The objective of this proposal is to analyze the kinetic properties and elucidate the regulatory mechanisms of molecular interactions of the T cell receptor (TCR) and coreceptor CD8 with peptide-major histocompatibility complex (pMHC) molecules, which are the first step of antigen recognition by the T cell and trigger adaptive immune responses. Our studies differ from previous binding studies in fluid phase using soluble molecules (three-dimensional or 3D binding) by analyzing these interactions in situ at the two- dimensional (2D) cross-junctional interface between a T cell and a surrogate antigen presenting cell using assays invented by the PI, which keeps the TCR and CD8 in their native environment with all regulatory mechanisms intact. Our preliminary data show drastic differences between 2D and 3D binding, including 1) 2D TCR/pMHC kinetics correlates with T cell response; 2) 2D analysis enables in situ measurements of TCR/pMHC/CD8 trimeric interactions and of antigen-induced TCR-CD8 cooperation via Lck-dependent signaling; 3) 2D parameters can be perturbed by pharmacological agents that inhibit signaling and/or disrupt the lateral organization of the cel membrane and cytoskeleton. Our hypothesis is that 2D kinetics of TCR and CD8 for pMHC binding determines a variety of functions of T cells in different stages, including discrimination f pathogens from self-antigens, thymic selection during development, and activation. This broad hypothesis will be tested in three integrated specific aims: 1) elucidate the mechanisms underlying how and why 2D kinetic parameters determine T cell responsiveness by determining whether and how they can be related to 3D kinetic parameters; 2) compare the 2D kinetics of pMHC binding to naive vs. activated, effector, and memory T cells, the resulting calcium signaling, and their correlations with T-cell responses; and 3) analyze 2D kinetics of pMHC binding to thymocytes in different maturation states and the resulting calcium signaling to determine thresholds for thymic selection. These studies will provide a new paradigm for understanding the kinetic requirements for interaction and cooperation of the TCR and CD8 as related to signaling initiation upon pMHC binding and serve as a foundation for a better understanding of a variety of immune functions.

Public Health Relevance

We propose to analyze the kinetic properties and elucidate the regulatory mechanisms of the molecular interactions of the T cell receptor and coreceptor CD8 with peptide-major histocompatibility complex molecules between a T cell and a target cell. These interactions are the first step of antigen recognition by the T cell and trigger adaptive immune responses, which contributes to defense against infection and is involved in a wide range of diseases including cancer, immunodeficiencies, autoimmunity, allergy, transplant rejection, and declined immune functions associated with aging.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
High Priority, Short Term Project Award (R56)
Project #
2R56AI038282-11A1
Application #
8533505
Study Section
Cellular and Molecular Immunology - A Study Section (CMIA)
Program Officer
Lapham, Cheryl K
Project Start
1995-09-01
Project End
2013-08-31
Budget Start
2012-09-01
Budget End
2013-08-31
Support Year
11
Fiscal Year
2012
Total Cost
$388,518
Indirect Cost
$124,768
Name
Georgia Institute of Technology
Department
Engineering (All Types)
Type
Schools of Engineering
DUNS #
097394084
City
Atlanta
State
GA
Country
United States
Zip Code
30332
Seo, Young-Jin; Jothikumar, Prithiviraj; Suthar, Mehul S et al. (2016) Local Cellular and Cytokine Cues in the Spleen Regulate In Situ T Cell Receptor Affinity, Function, and Fate of CD8(+) T Cells. Immunity 45:988-998
Liu, Baoyu; Chen, Wei; Natarajan, Kannan et al. (2015) The cellular environment regulates in situ kinetics of T-cell receptor interaction with peptide major histocompatibility complex. Eur J Immunol 45:2099-110
Hong, Jinsung; Persaud, Stephen P; Horvath, Stephen et al. (2015) Force-Regulated In Situ TCR-Peptide-Bound MHC Class II Kinetics Determine Functions of CD4+ T Cells. J Immunol 195:3557-64
Chen, Yunfeng; Liu, Baoyu; Ju, Lining et al. (2015) Fluorescence Biomembrane Force Probe: Concurrent Quantitation of Receptor-ligand Kinetics and Binding-induced Intracellular Signaling on a Single Cell. J Vis Exp :e52975
Liu, Baoyu; Chen, Wei; Evavold, Brian D et al. (2014) Accumulation of dynamic catch bonds between TCR and agonist peptide-MHC triggers T cell signaling. Cell 157:357-68
Zhu, Cheng (2014) Mechanochemitry: a molecular biomechanics view of mechanosensing. Ann Biomed Eng 42:388-404
Liu, Baoyu; Zhong, Shi; Malecek, Karolina et al. (2014) 2D TCR-pMHC-CD8 kinetics determines T-cell responses in a self-antigen-specific TCR system. Eur J Immunol 44:239-50
Casas, Javier; Brzostek, Joanna; Zarnitsyna, Veronika I et al. (2014) Ligand-engaged TCR is triggered by Lck not associated with CD8 coreceptor. Nat Commun 5:5624
Pryshchep, Sergey; Zarnitsyna, Veronika I; Hong, Jinsung et al. (2014) Accumulation of serial forces on TCR and CD8 frequently applied by agonist antigenic peptides embedded in MHC molecules triggers calcium in T cells. J Immunol 193:68-76
Chen, Wei; Zhu, Cheng (2013) Mechanical regulation of T-cell functions. Immunol Rev 256:160-76

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