title: Galectin-5 is bound onto the surface of rat reticulocyte exosomes and modulates vesicle uptake by macrophages.
abstract: Reticulocytes release small membrane vesicles termed exosomes during their maturation into erythrocytes. Exosomes are intraluminal vesicles of multivesicular endosomes released into the extracellular medium by fusion of these endosomal compartments with the plasma membrane. This secretion pathway contributes to reticulocyte plasma membrane remodeling by eliminating certain membrane glycoproteins. We show in this study that galectin-5, although mainly cytosolic, is also present on the cell surface of rat reticulocytes and erythrocytes. In addition, in reticulocytes, it resides in the endosomal compartment. We document galectin-5 translocation from the cytosol into the endosome lumen, leading to its secretion in association with exosomes. Galectin-5 bound onto the vesicle surface may function in sorting galactose-bearing glycoconjugates. Fittingly, we found that Lamp2, a major cellular glycoprotein presenting galectin-reactive poly-N-acetylactosamine chains, is lost during reticulocyte maturation. It is associated with released exosomes, suggestive of binding to galectin-5. Finally, we reveal that the uptake of rat reticulocyte exosomes by macrophages is dependent on temperature and the mechanoenzyme dynamin and that exosome uptake is decreased by adding galectin-5. These data imply galectin-5 functionality in the exosomal sorting pathway during rat reticulocyte maturation.
authors.affiliation: DIMNP, Université Montpellier II and I, CNRS (UMR 5235), Montpellier, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Barrès
authors.forename: Lionel
authors.initials: L
authors.lastname: Blanc
authors.forename: Pascale
authors.initials: P
authors.lastname: Bette-Bobillo
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.forename: Robert
authors.initials: R
authors.lastname: Mamoun
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Gabius
authors.forename: Michel
authors.initials: M
authors.lastname: Vidal
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D055354:Exosomes / Q000378:metabolism*; D037161:Galectins / Q000378:metabolism* / Q000502:physiology*; D052119:Lysosomal-Associated Membrane Protein 2 / Q000378:metabolism / Q000502:physiology; D008264:Macrophages / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012156:Reticulocytes / Q000378:metabolism*; D055571:Secretory Pathway / Q000502:physiology; D022161:Transport Vesicles / Q000378:metabolism
chemical_list: D000954:Antigens, Surface; D037161:Galectins; D052119:Lysosomal-Associated Membrane Protein 2; C092501:galectin 5