| First Author | Shen KY | Year | 2014 |
| Journal | J Immunol | Volume | 192 |
| Issue | 9 | Pages | 4233-41 |
| PubMed ID | 24683188 | Mgi Jnum | J:209973 |
| Mgi Id | MGI:5569192 | Doi | 10.4049/jimmunol.1302850 |
| Citation | Shen KY, et al. (2014) Molecular mechanisms of TLR2-mediated antigen cross-presentation in dendritic cells. J Immunol 192(9):4233-41 |
| abstractText | Cross-presentation is a key function of dendritic cells (DCs), which present exogenous Ags on MHC class I molecules to prime CTL responses. The effects of TLR triggering on the cross-presentation of exogenous Ags by DCs remain unclear. In this study, we used synthetic dipalmitoylated peptides and TLR2 agonist-conjugated peptides as models to elucidate the mechanisms of TLR2-mediated cross-presentation. We observed that the internalization of dipalmitoylated peptides by bone marrow-derived DCs was facilitated by TLR2 via clathrin-mediated endocytosis. The administration of these dipalmitoylated peptide-pulsed bone marrow-derived DCs eliminated established tumors through TLR2 signaling. We further demonstrated that the induction of Ag-specific CTL responses and tumor regression by dipalmitoylated peptides was TAP independent. In addition, presentation of dipalmitoylated peptides by MHC class I molecules was blocked in the presence of an endosomal acidification inhibitor (chloroquine) or a lysosomal degradation inhibitor (Z-FL-COCHO). The endocytosed dipalmitoylated peptide also passed rapidly from early endosome Ag-1-positive endosomes to RAS-related GTP-binding protein 7 (Rab7)-associated late endosomes compared with their nonlipidated counterparts. Furthermore, we found that dipalmitoylated peptide-upregulated Rab7 expression correlated with Ag presentation via the TLR2/MyD88 pathway. Both JNK and ERK signaling pathways are required for upregulation of Rab7. In summary, our data suggest that TLR2-mediated cross-presentation occurs through the upregulation of Rab7 and a TAP-independent pathway that prime CTL responses. |
