title: How a cytokine is chaperoned through the secretory pathway by complexing with its own receptor: lessons from interleukin-15 (IL-15)/IL-15 receptor alpha.
abstract: While it is well appreciated that receptors for secreted cytokines transmit ligand-induced signals, little is known about additional roles for cytokine receptor components in the control of ligand transport and secretion. Here, we show that interleukin-15 (IL-15) translocation into the endoplasmic reticulum occurs independently of the presence of IL-15 receptor alpha (IL-15R alpha). Subsequently, however, IL-15 is transported through the Golgi apparatus only in association with IL-15R alpha and then is secreted. This intracellular IL-15/IL-15R alpha complex already is formed in the endoplasmic reticulum and, thus, enables the further trafficking of complexed IL-15 through the secretory pathway. Just transfecting IL-15R alpha in cells, which transcribe but normally do not secrete IL-15, suffices to induce IL-15 secretion. Thus, we provide the first evidence of how a cytokine is chaperoned through the secretory pathway by complexing with its own high-affinity receptor and show that IL-15/IL-15R alpha offers an excellent model system for the further exploration of this novel mechanism for the control of cytokine secretion.
authors.affiliation: Department of Immunology and Cell Biology, Research Center Borstel, Parkallee 22, D-23845 Borstel, Germany.
authors.forename: Erwin H
authors.initials: EH
authors.lastname: Duitman
authors.forename: Zane
authors.initials: Z
authors.lastname: Orinska
authors.forename: Elena
authors.initials: E
authors.lastname: Bulanova
authors.forename: Ralf
authors.initials: R
authors.lastname: Paus
authors.forename: Silvia
authors.initials: S
authors.lastname: Bulfone-Paus
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004151:Dipeptides / Q000494:pharmacology; D004720:Endonucleases / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D019409:Interleukin-15 / Q000378:metabolism*; D053720:Interleukin-15 Receptor alpha Subunit / Q000378:metabolism*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D018832:Molecular Chaperones / Q000378:metabolism*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects
chemical_list: D004151:Dipeptides; D019409:Interleukin-15; D053720:Interleukin-15 Receptor alpha Subunit; D018832:Molecular Chaperones; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D007371:Interferon-gamma; D004720:Endonucleases; D010447:Peptide Hydrolases