1
|
Lee JH, Lee BH, Jeong S, Joh CSY, Nam HJ, Choi HS, Sserwadda H, Oh JW, Park CG, Jin SP, Kim HJ. Single-cell RNA sequencing identifies distinct transcriptomic signatures between PMA/ionomycin- and αCD3/αCD28-activated primary human T cells. Genomics Inform 2023; 21:e18. [PMID: 37704208 PMCID: PMC10326540 DOI: 10.5808/gi.23009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/01/2023] [Accepted: 04/03/2023] [Indexed: 07/08/2023] Open
Abstract
Immunologists have activated T cells in vitro using various stimulation methods, including phorbol myristate acetate (PMA)/ionomycin and αCD3/αCD28 agonistic antibodies. PMA stimulates protein kinase C, activating nuclear factor-κB, and ionomycin increases intracellular calcium levels, resulting in activation of nuclear factor of activated T cell. In contrast, αCD3/αCD28 agonistic antibodies activate T cells through ZAP-70, which phosphorylates linker for activation of T cell and SH2-domain-containing leukocyte protein of 76 kD. However, despite the use of these two different in vitro T cell activation methods for decades, the differential effects of chemical-based and antibody-based activation of primary human T cells have not yet been comprehensively described. Using single-cell RNA sequencing (scRNA-seq) technologies to analyze gene expression unbiasedly at the single-cell level, we compared the transcriptomic profiles of the non-physiological and physiological activation methods on human peripheral blood mononuclear cell-derived T cells from four independent donors. Remarkable transcriptomic differences in the expression of cytokines and their respective receptors were identified. We also identified activated CD4 T cell subsets (CD55+) enriched specifically by PMA/ionomycin activation. We believe this activated human T cell transcriptome atlas derived from two different activation methods will enhance our understanding, highlight the optimal use of these two in vitro T cell activation assays, and be applied as a reference standard when analyzing activated specific disease-originated T cells through scRNA-seq.
Collapse
Affiliation(s)
- Jung Ho Lee
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Brian H Lee
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Soyoung Jeong
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Christine Suh-Yun Joh
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Hyo Jeong Nam
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Hyun Seung Choi
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Henry Sserwadda
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Ji Won Oh
- Department of Anatomy, Yonsei University College of Medicine, Seoul 03722, Korea
| | - Chung-Gyu Park
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul 03080, Korea
- Transplantation Research Institute, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Seon-Pil Jin
- Department of Dermatology, Seoul National University Hospital, Seoul 03080, Korea
- Department of Dermatology, Seoul National University College of Medicine, Seoul 03080, Korea
- Medical Research Center, Institute of Human-Environmental Interface Biology, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Hyun Je Kim
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
- Genomic Medicine Institute, Seoul National University College of Medicine, Seoul 03080, Korea
- Seoul National University Hospital, Seoul 03080, Korea
| |
Collapse
|
2
|
Jiao J, Zhao X, Hou R, Wang Y, Chang W, Liang N, Liu Y, Xing J, Cao Y, Li X, Zhang K. Comparison of two commonly used methods for stimulating T cells. Biotechnol Lett 2019; 41:1361-1371. [DOI: 10.1007/s10529-019-02743-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 10/13/2019] [Indexed: 12/27/2022]
|
3
|
Omer B, Castillo PA, Tashiro H, Shum T, Huynh MTA, Cardenas M, Tanaka M, Lewis A, Sauer T, Parihar R, Lapteva N, Schmueck-Henneresse M, Mukherjee M, Gottschalk S, Rooney CM. Chimeric Antigen Receptor Signaling Domains Differentially Regulate Proliferation and Native T Cell Receptor Function in Virus-Specific T Cells. Front Med (Lausanne) 2018; 5:343. [PMID: 30619856 PMCID: PMC6297364 DOI: 10.3389/fmed.2018.00343] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 11/22/2018] [Indexed: 11/16/2022] Open
Abstract
The efficacy of T cells expressing chimeric antigen receptors (CARs) for solid tumors has been limited by insufficient CAR T cell expansion and persistence. The use of virus-specific T cells (VSTs) as carriers for CARs may overcome this limitation since CAR-VSTs can be boosted by viral vaccines or oncolytic viruses. However, there is limited understanding of the optimal combination of endodomains and their influence on the native T cell receptor (TCR) in VSTs. We therefore compared the function of GD2.CARs expressing the TCR zeta chain (ζ) alone or combined with endodomains from CD28 and 4-1BB in varicella zoster virus-specific (VZV) T cells. VZVSTs expressing GD2-CARs recognized VZV-derived peptides and killed GD2-expressing tumor cells. However, after repeated stimulation through their native TCR, the expansion of GD2-CAR.CD28ζ-VZVSTs was 3.3-fold greater (p < 0.001) than non-transduced VZVSTs, whereas GD2-CARζ- and GD2-CAR.41BBζ inhibited VZVST expansion (p < 0.01). Compared to control VZVSTs, GD2-CAR.ζ VZVSTs showed a greater frequency of apoptotic (p < 0.01) T cells, whereas prolonged downregulation of the native αβ TCR was observed in GD2-CAR.41BBζ VZVSTs (p < 0.001). We confirmed that CD28ζ can best maintain TCR function by expressing GD2.CARs in Epstein-Barr virus-specific T cells and CD19-CARs in VZVSTs. In response to CAR stimulation VSTs with CD28ζ endodomains also showed the greatest expansion (6 fold > GD2-CAR.41BBζ VZVSTs (p < 0.001), however anti-tumor efficacy was superior in GD2-CAR.41BBζ-VZVSTs. These findings demonstrate that CAR signaling domains can enhance or diminish the function of the native TCR and indicate that only CD28ζ may preserve the function of the native TCR in tonically signaling CAR-VSTs.
Collapse
Affiliation(s)
- Bilal Omer
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States.,Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
| | - Paul A Castillo
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Haruko Tashiro
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Thomas Shum
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Mai T A Huynh
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Mara Cardenas
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Miyuki Tanaka
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Andrew Lewis
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Tim Sauer
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Robin Parihar
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States.,Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
| | - Natalia Lapteva
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Michael Schmueck-Henneresse
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Malini Mukherjee
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States
| | - Stephen Gottschalk
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States.,Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States.,Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, United States
| | - Cliona M Rooney
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital, Texas Children's Hospital, Houston, TX, United States.,Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States.,Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, United States.,Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, United States
| |
Collapse
|
4
|
The T Cell Antigen Receptor α Transmembrane Domain Coordinates Triggering through Regulation of Bilayer Immersion and CD3 Subunit Associations. Immunity 2018; 49:829-841.e6. [PMID: 30389415 DOI: 10.1016/j.immuni.2018.09.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 08/15/2018] [Accepted: 09/07/2018] [Indexed: 12/18/2022]
Abstract
Initial molecular details of cellular activation following αβT cell antigen receptor (TCR) ligation by peptide-major histocompatibility complexes (pMHC) remain unexplored. We determined the nuclear magnetic resonance (NMR) structure of the TCRα subunit transmembrane (TM) domain revealing a bipartite helix whose segmentation fosters dynamic movement. Positively charged TM residues Arg251 and Lys256 project from opposite faces of the helix, with Lys256 controlling immersion depth. Their modification caused stepwise reduction in TCR associations with CD3ζζ homodimers and CD3εγ plus CD3εδ heterodimers, respectively, leading to an activated transcriptome. Optical tweezers revealed that Arg251 and Lys256 mutations altered αβTCR-pMHC bond lifetimes, while mutations within interacting TCRα connecting peptide and CD3δ CxxC motif juxtamembrane elements selectively attenuated signal transduction. Our findings suggest that mechanical forces applied during pMHC ligation initiate T cell activation via a dissociative mechanism, shifting disposition of those basic sidechains to rearrange TCR complex membrane topology and weaken TCRαβ and CD3 associations.
Collapse
|
5
|
Abstract
T cell receptors (TCRs) are protein complexes formed by six different polypeptides. In most T cells, TCRs are composed of αβ subunits displaying immunoglobulin-like variable domains that recognize peptide antigens associated with major histocompatibility complex molecules expressed on the surface of antigen-presenting cells. TCRαβ subunits are associated with the CD3 complex formed by the γ, δ, ε, and ζ subunits, which are invariable and ensure signal transduction. Here, we review how the expression and function of TCR complexes are orchestrated by several fine-tuned cellular processes that encompass (a) synthesis of the subunits and their correct assembly and expression at the plasma membrane as a single functional complex, (b) TCR membrane localization and dynamics at the plasma membrane and in endosomal compartments, (c) TCR signal transduction leading to T cell activation, and (d) TCR degradation. These processes balance each other to ensure efficient T cell responses to a variety of antigenic stimuli while preventing autoimmunity.
Collapse
Affiliation(s)
- Andrés Alcover
- Lymphocyte Cell Biology Unit, INSERM U1221, Department of Immunology, Institut Pasteur, Paris 75015, France; ,
| | - Balbino Alarcón
- Severo Ochoa Center for Molecular Biology, CSIC-UAM, Madrid 28049, Spain;
| | - Vincenzo Di Bartolo
- Lymphocyte Cell Biology Unit, INSERM U1221, Department of Immunology, Institut Pasteur, Paris 75015, France; ,
| |
Collapse
|
6
|
Bentov Y, Jurisicova A, Kenigsberg S, Casper RF. What maintains the high intra-follicular estradiol concentration in pre-ovulatory follicles? J Assist Reprod Genet 2015; 33:85-94. [PMID: 26552664 DOI: 10.1007/s10815-015-0612-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 10/28/2015] [Indexed: 12/13/2022] Open
Abstract
PURPOSE The purpose of the study was to establish the mechanism by which the estrogen concentration difference between the follicular fluid and the serum is maintained. METHODS We used dialysis membrane with a pore size of <3 KD to characterize the estrogen-binding capacity of the follicular fluid. We performed PCR, western blot, and ELISA on luteinized granulosa cells to determine if sex hormone-binding globulin (SHBG) is produced by granulosa cells, and finally we used affinity columns and mass spectrometry to identify the estrogen-binding protein in the follicular fluid. RESULTS We found that a significant estrogen concentration difference is maintained in a cell-free system and is lost with proteolysis of the follicular fluid proteins. Luteinized granulosa cells are likely not a source of SHBG, as we were not able to detect expression of SHBG in these cells. Perlecan was the most highly enriched follicular fluid protein in the affinity columns. CONCLUSIONS We were able to identify perlecan as the most likely candidate for the major estrogen-binding protein in the follicular fluid.
Collapse
Affiliation(s)
- Yaakov Bentov
- Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada. .,Toronto Center for Assisted Reproductive Technologies, Toronto, Canada. .,Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada.
| | - Andrea Jurisicova
- Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada.,Department of Physiology, University of Toronto, Toronto, Canada.,Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada
| | - Shlomit Kenigsberg
- CReATe Fertility Centre, Toronto, Canada.,Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada
| | - Robert F Casper
- Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada.,Toronto Center for Assisted Reproductive Technologies, Toronto, Canada.,Department of Physiology, University of Toronto, Toronto, Canada.,Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada
| |
Collapse
|
7
|
Naahidi S, Wang Y, Zhang M, Wang R, Jafari M, Yuan Y, Dixon B, Chen P. Evaluation of Biocompatibility of the AC8 Peptide and Its Potential Use as a Drug Carrier. Mol Pharm 2014; 11:3409-20. [PMID: 25055061 DOI: 10.1021/mp5001185] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sheva Naahidi
- Department
of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
- Waterloo
Institute for Nanotechnology, University of Waterloo, 200 University
Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Yujie Wang
- Department
of Pharmacy, Shanghai Third People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 201999, China
| | - Man Zhang
- Department
of Pharmacy, Shanghai Third People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 201999, China
| | - Rong Wang
- Department
of Pharmacy, Shanghai Third People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 201999, China
| | - Mousa Jafari
- Department
of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
- Waterloo
Institute for Nanotechnology, University of Waterloo, 200 University
Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Yongfang Yuan
- Department
of Pharmacy, Shanghai Third People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 201999, China
| | - Brian Dixon
- Department
of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - P. Chen
- Department
of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
- Waterloo
Institute for Nanotechnology, University of Waterloo, 200 University
Avenue West, Waterloo, Ontario N2L 3G1, Canada
| |
Collapse
|
8
|
Tan YX, Zikherman J, Weiss A. Novel tools to dissect the dynamic regulation of TCR signaling by the kinase Csk and the phosphatase CD45. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2013; 78:131-139. [PMID: 24100586 DOI: 10.1101/sqb.2013.78.020347] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Although the biochemical events induced by T-cell receptor (TCR) triggering have been well studied, both the mediators and function of basal signaling in T cells remain poorly understood. Furthermore, the precise mechanisms by which MHC-peptide interaction with the TCR disrupt the basal equilibrium to induce downstream signaling are also unclear. Here we describe novel approaches to understand the basal state of T cells and the mechanisms of TCR triggering by perturbing regulation of the Src family kinases (SFKs). The SFKs are critical proximal mediators of TCR signaling that are in turn tightly regulated by the tyrosine kinase Csk and the receptor-like tyrosine phosphatase CD45. We have developed a small-molecule analog-sensitive allele of Csk and an allelic series of mice in which expression of CD45 is varied across a broad range. Our studies have unmasked contributions of Csk and CD45 to maintain the basal state of T cells and also suggest that dynamic regulation of Csk may be involved in TCR triggering.
Collapse
Affiliation(s)
- Ying Xim Tan
- Division of Rheumatology, Rosalind Russell Medical Research Center for Arthritis, Department of Medicine, UCSF, San Francisco, CA, 94143, USA
| | - Julie Zikherman
- Division of Rheumatology, Rosalind Russell Medical Research Center for Arthritis, Department of Medicine, UCSF, San Francisco, CA, 94143, USA
| | - Arthur Weiss
- Division of Rheumatology, Rosalind Russell Medical Research Center for Arthritis, Department of Medicine, UCSF, San Francisco, CA, 94143, USA.,Howard Hughes Medical Institute, UCSF, San Francisco, CA, 94143, USA
| |
Collapse
|
9
|
Sigalov AB. Cells diversify transmembrane signaling through the controlled chaos of protein disorder. SELF/NONSELF 2011; 2:75-79. [PMID: 22299058 PMCID: PMC3268992 DOI: 10.4161/self.2.2.15756] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Accepted: 04/06/2011] [Indexed: 11/19/2022]
Abstract
Cell surface receptors function to transduce signals across the cell membrane leading to a variety of biologic responses. Structurally, these integral proteins can be classified into two main families, depending on whether extracellular ligand-binding and intracellular signaling domains are located on the same protein chain (single-chain receptors, SRs) or on separate subunits (multichain receptors, MRs). Since most MRs are immune receptors, they are all commonly referred to as multi-chain immune recognition receptors (MIRRs). Recent studies reveal that, in contrast to well-structured signaling domains of SRs, those of MIRRs represent intrinsically disordered regions, the regions that lack a well-defined three-dimensional structure under physiological conditions. Why did nature separate recognition and signaling functions of MIRRs? Why for MIRRs did nature select to provide highly specific signaling through the chaos of protein disorder? What mechanisms could control this chaos in the process of transmembrane signal transduction to provide the specificity and diversity of the immune response? Here, I summarize recent findings that may not only shed light on these and other questions but also add significantly to our understanding of receptor signaling, a fundamental process that plays a critical role in health and disease.
Collapse
|
10
|
Sigalov AB. The SCHOOL of nature: I. Transmembrane signaling. SELF/NONSELF 2010; 1:4-39. [PMID: 21559175 PMCID: PMC3091606 DOI: 10.4161/self.1.1.10832] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 11/30/2009] [Accepted: 12/01/2009] [Indexed: 11/19/2022]
Abstract
Receptor-mediated transmembrane signaling plays an important role in health and disease. Recent significant advances in our understanding of the molecular mechanisms linking ligand binding to receptor activation revealed previously unrecognized striking similarities in the basic structural principles of function of numerous cell surface receptors. In this work, I demonstrate that the Signaling Chain Homooligomerization (SCHOOL)-based mechanism represents a general biological mechanism of transmembrane signal transduction mediated by a variety of functionally unrelated single- and multichain activating receptors. within the SCHOOL platform, ligand binding-induced receptor clustering is translated across the membrane into protein oligomerization in cytoplasmic milieu. This platform resolves a long-standing puzzle in transmembrane signal transduction and reveals the major driving forces coupling recognition and activation functions at the level of protein-protein interactions-biochemical processes that can be influenced and controlled. The basic principles of transmembrane signaling learned from the SCHOOL model can be used in different fields of immunology, virology, molecular and cell biology and others to describe, explain and predict various phenomena and processes mediated by a variety of functionally diverse and unrelated receptors. Beyond providing novel perspectives for fundamental research, the platform opens new avenues for drug discovery and development.
Collapse
Affiliation(s)
- Alexander B Sigalov
- Department of Pathology; University of Massachusetts Medical School; Worcester, MA USA
| |
Collapse
|
11
|
Signaling Chain Homooligomerization (SCHOOL) Model. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 640:121-63. [DOI: 10.1007/978-0-387-09789-3_12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
12
|
Ma Z, Sharp KA, Janmey PA, Finkel TH. Surface-anchored monomeric agonist pMHCs alone trigger TCR with high sensitivity. PLoS Biol 2008; 6:e43. [PMID: 18303949 PMCID: PMC2253636 DOI: 10.1371/journal.pbio.0060043] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Accepted: 01/08/2008] [Indexed: 12/03/2022] Open
Abstract
At the interface between T cell and antigen-presenting cell (APC), peptide antigen presented by MHC (pMHC) binds to the T cell receptor (TCR) and initiates signaling. The mechanism of TCR signal initiation, or triggering, remains unclear. An interesting aspect of this puzzle is that although soluble agonist pMHCs cannot trigger TCR even at high concentrations, the same ligands trigger TCR very efficiently on the surface of APCs. Here, using lipid bilayers or plastic-based artificial APCs with defined components, we identify the critical APC-associated factors that confer agonist pMHCs with such potency. We found that CD4+ T cells are triggered by very low numbers of monomeric agonist pMHCs anchored on fluid lipid bilayers or fixed plastic surfaces, in the absence of any other APC surface molecules. Importantly, on bilayers, plastic surfaces, or real APCs, endogenous pMHCs did not enhance TCR triggering. TCR triggering, however, critically depended upon the adhesiveness of the surface and an intact T cell actin cytoskeleton. Based on these observations, we propose the receptor deformation model of TCR triggering to explain the remarkable sensitivity and specificity of TCR triggering. Using the T cell receptor (TCR) as a sensor, T cells of the immune system constantly migrate in lymphoid organs and probe the surface of antigen-presenting cells (APCs) for foreign antigens, a sign of pathogen infection. Antigen binding by TCRs leads to T cell activation and subsequent immune response to combat the pathogens. Interestingly, although T cells respond well to antigens on APCs, they do not recognize the same antigens in solution. What is it that makes antigens on APCs recognizable? To address this, we used lipid bilayers and plastic surfaces to construct artificial APCs with defined antigen number, composition, and configuration. We found that T cells respond to very few individual foreign antigens on artificial APCs, and contrary to some current opinion, formation of antigen clusters on APCs is not required for antigen recognition by T cells. TCR triggering, however, requires T cell adhesion to the APC surface and then occurs only if the T cells are able to move. We propose that at the dynamic T cell–APC interface, antigen on APCs activates T cells by applying force to the TCR and deforming its structure, which cannot be achieved by soluble antigens due to their lack of anchorage. Why is it that T cells are blind to antigens in solution but highly sensitive to antigens anchored on a surface? The authors show that this is not due to antigen clustering, but could involve mechanical forces associated with cell locomotion.
Collapse
Affiliation(s)
- Zhengyu Ma
- Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- * To whom correspondence should be addressed. E-mail: (ZM); (THF)
| | - Kim A Sharp
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Paul A Janmey
- Institute for Medicine and Engineering, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Terri H Finkel
- Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- * To whom correspondence should be addressed. E-mail: (ZM); (THF)
| |
Collapse
|
13
|
Llanes-Fernández L, del Carmen Arango-Prado M, Alcocer-González JM, Guerra-Yi ME, Franco-Odio S, Camacho-Rodríguez R, Madrid-Marina V, Tamez-Guerra R, Rodríguez-Padilla C. Association between the expression of IL-10 and T cell activation proteins loss in early breast cancer patients. J Cancer Res Clin Oncol 2008; 135:255-64. [DOI: 10.1007/s00432-008-0446-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 06/26/2008] [Indexed: 11/28/2022]
|
14
|
The extracellular part of ζ is buried in the T cell antigen receptor complex. Immunol Lett 2008; 116:203-10. [DOI: 10.1016/j.imlet.2007.11.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 11/27/2007] [Accepted: 11/30/2007] [Indexed: 11/22/2022]
|
15
|
Minguet S, Swamy M, Schamel WWA. The short length of the extracellular domain of zeta is crucial for T cell antigen receptor function. Immunol Lett 2007; 116:195-202. [PMID: 18207249 DOI: 10.1016/j.imlet.2007.11.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 11/27/2007] [Accepted: 11/30/2007] [Indexed: 11/15/2022]
Abstract
The T cell antigen receptor (TCR-CD3) consists of the pMHC-binding TCRalphabeta heterodimer and the signalling dimers CD3deltaepsilon, CD3gammaepsilon and zetazeta. The very short length of the extracellular domain (EC) of the zeta chain is preserved through evolution, however a rational explanation for this observation has not been elucidated. Here, we show that TCR-CD3 assembly is clearly defective when the murine zeta EC domain is artificially enlarged. Under these conditions, the TCR-CD3 complex is super-competent in transducing activation signals upon engagement. Furthermore, the TCR-CD3 complexes containing enlarged zeta EC domains underwent ligand-induced conformation changes with higher efficiency than TCR-CD3 complexes with an unmodified zeta EC domain. Together these data suggest that a short zeta EC domain is needed to correctly assemble the TCR-CD3 complex. When this domain is enlarged, the resulting TCR-CD3 complex is distorted leading to a hyperactive phenotype and enhanced T cell activation.
Collapse
Affiliation(s)
- Susana Minguet
- Max Planck Institute of Immunbiology and Faculty of Biology III, University of Freiburg, Stübeweg 51, 79108 Freiburg, Germany
| | | | | |
Collapse
|
16
|
Abstract
Through T cell receptors (TCRs), T cells can detect and respond to very small numbers of foreign peptides among a huge number of self-peptides presented by major histocompatibility complexes (pMHCs) on the surface of antigen-presenting cells (APCs). How T cells achieve such remarkable sensitivity and specificity through pMHC-TCR binding is an intensively pursued issue in immunology today; the key question is how pMHC-TCR binding initiates, or triggers, a signal from TCRs. Multiple competing models have been proposed, none of which fully explains the sensitivity and specificity of TCR triggering. What has been omitted from existing theories is that the pMHC-TCR interaction at the T cell/APC interface must be under constant mechanical stress, due to the dynamic nature of cell-cell interaction. Taking this condition into consideration, we propose the receptor deformation model of TCR triggering. In this model, TCR signaling is initiated by conformational changes of the TCR/CD3 complex, induced by a pulling force originating from the cytoskeleton and transmitted through pMHC-TCR binding interactions with enough strength to resist rupture. By introducing mechanical force into a model of T cell signal initiation, the receptor deformation model provides potential mechanistic solutions to the sensitivity and specificity of TCR triggering.
Collapse
Affiliation(s)
- Zhengyu Ma
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
| | | | | |
Collapse
|
17
|
Kesti T, Ruppelt A, Wang JH, Liss M, Wagner R, Taskén K, Saksela K. Reciprocal regulation of SH3 and SH2 domain binding via tyrosine phosphorylation of a common site in CD3epsilon. THE JOURNAL OF IMMUNOLOGY 2007; 179:878-85. [PMID: 17617578 DOI: 10.4049/jimmunol.179.2.878] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recruitment of cellular signaling proteins by the CD3 polypeptides of the TCR complex mediates T cell activation. We have screened a human Src homology 3 (SH3) domain phage display library for proteins that can bind to the proline-rich region of CD3epsilon. This screening identified Eps8L1 (epidermal growth factor receptor pathway substrate 8-like 1) together with the N-terminal SH3 domain of Nck1 and Nck2 as its preferred SH3 partners. Studies with recombinant proteins confirmed strong binding of CD3epsilon to Eps8L1 and Nck SH3 domains. CD3epsilon bound well also to Eps8 and Eps8L3, and modestly to Eps8L2, but not detectably to other SH3 domains tested. Interestingly, binding of Nck and Eps8L1 SH3 domains was mapped to a PxxDY motif that shared its tyrosine residue (Y166) with the ITAM of CD3epsilon. Phosphorylation of this residue abolished binding of Eps/Nck SH3 domains in peptide spot filter assays, as well as in cells cotransfected with a dominantly active Lck kinase. TCR ligation-induced binding and phosphorylation-dependent loss of binding were also demonstrated between Eps8L1 and endogenous CD3epsilon in Jurkat T cells. Thus, phosphorylation of Y166 serves as a molecular switch during T cell activation that determines the capacity of CD3epsilon to interact with either SH3 or SH2 domain-containing proteins.
Collapse
Affiliation(s)
- Tapio Kesti
- Department of Virology, Haartman Institute, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland
| | | | | | | | | | | | | |
Collapse
|
18
|
Bello R, Feito MJ, Ojeda G, Portolés P, Rojo JM. Loss of N-terminal charged residues of mouse CD3 epsilon chains generates isoforms modulating antigen T cell receptor-mediated signals and T cell receptor-CD3 interactions. J Biol Chem 2007; 282:22324-34. [PMID: 17561508 DOI: 10.1074/jbc.m701875200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The antigen T cell receptor (TCR)-CD3 complexes present on the cell surface of CD4(+) T lymphocytes and T cell lines express CD3 epsilon chain isoforms with different isoelectric points (pI), with important structural and functional consequences. The pI values of the isoforms fit the predicted pI values of CD3 epsilon chains lacking one, two, and three negatively charged amino acid residues present in the N-terminal region. Different T cells have different ratios of CD3 epsilon chain isoforms. At a high pI, degraded CD3 epsilon isoforms can be better recognized by certain anti-CD3 monoclonal antibodies such as YCD3-1, the ability of which to bind to the TCR-CD3 complex is directly correlated with the pI of CD3 epsilon. The abundance of CD3 epsilon isoforms can be modified by treatment of T cells with the proteinase inhibitor phenanthroline. In addition, these CD3 epsilon isoforms have functional importance. This is shown, first, by the different structure of TCR-CD3 complexes in cells possessing different amounts of isoforms (as observed in surface biotinylation experiments), by their different antigen responses, and by the stronger interaction between low pI CD3 epsilon isoforms and the TCR. Second, incubation of cells with phenanthroline diminished the proportion of degraded high pI CD3 epsilon isoforms, but also the ability of the cells to deliver early TCR activation signals. Third, cells expressing mutant CD3 epsilon chains lacking N-terminal acid residues showed facilitated recognition by antibody YCD3-1 and enhanced TCR-mediated activation. Furthermore, the binding avidity of antibody YCD3-1 was different in distinct thymus populations. These results suggest that changes in CD3 epsilon N-terminal chains might help to fine-tune the response of the TCR to its ligands in distinct activation situations or in thymus selection.
Collapse
Affiliation(s)
- Raquel Bello
- Departamento de Fisiopatología Celular y Molecular, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, E-28040 Madrid, Spain
| | | | | | | | | |
Collapse
|
19
|
Sigalov AB. Immune cell signaling: a novel mechanistic model reveals new therapeutic targets. Trends Pharmacol Sci 2006; 27:518-24. [PMID: 16908074 DOI: 10.1016/j.tips.2006.08.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 07/12/2006] [Accepted: 08/03/2006] [Indexed: 10/24/2022]
Abstract
Multichain immune recognition receptors (MIRRs) represent a family of surface receptors that is expressed on different cells and that transduces extracellular signals, leading to many biological responses. The most intriguing common structural feature of MIRR family members is that the extracellular recognition domains and the intracellular signaling domains are located on separate subunits. It is not clear how extracellular ligand binding triggers MIRRs and initiates intracellular signal-transduction processes. In this article, I suggest that the structural similarity of the MIRRs provides the basis for the similarity in the mechanisms of MIRR-mediated transmembrane signaling. This hypothesis assumes that the therapeutic strategies learned from a novel mechanistic model of MIRR-mediated signal transduction, the signaling chain homo-oligomerization model, are generalized for this entire family and have important implications for the treatment of many disorders that are mediated by immune cells, including HIV.
Collapse
Affiliation(s)
- Alexander B Sigalov
- Department of Pathology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
| |
Collapse
|
20
|
Myers MD, Dragone LL, Weiss A. Src-like adaptor protein down-regulates T cell receptor (TCR)-CD3 expression by targeting TCRzeta for degradation. ACTA ACUST UNITED AC 2005; 170:285-94. [PMID: 16027224 PMCID: PMC2171412 DOI: 10.1083/jcb.200501164] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Src-like adaptor protein (SLAP) down-regulates expression of the T cell receptor (TCR)–CD3 complex during a specific stage of thymocyte development when the TCR repertoire is selected. Consequently, SLAP−/− thymocytes display alterations in thymocyte development. Here, we have studied the mechanism of SLAP function. We demonstrate that SLAP-deficient thymocytes have increased TCRζ chain expression as a result of a defect in TCRζ degradation. Failure to degrade TCRζ leads to an increased pool of fully assembled TCR–CD3 complexes that are capable of recycling back to the cell surface. We also provide evidence that SLAP functions in a pathway that requires the phosphorylated TCRζ chain and the Src family kinase Lck, but not ZAP-70 (ζ-associated protein of 70 kD). These studies reveal a unique mechanism by which SLAP contributes to the regulation of TCR expression during a distinct stage of thymocyte development.
Collapse
MESH Headings
- Animals
- Cell Line, Tumor
- Down-Regulation
- Humans
- Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/metabolism
- Membrane Proteins/biosynthesis
- Membrane Proteins/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Phosphorylation
- Protein Binding
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins pp60(c-src)/genetics
- Proto-Oncogene Proteins pp60(c-src)/metabolism
- Receptor-CD3 Complex, Antigen, T-Cell/biosynthesis
- Receptor-CD3 Complex, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/biosynthesis
- Receptors, Antigen, T-Cell/genetics
- Signal Transduction
- T-Lymphocytes/physiology
- ZAP-70 Protein-Tyrosine Kinase
- src Homology Domains
Collapse
Affiliation(s)
- Margaret D Myers
- Department of Medicine, Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, CA 94143, USA
| | | | | |
Collapse
|
21
|
Sigalov AB. Multichain immune recognition receptor signaling: different players, same game? Trends Immunol 2005; 25:583-9. [PMID: 15489186 DOI: 10.1016/j.it.2004.08.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Alexander B Sigalov
- Department of Pathology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
| |
Collapse
|
22
|
Chakraborty D, Banerjee S, Sen A, Banerjee KK, Das P, Roy S. Leishmania donovani Affects Antigen Presentation of Macrophage by Disrupting Lipid Rafts. THE JOURNAL OF IMMUNOLOGY 2005; 175:3214-24. [PMID: 16116212 DOI: 10.4049/jimmunol.175.5.3214] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Leishmania donovani-infected splenic macrophages and P388D1 (P388D1(I)) failed to activate T cells in response to low dose of exogenous peptide. The membrane fluidity of P388D1(I) was greater than that of the normal counterpart P388D1(N), but could be reduced either by exposing the cell below phase transition point or by loading cholesterol into membrane (L-P388D1(I)), and this was associated with enhanced Ag-presenting ability of P388D1(I). Presentation of endogenous leishmanial Ag, kinetoplastid membrane protein-11, was also defective, but could be corrected by loading cholesterol into membrane. Because membrane rafts are important for Ag presentation at a low peptide dose, raft architecture of P388D1(I) was studied using raft (CD48 and cholera toxin-B) and non-raft (CD71) markers in terms of their colocalization with I-A(d). Binding of anti-CD48 mAb and cholera toxin B subunit decreased significantly in P388D1(I), and consequently, colocalization with I-A(d) was not seen, but this could be restored in L-P388D1(I). Conversely, colocalization between I-A(d) and CD71 remained unaffected regardless of the presence or the absence of intracellular parasites. P388D1(N) and L-P388D1(I), but not P388D1(I), formed peptide-dependent synapse with T cells quite efficiently and this was found to be corroborated with both intracellular Ca2+ mobilization in T cells and IL-2 production. This indicated that intracellular parasites disrupt the membrane rafts, possibly by increasing the membrane fluidity, which could be corrected by making the membrane rigid. This may be a strategy that intracellular L. donovani adopts to evade host immune system.
Collapse
|
23
|
Szymczak AL, Workman CJ, Gil D, Dilioglou S, Vignali KM, Palmer E, Vignali DAA. The CD3ε Proline-Rich Sequence, and Its Interaction with Nck, Is Not Required for T Cell Development and Function. THE JOURNAL OF IMMUNOLOGY 2005; 175:270-5. [PMID: 15972658 DOI: 10.4049/jimmunol.175.1.270] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The CD3epsilon proline-rich sequence (PRS) binds to the cytosolic adaptor molecule Nck after TCR ligation. It has been proposed that this interaction is essential for immunological synapse formation and T cell activation. To assess the physiological importance of the CD3epsilon PRS, we have generated mice that lack this motif (CD3epsilon.PRS(M)). Pull-down experiments demonstrated the inability of Nck to bind to the CD3epsilon PRS in thymocytes from mutant mice after TCR ligation. Surprisingly, no differences were observed in the number and percentage of T cell subsets in the thymus and spleen, and there was no apparent defect in positive or negative selection. Furthermore, the proliferative response of CD3epsilon.PRS(M) T cells to staphylococcal enterotoxin B and anti-CD3 Ab was normal. TCR surface expression, constitutive internalization, and Ag-induced down-modulation were also normal. These data suggest that the interaction between the CD3epsilon PRS and Nck, or any other Src homology 3 domain-containing molecule, is not essential for T cell development and function.
Collapse
Affiliation(s)
- Andrea L Szymczak
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | | | | | | | | | | | | |
Collapse
|
24
|
Abstract
The mechanism by which the ligand occupancy state of the T cell receptor complex is converted into intracellular signaling information has been a controversial topic. Although the majority of structural studies argue against a conformational change, recent studies support the possibility for such a change within the CD3 components of the TCR complex. In this commentary, the evidence for TCR conformational change is reviewed and potential mechanisms for its initiation are explored.
Collapse
Affiliation(s)
- Susan E Levin
- Rosalind Russell Medical Research Center for Arthritis, Howard Hughes Medical Institute, University of California, San Francisco, CA 94143, USA
| | | |
Collapse
|
25
|
Cebecauer M, Guillaume P, Mark S, Michielin O, Boucheron N, Bezard M, Meyer BH, Segura JM, Vogel H, Luescher IF. CD8+ cytotoxic T lymphocyte activation by soluble major histocompatibility complex-peptide dimers. J Biol Chem 2005; 280:23820-8. [PMID: 15805102 DOI: 10.1074/jbc.m500654200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CD8+ cytotoxic T lymphocyte (CTL) can recognize and kill target cells that express only a few cognate major histocompatibility complex class I-peptide (pMHC) complexes. To better understand the molecular basis of this sensitive recognition process, we studied dimeric pMHC complexes containing linkers of different lengths. Although dimers containing short (10-30-A) linkers efficiently bound to and triggered intracellular calcium mobilization and phosphorylation in cloned CTL, dimers containing long linkers (> or = 80 A) did not. Based on this and on fluorescence resonance energy transfer experiments, we describe a dimeric binding mode in which two T cell receptors engage in an anti-parallel fashion two pMHC complexes facing each other with their constant domains. This binding mode allows integration of diverse low affinity interactions, which increases the overall binding and, hence, the sensitivity of antigen recognition. In proof of this, we demonstrated that pMHC dimers containing one agonist and one null ligand efficiently activate CTL, corroborating the importance of endogenous pMHC complexes in antigen recognition.
Collapse
Affiliation(s)
- Marek Cebecauer
- Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, 1066 Epalinges, Switzerland
| | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Li N, Workman CJ, Martin SM, Vignali DAA. Biochemical Analysis of the Regulatory T Cell Protein Lymphocyte Activation Gene-3 (LAG-3; CD223). THE JOURNAL OF IMMUNOLOGY 2004; 173:6806-12. [PMID: 15557174 DOI: 10.4049/jimmunol.173.11.6806] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Lymphocyte activation gene-3 (LAG-3; CD223) is a CD4-related transmembrane protein that binds to MHC class II molecules. We have recently shown that LAG-3 is required for maximal regulatory T cell function, and that ectopic expression of LAG-3 is sufficient to confer regulatory activity. In this study we show that LAG-3 is cleaved within the D4 transmembrane domain connecting peptide into two fragments that remain membrane associated: a 54-kDa fragment that contains all the extracellular domains and oligomerizes with full-length LAG-3 (70 kDa) on the cell surface via the D1 domain, and a 16-kDa peptide that contains the transmembrane and cytoplasmic domains. This NH(2)-terminal fragment is subsequently released as soluble LAG-3 (sLAG-3), a process that is increased after T cell activation in vitro and in vivo, and is found in the sera of C57BL/6 and RAG-1(-/-) mice. Modulation of LAG-3 cleavage may contribute to the function of this key regulatory T cell protein.
Collapse
Affiliation(s)
- Nianyu Li
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | | | | | | |
Collapse
|