| First Author | Belizaire R | Year | 2009 |
| Journal | Proc Natl Acad Sci U S A | Volume | 106 |
| Issue | 41 | Pages | 17463-8 |
| PubMed ID | 19805168 | Mgi Jnum | J:153672 |
| Mgi Id | MGI:4366094 | Doi | 10.1073/pnas.0908583106 |
| Citation | Belizaire R, et al. (2009) Targeting proteins to distinct subcellular compartments reveals unique requirements for MHC class I and II presentation. Proc Natl Acad Sci U S A 106(41):17463-8 |
| abstractText | Peptides derived from exogenous proteins are presented by both MHC class I and II. Despite extensive study, the features of the endocytic pathway that mediate cross-presentation of exogenous antigens on MHC class I are not entirely understood and difficult to generalize to all proteins. Here, we used dendritic cells and macrophages to examine MHC class I and II presentation of hen egg-white lysozyme (HEL) in different forms, soluble and liposome encapsulated. Soluble HEL or HEL targeted to a late endosomal compartment only allowed for MHC class II presentation, in a process that was blocked by chloroquine and a cathepsin S (CatS) inhibitor; brefeldin A (BFA) also blocked presentation, indicating a requirement for nascent MHC class II. In contrast, liposome-encapsulated HEL targeted to early endosomes entered the MHC class I and II presentation pathways. Cross-presentation of HEL in early endosomal liposomes had several unique features: it was markedly increased by BFA and by blockade of the proteasome or CatS activity, it occurred independently of the transporter associated with antigen processing but required an MHC class I surface-stabilizing peptide, and it was inhibited by chloroquine. Remarkably, chloroquine facilitated MHC class I cross-presentation of soluble HEL and HEL in late endosomal liposomes. Altogether, MHC class I and II presentation of HEL occurred through pathways having distinct molecular and proteolytic requirements. Moreover, MHC class I sampled antigenic peptides from various points along the endocytic route. |
