Related Experiment Videos
Two distinct pathways mediated by PA28 and hsp90 in major histocompatibility complex class I antigen processing
Taketoshi Yamano1, Shigeo Murata, Naoki Shimbara
1Department of Molecular Medicine, Division of Immunology, Nagasaki University School of Medicine, Nagasaki 852-8523, Japan.
The Journal of Experimental Medicine
|July 18, 2002
Summary
Two pathways regulate antigen processing for MHC class I presentation: one uses proteasome activator (PA28), the other heat shock protein 90 (hsp90). Hsp90 compensates for PA28 deficiency, while interferon-gamma enhances the PA28 pathway.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- Major histocompatibility complex (MHC) class I molecules present intracellular antigens to T cells.
- The proteasome is the primary enzyme complex responsible for generating peptides for MHC class I presentation.
Purpose of the Study:
- To investigate the roles of heat shock protein 90 (hsp90) and proteasome activator (PA28) in antigen processing.
- To elucidate the interplay between hsp90, PA28, and interferon-gamma (IFN-γ) in regulating MHC class I ligand generation.
Main Methods:
- Utilized ovalbumin (OVA) as a model antigen.
- Employed PA28-deficient cells and wild-type cells.
- Used geldanamycin, an hsp90 inhibitor, and IFN-γ treatment.
Main Results:
- Both hsp90 and PA28 enhance OVA antigen processing.
- Hsp90 compensates for PA28 deficiency in antigen presentation.
- IFN-γ treatment enhances the PA28-dependent pathway while diminishing the hsp90-dependent pathway.
- IFN-γ-induced MHC class I expression is dependent on PA28.
Conclusions:
- Two distinct pathways, one involving PA28 and the other hsp90, regulate antigen processing for MHC class I presentation.
- These pathways can operate redundantly or specifically based on antigen type and cell context.
- PA28 plays a crucial role in IFN-γ-stimulated peptide supply for MHC class I.