title: MHC class I presentation of an exogenous polypeptide antigen encoded by the murine AIDS defective virus.
abstract: Peptides derived from endogenous proteins are presented by MHC class I molecules, whereas those derived from exogenous proteins are presented by MHC class II molecules. This strict segregation has been reconsidered in recent reports in which exogenous antigens are shown to be presented by MHC class I molecules in the phagocytic pathway. In this report, the presentation pathway of an exogenously added highly antigenic polypeptide encoded by the murine AIDS (MAIDS) defective virus gag p12 gene is investigated. A 25-mer polypeptide (P12-25) encoded within the gag p12 region of the MAIDS defective virus was found to be effective in stimulating unprimed B6 (H-2b) CD8+ T cells in vitro. The presentation of P12-25 is sensitive to cytochalasin B and D, brefeldin A and gelonin, a ribosome-inactivating protein synthesis inhibitor, but less sensitive or resistant to lactacystin, a highly specific inhibitor of the proteasome. Interestingly, CA-074, a selective inhibitor of cathepsin B, inhibited presentation of the polypeptide, indicating its involvement in the degradation of the P12-25 polypeptide. In fact, when P12-25 was digested with purified cathepsin B in vitro, a highly antigenic 11-mer peptide containing the class I (H-2Db)-binding motif was obtained. Our results favor the phagosome/macropinosome-to-cytosol-to-endoplasmic reticulum (ER)-to-cell surface pathway for exogenous antigens presented by MHC class I molecules. These findings may be relevant to exploiting peptide vaccines that specifically elicit CD8+ T cell immunity in vivo.
authors.affiliation: Department of Bacterial and Blood Products, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: S T
authors.initials: ST
authors.lastname: Yee
authors.forename: Y
authors.initials: Y
authors.lastname: Okada
authors.forename: K
authors.initials: K
authors.lastname: Ogasawara
authors.forename: S
authors.initials: S
authors.lastname: Omura
authors.forename: A
authors.initials: A
authors.lastname: Takatsuki
authors.forename: T
authors.initials: T
authors.lastname: Kakiuchi
authors.forename: D
authors.initials: D
authors.lastname: Muno
authors.forename: E
authors.initials: E
authors.lastname: Kominami
authors.forename: T
authors.initials: T
authors.lastname: Mizuochi
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation; D000998:Antiviral Agents / Q000494:pharmacology; D020126:Brefeldin A; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002401:Cathepsin B / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D005260:Female; D015683:Gene Products, gag / Q000235:genetics / Q000276:immunology*; D006183:H-2 Antigens / Q000276:immunology; D007376:Interleukin-2 / Q000378:metabolism; D009052:Leukemia Virus, Murine / Q000235:genetics* / Q000276:immunology*; D008285:Major Histocompatibility Complex / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016183:Murine Acquired Immunodeficiency Syndrome / Q000235:genetics / Q000276:immunology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010940:Plant Proteins / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D054789:Ribosome Inactivating Proteins, Type 1
chemical_list: D000998:Antiviral Agents; D003517:Cyclopentanes; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D015683:Gene Products, gag; D006183:H-2 Antigens; D007376:Interleukin-2; D019384:Nucleic Acid Synthesis Inhibitors; D010940:Plant Proteins; D011500:Protein Synthesis Inhibitors; D054789:Ribosome Inactivating Proteins, Type 1; C067713:lactacystin; C068250:N-(3-propylcarbamoyloxirane-2-carbonyl)-isoleucyl-proline; D020126:Brefeldin A; D015638:Cytochalasin D; D003571:Cytochalasin B; C025674:GEL protein, Gelonium multiflorum; D002401:Cathepsin B; D000111:Acetylcysteine