Enhanced endoplasmic reticulum entry of tumor antigen is crucial for cross-presentation induced by dendritic cell-targeted vaccination.
Efficient cross-presentation of protein Ags to CTLs by dendritic cells (DCs) is essential for the success of prophylactic and therapeutic vaccines. In this study, we report a previously underappreciated pathway involving Ag entry into the endoplasmic reticulum (ER) critically needed for T cell cross-priming induced by a DC-targeted vaccine. Directing the clinically relevant, melanoma Ag gp100 to mouse-derived DCs by molecular adjuvant and chaperone Grp170 substantially facilitates Ag access to the ER. Grp170 also strengthens the interaction of internalized protein Ag with molecular components involved in ER-associated protein dislocation and/or degradation, which culminates in cytosolic translocation for proteasome-dependent degradation and processing. Targeted disruption of protein retrotranslocation causes exclusive ER retention of tumor Ag in mouse bone marrow-derived DCs and splenic CD8(+) DCs. This results in the blockade of Ag ubiquitination and processing, which abrogates the priming of Ag-specific CD8(+) T cells in vitro and in vivo. Therefore, the improved ER entry of tumor Ag serves as a molecular basis for the superior cross-presenting capacity of Grp170-based vaccine platform. The ER access and retrotranslocation represents a distinct pathway that operates within DCs for cross-presentation and is required for the activation of Ag-specific CTLs by certain vaccines. These results also reinforce the importance of the ER-associated protein quality control machinery and the mode of the Ag delivery in regulating DC-elicited immune outcomes.
Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298;
Hongxia
H
Wang
Xiaofei
X
Yu
Chunqing
C
Guo
Daming
D
Zuo
Paul B
PB
Fisher
John R
JR
Subjeck
Xiang-Yang
XY
Wang
D036002:ADP Ribose Transferases / Q000494:pharmacology; D000276:Adjuvants, Immunologic; D019264:Adoptive Transfer; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D001427:Bacterial Toxins / Q000494:pharmacology; D001854:Bone Marrow Cells / Q000276:immunology; D019496:Cancer Vaccines / Q000276:immunology* / Q000493:pharmacokinetics; D019070:Cell Lineage; D002478:Cells, Cultured; D045142:Cross-Priming / Q000276:immunology*; D003600:Cytosol / Q000378:metabolism; D003713:Dendritic Cells / Q000145:classification / Q000276:immunology*; D004705:Endocytosis / Q000276:immunology; D004721:Endoplasmic Reticulum / Q000276:immunology*; D011992:Endosomes / Q000378:metabolism; D005098:Exotoxins / Q000494:pharmacology; D006023:Glycoproteins / Q000276:immunology*; D018840:HSP70 Heat-Shock Proteins / Q000276:immunology*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D059748:Proteolysis; D034741:RNA, Small Interfering / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000493:pharmacokinetics; D000069816:SEC Translocation Channels; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D054875:Ubiquitination; D014611:Vaccination / Q000379:methods*; D037521:Virulence Factors / Q000494:pharmacology; D058951:gp100 Melanoma Antigen / Q000235:genetics / Q000276:immunology* / Q000493:pharmacokinetics; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D000276:Adjuvants, Immunologic; D001427:Bacterial Toxins; D019496:Cancer Vaccines; D005098:Exotoxins; D006023:Glycoproteins; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D000069816:SEC Translocation Channels; D037521:Virulence Factors; D058951:gp100 Melanoma Antigen; D000097668:Pseudomonas aeruginosa Exotoxin A; C577653:SEC61A1 protein, mouse; C098410:glucose-regulated protein 170