title: Induction of endoplasmic reticulum-endosome fusion for antigen cross-presentation induced by poly (γ-glutamic acid) nanoparticles.
abstract: We previously reported that poly (γ-glutamic acid)-based nanoparticles (γ-PGA NPs) are excellent vaccine carriers for inducing efficient cross-presentation in dendritic cells, thereby producing strong antitumor immunity in vivo. Analyzing the mechanism of cross-presentation induced by γ-PGA NPs will be useful toward designing novel vaccine carriers. In this study, we show an intracellular mechanism of efficient cross-presentation induced by OVA-loaded γ-PGA NPs. Cross-presentation induced by γ-PGA NPs depended on cytoplasmic proteasomes and TAP, similar to the classical MHC class I presentation pathway for endogenous Ags. Intracellular behavior analyzed by confocal laser scanning microscopy revealed that encapsulated OVA and γ-PGA accumulated in both the endoplasmic reticulum (ER) and endosome compartments within 2 h. At the same time, electron microscopy analysis clearly showed that intracellular γ-PGA NPs and encapsulated Au NPs were enveloped in endosome-like vesicles, not in the ER. These findings strongly suggest that γ-PGA NPs enhance ER-endosome fusion for cross-presentation. Moreover, inhibition of ER translocon sec61 significantly decreased the γ-PGA NP/OVA-mediated cross-presentation efficiency, indicating that sec61 is important for transporting Ags from the fused ER-endosome to the cytoplasm. These findings imply that the ER-endosome complex is key for the efficient cross-presentation of Ags encapsulated in γ-PGA NPs.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Osaka University, Osaka 565-0871, Japan. yohe@phs.osaka-u.ac.jp
authors.forename: Yohei
authors.initials: Y
authors.lastname: Mukai
authors.forename: Tomoyo
authors.initials: T
authors.lastname: Yoshinaga
authors.forename: Mai
authors.initials: M
authors.lastname: Yoshikawa
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Matsuo
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsuo
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Niki
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yoshioka
authors.forename: Naoki
authors.initials: N
authors.lastname: Okada
authors.forename: Shinsaku
authors.initials: S
authors.lastname: Nakagawa
mesh_terms: D000818:Animals; D019496:Cancer Vaccines / Q000138:chemical synthesis / Q000235:genetics / Q000276:immunology*; D002478:Cells, Cultured; D045142:Cross-Priming / Q000235:genetics / Q000276:immunology*; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011992:Endosomes / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006183:H-2 Antigens / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007111:Immunity, Cellular / Q000235:genetics; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053758:Nanoparticles; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000235:genetics / Q000494:pharmacology; D011099:Polyglutamic Acid / Q000138:chemical synthesis / Q000235:genetics / Q000494:pharmacology*; D019444:Vaccines, DNA / Q000138:chemical synthesis / Q000235:genetics / Q000276:immunology*
chemical_list: D019496:Cancer Vaccines; D006183:H-2 Antigens; D019444:Vaccines, DNA; C508283:poly(gamma-glutamic acid)-graft-phenylalanine ethylester copolymer; D011099:Polyglutamic Acid; D010649:Phenylalanine