title: Late Endosomal Recycling of Open MHC-I Conformers.
abstract: With an increasing number of endosomal cargo molecules studied, it is becoming clear that endocytic routes are diverse, and the cell uses more pathways to adjust expression of cell surface proteins. Intracellular itinerary of integral membrane proteins that avoid the early endosomal recycling route is not enough studied. Therefore, we studied endocytic trafficking of empty Ld(eLd) molecules, an open form of murine MHC-I allele, in fibroblast-like cells. Pulse labeling of cell surface eLdwith mAbs and internalization kinetics suggest two steps of endosomal recycling: rapid and late. The same kinetics was also observed for human open MHC-I conformers. Kinetic modeling, using in-house developed software for multicompartment analysis, colocalization studies and established protocols for enriched labeling of the late endosomal (LE) pool of eLddemonstrated that the late step of recycling occurs from an LE compartment. Although the majority of eLddistributed into pre-degradative multivesicular bodies (MVBs), these LE subsets were not a source for eLdrecycling. The LE recycling of eLddid not require Rab7 membrane domains, as demonstrated by Rab7-silencing, but required vectorial LE motility, suggesting that LE recycling occurs from dynamic tubulovesicular LE domains prior segregation of eLdin MVBs. Thus, our study indicates that LE system should not be simply considered as a feeder for loading of the degradative tract of the cell but also as a feeder for loading of the plasma membrane and thereby contribute to the maintenance of homeostasis of plasma membrane proteins. J. Cell. Physiol. 232: 872-887, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Faculty of Medicine, Department of Physiology and Immunology, University of Rijeka, Rijeka, Croatia.
authors.forename: Hana
authors.initials: H
authors.lastname: Mahmutefendić
authors.affiliation: Faculty of Medicine, Department of Physiology and Immunology, University of Rijeka, Rijeka, Croatia.
authors.forename: Gordana
authors.initials: G
authors.lastname: Blagojević Zagorac
authors.affiliation: Department of Biotechnology, University of Rijeka, Rijeka, Croatia.
authors.forename: Kristina
authors.initials: K
authors.lastname: Grabušić
authors.affiliation: Faculty of Medicine, Department of Physiology and Immunology, University of Rijeka, Rijeka, Croatia.
authors.forename: Ljerka
authors.initials: L
authors.lastname: Karleuša
authors.affiliation: Faculty of Engineering, Department of Mathematics, Physics, Foreign Languages and Kinesiology, University of Rijeka, Rijeka, Croatia.
authors.forename: Senka
authors.initials: S
authors.lastname: Maćešić
authors.affiliation: Antigen Presentation & T/NK Cell Activation Group, Clinical Cooperation Unit Applied Tumor Immunity, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Momburg
authors.affiliation: Faculty of Medicine, Department of Physiology and Immunology, University of Rijeka, Rijeka, Croatia.
authors.forename: Pero
authors.initials: P
authors.lastname: Lučin
mesh_terms: D016475:3T3 Cells; D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002451:Cell Compartmentation / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003198:Computer Simulation; D004705:Endocytosis / Q000187:drug effects; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism*; D020868:Gene Silencing / Q000187:drug effects; D006367:HeLa Cells; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D051379:Mice; D055571:Secretory Pathway / Q000187:drug effects; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000090802:rab7 GTP-Binding Proteins
chemical_list: D015395:Histocompatibility Antigens Class I; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; C000716465:rab7 GTP-binding proteins, mouse; D020126:Brefeldin A; D020691:rab GTP-Binding Proteins