51
|
Coscoy L, Ganem D. Kaposi's sarcoma-associated herpesvirus encodes two proteins that block cell surface display of MHC class I chains by enhancing their endocytosis. Proc Natl Acad Sci U S A 2000; 97:8051-6. [PMID: 10859362 PMCID: PMC16668 DOI: 10.1073/pnas.140129797] [Citation(s) in RCA: 358] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Down-regulation of the cell surface display of class I MHC proteins is an important mechanism of immune evasion by human and animal viruses. Herpesviruses in particular encode a variety of proteins that function to lower MHC I display by several mechanisms. These include binding and retention of MHC I chains in the endoplasmic reticulum, dislocation of class I chains from the ER, inhibition of the peptide transporter (TAP) involved in antigen presentation, and shunting of newly assembled chains to lysosomes. Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is a human herpesvirus strongly linked to the development of KS and to certain AIDS-associated lymphoproliferative disorders. Here we show that KSHV encodes two distinctive gene products that function to dramatically reduce cell surface MHC I expression. These viral proteins are localized predominantly to the ER. However, unlike previously described MHC I inhibitors, they do not interfere with the synthesis, translocation, or assembly of class I chains, nor do they retain them in the ER. Rather, they act to enhance endocytosis of MHC I from the cell surface; internalized class I chains are delivered to endolysosomal vesicles, where they undergo degradation. These KSHV proteins define a mechanism of class I down-regulation distinct from the mechanisms of other herpesviruses and are likely to contribute importantly to immune evasion during viral infection.
Collapse
Affiliation(s)
- L Coscoy
- Howard Hughes Medical Institute and Departments of Microbiology and Medicine, University of California, San Francisco, CA 94143, USA
| | | |
Collapse
|
52
|
Abeyama K, Eng W, Jester JV, Vink AA, Edelbaum D, Cockerell CJ, Bergstresser PR, Takashima A. A role for NF-kappaB-dependent gene transactivation in sunburn. J Clin Invest 2000; 105:1751-9. [PMID: 10862790 PMCID: PMC378515 DOI: 10.1172/jci9745] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Exposure of skin to ultraviolet (UV) radiation is known to induce NF-kappaB activation, but the functional role for this pathway in UV-induced cutaneous inflammation remains uncertain. In this study, we examined whether experimentally induced sunburn reactions in mice could be prevented by blocking UV-induced, NF-kappaB-dependent gene transactivation with oligodeoxynucleotides (ODNs) containing the NF-kappaB cis element (NF-kappaB decoy ODNs). UV-induced secretion of IL-1, IL-6, TNF-alpha, and VEGF by skin-derived cell lines was inhibited by the decoy ODNs, but not by the scrambled control ODNs. Systemic or local injection of NF-kappaB decoy ODNs also inhibited cutaneous swelling responses to UV irradiation. Moreover, local UV-induced inflammatory changes (swelling, leukocyte infiltration, epidermal hyperplasia, and accumulation of proinflammatory cytokines) were all inhibited specifically by topically applied decoy ODNs. Importantly, these ODNs had no effect on alternative types of cutaneous inflammation caused by irritant or allergic chemicals. These results indicate that sunburn reactions culminate from inflammatory events that are triggered by UV-activated transcription of NF-kappaB target genes, rather than from nonspecific changes associated with tissue damage.
Collapse
Affiliation(s)
- K Abeyama
- Department of Dermatology, and. Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | | | | | | | | | | | | | |
Collapse
|
53
|
Liou J, Kiefer F, Dang A, Hashimoto A, Cobb MH, Kurosaki T, Weiss A. HPK1 is activated by lymphocyte antigen receptors and negatively regulates AP-1. Immunity 2000; 12:399-408. [PMID: 10795738 DOI: 10.1016/s1074-7613(00)80192-2] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The serine/threonine kinase HPK1 is a member of the germinal center kinase (GCK) family that has been implicated in the regulation of MAP kinase pathways. Here, we demonstrate the involvement of HPK1 in antigen receptor signaling. Engagement of the TCR or the BCR resulted in a marked induction of HPK1 catalytic activity. Subsequent analysis revealed that Src and Syk/ZAP-70 tyrosine kinases and the adaptor proteins LAT, SLP-76, BLNK, Grb2, and Grap are involved in HPK1 activation. Overexpression of HPK1 inhibited TCR activation of AP-1 and ERK2, whereas the kinase-inactive mutant of HPK1 potentiated these responses. Neither form of HPK1 affected PMA or v-Ras activation of AP-1 and ERK2. Thus, HPK1 is a negative regulator of the TCR-induced AP-1 response pathway.
Collapse
Affiliation(s)
- J Liou
- Department of Medicine, Howard Hughes Medical Institute, University of California, San Francisco 94143, USA
| | | | | | | | | | | | | |
Collapse
|
54
|
Li S, Ouyang Y, Yang GH, Pestka JJ. Modulation of transcription factor AP-1 activity in murine EL-4 thymoma cells by vomitoxin (deoxynivalenol). Toxicol Appl Pharmacol 2000; 163:17-25. [PMID: 10662601 DOI: 10.1006/taap.1999.8859] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Trichothecene mycotoxins have been reported to suppress or superinduce cytokine mRNA expression by leukocytes both in vitro and in vivo. Modulation of transcription factor activities may be critical for these observations. Here, the effect of trichothecene vomitoxin (VT, deoxynivalenol) on activator protein-1 (AP-1) activity was determined in the murine EL-4 thymoma. Electrophoretic mobility shift assay (EMSA) revealed that VT modulated AP-1 binding activity in a concentration- and time-dependent manner when using a synchronous model in which VT was added concurrently with phorbol 12-myristate 13-acetate (PMA) and ionomycin (ION) to EL-4 cells. Induction of AP-1 binding activity by PMA/ION was suppressed in the presence of VT for a short period (1 to 12 h), but was enhanced upon prolonged VT exposure (48 to 72 h). VT also enhanced AP-1 binding activity when added to the cell culture 12 h after PMA/ION activation (delayed synchronous model). Using specific antibodies against AP-1 complex proteins, it was demonstrated by gel supershift assay that VT preferentially affected phosphorylated c-Jun, Jun B, c-Fos, and Fra-2 binding activities, whereas it did not alter Jun D and Fra-1 binding. A transient transfection assay demonstrated that these increased binding activities are associated with enhanced AP-1 transactivation potential. Elevation of AP-1 activity may contribute to cytokine dysregulation and immunotoxic effects associated with exposure to trichothecene mycotoxins such as VT.
Collapse
Affiliation(s)
- S Li
- Department of Food Science, Michigan State University, East Lansing, Michigan, 48824, USA
| | | | | | | |
Collapse
|
55
|
Sosinowski T, Pandey A, Dixit VM, Weiss A. Src-like adaptor protein (SLAP) is a negative regulator of T cell receptor signaling. J Exp Med 2000; 191:463-74. [PMID: 10662792 PMCID: PMC2195826 DOI: 10.1084/jem.191.3.463] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Initiation of T cell antigen receptor (TCR) signaling is dependent on Lck, a Src family kinase. The Src-like adaptor protein (SLAP) contains Src homology (SH)3 and SH2 domains, which are highly homologous to those of Lck and other Src family members. Because of the structural similarity between Lck and SLAP, we studied its potential role in TCR signaling. Here, we show that SLAP is expressed in T cells, and that when expressed in Jurkat T cells it can specifically inhibit TCR signaling leading to nuclear factor of activated T cells (NFAT)-, activator protein 1 (AP-1)-, and interleukin 2-dependent transcription. The SH3 and SH2 domains of SLAP are required for maximal attenuation of TCR signaling. This inhibitory activity can be bypassed by the combination of phorbol myristate acetate (PMA) and ionomycin, suggesting that SLAP acts proximally in the TCR signaling pathway. SLAP colocalizes with endosomes in Jurkat and in HeLa cells, and is insoluble in mild detergents. In stimulated Jurkat cells, SLAP associates with a molecular signaling complex containing CD3zeta, ZAP-70, SH2 domain-containing leukocyte protein of 76 kD (SLP-76), Vav, and possibly linker for activation of T cells (LAT). These results suggest that SLAP is a negative regulator of TCR signaling.
Collapse
Affiliation(s)
- Tomasz Sosinowski
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94143-0795
| | - Akhilesh Pandey
- Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
| | | | - Arthur Weiss
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94143-0795
- Department of Medicine, University of California at San Francisco, San Francisco, California 94143-0795
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143-0795
| |
Collapse
|
56
|
Lynch KW, Weiss A. A model system for activation-induced alternative splicing of CD45 pre-mRNA in T cells implicates protein kinase C and Ras. Mol Cell Biol 2000; 20:70-80. [PMID: 10594010 PMCID: PMC85051 DOI: 10.1128/mcb.20.1.70-80.2000] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multiple isoforms of the protein tyrosine phosphatase CD45 are expressed on the surface of human T cells. Interestingly, the expression of these isoforms has been shown to vary significantly upon T-cell activation. In this report, we describe a novel cell line-based model system in which we can mimic the activation-induced alternative splicing of CD45 observed in primary T cells. Of the many proximal signaling events induced by T-cell stimulation, we show that activation of protein kinase C and activation of Ras are important for the switch toward the exclusion of CD45 variable exons, whereas events related to Ca(2+) flux are not. In addition, the ability of cycloheximide to block the activation-induced alternative splicing of CD45 suggests a requirement for de novo protein synthesis. We further demonstrate that sequences which have previously been implicated in the tissue-specific regulation of CD45 variable exons are likewise necessary and sufficient for activation-induced splicing. These results provide an initial understanding of the requirements for CD45 alternative splicing upon T-cell activation, and they confirm the importance of this novel cell line in facilitating a more detailed analysis of the activation-induced regulation of CD45 than has been previously possible.
Collapse
Affiliation(s)
- K W Lynch
- Departments of Medicine, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, California 94143-0795, USA
| | | |
Collapse
|
57
|
Lin J, Weiss A, Finco TS. Localization of LAT in glycolipid-enriched microdomains is required for T cell activation. J Biol Chem 1999; 274:28861-4. [PMID: 10506128 DOI: 10.1074/jbc.274.41.28861] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
LAT, a transmembrane adapter protein found in glycolipid-enriched microdomains (GEMs), is essential for T cell activation. In this study, we have utilized a LAT-deficient mutant of the Jurkat T cell line, J.CaM2, to explore various requirements for LAT function. First, we demonstrate that LAT must be present in GEMs for coupling T cell receptor (TCR) engagement to activation of the Ras signaling pathway, increases in intracellular Ca(2+), and induction of the transcription factor nuclear factor of activated T cells (NF-AT). Second, we show that the extracellular and transmembrane domains of LAT are dispensable for these TCR-mediated events once LAT has localized to GEMs. These results provide important insights into both the structural domains of LAT and its subcellular localization that are required for effective TCR signaling.
Collapse
Affiliation(s)
- J Lin
- Department of Medicine, Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | | | | |
Collapse
|
58
|
Gonsky R, Deem RL, Lee DH, Chen A, Targan SR. CD28 Costimulation Augments IL-2 Secretion of Activated Lamina Propria T Cells by Increasing mRNA Stability Without Enhancing IL-2 Gene Transactivation. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.11.6621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
The pathways leading to activation in lamina propria (LP) T cells are different from peripheral T cells. LP T cells exhibit enhanced IL-2 secretion when activated through the CD2 pathway. Coligation of CD28 leads to synergistic enhancement of IL-2 secretion. Previous studies have characterized the CD28 augmentation of TCR-mediated signaling in peripheral blood T cells through transcriptional activation of an IL-2 promoter CD28 response element (CD28RE), along with enhanced mRNA stability. This study characterized molecular events involved in CD28 costimulation of IL-2 production in LP mononuclear cells (LPMC). LPMC exhibited increased IL-2 production in response to CD28 costimulation, compared with cells activated through CD2 alone. IL-2 secretion was paralleled by increased expression of IL-2 mRNA, resulting from enhanced IL-2 mRNA stability. In contrast to transcriptional activation in PBMC, EMSA revealed that CD28 coligation of CD2-activated LPMC does not result in increased binding of trans-factors to the CD28RE, nor did Western blots detect changes in I-κBα or I-κBβ levels following CD28 coligation. Furthermore, CD28 coligation fails to enhance IL-2 promoter-reporter or RE/AP construct expression in CD2-activated LPMC. The results reported herein indicate that the molecular mechanisms involved in CD28 cosignaling and regulation of IL-2 secretion in LP T cells are unique to that compartment and differ from those seen in peripheral blood T cells. These observations suggest a biological significance for different mechanisms of IL-2 activation in initiation and maintenance of the cytokine repertoire found in the mucosa.
Collapse
Affiliation(s)
- Rivkah Gonsky
- *Inflammatory Bowel Disease Research Center, Cedars-Sinai Medical Center, Los Angeles, CA 90048; and
| | - Richard L. Deem
- *Inflammatory Bowel Disease Research Center, Cedars-Sinai Medical Center, Los Angeles, CA 90048; and
| | - Doo Han Lee
- † Seoul Surgical Clinic Banpo-4-dong 57-3, Seochogu, Seoul, Korea
| | - Alice Chen
- *Inflammatory Bowel Disease Research Center, Cedars-Sinai Medical Center, Los Angeles, CA 90048; and
| | - Stephan R. Targan
- *Inflammatory Bowel Disease Research Center, Cedars-Sinai Medical Center, Los Angeles, CA 90048; and
| |
Collapse
|
59
|
Aune TM, Mora AL, Kim S, Boothby M, Lichtman AH. Costimulation Reverses the Defect in IL-2 But Not Effector Cytokine Production by T Cells with Impaired IκBα Degradation. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.10.5805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Although the transcriptional basis for states of unresponsiveness in primary T cells is unclear, tolerant B lymphocytes exhibit inhibition of both c-Jun N-terminal kinase induction and IκBα (inhibitor of NF-κBα) degradation, leading to lower levels of both nuclear AP-1 and NF-κB. Expression of an IκBα mutant resistant to signal-induced degradation in transgenic T cells caused markedly deficient effector cytokine (IL-4, IFN-γ) production after primary TCR stimulation despite a detectable level of nuclear NF-κB. A TCR response element from the IFN-γ promoter, despite lacking detectable NF-κB/Rel sites, was also unresponsive to TCR ligation. Nuclear induction of AP-1 proteins in response to T cell activation was diminished in transgenic T cells. Costimulation induced by anti-CD28 mAb increased IL-2 production, but failed to reverse the defects in effector cytokine production. Taken together, these data indicate that impaired NF-κB/Rel signaling in T cells interferes with the signal transduction pathways required for efficient induction of effector cytokine production.
Collapse
Affiliation(s)
| | - Ana L. Mora
- †Microbiology/Immunology, Vanderbilt University Medical School, Nashville, TN 37232; and
| | - Somee Kim
- ‡Department of Pathology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
| | - Mark Boothby
- †Microbiology/Immunology, Vanderbilt University Medical School, Nashville, TN 37232; and
| | - Andrew H. Lichtman
- ‡Department of Pathology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115
| |
Collapse
|
60
|
Lagunoff M, Majeti R, Weiss A, Ganem D. Deregulated signal transduction by the K1 gene product of Kaposi's sarcoma-associated herpesvirus. Proc Natl Acad Sci U S A 1999; 96:5704-9. [PMID: 10318948 PMCID: PMC21924 DOI: 10.1073/pnas.96.10.5704] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Kaposi's sarcoma (KS)-associated herpesvirus is a lymphotropic virus strongly implicated in the pathogenesis of KS and several lymphoproliferative disorders. The KS-associated herpesvirus K1 gene encodes a transmembrane protein bearing a functional immunoreceptor tyrosine-based activation motif (ITAM)-like sequence; it previously has been proposed to be important in viral tumorigenesis because its expression can trigger cell proliferation in vitro and in vivo. Here we show that expression of the full-length K1 protein can initiate calcium-dependent signal transduction in B cells; however, unlike other ITAM-based signal transduction events, K1 signaling occurs constitutively, in the absence of exogenous crosslinking ligands. This property is caused by its cysteine-rich ectodomain, which when transferred to other consensus ITAMs induces constitutive signaling. Although ITAM-based signaling by K1 involves classical syk and phospholipase C gamma2 activation, both ITAM- and syk-independent signaling pathways are activated by K1 expression. These studies indicate that K1 is a deregulated signaling molecule with pleitropic effects that may explain its known growth deregulatory properties.
Collapse
Affiliation(s)
- M Lagunoff
- Howard Hughes Medical Institute and Departments of Microbiology and Immunology and of Medicine, University of California, San Francisco, CA 94143-0414, USA
| | | | | | | |
Collapse
|
61
|
Chan ED, Winston BW, Uh ST, Wynes MW, Rose DM, Riches DWH. Evaluation of the Role of Mitogen-Activated Protein Kinases in the Expression of Inducible Nitric Oxide Synthase by IFN-γ and TNF-α in Mouse Macrophages. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.1.415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The expression of inducible nitric oxide synthase (iNOS) by macrophages is stimulated by coexposure to IFN-γ and a number of stimuli, including TNF-α. Recent work has shown that TNF-α activates members of the mitogen-activated protein kinase family that subsequently trans-activate transcription factors implicated in the regulation of iNOS expression. The objective of this study was to systematically evaluate the role of: 1) p42mapk/erk2, 2) p46 c-Jun NH2-terminal kinase/stress-activated protein kinase (p46 JNK/SAPK), and 3) p38mapk in the induction of iNOS expression during costimulation of mouse macrophages with IFN-γ and TNF-α. All three kinases were activated during costimulation with IFN-γ and TNF-α. However, specific antagonism of the p42mapk/erk2 and p38mapk with PD98059 and SKF86002, respectively, had no effect on the induction of iNOS expression. In contrast, blockade of all three kinases with N-acetylcysteine completely blocked the induction of iNOS expression. In addition, specific antagonism of the JNK/SAPK upstream kinases MEKK (mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase) and MKK4 (mitogen-activated protein kinase kinase 4) with dominant inhibitory mutants blocked transcriptional activation of the iNOS promoter in response to costimulation with IFN-γ and TNF-α. Collectively, these findings support the involvement of p46 JNK/SAPK and its upstream kinases in regulating the induction of iNOS following ligation of the TNF-α receptor CD120a (p55) in the presence of IFN-γ.
Collapse
Affiliation(s)
- Edward D. Chan
- ‡Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine,
| | - Brent W. Winston
- ∥Faculty of Medicine, Division of Critical Care Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Soo-Taek Uh
- ‡Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine,
| | - Murry W. Wynes
- ¶Department of Immunology, University of Colorado Health Sciences Center, Denver, CO 80262; and
| | | | - David W. H. Riches
- ‡Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine,
- ¶Department of Immunology, University of Colorado Health Sciences Center, Denver, CO 80262; and
- §Department of Pharmacology, and
- *Division of Basic Sciences, Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206
- †Department of Biochemistry and Molecular Genetics,
| |
Collapse
|
62
|
Zhao Q, Williams BL, Abraham RT, Weiss A. Interdomain B in ZAP-70 regulates but is not required for ZAP-70 signaling function in lymphocytes. Mol Cell Biol 1999; 19:948-56. [PMID: 9858619 PMCID: PMC83953 DOI: 10.1128/mcb.19.1.948] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The protein tyrosine kinase ZAP-70 plays an important role in T-cell activation and development. After T-cell receptor stimulation, ZAP-70 associates with the receptor and is phosphorylated on many tyrosines, including Y292, Y315, and Y319 within interdomain B. Previously, we demonstrated that Y292 negatively regulates ZAP-70 function and that Y315 positively regulates ZAP-70 function by interacting with Vav. Recent studies have suggested that Y319 also positively regulate ZAP-70 function. Paradoxically, removal of interdomain B (to create the construct designated Delta), containing the Y292, Y315, and Y319 sites, did not eliminate the ability of ZAP-70 to induce multiple gene reporters in Syk-deficient DT-40 B cells and ZAP-70/Syk-deficient Jurkat cells. Here we show that Delta still utilizes the same pathways as wild-type ZAP-70 to mediate NF-AT induction. This is manifested by the ability of Delta to restore induction of calcium fluxes and mitogen-activated protein kinase activation and by the ability of dominant negative Ras and FK506 to block the induction of NF-AT activity mediated by Delta. Biochemically we show that the stimulated tyrosine phosphorylation of Vav, Shc, and ZAP-70 itself is diminished, whereas that of Slp-76 is increased in cells reconstituted with Delta. Deletion of interdomain B did not affect the ability of ZAP-70 to bind to the receptor. The in vitro kinase activity of ZAP-70 lacking interdomain B was markedly reduced, but the kinase activity was still required for the protein's in vivo activity. Based on these data, we concluded that interdomain B regulates but is not required for ZAP-70 signaling function leading to cellular responses.
Collapse
Affiliation(s)
- Q Zhao
- Department of Medicine, Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143-0795, USA
| | | | | | | |
Collapse
|
63
|
Shapiro VS, Mollenauer MN, Weiss A. Cutting Edge: Nuclear Factor of Activated T Cells and AP-1 Are Insufficient for IL-2 Promoter Activation: Requirement for CD28 Up-Regulation of RE/AP. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.12.6455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
IL-2 gene transcription in T cells requires both TCR and costimulatory signals. IL-2 promoter activation in Jurkat T cells stimulated with superantigen presented by Raji B cells requires CD28 activation. The addition of rCTLA4Ig, which blocks CD28 binding to its ligand, to the cultures decreased IL-2 promoter activation by >80%. Interestingly, CTLA4Ig did not significantly inhibit the activation of either NF of activated T cells (NFAT) or AP-1 reporters. Therefore, activation of NFAT and AP-1 is insufficient for IL-2 promoter activation. In contrast, an RE/AP reporter was blocked by CTLA4Ig by >90%. Thus, the requirement for CD28 in IL-2 promoter activation appears to be due to RE/AP and not the NFAT or AP-1 sites. In addition, these data suggest that transcriptional activation of RE/AP is not mediated by NFAT, because activation of a NFAT reporter is not affected by the addition of CTLA4Ig.
Collapse
Affiliation(s)
| | | | - Arthur Weiss
- *Department of Medicine and
- †Howard Hughes Medical Institute, University of California, San Francisco, CA 94143
| |
Collapse
|
64
|
Finco TS, Kadlecek T, Zhang W, Samelson LE, Weiss A. LAT is required for TCR-mediated activation of PLCgamma1 and the Ras pathway. Immunity 1998; 9:617-26. [PMID: 9846483 DOI: 10.1016/s1074-7613(00)80659-7] [Citation(s) in RCA: 415] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, we present the further characterization of a mutant Jurkat T cell line, J.CaM2, that is defective in TCR-mediated signal transduction. Although initial TCR-mediated signaling events such as the inducible tyrosine phosphorylation of the TCR-zeta chain and ZAP-70 are intact in J.CaM2, subsequent events, including increases in intracellular calcium, Ras activation, and IL-2 gene expression are defective. Subsequent analysis of J.CaM2 demonstrated a severe deficiency in pp36/LAT expression, a recently cloned adaptor protein implicated in TCR signaling. Importantly, reexpression of LAT in J.CaM2 restored all aspects of TCR signaling. These results demonstrate a necessary and exclusive role for LAT in T cell activation.
Collapse
Affiliation(s)
- T S Finco
- Department of Medicine, The Howard Hughes Medical Institute, University of California at San Francisco, 94143, USA
| | | | | | | | | |
Collapse
|
65
|
Abstract
Optimal T cell activation and interleukin-2 production requires a second signal in addition to antigen-mediated T cell receptor (TCR) signaling. The CD28 molecule has been demonstrated to act as an effective costimulatory molecule upon binding by B7.1 or B7.2 present on antigen-presenting cells. The CD28 signal acts in concert with the TCR signal to significantly augment activation of the NF-kappaB family of transcription factors. The interleukin-2 gene is regulated by NF-kappaB among other transcription factors, in part, via a CD28 responsive element (CD28RE) present in the IL-2 promoter. Enhanced activation of NF-kappaB by CD28 is mediated by rapid phosphorylation and proteasome-mediated degradation of the NF-kappaB inhibitory proteins IkappaB alpha and IkappaB beta, which allows for accelerated nuclear expression of the liberated NF-kappaB. Herein, we provide evidence that the catalytic activities of two recently identified IkappaB kinases, IKKalpha and IKKbeta, are significantly elevated when T cells are stimulated through CD28 in addition to mitogen treatment. Catalytically inactive forms of IKKs are able to block the in vivo phosphorylation of IkappaB alpha induced by mitogen and CD28. Furthermore, CD28-mediated reporter gene transactivation of the CD28RE/AP-1 composite element is consistently attenuated by the IKK mutants. These findings suggest that cellular signaling pathways initiated at the TCR and CD28 converge at or upstream of IKK, resulting in more robust kinase activity and enhanced and prolonged NF-kappaB activation.
Collapse
Affiliation(s)
- E W Harhaj
- Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey Medical Center, Hershey, Pennsylvania 17033, USA
| | | |
Collapse
|
66
|
Yablonski D, Kuhne MR, Kadlecek T, Weiss A. Uncoupling of nonreceptor tyrosine kinases from PLC-gamma1 in an SLP-76-deficient T cell. Science 1998; 281:413-6. [PMID: 9665884 DOI: 10.1126/science.281.5375.413] [Citation(s) in RCA: 354] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Activation of nonreceptor protein tyrosine kinases (PTKs) is essential for T cell receptor (TCR) responsiveness; however, the function of individual PTK substrates is often uncertain. A mutant T cell line was isolated that lacked expression of SLP-76 (SH2 domain-containing leukocyte protein of 76 kilodaltons), a hematopoietically expressed adaptor protein and PTK substrate. SLP-76 was not required for TCR-induced tyrosine phosphorylation of most proteins, but was required for optimal tyrosine phosphorylation and activation of phospholipase C-gamma1 (PLC-gamma1), as well as Ras pathway activation. TCR-inducible gene expression was dependent on SLP-76. Thus, coupling of TCR-regulated PTKs to downstream signaling pathways requires SLP-76.
Collapse
Affiliation(s)
- D Yablonski
- Department of Medicine, Howard Hughes Medical Institute, Box 0795, University of California, San Francisco, San Francisco, CA 94143-0795, USA
| | | | | | | |
Collapse
|
67
|
Woodside DG, McIntyre BW. Inhibition of CD28/CD3-Mediated Costimulation of Naive and Memory Human T Lymphocytes by Intracellular Incorporation of Polyclonal Antibodies Specific for the Activator Protein-1 Transcriptional Complex. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.2.649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
A number of indirect methods have been utilized in demonstrating activator protein-1 transcription factor function in IL-2 promoter activity. However, there has been no direct demonstration that activator protein-1 is involved in CD28-dependent costimulation of IL-2 gene transcription in freshly isolated naive and memory human T lymphocytes. To address this issue, the method of scrape loading was applied to purified peripheral blood T lymphocytes. Since scrape loading relies on adherent cells, peripheral blood human T (PB-T) cells were immobilized on the nonspecific cell attachment factor poly-l-lysine. Cells scraped off poly-l-lysine in the presence of Ig FITC efficiently incorporated Ig, with relatively uniform fluorescence. T cells retained their physical parameters as measured by forward and side light scatter, and functional activity as measured by costimulation of proliferation and IL-2 production after being scraped off this substrate. CD28/CD3-costimulated T cells produced intracellular IL-2 from all subsets measured (CD4+, CD4−, CD45RO+, and CD45RO−). IL-2 production and intracellular accumulation in nonscraped PB-T cells activated with CD28/CD3 coligation were skewed favoring CD45RO+ and CD4+ subsets, as was IL-2 production in scraped PB-T cells. The intracellular incorporation of Abs specific for c-Fos and c-Jun family members by scrape loading inhibited the production and intracellular accumulation of IL-2 within 6 h of costimulation with PMA/ionomycin, or costimulation by CD28 and CD3 ligation. Scrape loading thus provides an efficient mechanism for intracellular incorporation of macromolecules, and the first direct evidence that c-Fos and c-Jun are involved in transcription of the IL-2 gene within its correct chromosomal context, in resting human T lymphocyte subpopulations.
Collapse
Affiliation(s)
- Darren G. Woodside
- Department of Immunology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030
| | - Bradley W. McIntyre
- Department of Immunology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030
| |
Collapse
|
68
|
Abstract
Antigen receptors on lymphocytes play a central role in immune regulation by transmitting signals that positively or negatively regulate lymphocyte survival, migration, growth, and differentiation. This review focuses on how opposing positive or negative cellular responses are brought about by antigen receptor signaling. Four types of extracellular inputs shape the response to antigen: (a) the concentration of antigen; (b) the avidity with which antigen is bound; (c) the timing and duration of antigen encounter; and (d) the association of antigen with costimuli from pathogens, the innate immune system, or other lymphocytes. Intracellular signaling by antigen receptors is not an all-or-none event, and these external variables alter both the quantity and quality of signaling. Recent findings in B lymphocytes have clearly illustrated that these external inputs affect the magnitude and duration of the intracellular calcium response, which in turn contributes to differential triggering of the transcriptional regulators NF kappa B, JNK, NFAT, and ERK. The regulation of calcium responses involves a network of tyrosine kinases (e.g. lyn, syk), tyrosine or lipid phosphatases (CD45, SHP-1, SHIP), and accessory molecules (CD21/CD19, CD22, FcR gamma 2b). Understanding the biochemistry and logic behind these integrative processes will allow development of more selective and efficient pharmaceuticals that suppress, modify, or augment immune responses in autoimmunity, transplantation, allergy, vaccines, and cancer.
Collapse
Affiliation(s)
- J I Healy
- Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305, USA.
| | | |
Collapse
|
69
|
Ferreira V, Tarantino N, Körner M. Discrimination between RelA and RelB transcriptional regulation by a dominant negative mutant of IkappaBalpha. J Biol Chem 1998; 273:592-9. [PMID: 9417120 DOI: 10.1074/jbc.273.1.592] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
RelA and RelB belong to the nuclear factor-kappaB (NF-kappaB-Rel) transcription factor family. Both proteins are structurally and functionally related, but their intracellular and tissue distributions are different. In resting cells, RelB is found mostly in the nucleus, whereas RelA is sequestered in the cytosol by protein inhibitors, among which IkappaBalpha is the dominant form in lymphocytes. Upon cellular activation IkappaBalpha is proteolyzed, allowing RelA dimers to enter the nucleus and activate target genes. To study the selectivity of gene regulation by RelA and RelB, we generated T cell lines stably expressing a dominant negative mutant of IkappaBalpha. We show that selective inhibition of RelA-NF-kappaB decreased induction of NFKB1, interleukin-2, and interleukin-2Ralpha genes but not c-myc. Transcription driven by the IkappaBalpha promoter was blocked by the transgenic IkappaBalpha; however, wild type IkappaBalpha was expressed in the transgenic cell clones but with much slower kinetics than that in control cells. Wild type IkappaBalpha expression was concomitant with RelB up-regulation, suggesting that RelB could be involved in transcription of IkappaBalpha through binding to an alternative site. These results indicate that RelB and RelA have both distinct and overlapping effects on gene expression.
Collapse
Affiliation(s)
- V Ferreira
- Laboratoire d'Immunologie Cellulaire, CNRS URA 625, Bat. CERVI, Hôpital de la Pitié Salpêtrière, 83, Bd. de l'Hôpital, 75013 Paris, France
| | | | | |
Collapse
|
70
|
Shapiro VS, Truitt KE, Imboden JB, Weiss A. CD28 mediates transcriptional upregulation of the interleukin-2 (IL-2) promoter through a composite element containing the CD28RE and NF-IL-2B AP-1 sites. Mol Cell Biol 1997; 17:4051-8. [PMID: 9199340 PMCID: PMC232258 DOI: 10.1128/mcb.17.7.4051] [Citation(s) in RCA: 170] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Mutagenesis studies have demonstrated the requirement for the CD28-responsive element (CD28RE) within the interleukin-2 (IL-2) promoter for transcriptional upregulation by CD28. Here, we demonstrate that CD28 responsiveness is conferred by a composite element containing both the CD28RE and the NF-IL-2B AP-1 sites (RE/AP). Mutations at either site within the RE/AP composite element abolish activity. The RE/AP composite element is a site for signal integration within the IL-2 promoter, since its activation is dependent on at least two separate signalling pathways being activated, through the T-cell receptor, CD28, and/or phorbol myristate acetate. Activation is maximal when all three signals occur simultaneously. By using a panel of CD28 cytoplasmic domain mutants, it was found that the transcriptional activation of the RE/AP composite element correlates exactly with the pattern of IL-2 secretion induced by these mutants upon stimulation. Similar to the upregulation of IL-2 secretion, the transcriptional upregulation of the RE/AP composite element by CD28 is FK506 insensitive. The pattern of activation of the RE/AP composite element is different from that observed for either an NFAT or consensus AP-1 site, implying that RE/AP represents a unique element. Using gel shift analysis, we demonstrate that stimulation by CD28 induces the association of the NF-kappaB family member c-Rel to the CD28RE within the RE/AP composite element. The transcriptional upregulation of IL-2 by CD28 appears, therefore, to be mediated through the RE/AP composite element, involving the association of c-Rel with the CD28RE.
Collapse
Affiliation(s)
- V S Shapiro
- Department of Medicine, Howard Hughes Medical Institute, University of California, San Francisco 94143, USA
| | | | | | | |
Collapse
|