Abstract
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.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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ADP Ribose Transferases / pharmacology
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Adjuvants, Immunologic*
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Adoptive Transfer
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Animals
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Antigen Presentation / immunology*
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Bacterial Toxins / pharmacology
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Bone Marrow Cells / immunology
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Cancer Vaccines / immunology*
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Cancer Vaccines / pharmacokinetics
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Cell Lineage
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Cells, Cultured
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Cross-Priming / immunology*
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Cytosol / metabolism
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Dendritic Cells / classification
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Dendritic Cells / immunology*
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Endocytosis / immunology
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Endoplasmic Reticulum / immunology*
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Endosomes / metabolism
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Exotoxins / pharmacology
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Glycoproteins / immunology*
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HSP70 Heat-Shock Proteins / immunology*
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Membrane Proteins / antagonists & inhibitors
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Membrane Proteins / genetics
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Membrane Proteins / physiology
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Mice
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Mice, Inbred C57BL
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Mice, Transgenic
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Protein Processing, Post-Translational
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Protein Transport
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Proteolysis
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Pseudomonas aeruginosa Exotoxin A
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RNA, Small Interfering / pharmacology
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Recombinant Fusion Proteins / immunology
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Recombinant Fusion Proteins / pharmacokinetics
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SEC Translocation Channels
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Spleen / cytology
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Spleen / immunology
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T-Lymphocytes, Cytotoxic / immunology*
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Ubiquitination
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Vaccination / methods*
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Virulence Factors / pharmacology
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gp100 Melanoma Antigen / genetics
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gp100 Melanoma Antigen / immunology*
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gp100 Melanoma Antigen / pharmacokinetics
Substances
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Adjuvants, Immunologic
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Bacterial Toxins
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Cancer Vaccines
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Exotoxins
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Glycoproteins
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HSP70 Heat-Shock Proteins
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Membrane Proteins
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RNA, Small Interfering
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Recombinant Fusion Proteins
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SEC Translocation Channels
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SEC61A1 protein, mouse
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Virulence Factors
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glucose-regulated protein 170
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gp100 Melanoma Antigen
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ADP Ribose Transferases