title: Heat shock protein 90 mediates efficient antigen cross presentation through the scavenger receptor expressed by endothelial cells-I.
abstract: Ag cross presentation is an important mechanism for CD8(+) T cell activation by APCs. We have investigated mechanisms involved in heat shock protein 90 (Hsp90) chaperone-mediated cross presentation of OVA-derived Ags. Hsp90-OVA peptide complexes bound to scavenger receptor expressed by endothelial cells (SREC-I) on the surface of APCs. SREC-I then mediated internalization of Hsp90-OVA polypeptide complexes through a Cdc42-regulated, dynamin-independent endocytic pathway known as the GPI-anchored protein-enriched early endosomal compartment to recycling endosomes. Peptides that did not require processing could then be loaded directly onto MHC class I in endosomes, whereas longer peptides underwent endosomal and cytosomal processing by aminopeptidases and proteases. Cross presentation of Hsp90-chaperoned peptides through this pathway to CD8(+) T cells was highly efficient compared with processing of free polypeptides. In addition, Hsp90 also activated c-Src kinase associated with SREC-I, an activity that we determined to be required for effective cross presentation. Extracellular Hsp90 can thus convey antigenic peptides through an efficient endocytosis pathway in APCs and facilitate cross presentation in a highly regulated manner.
authors.affiliation: Division of Molecular and Cellular Biology, Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
authors.forename: Ayesha
authors.initials: A
authors.lastname: Murshid
authors.forename: Jianlin
authors.initials: J
authors.lastname: Gong
authors.forename: Stuart K
authors.initials: SK
authors.lastname: Calderwood
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D045142:Cross-Priming / Q000276:immunology*; D003600:Cytosol / Q000276:immunology / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D011992:Endosomes / Q000276:immunology / Q000378:metabolism; D017261:Glycosylphosphatidylinositols; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000276:immunology; D051128:Scavenger Receptors, Class F / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology
chemical_list: D017261:Glycosylphosphatidylinositols; D018841:HSP90 Heat-Shock Proteins; C495126:SCARF1 protein, human; D051128:Scavenger Receptors, Class F