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Callahan A, Chua XY, Griffith AA, Hildebrandt T, Fu G, Hu M, Wen R, Salomon AR. Deep phosphotyrosine characterisation of primary murine T cells using broad spectrum optimisation of selective triggering. Proteomics 2024:e2400106. [PMID: 39091061 DOI: 10.1002/pmic.202400106] [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: 04/01/2024] [Revised: 07/11/2024] [Accepted: 07/12/2024] [Indexed: 08/04/2024]
Abstract
Sequencing the tyrosine phosphoproteome using MS-based proteomics is challenging due to the low abundance of tyrosine phosphorylation in cells, a challenge compounded in scarce samples like primary cells or clinical samples. The broad-spectrum optimisation of selective triggering (BOOST) method was recently developed to increase phosphotyrosine sequencing in low protein input samples by leveraging tandem mass tags (TMT), phosphotyrosine enrichment, and a phosphotyrosine-loaded carrier channel. Here, we demonstrate the viability of BOOST in T cell receptor (TCR)-stimulated primary murine T cells by benchmarking the accuracy and precision of the BOOST method and discerning significant alterations in the phosphoproteome associated with receptor stimulation. Using 1 mg of protein input (about 20 million cells) and BOOST, we identify and precisely quantify more than 2000 unique pY sites compared to about 300 unique pY sites in non-BOOST control samples. We show that although replicate variation increases when using the BOOST method, BOOST does not jeopardise quantitative precision or the ability to determine statistical significance for peptides measured in triplicate. Many pY previously uncharacterised sites on important T cell signalling proteins are quantified using BOOST, and we identify new TCR responsive pY sites observable only with BOOST. Finally, we determine that the phase-spectrum deconvolution method on Orbitrap instruments can impair pY quantitation in BOOST experiments.
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Affiliation(s)
- Aurora Callahan
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Xien Yu Chua
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Alijah A Griffith
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Tobias Hildebrandt
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island, USA
| | - Guoping Fu
- Versiti Blood Research Institute, Milwaukee, Wisconsin, USA
| | - Mengzhou Hu
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island, USA
| | - Renren Wen
- Versiti Blood Research Institute, Milwaukee, Wisconsin, USA
| | - Arthur R Salomon
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, USA
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island, USA
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2
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Lotze MT, Olejniczak SH, Skokos D. CD28 co-stimulation: novel insights and applications in cancer immunotherapy. Nat Rev Immunol 2024:10.1038/s41577-024-01061-1. [PMID: 39054343 DOI: 10.1038/s41577-024-01061-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2024] [Indexed: 07/27/2024]
Abstract
Substantial progress in understanding T cell signalling, particularly with respect to T cell co-receptors such as the co-stimulatory receptor CD28, has been made in recent years. This knowledge has been instrumental in the development of innovative immunotherapies for patients with cancer, including immune checkpoint blockade antibodies, adoptive cell therapies, tumour-targeted immunostimulatory antibodies, and immunostimulatory small-molecule drugs that regulate T cell activation. Following the failed clinical trial of a CD28 superagonist antibody in 2006, targeted CD28 agonism has re-emerged as a technologically viable and clinically promising strategy for cancer immunotherapy. In this Review, we explore recent insights into the molecular functions and regulation of CD28. We describe how CD28 is central to the success of current cancer immunotherapies and examine how new questions arising from studies of CD28 as a clinical target have enhanced our understanding of its biological role and may guide the development of future therapeutic strategies in oncology.
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Affiliation(s)
- Michael T Lotze
- Department of Surgery, University of Pittsburgh Hillman Cancer Center, Pittsburgh, PA, USA.
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA, USA.
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Scott H Olejniczak
- Department of Immunology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA.
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3
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Ahn MJ, Kim EH, Choi Y, Chae CH, Kim P, Kim SH. Novel hematopoietic progenitor kinase 1 inhibitor KHK-6 enhances T-cell activation. PLoS One 2024; 19:e0305261. [PMID: 38923962 PMCID: PMC11207149 DOI: 10.1371/journal.pone.0305261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 05/28/2024] [Indexed: 06/28/2024] Open
Abstract
Inhibiting the functional role of negative regulators in immune cells is an effective approach for developing immunotherapies. The serine/threonine kinase hematopoietic progenitor kinase 1 (HPK1) involved in the T-cell receptor signaling pathway attenuates T-cell activation by inducing the degradation of SLP-76 through its phosphorylation at Ser-376, reducing the immune response. Interestingly, several studies have shown that the genetic ablation or pharmacological inhibition of HPK1 kinase activity improves the immune response to cancers by enhancing T-cell activation and cytokine production; therefore, HPK1 could be a promising druggable target for T-cell-based cancer immunotherapy. To increase the immune response against cancer cells, we designed and synthesized KHK-6 and evaluated its cellular activity to inhibit HPK1 and enhance T-cell activation. KHK-6 inhibited HPK1 kinase activity with an IC50 value of 20 nM and CD3/CD28-induced phosphorylation of SLP-76 at Ser-376 Moreover, KHK-6 significantly enhanced CD3/CD28-induced production of cytokines; proportion of CD4+ and CD8+ T cells that expressed CD69, CD25, and HLA-DR markers; and T-cell-mediated killing activity of SKOV3 and A549 cells. In conclusion, KHK-6 is a novel ATP-competitive HPK1 inhibitor that blocks the phosphorylation of HPK1 downstream of SLP-76, enhancing the functional activation of T cells. In summary, our study showed the usefulness of KHK-6 in the drug discovery for the HPK1-inhibiting immunotherapy.
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Affiliation(s)
- Min Jeong Ahn
- Therapeutics & Biotechnology Division, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
- Graduate School of New Drug Discovery and Development, Chungnam National University, Daejeon, Republic of Korea
| | - Eun Hye Kim
- Therapeutics & Biotechnology Division, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
| | - Yunha Choi
- Therapeutics & Biotechnology Division, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
- Medicinal Chemistry & Pharmacology, University of Science and Technology, Daejeon, Republic of Korea
| | - Chong Hak Chae
- Therapeutics & Biotechnology Division, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
| | - Pilho Kim
- Therapeutics & Biotechnology Division, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
- Medicinal Chemistry & Pharmacology, University of Science and Technology, Daejeon, Republic of Korea
| | - Seong Hwan Kim
- Therapeutics & Biotechnology Division, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
- Graduate School of New Drug Discovery and Development, Chungnam National University, Daejeon, Republic of Korea
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4
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Weiss A. Peeking Into the Black Box of T Cell Receptor Signaling. Annu Rev Immunol 2024; 42:1-20. [PMID: 37788477 DOI: 10.1146/annurev-immunol-090222-112028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
I have spent more than the last 40 years at the University of California, San Francisco (UCSF), studying T cell receptor (TCR) signaling. I was blessed with supportive mentors, an exceptionally talented group of trainees, and wonderful collaborators and colleagues during my journey who have enabled me to make significant contributions to our understanding of how the TCR initiates signaling. TCR signaling events contribute to T cell development as well as to mature T cell activation and differentiation.
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Affiliation(s)
- Arthur Weiss
- Division of Rheumatology, Department of Medicine, University of California, San Francisco, California, USA;
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5
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Kunkl M, Amormino C, Spallotta F, Caristi S, Fiorillo MT, Paiardini A, Kaempfer R, Tuosto L. Bivalent binding of staphylococcal superantigens to the TCR and CD28 triggers inflammatory signals independently of antigen presenting cells. Front Immunol 2023; 14:1170821. [PMID: 37207220 PMCID: PMC10189049 DOI: 10.3389/fimmu.2023.1170821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 04/21/2023] [Indexed: 05/21/2023] Open
Abstract
Staphylococcus aureus superantigens (SAgs) such as staphylococcal enterotoxin A (SEA) and B (SEB) are potent toxins stimulating T cells to produce high levels of inflammatory cytokines, thus causing toxic shock and sepsis. Here we used a recently released artificial intelligence-based algorithm to better elucidate the interaction between staphylococcal SAgs and their ligands on T cells, the TCR and CD28. The obtained computational models together with functional data show that SEB and SEA are able to bind to the TCR and CD28 stimulating T cells to activate inflammatory signals independently of MHC class II- and B7-expressing antigen presenting cells. These data reveal a novel mode of action of staphylococcal SAgs. By binding to the TCR and CD28 in a bivalent way, staphylococcal SAgs trigger both the early and late signalling events, which lead to massive inflammatory cytokine secretion.
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Affiliation(s)
- Martina Kunkl
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Rome, Italy
| | - Carola Amormino
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Rome, Italy
| | - Francesco Spallotta
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Rome, Italy
- Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University, Rome, Italy
| | - Silvana Caristi
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Rome, Italy
| | - Maria Teresa Fiorillo
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Rome, Italy
| | - Alessandro Paiardini
- Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, Rome, Italy
| | - Raymond Kaempfer
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Loretta Tuosto
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Rome, Italy
- Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University, Rome, Italy
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6
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Ruminski K, Celis-Gutierrez J, Jarmuzynski N, Maturin E, Audebert S, Malissen M, Camoin L, Voisinne G, Malissen B, Roncagalli R. Mapping the SLP76 interactome in T cells lacking each of the GRB2-family adaptors reveals molecular plasticity of the TCR signaling pathway. Front Immunol 2023; 14:1139123. [PMID: 37006259 PMCID: PMC10057548 DOI: 10.3389/fimmu.2023.1139123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 03/02/2023] [Indexed: 03/17/2023] Open
Abstract
The propagation and diversification of signals downstream of the T cell receptor (TCR) involve several adaptor proteins that control the assembly of multimolecular signaling complexes (signalosomes). The global characterization of changes in protein-protein interactions (PPI) following genetic perturbations is critical to understand the resulting phenotypes. Here, by combining genome editing techniques in T cells and interactomics studies based on affinity purification coupled to mass spectrometry (AP-MS) analysis, we determined and quantified the molecular reorganization of the SLP76 interactome resulting from the ablation of each of the three GRB2-family adaptors. Our data showed that the absence of GADS or GRB2 induces a major remodeling of the PPI network associated with SLP76 following TCR engagement. Unexpectedly, this PPI network rewiring minimally affects proximal molecular events of the TCR signaling pathway. Nevertheless, during prolonged TCR stimulation, GRB2- and GADS-deficient cells displayed a reduced level of activation and cytokine secretion capacity. Using the canonical SLP76 signalosome, this analysis highlights the plasticity of PPI networks and their reorganization following specific genetic perturbations.
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Affiliation(s)
- Kilian Ruminski
- Centre d’Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, Marseille, France
| | - Javier Celis-Gutierrez
- Centre d’Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, Marseille, France
- Centre d’Immunophénomique, Aix Marseille Université, INSERM, CNRS UMR, Marseille, France
| | - Nicolas Jarmuzynski
- Centre d’Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, Marseille, France
- Centre d’Immunophénomique, Aix Marseille Université, INSERM, CNRS UMR, Marseille, France
| | - Emilie Maturin
- Centre d’Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, Marseille, France
| | - Stephane Audebert
- Institut Paoli-Calmettes, CRCM, Aix Marseille Université, CNRS, INSERM, Marseille Protóomique, Marseille, France
| | - Marie Malissen
- Centre d’Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, Marseille, France
- Centre d’Immunophénomique, Aix Marseille Université, INSERM, CNRS UMR, Marseille, France
| | - Luc Camoin
- Institut Paoli-Calmettes, CRCM, Aix Marseille Université, CNRS, INSERM, Marseille Protóomique, Marseille, France
| | - Guillaume Voisinne
- Centre d’Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, Marseille, France
| | - Bernard Malissen
- Centre d’Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, Marseille, France
- Centre d’Immunophénomique, Aix Marseille Université, INSERM, CNRS UMR, Marseille, France
- *Correspondence: Romain Roncagalli, ; Bernard Malissen,
| | - Romain Roncagalli
- Centre d’Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, Marseille, France
- *Correspondence: Romain Roncagalli, ; Bernard Malissen,
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7
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Griffith AA, Callahan KP, King NG, Xiao Q, Su X, Salomon AR. SILAC Phosphoproteomics Reveals Unique Signaling Circuits in CAR-T Cells and the Inhibition of B Cell-Activating Phosphorylation in Target Cells. J Proteome Res 2022; 21:395-409. [PMID: 35014847 PMCID: PMC8830406 DOI: 10.1021/acs.jproteome.1c00735] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Chimeric antigen receptor (CAR) is a single-pass transmembrane receptor designed to specifically target and eliminate cancers. While CARs prove highly efficacious against B cell malignancies, the intracellular signaling events which promote CAR T cell activity remain elusive. To gain further insight into both CAR T cell signaling and the potential signaling response of cells targeted by CAR, we analyzed phosphopeptides captured by two separate phosphoenrichment strategies from third generation CD19-CAR T cells cocultured with SILAC labeled Raji B cells by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Here, we report that CD19-CAR T cells upregulated several key phosphorylation events also observed in canonical T cell receptor (TCR) signaling, while Raji B cells exhibited a significant decrease in B cell receptor-signaling related phosphorylation events in response to coculture. Our data suggest that CD19-CAR stimulation activates a mixture of unique CD19-CAR-specific signaling pathways and canonical TCR signaling, while global phosphorylation in Raji B cells is reduced after association with the CD19-CAR T cells.
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Affiliation(s)
- Alijah A. Griffith
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI, 02912
| | - Kenneth P. Callahan
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI, 02912
| | - Nathan Gordo King
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI, 02912
| | - Qian Xiao
- Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT, 06520
| | - Xiaolei Su
- Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT, 06520
| | - Arthur R. Salomon
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI, 02912,
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8
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Wada J, Rathnayake U, Jenkins LM, Singh A, Mohammadi M, Appella E, Randazzo PA, Samelson LE. In vitro reconstitution reveals cooperative mechanisms of adapter protein-mediated activation of phospholipase C-γ1 in T cells. J Biol Chem 2022; 298:101680. [PMID: 35124007 PMCID: PMC8908268 DOI: 10.1016/j.jbc.2022.101680] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 01/31/2022] [Accepted: 02/01/2022] [Indexed: 12/16/2022] Open
Abstract
Activation of T cells upon engagement of the T cell antigen receptor rapidly leads to a number of phosphorylation and plasma membrane recruitment events. For example, translocation of phospholipase-Cγ1 (PLC−γ1) to the plasma membrane and its association with the transmembrane adapter protein LAT and two other adapter proteins, Gads and SLP-76, are critical events in the early T cell activation process. We have previously characterized the formation of a tetrameric LAT-Gads-SLP-76-PLC−γ1 complex by reconstitution in vitro and have also characterized the thermodynamics of tetramer formation. In the current study, we define how PLC−γ1 recruitment to liposomes, which serve as a plasma membrane surrogate, and PLC−γ1 activation are regulated both independently and additively by recruitment of PLC−γ1 to phosphorylated LAT, by formation of the LAT-Gads-SLP-76-PLC−γ1 tetramer, and by tyrosine phosphorylation of PLC−γ1. The recently solved structure of PLC−γ1 indicates that, in the resting state, several PLC−γ1 domains inhibit its enzymatic activity and contact with the plasma membrane. We propose the multiple cooperative steps that we observed likely lead to conformational alterations in the regulatory domains of PLC−γ1, enabling contact with its membrane substrate, disinhibition of PLC−γ1 enzymatic activity, and production of the phosphoinositide cleavage products necessary for T cell activation.
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9
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De Silva D, Ferguson L, Chin GH, Smith BE, Apathy RA, Roth TL, Blaeschke F, Kudla M, Marson A, Ingolia NT, Cate JHD. Robust T cell activation requires an eIF3-driven burst in T cell receptor translation. eLife 2021; 10:e74272. [PMID: 34970966 PMCID: PMC8758144 DOI: 10.7554/elife.74272] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/30/2021] [Indexed: 11/13/2022] Open
Abstract
Activation of T cells requires a rapid surge in cellular protein synthesis. However, the role of translation initiation in the early induction of specific genes remains unclear. Here, we show human translation initiation factor eIF3 interacts with select immune system related mRNAs including those encoding the T cell receptor (TCR) subunits TCRA and TCRB. Binding of eIF3 to the TCRA and TCRB mRNA 3'-untranslated regions (3'-UTRs) depends on CD28 coreceptor signaling and regulates a burst in TCR translation required for robust T cell activation. Use of the TCRA or TCRB 3'-UTRs to control expression of an anti-CD19 chimeric antigen receptor (CAR) improves the ability of CAR-T cells to kill tumor cells in vitro. These results identify a new mechanism of eIF3-mediated translation control that can aid T cell engineering for immunotherapy applications.
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Affiliation(s)
- Dasmanthie De Silva
- Department of Molecular and Cell Biology, University of California-BerkeleyBerkeleyUnited States
- The J. David Gladstone InstitutesSan FranciscoUnited States
| | - Lucas Ferguson
- Department of Molecular and Cell Biology, University of California-BerkeleyBerkeleyUnited States
| | - Grant H Chin
- Department of Molecular and Cell Biology, University of California-BerkeleyBerkeleyUnited States
| | - Benjamin E Smith
- School of Optometry, University of California, BerkeleyBerkeleyUnited States
| | - Ryan A Apathy
- Department of Microbiology and Immunology, University of California, San FranciscoSan FranciscoUnited States
| | - Theodore L Roth
- Department of Microbiology and Immunology, University of California, San FranciscoSan FranciscoUnited States
| | | | - Marek Kudla
- Department of Molecular and Cell Biology, University of California-BerkeleyBerkeleyUnited States
| | - Alexander Marson
- Department of Microbiology and Immunology, University of California, San FranciscoSan FranciscoUnited States
- Gladstone-UCSF Institute of Genomic ImmunologySan FranciscoUnited States
- Diabetes Center, University of California, San FranciscoSan FranciscoUnited States
- Chan Zuckerberg BiohubSan FranciscoUnited States
- Department of Medicine, University of California, San FranciscoSan FranciscoUnited States
- Parker Institute for Cancer ImmunotherapySan FranciscoUnited States
- Innovative Genomics Institute, University of California, BerkeleyBerkeleyUnited States
| | - Nicholas T Ingolia
- Department of Molecular and Cell Biology, University of California-BerkeleyBerkeleyUnited States
- California Institute for Quantitative Biosciences, University of California, BerkeleyBerkeleyUnited States
| | - Jamie HD Cate
- Department of Molecular and Cell Biology, University of California-BerkeleyBerkeleyUnited States
- The J. David Gladstone InstitutesSan FranciscoUnited States
- Innovative Genomics Institute, University of California, BerkeleyBerkeleyUnited States
- California Institute for Quantitative Biosciences, University of California, BerkeleyBerkeleyUnited States
- Department of Chemistry, University of California-BerkeleyBerkeleyUnited States
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National LaboratoryBerkeleyUnited States
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10
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Ashouri JF, Lo W, Nguyen TTT, Shen L, Weiss A. ZAP70, too little, too much can lead to autoimmunity*. Immunol Rev 2021; 307:145-160. [PMID: 34923645 PMCID: PMC8986586 DOI: 10.1111/imr.13058] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 12/05/2021] [Indexed: 12/21/2022]
Abstract
Establishing both central and peripheral tolerance requires the appropriate TCR signaling strength to discriminate self‐ from agonist‐peptide bound to self MHC molecules. ZAP70, a cytoplasmic tyrosine kinase, directly interacts with the TCR complex and plays a central and requisite role in TCR signaling in both thymocytes and peripheral T cells. By studying ZAP70 hypomorphic mutations in mice and humans with a spectrum of hypoactive or hyperactive activities, we have gained insights into mechanisms of central and peripheral tolerance. Interestingly, both hypoactive and hyperactive ZAP70 can lead to the development of autoimmune diseases, albeit through distinct mechanisms. Immature thymocytes and mature T cells rely on normal ZAP70 function to complete their development in the thymus and to modulate T cell responses in the periphery. Hypoactive ZAP70 function compromises key developmental checkpoints required to establish central tolerance, allowing thymocytes with potentially self‐reactive TCRs a greater chance to escape negative selection. Such ‘forbidden clones’ may escape into the periphery and may pose a greater risk for autoimmune disease development since they may not engage negative regulatory mechanisms as effectively. Hyperactive ZAP70 enhances thymic negative selection but some thymocytes will, nonetheless, escape negative selection and have greater sensitivity to weak and self‐ligands. Such cells must be controlled by mechanisms involved in anergy, expansion of Tregs, and upregulation of inhibitory receptors or signaling molecules. However, such potentially autoreactive cells may still be able to escape control by peripheral negative regulatory constraints. Consistent with findings in Zap70 mutants, the signaling defects in at least one ZAP70 substrate, LAT, can also lead to autoimmune disease. By dissecting the similarities and differences among mouse models of patient disease or mutations in ZAP70 that affect TCR signaling strength, we have gained insights into how perturbed ZAP70 function can lead to autoimmunity. Because of our work and that of others on ZAP70, it is likely that perturbations in other molecules affecting TCR signaling strength will be identified that also overcome tolerance mechanisms and cause autoimmunity. Delineating these molecular pathways could lead to the development of much needed new therapeutic targets in these complex diseases.
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Affiliation(s)
- Judith F. Ashouri
- Department of Medicine Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center University of California, San Francisco San Francisco California USA
| | - Wan‐Lin Lo
- Division of Microbiology and Immunology Department of Pathology University of Utah Salt Lake City Utah USA
| | - Trang T. T. Nguyen
- Department of Medicine Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center University of California, San Francisco San Francisco California USA
| | - Lin Shen
- Department of Medicine Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center University of California, San Francisco San Francisco California USA
| | - Arthur Weiss
- Department of Medicine Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center University of California, San Francisco San Francisco California USA
- Howard Hughes Medical Institute University of California, San Francisco San Francisco California USA
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