Puromycin-sensitive aminopeptidase limits MHC class I presentation in dendritic cells but does not affect CD8 T cell responses during viral infections
Department of Pathology
Life Sciences | Medicine and Health Sciences
Previous experiments using enzyme inhibitors, cell lysates, and purified enzyme have suggested that puromycin-sensitive aminopeptidase (PSA) plays a role in creating and destroying MHC class I-presented peptides although its precise contribution to these processes is unknown. To examine the importance of this enzyme in MHC class I Ag presentation, we have generated PSA-deficient mice and cell lines from these animals. PSA-deficient mice are smaller and do not reproduce as well as wild type mice. In addition, dendritic cells from PSA-deficient mice display more MHC class I molecules on the cell surface, suggesting that PSA normally limits Ag presentation by destroying certain peptides in these key APCs. Surprisingly, MHC class I levels are not altered on other PSA-deficient cells and the processing and presentation of peptide precursors in PSA-deficient fibroblasts is normal. Moreover, PSA-deficient mice have normal numbers of T cells in the periphery, and respond as well as wild type mice to eight epitopes from three viruses. These data indicate that PSA may play a role in limiting MHC class I Ag presentation in dendritic cells in vivo but that it is not essential for generating most MHC class I-presented peptides or for stimulating CTL responses to several Ags.
J Immunol. 2008 Feb 1;180(3):1704-12.
Journal of immunology (Baltimore, Md. : 1950)
Towne, Charles Fenton; York, Ian A.; Neijssen, Joost J.; Karow, Margaret L.; Murphy, Andrew J.; Valenzuela, David M.; Yancopoulos, George D.; Neefjes, Jacques J.; and Rock, Kenneth L., "Puromycin-sensitive aminopeptidase limits MHC class I presentation in dendritic cells but does not affect CD8 T cell responses during viral infections" (2008). GSBS Student Publications. 1433.