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The cytoplasmic tail of invariant chain modulates antigen processing and presentation
Tone F Gregers1, Tommy W Nordeng, Hanne C G Birkeland
1Division of Molecular Cell Biology, Department of Biology, University of Oslo, Oslo, Norway.
European Journal of Immunology
|January 28, 2003
Summary
High invariant chain (Ii) levels delay antigen and Ii degradation, impairing antigen presentation. A mutant Ii lacking specific cytoplasmic tail charges prevents this delay, highlighting Ii's role in modulating immune responses.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- The MHC class II-associated invariant chain (Ii) is crucial for antigen processing and presentation.
- Understanding Ii's function in endocytic transport is key to deciphering immune responses.
Purpose of the Study:
- To investigate the impact of Iip33 expression on endocytic transport and antigen presentation.
- To elucidate the role of the invariant chain's cytoplasmic tail in modulating these processes.
Main Methods:
- Expression of wild-type and mutant invariant chain (Ii) in cells.
- Analysis of endocytic transport and degradation of endocytosed antigens and Ii.
- Assessment of MHC class II-restricted epitope presentation.
Main Results:
- High levels of wild-type Iip33 expression delayed the degradation of both endocytosed antigen and Ii.
- A mutant Ii with altered cytoplasmic tail charge distribution did not cause this degradation delay.
- The Ii mutant showed reduced enhancement of an Ii-dependent MHC class II-restricted epitope presentation.
- Exposed negative charges in the Ii cytoplasmic tail promote endosome fusion, leading to endosomal retention.
Conclusions:
- The Iip33 cytoplasmic tail possesses a property that modulates antigen processing and presentation.
- Charge distribution in the Ii cytoplasmic tail influences endocytic transport and antigen presentation efficiency.
- Invariant chain's role extends to regulating endosome fusion and retention, impacting immune cell function.