title: Rapid endocytosis of interleukin-15 by cerebral endothelia.
abstract: Interleukin (IL)-15 receptors are present in the cerebral endothelia composing the blood-brain barrier where they show robust up-regulation by neuroinflammation. To determine how IL15 receptor subunits participate in the endocytosis and intracellular trafficking of IL15, we performed confocal microscopic imaging and radioactive tracer uptake assays in primary brain microvessel endothelial cells and related cell lines transfected with modulatory molecules. By immunostaining and co-localization studies with organelle markers, we showed that IL15 was rapidly endocytosed via lipid rafts and was directed to diverse intracellular pathways. During the course of intracellular trafficking, Alexa dye-conjugated IL15 was partially co-localized with both the specific receptor IL15Rα and the co-receptor IL2Rγ. However, deletion of one of the receptor subunits had only a minor effect in slowing IL15 uptake when primary brain microvessel endothelial cells from the receptor knockout mice were compared with those from wildtype mice. IL15 was trafficked to early, recycling, and late endosomes, to the Golgi, and to lysosomes. The diffuse distribution suggests that IL15 activates multiple endothelial signaling events.
authors.affiliation: Blood-Brain Barrier Group, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA.
authors.forename: Kirsten P
authors.initials: KP
authors.lastname: Stone
authors.forename: Abba J
authors.initials: AJ
authors.lastname: Kastin
authors.forename: Hung
authors.initials: H
authors.lastname: Hsuchou
authors.forename: Chuanhui
authors.initials: C
authors.lastname: Yu
authors.forename: Weihong
authors.initials: W
authors.lastname: Pan
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000235:genetics; D002460:Cell Line; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D004705:Endocytosis / Q000502:physiology*; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism* / Q000502:physiology; D053631:Interleukin Receptor Common gamma Subunit / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D019409:Interleukin-15 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D021381:Protein Transport / Q000235:genetics; D051381:Rats; D053647:Receptors, Interleukin-15 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: C508025:Il15ra protein, mouse; D018836:Inflammation Mediators; D053631:Interleukin Receptor Common gamma Subunit; D019409:Interleukin-15; D053647:Receptors, Interleukin-15