title: Dynamic Changes in the Intracellular Association of Selected Rab Small GTPases with MHC Class II and DM during Dendritic Cell Maturation.
abstract: Antigen processing for presentation by major histocompatibility complex class II (MHCII) molecules requires the latter to travel through the endocytic pathway together with its chaperons: the invariant chain (Ii) and DM. Nevertheless, the nature of the compartments where MHCII molecules travel to acquire peptides lacks definition regarding molecules involved in intracellular vesicular trafficking, such as Rab small GTPases. We aimed to define which Rab proteins are present during the intracellular transport of MHCII, DM, and Ii through the endocytic pathway on their route to the cell surface during dendritic cell (DC) maturation. We examined, by means of three-color confocal microscopy, the association of MHCII, DM, and Ii with Rab5, Rab7, Rab9, and Rab11 during the maturation of bone marrow-derived or spleen DC in response to LPS as an inflammatory stimulus. Prior to the stage of immature DC, MHCII migrated from diffuse small cytoplasmic vesicles, predominantly Rab5+Rab7- and Rab5+Rab7+ into a pericentriolar Rab5+Rab7+Rab9+ cluster, with Rab11+ areas. As DC reached the mature phenotype, MHCII left the pericentriolar endocytic compartments toward the cell surface in Rab11+ and Rab9+Rab11+ vesicles. The invariant chain and MHCII transport pathways were not identical. DM and MHCII appeared to arrive to pericentriolar endocytic compartments of immature DC through partially different routes. The association of MHCII molecules with distinct Rab GTPases during DC maturation suggests that after leaving the biosynthetic pathway, MHCII sequentially traffic from typical early endosomes to multivesicular late endosomes to finally arrive at the cell surface in Rab11+ recycling-type endosomes. In immature DCs, DM encounters transiently MHCII in the Rab5+Rab7+Rab9+ compartments, to remain there in mature DC.
authors.affiliation: Research Unit on Autoimmune Diseases, Research Unit on Immunochemistry, Centro México Nacional Siglo XXI, IMSS, Instituto Mexicano del Seguro Social, Mexico City, Distrito Federal, Mexico; Centro Dermatológico "Dr. Ladislao de la Pascua", Secretaría de Salud del Distrito Federal, Mexico City, Distrito Federal, Mexico.
authors.forename: Gibrán
authors.initials: G
authors.lastname: Pérez-Montesinos
authors.affiliation: Hospital Juárez de México, Secretaría de Salud , Mexico City, Distrito Federal , Mexico.
authors.forename: Orestes
authors.initials: O
authors.lastname: López-Ortega
authors.affiliation: Hospital Juárez de México, Secretaría de Salud , Mexico City, Distrito Federal , Mexico.
authors.forename: Jessica
authors.initials: J
authors.lastname: Piedra-Reyes
authors.affiliation: Research Unit on Autoimmune Diseases, Research Unit on Immunochemistry, Centro México Nacional Siglo XXI, IMSS, Instituto Mexicano del Seguro Social , Mexico City, Distrito Federal , Mexico.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Bonifaz
authors.affiliation: Research Unit on Autoimmune Diseases, Research Unit on Immunochemistry, Centro México Nacional Siglo XXI, IMSS, Instituto Mexicano del Seguro Social, Mexico City, Distrito Federal, Mexico; Hospital Juárez de México, Secretaría de Salud, Mexico City, Distrito Federal, Mexico.
authors.forename: José
authors.initials: J
authors.lastname: Moreno
keywords: H2DM; Rab GTPases; dendritic cells; endocytic pathway; major histocompatibility complex class II molecules