MHC class I antigen processing distinguishes endogenous antigens based on their translation from cellular vs. viral mRNA

BP Dolan, AA Sharma, JS Gibbs… - Proceedings of the …, 2012 - National Acad Sciences
BP Dolan, AA Sharma, JS Gibbs, TJ Cunningham, JR Bennink, JW Yewdell
Proceedings of the National Academy of Sciences, 2012National Acad Sciences
To better understand the generation of MHC class I-associated peptides, we used a model
antigenic protein whose proteasome-mediated degradation is rapidly and reversibly
controlled by Shield-1, a cell-permeant drug. When expressed from a stably transfected
gene, the efficiency of antigen presentation is∼ 2%, that is, one cell-surface MHC class I–
peptide complex is generated for every 50 folded source proteins degraded upon Shield-1
withdrawal. By contrast, when the same protein is expressed by vaccinia virus, its antigen …
To better understand the generation of MHC class I-associated peptides, we used a model antigenic protein whose proteasome-mediated degradation is rapidly and reversibly controlled by Shield-1, a cell-permeant drug. When expressed from a stably transfected gene, the efficiency of antigen presentation is ∼2%, that is, one cell-surface MHC class I–peptide complex is generated for every 50 folded source proteins degraded upon Shield-1 withdrawal. By contrast, when the same protein is expressed by vaccinia virus, its antigen presentation efficiency is reduced ∼10-fold to values similar to those reported for other vaccinia virus-encoded model antigens. Virus infection per se does not modify the efficiency of antigen processing. Rather, the efficiency difference between cellular and virus-encoded antigens is based on whether the antigen is synthesized from transgene- vs. virus-encoded mRNA. Thus, class I antigen-processing machinery can distinguish folded proteins based on the precise details of their synthesis to modulate antigen presentation efficiency.
National Acad Sciences