title: Sequential cleavage by metallopeptidases and proteasomes is involved in processing HIV-1 ENV epitope for endogenous MHC class I antigen presentation.
abstract: Antigenic peptides derived from viral proteins by multiple proteolytic cleavages are bound by MHC class I molecules and recognized by CTL. Processing predominantly takes place in the cytosol of infected cells by the action of proteasomes. To identify other proteases involved in the endogenous generation of viral epitopes, specifically those derived from proteins routed to the secretory pathway, we investigated presentation of the HIV-1 ENV 10-mer epitope 318RGPGRAFVTI327 (p18) to specific CTL in the presence of diverse protease inhibitors. Both metalloproteinase and proteasome inhibitors decreased CTL recognition of the p18 epitope expressed from either native gp160 or from a chimera based on the hepatitis B virus secretory core protein as carrier protein. Processing of this epitope from both native ENV and the hepatitis B virus secretory core chimeric protein appeared to proceed by a TAP-dependent pathway that involved sequential cleavage by proteasomes and metallo-endopeptidases; however, other protease activities could replace the function of the lactacystin-sensitive proteasomes. By contrast, in a second TAP-independent pathway we detected no contribution of metallopeptidases for processing the ENV epitope from the chimeric protein. These results show that, in the classical TAP-dependent MHC class I pathway, endogenous Ag processing of viral proteins to yield the p18 10-mer epitope requires metallo-endopeptidases in addition to proteasomes.
authors.affiliation: Centro Nacional de Biología Fundamental, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: D
authors.initials: D
authors.lastname: López
authors.forename: B C
authors.initials: BC
authors.lastname: Gil-Torregrosa
authors.forename: C
authors.initials: C
authors.lastname: Bergmann
authors.forename: M
authors.initials: M
authors.lastname: Del Val
mesh_terms: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters / Q000502:physiology; D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects; D002461:Cell Line, Transformed; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D018984:Epitopes, T-Lymphocyte / Q000378:metabolism*; D019302:HIV Envelope Protein gp160 / Q000378:metabolism*; D015497:HIV-1 / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D006513:Hepatitis B e Antigens / Q000235:genetics / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis / Q000187:drug effects; D007976:Leupeptins / Q000494:pharmacology; D008666:Metalloendopeptidases / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D009097:Multienzyme Complexes / Q000378:metabolism*; D010436:Pepstatins / Q000494:pharmacology; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism
chemical_list: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters; D015853:Cysteine Proteinase Inhibitors; D018984:Epitopes, T-Lymphocyte; D019302:HIV Envelope Protein gp160; D006513:Hepatitis B e Antigens; D015395:Histocompatibility Antigens Class I; D007976:Leupeptins; D009097:Multienzyme Complexes; D010436:Pepstatins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C073119:TAP1 protein, human; C486171:Tap1 protein, mouse; C014195:Streptomyces pepsin inhibitor; C067713:lactacystin; D003546:Cysteine Endopeptidases; D008666:Metalloendopeptidases; D046988:Proteasome Endopeptidase Complex; C032854:leupeptin; C031375:pepstatin; D000111:Acetylcysteine