The molecular events that regulate MHC restricted antigen presentation are poorly understood at this time. This proposal is based on the hypotheses that MHC Class II-peptide interactions are initiated in an intracellular compartment and that the intracellular trafficking patterns that lead to expression of an MHC-antigen complex at the cell surface are regulated events. We will use molecular and biochemical approaches to define the intracellular sorting events that lead to Class II localization in specific intracellular compartments in the endocytic pathway. Specifically, we will test our hypothesis that sequences within the Class II molecule (beta 80-84) control localization within late endosomal or lysosomal compartments by transferring the Class II sequence to a Class I molecule and determining if this altered Class I sequence is localized in the endocytic pathway. In addition, we will use a mutant class II molecule that lacks endosomal localization in the absence of Ii, but is dramatically localized in these compartments in the presence of Ii, to dissect the mechanism by which invariant chain enhances the expression of Class II molecules in the endocytic compartments of APC. In addition to these genetic techniques, two different methods (vectorial tagging of endosomal proteins and endosome vesicle purification using colloidal iron and electromagnetic isolation) will be established to selectively isolate proteins expressed in the endocytic pathway. These techniques, coupled with biochemical analyses of MHC and associated molecules will be used to define the sequence of events that leads to selective trafficking of MHC Class II and invariant chain molecules into the endocytic compartments, localization in specific subcompartments in this pathway and egress from these compartments for expression at the cell surface. Finally, because the goal of this work is to identify the importance of intracellular activities of Class II with antigen presentation, we will perform functional analyses on APC that have been constructed to vary in the sites of Class II localization. These APC will be used in antigen presentation assays designed to both concentrate and localize antigens in subsites within the endocytic pathway. The results of our analyses will allow us to understand the molecular events that regulate formation of peptide:Class II complexes at the cell surface for recognition by CD4 T cells leading to protective immune responses or to autoimmune phenomena.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
1R01AI034359-01A1
Application #
2069485
Study Section
Immunobiology Study Section (IMB)
Project Start
1994-05-01
Project End
1998-01-31
Budget Start
1994-05-01
Budget End
1995-01-31
Support Year
1
Fiscal Year
1994
Total Cost
Indirect Cost
Name
University of Chicago
Department
Pathology
Type
Schools of Medicine
DUNS #
225410919
City
Chicago
State
IL
Country
United States
Zip Code
60637
McFarland, Benjamin J; Katz, John F; Sant, Andrea J et al. (2005) Energetics and cooperativity of the hydrogen bonding and anchor interactions that bind peptides to MHC class II protein. J Mol Biol 350:170-83
Chaves, Francisco A; Hou, Ping; Wu, Shenhong et al. (2005) Replacement of the membrane proximal region of I-A(d) MHC class II molecule with I-E-derived sequences promotes production of an active and stable soluble heterodimer without altering peptide-binding specificity. J Immunol Methods 300:74-92
Lazarski, Christopher A; Chaves, Francisco A; Jenks, Scott A et al. (2005) The kinetic stability of MHC class II:peptide complexes is a key parameter that dictates immunodominance. Immunity 23:29-40
McFarland, B J; Katz, J F; Beeson, C et al. (2001) Energetic asymmetry among hydrogen bonds in MHC class II*peptide complexes. Proc Natl Acad Sci U S A 98:9231-6
Arneson, L S; Katz, J F; Liu, M et al. (2001) Hydrogen bond integrity between MHC class II molecules and bound peptide determines the intracellular fate of MHC class II molecules. J Immunol 167:6939-46
Arneson, L S; Peterson, M; Sant, A J (2000) The MHC class II molecule I-Ag7 exists in alternate conformations that are peptide dependent. J Immunol 165:2059-67
McFarland, B J; Sant, A J; Lybrand, T P et al. (1999) Ovalbumin(323-339) peptide binds to the major histocompatibility complex class II I-A(d) protein using two functionally distinct registers. Biochemistry 38:16663-70
McFarland, B J; Beeson, C; Sant, A J (1999) Cutting edge: a single, essential hydrogen bond controls the stability of peptide-MHC class II complexes. J Immunol 163:3567-71
Ceman, S; Wu, S; Jardetzky, T S et al. (1998) Alteration of a single hydrogen bond between class II molecules and peptide results in rapid degradation of class II molecules after invariant chain removal. J Exp Med 188:2139-49
Peterson, M; Sant, A J (1998) The inability of the nonobese diabetic class II molecule to form stable peptide complexes does not reflect a failure to interact productively with DM. J Immunol 161:2961-7

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