title: AP2 clathrin adaptor complex, but not AP1, controls the access of the major histocompatibility complex (MHC) class II to endosomes.
abstract: Newly synthesized MHC II alpha- and beta-chains associated with the invariant chain chaperone (Ii) enter the endocytic pathway for Ii degradation and loading with peptides before transport to the cell surface. It is unclear how alphabetaIi complexes are sorted from the Golgi apparatus and directed to endosomes. However, indirect evidence tends to support direct transport involving the AP1 clathrin adaptor complex. Surprisingly, we show here that knocking down the production of AP1 by RNA interference did not affect the trafficking of alphabetaIi complexes. In contrast, AP2 depletion led to a large increase in surface levels of alphabetaIi complexes, inhibited their rapid internalization, and strongly delayed the appearance of mature MHC II in intracellular compartments. Thus, in the cell systems studied here, rapid internalization of alphabetaIi complexes via an AP2-dependent pathway represents a key step for MHC II delivery to endosomes and lysosomes.
authors.affiliation: INSERM U520 Institut Curie, Section de Recherche, Paris, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Dugast
authors.forename: Hélène
authors.initials: H
authors.lastname: Toussaint
authors.forename: Christelle
authors.initials: C
authors.lastname: Dousset
authors.forename: Philippe
authors.initials: P
authors.lastname: Benaroch
mesh_terms: D033961:Adaptor Protein Complex 1 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D033962:Adaptor Protein Complex 2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002451:Cell Compartmentation; D002460:Cell Line; D004247:DNA / Q000235:genetics; D011992:Endosomes / Q000276:immunology* / Q000378:metabolism*; D006367:HeLa Cells; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008247:Lysosomes / Q000276:immunology / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection
chemical_list: D033961:Adaptor Protein Complex 1; D033962:Adaptor Protein Complex 2; D000949:Histocompatibility Antigens Class II; D034741:RNA, Small Interfering; D004247:DNA