Heat shock protein 90 targets a chaperoned peptide to the static early endosome for efficient cross-presentation by human dendritic cells.
Bottom Line: In this study, we found that an Hsp90-cancer antigen peptide complex was efficiently cross-presented by human monocyte-derived DCs and induced peptide-specific CTLs.Furthermore, we observed that the internalized Hsp90-peptide complex was strictly sorted to the Rab5(+), EEA1(+) static early endosome and the Hsp90-chaperoned peptide was processed and bound to MHC class I molecules through an endosome-recycling pathway.Our data indicate that targeting of the antigen to a "static" early endosome by Hsp90 is essential for efficient cross-presentation.
Affiliation: Department of Pathology, Sapporo Medical University School of Medicine, Sapporo, Japan; United Graduate School of Veterinary Sciences, Yamaguchi University, Yamaguchi, Japan.Show MeSH
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Mentions: We first examined whether human Hsp90 facilitated cross-presentation of the chaperoned precursor peptide by human Mo-DCs. The Mo-DCs were pulsed with Hsp90 alone, the survivin-2B75-93 precursor peptide alone, a simple mixture of both, a complex of them generated in vitro at double concentration, or survivin-2B80-88 peptide (for positive control) for 2 h at 37°C and then fixed, washed, and cultured with survivin-2B80-88-specific CTL clone. The Hsp90–survivin-2B75-93 precursor peptide complex elicited a significant amount of IFN-γ production both at 100 and 100 μg/mL, whereas Hsp90 alone, survivin-2B75-93 precursor peptide alone, or a simple mixture of both did not induce IFN-γ production by CTLs (Fig.1a). Strikingly, IFN-γ production induced by Hsp90–survivin-2B precursor peptide complex was much greater than that induced by survivin-2B peptide. These results indicated that cross-presentation of survivin-2B-derived peptide was enhanced when an exogenous precursor peptide was complexed to Hsp90. To confirm these observations, we compared the efficacy of CTL activation between survivin-2B80-88 peptide and Hsp90–survivin-2B75-93 precursor peptide complex in a dose titration assay (Fig.1b). We observed that stimulation of the survivin-2B80-88-specific CTL clone with Hsp90–survivin-2B75-93 precursor peptide complex was more effective than stimulation with survivin-2B80-88 peptide at any dose.
Affiliation: Department of Pathology, Sapporo Medical University School of Medicine, Sapporo, Japan; United Graduate School of Veterinary Sciences, Yamaguchi University, Yamaguchi, Japan.