Major Histocompatibility Complex (MHC) class I glycoproteins, the products of HLA-A, B and C genes in humans, are critical for T cell mediated immune responses to viruses and intracellular pathogens. They are glycoproteins that form a heterodimer with a small molecule, ?2-microglobulin (?2m), and associate in the endoplasmic reticulum (ER) of a cell with peptides derived from cellular proteins. These include, when the cell is infected, pathogen-encoded proteins. Surface complexes of MHC class I molecules with pathogen-derived peptides are recognized by CD8-positive T cells that can kill the infected cell. The goal of this proposal is to understand the detailed molecular processes that result in the formation and cell surface expression of MHC class I complexes that contain peptides of extraordinarily high affinity, which is essential for CD8-T cell responses that can rid an infected individual of the pathogen. Binding of peptides to MHC class I molecules occurs within a multi-protein assembly called the Peptide Loading Complex, or PLC. The PLC consists of MHC class I molecules themselves, a heterodimeric transporter called the Transporter associated with Antigen Processing (TAP) that delivers the peptides into the ER, tapasin, a membrane glycoprotein that, with a soluble molecule, ERp57, forms a disulfide-linked heterodimer that can mediate peptide exchange by the class I molecules to ultimately generate high affinity complexes, and a second soluble protein called calreticulin. The interactions responsible for the stability of the PLC involve specific associations of TAP and tapasin within the membrane, and between the luminal domains of tapasin and the MHC class I molecule. There are also interactions between ERp57 and calreticulin and a glycan-dependent interaction of the MHC class I glycoprotein with calreticulin that are shared by other folding glycoproteins in the ER. Th glycan structure is characteristically dynamically maintained by the action of two opposing enzymes, one, glucosidase II, that removes a terminal glucose residue, and a second, UDP-glucose glycoprotein transferase 1 (UGT1) that replaces the glucose when the glycoprotein bearing the glycan is improperly folded. This proposal seeks to determine the roles of these various interactions and enzymatic mechanisms in mediating the assembly of MHC class I molecules with high affinity peptides in the ER.

Public Health Relevance

CD8-positive T cells eliminate virally infected cells from infected individuals and are critical for effective immune responses. They recognize a complex on the surface of an infected cell comprised of a peptide derived from a viral protein and, in humans, an HLA-A, B or C molecule encoded by the infected cell. This proposal seeks to understand in detail how the HLA-peptide complexes, critical for recognition by the T cells, are made.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI097206-03
Application #
8662182
Study Section
Cellular and Molecular Immunology - B Study Section (CMIB)
Program Officer
Gondre-Lewis, Timothy A
Project Start
2012-06-15
Project End
2016-05-31
Budget Start
2014-06-01
Budget End
2015-05-31
Support Year
3
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Yale University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
City
New Haven
State
CT
Country
United States
Zip Code
06510
Arshad, Najla; Cresswell, Peter (2018) Tumor-associated calreticulin variants functionally compromise the peptide loading complex and impair its recruitment of MHC-I. J Biol Chem 293:9555-9569
Lu, Qiao; Grotzke, Jeff E; Cresswell, Peter (2018) A novel probe to assess cytosolic entry of exogenous proteins. Nat Commun 9:3104
Grotzke, Jeff E; Kozik, Patrycja; Morel, Jean-David et al. (2017) Sec61 blockade by mycolactone inhibits antigen cross-presentation independently of endosome-to-cytosol export. Proc Natl Acad Sci U S A 114:E5910-E5919
Grotzke, Jeff E; Sengupta, Debrup; Lu, Qiao et al. (2017) The ongoing saga of the mechanism(s) of MHC class I-restricted cross-presentation. Curr Opin Immunol 46:89-96
Grotzke, Jeff E; Cresswell, Peter (2015) Are ERAD components involved in cross-presentation? Mol Immunol 68:112-5
Samie, Mohammad; Cresswell, Peter (2015) The transcription factor TFEB acts as a molecular switch that regulates exogenous antigen-presentation pathways. Nat Immunol 16:729-36
Leonhardt, Ralf M; Abrahimi, Parwiz; Mitchell, Susan M et al. (2014) Three tapasin docking sites in TAP cooperate to facilitate transporter stabilization and heterodimerization. J Immunol 192:2480-94
Grotzke, Jeff E; Lu, Qiao; Cresswell, Peter (2013) Deglycosylation-dependent fluorescent proteins provide unique tools for the study of ER-associated degradation. Proc Natl Acad Sci U S A 110:3393-8
Blum, Janice S; Wearsch, Pamela A; Cresswell, Peter (2013) Pathways of antigen processing. Annu Rev Immunol 31:443-73
Panter, Michaela S; Jain, Ankur; Leonhardt, Ralf M et al. (2012) Dynamics of major histocompatibility complex class I association with the human peptide-loading complex. J Biol Chem 287:31172-84

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