phosphorylated at Ser-17 by cyclic AMP-dependent protein kinase A and at Ser-12 by calcium-phospholipid-dependent protein kinase C (when stimulated by 12-O-tetradecanoyl phorbol acetate). We tested the effects of Ser----Ala and Ser----Glu mutations at these sites in pp60c-src and in pp60c-src(F527) (a mutant whose transforming activities are enhanced by Tyr-527----Phe mutation) by transfecting single-, double-, and triple-mutant src expression plasmids into NIH 3T3 cells. Tryptic phosphopeptide analyses of the mutant proteins confirmed prior biochemical identifications of the phosphorylation sites and showed that neither separate nor coordinate mutations at Ser-12 and Ser-17 affected Tyr-416, Tyr-527, or Ser-48 phosphorylation or prevented mitosis-specific phosphorylations of either pp60c-src or pp60c-src(F527). Ser-12 mutation did not affect phosphorylation of the Ser-17-containing peptide, but mutation of Ser-17 significantly increased phosphorylation at Ser-12. Specific kinase activities (both with and without in vivo 12-O-tetradecanoyl phorbol acetate treatment) and the abilities of pp60c-src and pp60c-src(F527) to induce foci, transformed morphologies, and anchorage-independent growth were unaffected by any of the serine mutations. Thus, pp60c-src transforming activity in NIH 3T3 cells is relatively insensitive to phosphorylation at these sites, but there is a suggestion that Ser-17 phosphorylation may have a subtle regulatory effect.
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15
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Hornbeck P, Nakabayashi H, Fowlkes BJ, Paul WE, Kligman D. A major myristylated substrate of protein kinase C and protein kinase C itself are differentially regulated during murine B- and T-lymphocyte development and activation. Mol Cell Biol 1989; 9:3727-35. [PMID: 2789336 PMCID: PMC362433 DOI: 10.1128/mcb.9.9.3727-3735.1989] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The regulation and expression of protein kinase C (PKC) and phosphomyristin C (PMC) (a principal substrate of PKC which is the major myristylated protein in lymphocyte and glioma lines that express it) in murine B and T lymphocytes were investigated. Both PMC and PKC are differentially regulated during T-cell development. The level of PMC expression is highest in CD4-8-, intermediate in CD4+8+, and lowest in J11d-, CD4, or CD8 single-positive thymocytes. PKC is equally expressed by all three thymic populations. In striking contrast to thymocytes, resting peripheral lymph node T cells and T-cell clones express little if any PMC and reduced levels of PKC. Neither PKC nor PMC is significantly induced upon the activation of lymph node T cells: treatment with anti-CD3 antibodies or anti-CD3 and interleukin-2 fails to induce PKC, whereas PMC is not induced by anti-CD3 alone and is only slightly induced by anti-CD3 and interleukin-2. In contrast to the situation with T cells, PMC and PKC are constitutively expressed at moderate levels in mature B cells. PMC is greatly increased in B-cell blasts generated by cross-linking the antigen receptor with anti-immunoglobulin. These results demonstrate that PMC and PKC are differentially regulated during the development and activation of B and T cells, suggesting that cellular events that rely upon PKC and PMC may differ during ontogeny and activation of different lymphocyte subsets.
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Affiliation(s)
- P Hornbeck
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892
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16
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Yaciuk P, Choi JK, Shalloway D. Mutation of amino acids in pp60c-src that are phosphorylated by protein kinases C and A. Mol Cell Biol 1989; 9:2453-63. [PMID: 2474754 PMCID: PMC362318 DOI: 10.1128/mcb.9.6.2453-2463.1989] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The product of the c-src proto-oncogene, pp60c-src, is phosphorylated at Ser-17 by cyclic AMP-dependent protein kinase A and at Ser-12 by calcium-phospholipid-dependent protein kinase C (when stimulated by 12-O-tetradecanoyl phorbol acetate). We tested the effects of Ser----Ala and Ser----Glu mutations at these sites in pp60c-src and in pp60c-src(F527) (a mutant whose transforming activities are enhanced by Tyr-527----Phe mutation) by transfecting single-, double-, and triple-mutant src expression plasmids into NIH 3T3 cells. Tryptic phosphopeptide analyses of the mutant proteins confirmed prior biochemical identifications of the phosphorylation sites and showed that neither separate nor coordinate mutations at Ser-12 and Ser-17 affected Tyr-416, Tyr-527, or Ser-48 phosphorylation or prevented mitosis-specific phosphorylations of either pp60c-src or pp60c-src(F527). Ser-12 mutation did not affect phosphorylation of the Ser-17-containing peptide, but mutation of Ser-17 significantly increased phosphorylation at Ser-12. Specific kinase activities (both with and without in vivo 12-O-tetradecanoyl phorbol acetate treatment) and the abilities of pp60c-src and pp60c-src(F527) to induce foci, transformed morphologies, and anchorage-independent growth were unaffected by any of the serine mutations. Thus, pp60c-src transforming activity in NIH 3T3 cells is relatively insensitive to phosphorylation at these sites, but there is a suggestion that Ser-17 phosphorylation may have a subtle regulatory effect.
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Affiliation(s)
- P Yaciuk
- Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802
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17
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Platelet-derived growth factor induces multisite phosphorylation of pp60c-src and increases its protein-tyrosine kinase activity. Mol Cell Biol 1989. [PMID: 2463476 DOI: 10.1128/mcb.8.8.3345] [Citation(s) in RCA: 155] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have shown previously that pp60c-src is a substrate for protein kinase C in vivo and that the target of protein kinase C phosphorylation in mammalian pp60c-src is serine 12. We now demonstrate that in addition to tumor promoters, all activators of phosphatidylinositol turnover that we have tested in fibroblasts (platelet-derived growth factor, fibroblast growth factor, serum, vasopressin, sodium orthovanadate, and prostaglandin F2 alpha) lead to the phosphorylation of pp60c-src at serine 12. In addition to stimulating serine 12 phosphorylation in pp60c-src, platelet-derived growth factor treatment of quiescent fibroblasts induces phosphorylation of one or two additional serine residues and one tyrosine residue within the N-terminal 16 kilodaltons of the enzyme and activates its immune complex protein-tyrosine kinase activity.
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18
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Thompson CB, Lindsten T, Ledbetter JA, Kunkel SL, Young HA, Emerson SG, Leiden JM, June CH. CD28 activation pathway regulates the production of multiple T-cell-derived lymphokines/cytokines. Proc Natl Acad Sci U S A 1989; 86:1333-7. [PMID: 2465550 PMCID: PMC286684 DOI: 10.1073/pnas.86.4.1333] [Citation(s) in RCA: 455] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
CD28 is a 44-kDa glycoprotein expressed as a homodimer on the surface of a major subset of human T cells. Previous studies have demonstrated that the binding of monoclonal antibodies to the CD28 surface antigen can augment the proliferation of purified human T cells stimulated with suboptimal doses of mitogens or anti-T-cell receptor/CD3 complex antibodies. In this report, we show that CD28 stimulation augments T-cell immune responses by specifically inducing a 5- to 50-fold enhancement in the expression and secretion of interleukin 2, tumor necrosis factor type alpha, lymphotoxin, interferon gamma, and granulocyte-macrophage colony-stimulating factor in normal human T cells stimulated to proliferate by crosslinking of the T-cell receptor/CD3 complex. This CD28-mediated induction of lymphokine/cytokine gene expression occurred even in T cells stimulated with optimal concentrations of mitogens or anti-T-cell receptor/CD3 antibodies, although under these conditions CD28 activation failed to enhance the proliferative response. The activation pathway induced by stimulation of CD28 is distinct from other biochemical pathways that induce lymphokines/cytokines because CD28 stimulation can induce lymphokine/cytokine gene expression in the presence of the immunosuppressant cyclosporine. Together these data suggest that the CD28 cell surface molecule is part of a distinct activation pathway that specifically modulates the expression of multiple lymphokine/cytokine genes.
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Affiliation(s)
- C B Thompson
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor 48109
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19
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Stewart SJ, Prpic V, Johns JA, Powers FS, Graber SE, Forbes JT, Exton JH. Bacterial toxins affect early events of T lymphocyte activation. J Clin Invest 1989; 83:234-42. [PMID: 2536043 PMCID: PMC303667 DOI: 10.1172/jci113865] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The effects of pertussis toxin and cholera toxin on early events of T lymphocyte activation were examined in the T lymphocyte cell line, Jurkat. Pertussis toxin treatment of these T cells increased inositol phosphates production and led to increases in intracellular free calcium concentration. These effects were produced by the isolated B (binding) subunit of pertussis toxin, alone. Inositol phosphates production resulting from perturbation of the T cell antigen receptor-CD3 complex by MAb was not affected by pertussis toxin treatment but was markedly inhibited by cholera toxin. This effect of cholera toxin paralleled elevations in cAMP content. However, forskolin, in concentrations equipotent for cAMP production, was a weaker inhibitor of inositol phosphates production. Cholera toxin inhibition of inositol phosphates production did not result from inhibition of baseline incorporation of inositol into phosphoinositide substrates of phospholipase C. These studies underline the complexity of toxin effects on cellular systems and suggest that other approaches will be required to implicate guanine nucleotide-binding regulatory proteins in control of the early events of T lymphocyte activation. However, the data presented here provide a molecular basis for the clinical observations of lymphocytosis and the in vitro observations of lymphocyte mitogenesis after pertussis toxin stimulation.
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Affiliation(s)
- S J Stewart
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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20
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Alterations of the lymphocyte-specific protein tyrosine kinase (p56lck) during T-cell activation. Mol Cell Biol 1988. [PMID: 3141789 DOI: 10.1128/mcb.8.10.4353] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lymphocyte-specific tyrosine protein kinase p56lck is abundantly expressed in L3T4+ (CD4+) and Lyt-2+ (CD8+) T-lymphocytes, where it is predominantly phosphorylated in vivo on the carboxy-terminal tyrosine residue 505 (Y-505). Upon exposure to activating signals (mitogenic lectins, antibodies to the T-cell receptor), the p56lck expressed in normal cloned murine T-cells is modified into a product which migrates at approximately 59 kilodaltons on sodium dodecyl sulfate-polyacrylamide gels and which possesses several amino-terminal serine phosphorylations. The changes in both mobility and amino-terminal phosphorylation can be reproduced by known activators of protein kinase C (4 alpha-phorbol 12 beta-myristate, dioctanoylglycerol), suggesting that this signal transduction pathway (or related pathways) mediates at least part of these events. Interestingly, agents raising intracellular calcium (such as A23187) cause the appearance of several of these amino-terminal phosphorylation changes but do not cause the pronounced shift in electrophoretic mobility. These data suggest that at least two serine kinase systems are implicated in the alterations of p56lck associated with T-cell activation and that the lck gene product plays a critical role in normal T-cell physiology.
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21
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Veillette A, Horak ID, Horak EM, Bookman MA, Bolen JB. Alterations of the lymphocyte-specific protein tyrosine kinase (p56lck) during T-cell activation. Mol Cell Biol 1988; 8:4353-61. [PMID: 3141789 PMCID: PMC365508 DOI: 10.1128/mcb.8.10.4353-4361.1988] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The lymphocyte-specific tyrosine protein kinase p56lck is abundantly expressed in L3T4+ (CD4+) and Lyt-2+ (CD8+) T-lymphocytes, where it is predominantly phosphorylated in vivo on the carboxy-terminal tyrosine residue 505 (Y-505). Upon exposure to activating signals (mitogenic lectins, antibodies to the T-cell receptor), the p56lck expressed in normal cloned murine T-cells is modified into a product which migrates at approximately 59 kilodaltons on sodium dodecyl sulfate-polyacrylamide gels and which possesses several amino-terminal serine phosphorylations. The changes in both mobility and amino-terminal phosphorylation can be reproduced by known activators of protein kinase C (4 alpha-phorbol 12 beta-myristate, dioctanoylglycerol), suggesting that this signal transduction pathway (or related pathways) mediates at least part of these events. Interestingly, agents raising intracellular calcium (such as A23187) cause the appearance of several of these amino-terminal phosphorylation changes but do not cause the pronounced shift in electrophoretic mobility. These data suggest that at least two serine kinase systems are implicated in the alterations of p56lck associated with T-cell activation and that the lck gene product plays a critical role in normal T-cell physiology.
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Affiliation(s)
- A Veillette
- Laboratory of Tumor Virus Biology, National Cancer Institute, Bethesda, Maryland 20892
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22
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Gould KL, Hunter T. Platelet-derived growth factor induces multisite phosphorylation of pp60c-src and increases its protein-tyrosine kinase activity. Mol Cell Biol 1988; 8:3345-56. [PMID: 2463476 PMCID: PMC363570 DOI: 10.1128/mcb.8.8.3345-3356.1988] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We have shown previously that pp60c-src is a substrate for protein kinase C in vivo and that the target of protein kinase C phosphorylation in mammalian pp60c-src is serine 12. We now demonstrate that in addition to tumor promoters, all activators of phosphatidylinositol turnover that we have tested in fibroblasts (platelet-derived growth factor, fibroblast growth factor, serum, vasopressin, sodium orthovanadate, and prostaglandin F2 alpha) lead to the phosphorylation of pp60c-src at serine 12. In addition to stimulating serine 12 phosphorylation in pp60c-src, platelet-derived growth factor treatment of quiescent fibroblasts induces phosphorylation of one or two additional serine residues and one tyrosine residue within the N-terminal 16 kilodaltons of the enzyme and activates its immune complex protein-tyrosine kinase activity.
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Affiliation(s)
- K L Gould
- Molecular Biology and Virology Laboratory, Salk Institute, San Diego, California 92138
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23
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T-cell proliferation involving the CD28 pathway is associated with cyclosporine-resistant interleukin 2 gene expression. Mol Cell Biol 1988. [PMID: 2830495 DOI: 10.1128/mcb.7.12.4472] [Citation(s) in RCA: 346] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD28 is a homodimeric glycoprotein expressed on the surface of a major subset of human T cells that has recently been identified as a member of the immunoglobulin supergene family. The binding of monoclonal antibodies to the CD28 antigen on purified T cells does not result in proliferation; however, previous studies have shown that the combination of CD28 stimulation and protein kinase C activation by phorbol myristate acetate (PMA) results in T-cell proliferation that is independent of both accessory cells and activation of the T-cell receptor-CD3 complex. In the present study, effects of stimulation by anti-CD28 on cell cycle progression and on the interleukin 2 (IL-2) and IL-2 receptor system have been investigated on primary cultures of purified peripheral-blood CD28+ T cells. There was no measurable effect on cell size or on DNA synthesis after stimulation of resting (G0) cells by CD28 alone. After 3 h of activation of T cells by PMA alone, a slight (8%) increase in cell volume occurred that did not progress to DNA synthesis. In contrast, T-cell stimulation by CD28 in combination with PMA resulted in a progressive increase in cell volume in approximately 100% of cells at 12 to 14 h after stimulation. Northern blot (RNA blot) analysis revealed that CD28 stimulation alone failed to cause expression of the alpha chain of the IL-2 receptor or of IL-2 mRNA, and in accord with previous studies, stimulation by PMA alone resulted in the accumulation of IL-2 receptor transcripts but no detectable IL-2 mRNA. In contrast, T-cell stimulation by the combination of CD28 and PMA resulted in the appearance of IL-2 transcripts and enhanced expression of IL-2 receptor mRNA. Functional studies revealed that the proliferation induced by CD28 and PMA stimulation was entirely resistant to cyclosporine, in contrast to T-cell activation induced by the CD3-T-cell receptor complex. Cyclosporine was found not to affect the accumulation of IL-2 mRNA after CD28 plus PMA stimulation, although there was no detectable IL-2 mRNA after stimulation by CD3 in the presence of the drug. Furthermore, stimulation by CD28 in combination with immobilized CD3 antibodies caused a striking enhancement of IL-2 mRNA expression that was, in part, resistant to the effects of cyclosporine. These studies indicate that the CD28 molecule synergizes with protein kinase C activation to induce IL-2 gene expression and demonstrate that stimulation by the CD28 pathway can cause vigorous T-cell proliferation even in the presence of cyclosporine and that cyclosporine does not prevent transcription of 16-2 mRNA, as has been suggested previously. Moreover, these findings suggest that a potential role for the CD28 molecule in vivo may be to augment IL-2 production after stimulation of the CD3-T-cell receptor molecular complex and thereby to amplify an antigen-specific immune response. Finally, these results provide further evidence that the CD28 molecule triggers T-cell proliferation in a manner that differs biochemically from CD3-T-cell receptor-induced proliferation.
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24
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June CH, Ledbetter JA, Gillespie MM, Lindsten T, Thompson CB. T-cell proliferation involving the CD28 pathway is associated with cyclosporine-resistant interleukin 2 gene expression. Mol Cell Biol 1987; 7:4472-81. [PMID: 2830495 PMCID: PMC368131 DOI: 10.1128/mcb.7.12.4472-4481.1987] [Citation(s) in RCA: 151] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
CD28 is a homodimeric glycoprotein expressed on the surface of a major subset of human T cells that has recently been identified as a member of the immunoglobulin supergene family. The binding of monoclonal antibodies to the CD28 antigen on purified T cells does not result in proliferation; however, previous studies have shown that the combination of CD28 stimulation and protein kinase C activation by phorbol myristate acetate (PMA) results in T-cell proliferation that is independent of both accessory cells and activation of the T-cell receptor-CD3 complex. In the present study, effects of stimulation by anti-CD28 on cell cycle progression and on the interleukin 2 (IL-2) and IL-2 receptor system have been investigated on primary cultures of purified peripheral-blood CD28+ T cells. There was no measurable effect on cell size or on DNA synthesis after stimulation of resting (G0) cells by CD28 alone. After 3 h of activation of T cells by PMA alone, a slight (8%) increase in cell volume occurred that did not progress to DNA synthesis. In contrast, T-cell stimulation by CD28 in combination with PMA resulted in a progressive increase in cell volume in approximately 100% of cells at 12 to 14 h after stimulation. Northern blot (RNA blot) analysis revealed that CD28 stimulation alone failed to cause expression of the alpha chain of the IL-2 receptor or of IL-2 mRNA, and in accord with previous studies, stimulation by PMA alone resulted in the accumulation of IL-2 receptor transcripts but no detectable IL-2 mRNA. In contrast, T-cell stimulation by the combination of CD28 and PMA resulted in the appearance of IL-2 transcripts and enhanced expression of IL-2 receptor mRNA. Functional studies revealed that the proliferation induced by CD28 and PMA stimulation was entirely resistant to cyclosporine, in contrast to T-cell activation induced by the CD3-T-cell receptor complex. Cyclosporine was found not to affect the accumulation of IL-2 mRNA after CD28 plus PMA stimulation, although there was no detectable IL-2 mRNA after stimulation by CD3 in the presence of the drug. Furthermore, stimulation by CD28 in combination with immobilized CD3 antibodies caused a striking enhancement of IL-2 mRNA expression that was, in part, resistant to the effects of cyclosporine. These studies indicate that the CD28 molecule synergizes with protein kinase C activation to induce IL-2 gene expression and demonstrate that stimulation by the CD28 pathway can cause vigorous T-cell proliferation even in the presence of cyclosporine and that cyclosporine does not prevent transcription of 16-2 mRNA, as has been suggested previously. Moreover, these findings suggest that a potential role for the CD28 molecule in vivo may be to augment IL-2 production after stimulation of the CD3-T-cell receptor molecular complex and thereby to amplify an antigen-specific immune response. Finally, these results provide further evidence that the CD28 molecule triggers T-cell proliferation in a manner that differs biochemically from CD3-T-cell receptor-induced proliferation.
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Affiliation(s)
- C H June
- Naval Medical Research Institute, Bethesda, Maryland 20814
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25
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McCarley DJ, Parsons SJ. Reduced tyrosine kinase specific activity is associated with hypophosphorylation of pp60c-src in cells infected with avian erythroblastosis virus. Proc Natl Acad Sci U S A 1987; 84:5793-7. [PMID: 3112775 PMCID: PMC298949 DOI: 10.1073/pnas.84.16.5793] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Avian erythroblastosis virus (AEV) is a replication-defective retrovirus that causes erythroblastosis and sarcomas in chickens and transforms immature erythroid cells and fibroblasts in culture. AEV encodes two oncogenes, v-erbA and v-erbB, whose products are closely related to the thyroxine receptor and the epidermal growth factor receptor, respectively. Since tyrosine protein kinases have been implicated in the process of normal growth signal transduction, we wished to study the possible consequences of the expression of these mutated, growth-regulating receptor genes on the activity of the cellular tyrosine kinase pp60c-src. A continuous cell line from AEV-infected quail embryo fibroblasts was derived that exhibited a typical transformed phenotype and expressed the viral oncogene products, p75gag-erbA and gp66-68erbB. Using an immune-complex kinase assay, we found that the specific activity of pp60c-src in AEV-transformed quail cells was decreased by a factor of 6-30 relative to that found in uninfected quail cells. A concomitant 50-80% reduction of 32Pi incorporation into the pp60c-src protein from radiolabeled, transformed cells was also observed, indicating a relationship between hypophosphorylation and diminished enzyme activity. Partial proteolytic phosphopeptide analysis revealed a decrease in phosphorylation of both serine- and tyrosine-containing peptides, suggesting an activation of specific phosphatases or inhibition of specific kinases in the AEV-transformed quail cells. Similar results were found in pp60c-src precipitated from AEV-transformed chicken and rat cells.
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