1
|
Courtney AH, Lo WL, Weiss A. TCR Signaling: Mechanisms of Initiation and Propagation. Trends Biochem Sci 2017; 43:108-123. [PMID: 29269020 DOI: 10.1016/j.tibs.2017.11.008] [Citation(s) in RCA: 329] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 11/21/2017] [Accepted: 11/21/2017] [Indexed: 10/18/2022]
Abstract
The mechanisms by which a T cell detects antigen using its T cell antigen receptor (TCR) are crucial to our understanding of immunity and the harnessing of T cells therapeutically. A hallmark of the T cell response is the ability of T cells to quantitatively respond to antigenic ligands derived from pathogens while remaining inert to similar ligands derived from host tissues. Recent studies have revealed exciting properties of the TCR and the behaviors of its signaling effectors that are used to detect and discriminate between antigens. Here we highlight these recent findings, focusing on the proximal TCR signaling molecules Zap70, Lck, and LAT, to provide mechanistic models and insights into the exquisite sensitivity and specificity of the TCR.
Collapse
Affiliation(s)
- Adam H Courtney
- Division of Rheumatology, Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA; Howard Hughes Medical Institute (HHMI), San Francisco, CA 94143, USA
| | - Wan-Lin Lo
- Division of Rheumatology, Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA; Howard Hughes Medical Institute (HHMI), San Francisco, CA 94143, USA
| | - Arthur Weiss
- Division of Rheumatology, Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA; Howard Hughes Medical Institute (HHMI), San Francisco, CA 94143, USA.
| |
Collapse
|
2
|
Abstract
The excitement surrounding checkpoint inhibitors in the treatment of patients with cancer exemplifies a triumph of the long-term value of investing in basic science and fundamental questions of T-cell signaling. The pharmaceutical future actively embraces ways of making more patients’ cancers responsive to these inhibitors. Such a process will be aided by elucidation of signaling and regulation. With thousands of articles spread across almost 30 years, this commentary can touch only on portions of the canonical picture of T-cell signaling and provide a few parables from work on mammalian (or mechanistic) target of rapamycin (mTOR) pathways as they link to early and later phases of lymphocyte activation. The piece will turn a critical eye to some issues with models about these pathways in T cells. Many of the best insights lie in the future despite all that is uncovered already, but a contention is that further therapeutic successes will be fostered by dealing with disparities among findings and attention to the temporal, spatial, and stochastic aspects of T-cell responses. Finally, thoughts on some (though not all) items urgently needed for future progress will be mooted.
Collapse
Affiliation(s)
- Mark Boothby
- Department of Pathology, Microbiology & Immunology, Vanderbilt University, Nashville, TN, USA
| |
Collapse
|
3
|
Characterization of the binding profile of peptide to transporter associated with antigen processing (TAP) using Gaussian process regression. Comput Biol Med 2011; 41:865-70. [DOI: 10.1016/j.compbiomed.2011.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 07/10/2011] [Accepted: 07/18/2011] [Indexed: 11/22/2022]
|
4
|
Owen DM, Gaus K, Magee AI, Cebecauer M. Dynamic organization of lymphocyte plasma membrane: lessons from advanced imaging methods. Immunology 2010; 131:1-8. [PMID: 20646076 DOI: 10.1111/j.1365-2567.2010.03319.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Lipids and lipid domains are suggested to play an essential role in the heterogeneous organization of the plasma membrane in eukaryotic cells, including cells of the immune system. We summarize the results of advanced imaging and physical studies of membrane organization with special focus on the plasma membrane of lymphocytes. We provide a comprehensive up-to-date view on the existence of membrane lipid and protein clusters such as lipid rafts and suggest research directions to better understand these highly dynamic entities on the surface of immune cells.
Collapse
Affiliation(s)
- Dylan M Owen
- Centre for Vascular Research, University of New South Wales, Sydney, NSW, Australia
| | | | | | | |
Collapse
|
5
|
Han LY, Fletcher MS, Urbauer DL, Mueller P, Landen CN, Kamat AA, Lin YG, Merritt WM, Spannuth WA, Deavers MT, De Geest K, Gershenson DM, Lutgendorf SK, Ferrone S, Sood AK. HLA class I antigen processing machinery component expression and intratumoral T-Cell infiltrate as independent prognostic markers in ovarian carcinoma. Clin Cancer Res 2008; 14:3372-9. [PMID: 18519766 DOI: 10.1158/1078-0432.ccr-07-4433] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE Defects in the antigen processing machinery (APM) may provide tumor cells with a mechanism to escape immune recognition. The purpose of this study is to determine the clinical significance of APM component down-regulation and tumor-infiltrating T cells in ovarian carcinoma. EXPERIMENTAL DESIGN After institutional review board approval, tumor samples from 150 patients with invasive epithelial ovarian cancers were examined for TAP1, TAP2, tapasin, HLA class I heavy chain (HLA-HC), beta 2 microglobulin, and T-cell (CD3+ and CD8+) tumor infiltration using immunohistochemistry. RESULTS The majority of tumors had either heterogeneous or positive expression of TAP1, TAP2, HLA-HC, and beta 2 microglobulin (66.7%, 73.3%, 70.7%, and 63.3%, respectively), except tapasin for which 58% of the tumors lacked expression. Furthermore, 67% and 88% of the lesions possessed intratumoral and peritumoral CD3+ or CD8+ cells, respectively. The majority of APM component expression examined was significantly associated with both intratumoral and peritumoral T-cell infiltration (P < 0.05). The expression of APM components and the presence of intratumoral T-cell infiltrates were significantly associated with improved survival (all P < or = 0.01); however, peritumoral T-cell infiltrates did not significantly affect survival (P = 0.33). APM component down-regulation (P < 0.001), lack of intratumoral T-cell infiltrates (P = 0.03), and suboptimal cytoreduction (P < 0.001) were independent prognostic markers for death from ovarian carcinoma. CONCLUSION The negative effect of APM component down-regulation by itself and in combination with absent intratumoral T-cell infiltration on the survival of patients with ovarian carcinoma implies a role for immune escape in addition to immunosurveillance in the clinical course of disease.
Collapse
Affiliation(s)
- Liz Y Han
- Department of Gynecologic Oncology, The University of Texas M D Anderson Cancer Center, 1155 Herman Pressler, CPB6.3244, Unit 1362, Houston, TX 77030, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Du Q, Huang R, Wei Y, Wang C, Chou K. Peptide reagent design based on physical and chemical properties of amino acid residues. J Comput Chem 2007; 28:2043-50. [PMID: 17450553 PMCID: PMC7166493 DOI: 10.1002/jcc.20732] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 02/18/2007] [Accepted: 02/19/2007] [Indexed: 11/30/2022]
Abstract
It has tremendous values for both drug discovery and basic research to develop a solid bioinformatical tool for guiding peptide reagent design. Based on the physical and chemical properties of amino acids, a new strategy for peptide reagent design, the so-called AABPD (amino acid based-peptide design), is proposed. The peptide samples in a training dataset are described by a series of HMLP (heuristic molecular lipophilicity potential) parameters and other physicochemical properties of amino acid residues that form a three-dimensional data matrix where each component is defined by three indexes: the first index refers to the peptide samples, the second to the amino acid positions, and the third to the amino acid parameters. The binding free energy between a peptide ligand and its protein receptor is calculated by a linear free energy equation through the physicochemical parameters, resulting in a set of simultaneous linear equations between the bioactivity of the peptides and the physicochemical properties of amino acids. An iterative double least square technique is developed for the solution of the three-dimensional simultaneous linear equation set to determine the amino acid position coefficients of peptide sequence and the physicochemical parameter coefficients of amino acid residues alternately. The two sets of coefficients thus obtained are used for predicting the bioactivity of other query peptide reagents. Two calculation examples, the peptide substrate specificity of the SARS coronavirus 3C-like proteinase and the affinity prediction for epitope-peptides with Class I MHC molecules are studied by using the peptide reagent design strategy.
Collapse
Affiliation(s)
- Qi‐Shi Du
- Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, Guangxi University, Nanning, Guangxi, 530004, China
- Institute of Bioinformatics and Drug Discovery, Tianjin Normal University, Tianjin, 300074, China
- Gordon Life Science Institute, San Diego, California 92130, USA
| | - Ri‐Bo Huang
- Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, Guangxi University, Nanning, Guangxi, 530004, China
- Guangxi Academy of Sciences, 98 Daling Road, Nanning, Guangxi 530004, China
| | - Yu‐Tuo Wei
- Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, Guangxi University, Nanning, Guangxi, 530004, China
| | - Cheng‐Hua Wang
- Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, Guangxi University, Nanning, Guangxi, 530004, China
| | - Kuo‐Chen Chou
- Gordon Life Science Institute, San Diego, California 92130, USA
| |
Collapse
|
7
|
Zhao C, Zhang H, Luan F, Zhang R, Liu M, Hu Z, Fan B. QSAR method for prediction of protein-peptide binding affinity: application to MHC class I molecule HLA-A*0201. J Mol Graph Model 2006; 26:246-54. [PMID: 17275373 DOI: 10.1016/j.jmgm.2006.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Accepted: 12/05/2006] [Indexed: 11/29/2022]
Abstract
The support vector machine (SVM), which is a novel algorithm from the machine learning community, was used to develop quantitative structure-activity relationship (QSAR) models for predicting the binding affinity of 152 nonapeptides, which can bind to class I MHC HLA-A*201 molecule. Each peptide was represented by a large pool of descriptors including constitutional, topological descriptors and physical-chemical properties. The heuristic method (HM) was then used to search the descriptor space for selecting the proper ones responsible for binding affinity. The four descriptors were obtained to build linear models based on HM and nonlinear models based on SVM method. The best results are found using SVM: root mean-square (RMS) errors for training, test and whole data set were 0.383, 0.385 and 0.384, respectively. This paper allow the prediction of the binding affinity of new, untested peptides and, through the analysis of contribution of each parameter of different residue at specific position of peptidic ligands, to understand nature of the forces governing binding behavior and suggest new ideas for further synthesis of high-affinity peptides.
Collapse
Affiliation(s)
- Chunyan Zhao
- Department of Chemistry, Lanzhou University, Lanzhou 730000, China
| | | | | | | | | | | | | |
Collapse
|
8
|
Melar M, Ott DE, Hope TJ. Physiological levels of virion-associated human immunodeficiency virus type 1 envelope induce coreceptor-dependent calcium flux. J Virol 2006; 81:1773-85. [PMID: 17121788 PMCID: PMC1797554 DOI: 10.1128/jvi.01316-06] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Human immunodeficiency virus (HIV) entry into target cells requires the engagement of receptor and coreceptor by envelope glycoprotein (Env). Coreceptors CCR5 and CXCR4 are chemokine receptors that generate signals manifested as calcium fluxes in response to binding of the appropriate ligand. It has previously been shown that engagement of the coreceptors by HIV Env can also generate Ca(2+) fluxing. Since the sensitivity and therefore the physiological consequence of signaling activation in target cells is not well understood, we addressed it by using a microscopy-based approach to measure Ca(2+) levels in individual CD4(+) T cells in response to low Env concentrations. Monomeric Env subunit gp120 and virion-bound Env were able to activate a signaling cascade that is qualitatively different from the one induced by chemokines. Env-mediated Ca(2+) fluxing was coreceptor mediated, coreceptor specific, and CD4 dependent. Comparison of the observed virion-mediated Ca(2+) fluxing with the exact number of viral particles revealed that the viral threshold necessary for coreceptor activation of signaling in CD4(+) T cells was quite low, as few as two virions. These results indicate that the physiological levels of virion binding can activate signaling in CD4(+) T cells in vivo and therefore might contribute to HIV-induced pathogenesis.
Collapse
Affiliation(s)
- Marta Melar
- Northwestern University, Department of Cell and Molecular Biology, Feinberg School of Medicine, Ward 8-140, 303 E. Chicago Ave., Chicago, IL 60611, USA
| | | | | |
Collapse
|
9
|
Abstract
Since the first crystal structure determinations of alphabeta T cell receptors (TCRs) bound to class I MHC-peptide (pMHC) antigens in 1996, a sizable database of 24 class I and class II TCR/pMHC complexes has been accumulated that now defines a substantial degree of structural variability in TCR/pMHC recognition. Recent determination of free and bound gammadelta TCR structures has enabled comparisons of the modes of antigen recognition by alphabeta and gammadelta T cells and antibodies. Crystal structures of TCR accessory (CD4, CD8) and coreceptor molecules (CD3epsilondelta, CD3epsilongamma) have further advanced our structural understanding of most of the components that constitute the TCR signaling complex. Despite all these efforts, the structural basis for MHC restriction and signaling remains elusive as no structural features that define a common binding mode or signaling mechanism have yet been gleaned from the current set of TCR/pMHC complexes. Notwithstanding, the impressive array of self, foreign (microbial), and autoimmune TCR complexes have uncovered the diverse ways in which antigens can be specifically recognized by TCRs.
Collapse
Affiliation(s)
- Markus G Rudolph
- Department of Molecular Structural Biology, University of Göttingen, 37077 Göttingen, Germany.
| | | | | |
Collapse
|
10
|
Wittmann JG, Rudolph MG. Crystal structure of Rab9 complexed to GDP reveals a dimer with an active conformation of switch II. FEBS Lett 2004; 568:23-9. [PMID: 15196914 DOI: 10.1016/j.febslet.2004.05.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Revised: 05/03/2004] [Accepted: 05/04/2004] [Indexed: 11/29/2022]
Abstract
The small GTPase Rab9 is an essential regulator of vesicular transport from the late endosome to the trans-Golgi network, as monitored by the redirection of the mannose-6-phosphate receptors. The crystal structure of Rab9 complexed to GDP, Mg(2+), and Sr(2+) reveals a unique dimer formed by an intermolecular beta-sheet that buries the switch I regions. Surface area and shape complementarity calculations suggest that Rab9 dimers can form an inactive, membrane-bound pool of Rab9 . GDP that is independent of GDI. Mg(2+)-bound Rab9 represents an inactive state, but Sr(2+)-bound Rab9 . GDP displays activated switch region conformations, mimicking those of the GTP state. A hydrophobic tetrad is formed resembling an effector-discriminating epitope found only in GTP-bound Rab proteins.
Collapse
Affiliation(s)
- Julia G Wittmann
- Department of Molecular Structural Biology and GZMB, Justus-von-Liebig-Weg 11, Georg-August University, 37077 Göttingen, Germany
| | | |
Collapse
|
11
|
Anikeeva N, Lebedeva T, Krogsgaard M, Tetin SY, Martinez-Hackert E, Kalams SA, Davis MM, Sykulev Y. Distinct molecular mechanisms account for the specificity of two different T-cell receptors. Biochemistry 2003; 42:4709-16. [PMID: 12705834 DOI: 10.1021/bi026864+] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Analysis of the thermodynamics of the interactions between the D3 T-cell receptor (TCR) and its natural ligand, an HIV peptide bound to a HLA-A0201 (HLA-A2) major histocompatibility complex (MHC) protein, shows both similarities and striking differences when compared with the 2B4 TCR binding to its peptide-MHC ligand. The equilibrium thermodynamic parameters of both reactions are consistent with a conformational adjustment at the binding interface during the formation of specific TCR-peptide-MHC complexes. However, osmolytic reagents that dehydrate protein surfaces have profoundly different effects on the strength of the two reactions, indicating that water molecules make very different contributions-enhancing the binding of D3 TCR but weakening the binding of 2B4 TCR. The use of these different mechanisms by TCRs to recognize ligands might be an important means augmenting their inherent cross-reactivity.
Collapse
MESH Headings
- Circular Dichroism
- Cytochrome c Group/immunology
- Cytochrome c Group/metabolism
- Gene Products, gag
- HLA-A2 Antigen/metabolism
- Hydrogen-Ion Concentration
- Kinetics
- Ligands
- Macromolecular Substances
- Osmolar Concentration
- Peptide Fragments
- Peptides/chemistry
- Peptides/immunology
- Peptides/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Temperature
- Thermodynamics
- Water/chemistry
- env Gene Products, Human Immunodeficiency Virus
Collapse
Affiliation(s)
- Nadja Anikeeva
- Department of Microbiology and Immunology and Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Farrell HE, Davis-Poynter NJ, Andrews DM, Degli-Esposti MA. Function of CMV-encoded MHC class I homologues. Curr Top Microbiol Immunol 2002; 269:131-51. [PMID: 12224506 DOI: 10.1007/978-3-642-59421-2_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
Homologues of MHC class I proteins have been identified in the genomes of human, murine and rat cytomegaloviruses (CMVs). Given the pivotal role of the MHC class I protein in cellular immunity, it has been postulated that the viral homologues subvert the normal antiviral immune response of the host, thus promoting virus replication and dissemination in an otherwise hostile environment. This review focuses on recent studies of the CMV MHC class I homologues at the molecular, cellular and whole animal level and presents current hypotheses for their roles in the CMV life cycle.
Collapse
Affiliation(s)
- H E Farrell
- Animal Health Trust, Virology Section, Kentford, Newmarket, Suffolk CB8 7UU, UK
| | | | | | | |
Collapse
|
13
|
Kjer-Nielsen L, Clements CS, Brooks AG, Purcell AW, McCluskey J, Rossjohn J. The 1.5 A crystal structure of a highly selected antiviral T cell receptor provides evidence for a structural basis of immunodominance. Structure 2002; 10:1521-32. [PMID: 12429093 DOI: 10.1016/s0969-2126(02)00878-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Despite a potential repertoire of >10(15) alphabeta T cell receptors (TcR), the HLA B8-restricted cytolytic T cell response to a latent antigen of Epstein-Barr virus (EBV) is strikingly limited in the TcR sequences that are selected. Even in unrelated individuals this response is dominated by a single highly restricted TcR clonotype that selects identical combinations of hypervariable Valpha, Vbeta, D, J, and N region genes. We have determined the 1.5 A crystal structure of this "public" TcR, revealing that five of the six hypervariable loops adopt novel conformations providing a unique combining site that contains a deep pocket predicted to overlay the HLA B8-peptide complex. The findings suggest a structural basis for the immunodominance of this clonotype in the immune response to EBV.
Collapse
MESH Headings
- Amino Acid Sequence
- Binding Sites
- Crystallography, X-Ray
- DNA, Complementary/metabolism
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/immunology
- Humans
- Ligands
- Models, Molecular
- Molecular Sequence Data
- Plasmids/metabolism
- Protein Conformation
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/metabolism
Collapse
Affiliation(s)
- Lars Kjer-Nielsen
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia
| | | | | | | | | | | |
Collapse
|
14
|
Sedwick CE, Altman A. Ordered just so: lipid rafts and lymphocyte function. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2002; 2002:re2. [PMID: 11880687 DOI: 10.1126/stke.2002.122.re2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Immunologists have long been occupied with the description of cellular activation signaling events that originate with the stimulation of multichain immunoreceptors at the cell surface. These signals are transmitted by a protein-partner-signaling cascade through the cytoplasm to the nucleus, where they culminate in changes in gene expression, metabolic state, and entry into cell cycle. For T cells and B cells, these signaling cascades start with the ligation of the T cell receptor (TCR) and B cell receptor (BCR), respectively, and result in the recruitment and activation of related families of signaling molecules at the cell surface. Until recently, this gathering of signaling proteins was thought to occur within the featureless plasma membrane, a cellular organ that was envisioned as a boundary between the inner and outer components of the cell, but which contributed little to the signaling process. However, the past few years have seen the gradual realization that activation of signaling in lymphocytes takes place in and around specialized membrane subdomains called lipid rafts (also known as DIGs and GEMs). Here, we provide a brief overview of the analogous structures and compositions of lipid raft-associated signaling complexes in T cells and B cells, and the ways in which lymphocytes--and their pathogen adversaries--use lipid rafts to their benefit.
Collapse
Affiliation(s)
- Caitlin E Sedwick
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, 10355 Science Center Drive, San Diego, CA 92121, USA
| | | |
Collapse
|
15
|
Sedwick CE, Altman A. Ordered Just So: Lipid Rafts and Lymphocyte Function. Sci Signal 2002. [DOI: 10.1126/scisignal.1222002re2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
|
16
|
Abstract
Crystal structures of 11 complexes of TCRs with peptide/MHC (pMHC), that represent 6 independent TCRs, constitute the current structural database for deriving general insights into how alphabeta TCRs recognise peptide-bound MHC class I or class II. The TCRs adopt a roughly diagonal orientation on top of the pMHCs, but the identification of a set of conserved interactions that dictate this orientation is not apparent. Furthermore, the specific interaction of each TCR with its cognate pMHC partner is quite variable and also involves bound water molecules at the TCR/pMHC interface. In two of the systems, the structural basis for binding of altered peptide ligands has illustrated that the only significant conformational changes occur in the TCR/pMHC interface, but their small magnitude is inconsistent with the enormous variation in signalling outcomes. The TCRs adjust to different agonist, partial agonist and antagonist peptides by subtle conformational changes in their complementarity-determining regions, as previously observed in induced-fit mechanisms of antibody/antigen recognition. Alloreactive-complex structures determined or modelled so far indicate increased interactions of the TCR beta-chain with the pMHC compared with their syngeneic counterparts.
Collapse
MESH Headings
- Animals
- Antigen Presentation/immunology
- Humans
- Ligands
- Major Histocompatibility Complex/immunology
- Peptides/chemistry
- Peptides/immunology
- Protein Binding
- Protein Conformation
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, gamma-delta/chemistry
- Receptors, Antigen, T-Cell, gamma-delta/immunology
Collapse
Affiliation(s)
- Markus G Rudolph
- The Scripps Research Institute, Department of Molecular Biology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | |
Collapse
|
17
|
Mattingly RR, Felczak A, Chen CC, McCabe MJ, Rosenspire AJ. Low concentrations of inorganic mercury inhibit Ras activation during T cell receptor-mediated signal transduction. Toxicol Appl Pharmacol 2001; 176:162-8. [PMID: 11714248 DOI: 10.1006/taap.2001.9272] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mercury is widespread in the environment and consequently there are large populations that are currently exposed to low levels of mercury as a result of ubiquitous environmental factors. Whether these environmental levels of mercury are harmful is a matter of current debate, with epidemiological and animal studies suggesting detrimental effects on the immune and nervous systems. However, specific cellular effects of low concentrations of mercury have been hard to characterize. We now demonstrate that subtoxic concentrations of HgCl(2) can potently (maximal at 1 microM) increase Ras.GTP levels in Jurkat, a human T cell line. Remarkably, this activation of Ras occurs without a concomitant increase in MAP kinase activation, suggesting that mercury may direct Ras into a nonproductive state. In addition to its direct effect on Ras, concentrations of HgCl(2) as low as 0.6 microM inhibited the ability of the T cell receptor to activate Ras and MAP kinase. The inhibitory effect of mercury is selective, as activation of MAP kinase by phorbol diesters remain intact. Since the Ras/MAP kinase pathway is both highly conserved and central to signal transduction processes mediated by a myriad of diverse membrane receptor systems in a variety of cell types, these results suggest a mechanism for adverse health effects resulting from exposure to low levels of mercury. They also support a model for regulation of the Ras/MAP kinase pathway, whereby partial but unproductive activation of Ras can diminish signaling from cell surface receptors.
Collapse
Affiliation(s)
- R R Mattingly
- Department of Pharmacology, Wayne State University, Detroit, Michigan 48201, USA
| | | | | | | | | |
Collapse
|
18
|
Doytchinova IA, Flower DR. Toward the quantitative prediction of T-cell epitopes: coMFA and coMSIA studies of peptides with affinity for the class I MHC molecule HLA-A*0201. J Med Chem 2001; 44:3572-81. [PMID: 11606121 DOI: 10.1021/jm010021j] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A set of 102 peptides with affinity for the class I MHC HLA-A0201 molecule was subjected to three-dimensional quantitative structure-affinity relationship (3D QSAR) studies using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). A test set of 50 peptides was used to determine the predictive value of the models. The CoMFA models gave q(2) and r(2)pred below 0.5. The best CoMSIA model has q(2) = 0.542 and r(2)pred = 0.679, and includes hydrophobic, steric, and H-bond donor fields. The hydrophobic interactions play a dominant role in peptide-MHC molecule binding. CoMSIA coefficient contour maps were used to analyze the structural features of the peptides accounting for the affinity in terms of the three positively contributing physicochemical properties: local hydrophobicity, steric bulk and hydrogen-bond-donor ability.
Collapse
Affiliation(s)
- I A Doytchinova
- Edward Jenner Institute for Vaccine Research, Compton, Berkshire, RG20 7NN, UK.
| | | |
Collapse
|
19
|
Garcia KC, Radu CG, Ho J, Ober RJ, Ward ES. Kinetics and thermodynamics of T cell receptor- autoantigen interactions in murine experimental autoimmune encephalomyelitis. Proc Natl Acad Sci U S A 2001; 98:6818-23. [PMID: 11391002 PMCID: PMC34436 DOI: 10.1073/pnas.111161198] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2000] [Accepted: 04/02/2001] [Indexed: 11/18/2022] Open
Abstract
In the current study, cellular and molecular approaches have been used to analyze the biophysical nature of T cell receptor (TCR)-peptide MHC (pMHC) interactions for two autoreactive TCRs. These two TCRs recognize the N-terminal epitope of myelin basic protein (MBP1-11) bound to the MHC class II protein, I-A(u), and are associated with murine experimental autoimmune encephalomyelitis. Mice transgenic for the TCRs have been generated and characterized in other laboratories. These analyses indicate that the mice either develop encephalomyelitis spontaneously (172.10 TCR) or only if immunized with autoantigen in adjuvant (1934.4 TCR). Here, we show that the 172.10 TCR binds MBP1-11:I-A(u) with a 4-5-fold higher affinity than the 1934.4 TCR. Consistent with the higher affinity, 172.10 T hybridoma cells are significantly more responsive to autoantigen than 1934.4 cells. The interaction of the 172.10 TCR with cognate ligand is more entropically unfavorable than that of the 1934.4 TCR, indicating that the 172.10 TCR undergoes greater conformational rearrangements upon ligand binding. The studies therefore suggest a correlation between the strength and plasticity of a TCR-pMHC interaction and the frequency of spontaneous disease in the corresponding TCR transgenic mice. The comparative analysis of these two TCRs has implications for understanding autoreactive T cell recognition and activation.
Collapse
Affiliation(s)
- K C Garcia
- Center for Immunology and Cancer Immunobiology Center, University of Texas Southwestern Medical Center, Dallas, TX 75390-8576, USA
| | | | | | | | | |
Collapse
|
20
|
Puga A, Maier A, Medvedovic M. The transcriptional signature of dioxin in human hepatoma HepG2 cells. Biochem Pharmacol 2000; 60:1129-42. [PMID: 11007951 DOI: 10.1016/s0006-2952(00)00403-2] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We have used a high density microarray hybridization approach to characterize the transcriptional response of human hepatoma HepG2 cells to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We find that exposure to 10 nM TCDD for 8 hr alters by at least a factor of 2.1 the expression of 310 known genes and of an equivalent number of expressed sequence tags. Treatment with TCDD in the presence of 20 microg/mL of cycloheximide blocked the effect on 202 of these genes, allowing us to distinguish between primary effects of TCDD exposure, which take place whether cycloheximide is present or not, and secondary effects, which are blocked by inhibition of protein synthesis. Of the 310 known genes affected by TCDD, 30 are up-regulated and 78 are down-regulated regardless of cycloheximide treatment, and 84 are up-regulated and 118 are down-regulated only when protein synthesis is not inhibited. Functional clustering of genes regulated by TCDD reveals many potential physiological interactions that might shed light on the multiple biological effects of this compound. Our results, however, suggest that arriving at a sound understanding of the molecular mechanisms governing the biological outcome of TCDD exposure promises to be orders of magnitude more complicated than might have been previously imagined.
Collapse
Affiliation(s)
- A Puga
- Center for Environmental Genetics and Department of Environmental Health, University of Cincinnati Medical Center, P.O. Box 670056, Cincinnati, OH 45267-0056, USA.
| | | | | |
Collapse
|