Differential localization of IL-2- and -15 receptor chains in membrane rafts of human T cells.
We studied whether cytokine receptors (Rs) on T cells associate with lipid microdomains ("rafts"). Low-dose phytohemagglutinin (PHA)-stimulated human T cells were separated into cytoplasmic, membrane, and raft fractions by buoyant density centrifugation. Examination of these fractions for the presence of interleukin (IL)-2- and -15R chains and associated signaling molecules by Western blotting revealed marked, selective enrichment of the IL-2/15R beta-chain in rafts before IL-2 stimulation. After IL-2 stimulation, a substantial amount of the beta-chain was found in the membrane fraction. This partial translocation was also observed for the beta-chain-associated molecules JAK-1, p56(lck), and grb-2. Finally, raft disruption with methyl-beta-cyclodextrin (MBCD) attenuated IL-2-induced tyrosine phosphorylation events and selectively decreased the surface expression of the IL-2/15R beta-chain detected by flow cytometry. These results show that the IL-2/15R beta-chain is enriched in rafts obtained from low-dose, PHA-stimulated T cells, that IL-2 binding alters this enrichment, and that this enrichment may be functionally relevant as a possible mechanism to ensure cytokine selectivity and specificity.
Goebel
Jens
J
Department of Pediatrics, Section of Pediatric Nephrology, Kentucky Clinic Building, University Medical Center, University of Kentucky, Lexington, KY 40536-0284, USA. jwgoeb0@uky.edu
Forrest
Kathy
K
Morford
Lorri
L
Roszman
Thomas L
TL
D002478:Cells, Cultured; D003505:Cyclodextrins / Q000494:pharmacology; D005677:G(M1) Ganglioside / Q000032:analysis; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D053646:Interleukin-2 Receptor beta Subunit; D008213:Lymphocyte Activation; D021962:Membrane Microdomains / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology; D021122:Protein Subunits; D018123:Receptors, Interleukin / Q000032:analysis*; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2 / Q000032:analysis*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000737:chemistry / Q000187:drug effects / Q000276:immunology*; D047392:beta-Cyclodextrins
D003505:Cyclodextrins; C508024:IL15RA protein, human; C508020:IL2RB protein, human; D007376:Interleukin-2; D053646:Interleukin-2 Receptor beta Subunit; D021122:Protein Subunits; D018123:Receptors, Interleukin; D053647:Receptors, Interleukin-15; D015375:Receptors, Interleukin-2; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D005677:G(M1) Ganglioside