title: MHC I Expression Regulates Co-clustering and Mobility of Interleukin-2 and -15 Receptors in T Cells.
abstract: MHC glycoproteins form supramolecular clusters with interleukin-2 and -15 receptors in lipid rafts of T cells. The role of highly expressed MHC I in maintaining these clusters is unknown. We knocked down MHC I in FT7.10 human T cells, and studied protein clustering at two hierarchic levels: molecular aggregations and mobility by Förster resonance energy transfer and fluorescence correlation spectroscopy; and segregation into larger domains or superclusters by superresolution stimulated emission depletion microscopy. Fluorescence correlation spectroscopy-based molecular brightness analysis revealed that the studied molecules diffused as tight aggregates of several proteins of a kind. Knockdown reduced the number of MHC I containing molecular aggregates and their average MHC I content, and decreased the heteroassociation of MHC I with IL-2Rα/IL-15Rα. The mobility of not only MHC I but also that of IL-2Rα/IL-15Rα increased, corroborating the general size decrease of tight aggregates. A multifaceted analysis of stimulated emission depletion images revealed that the diameter of MHC I superclusters diminished from 400-600 to 200-300 nm, whereas those of IL-2Rα/IL-15Rα hardly changed. MHC I and IL-2Rα/IL-15Rα colocalized with GM1 ganglioside-rich lipid rafts, but MHC I clusters retracted to smaller subsets of GM1- and IL-2Rα/IL-15Rα-rich areas upon knockdown. Our results prove that changes in expression level may significantly alter the organization and mobility of interacting membrane proteins.
authors.affiliation: Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Mocsár
authors.affiliation: Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Julianna
authors.initials: J
authors.lastname: Volkó
authors.affiliation: Department of Applied Physics/Experimental Biomolecular Physics, Royal Institute of Technology, Albanova University Center, Stockholm, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rönnlund
authors.affiliation: Department of Applied Physics/Experimental Biomolecular Physics, Royal Institute of Technology, Albanova University Center, Stockholm, Sweden.
authors.forename: Jerker
authors.initials: J
authors.lastname: Widengren
authors.affiliation: Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Péter
authors.initials: P
authors.lastname: Nagy
authors.affiliation: Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Cell Biology and Signaling Research Group of the Hungarian Academy of Sciences and the University of Debrecen, Debrecen, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Szöllősi
authors.affiliation: German Cancer Research Center, Biophysics of Macromolecules, Heidelberg, Germany.
authors.forename: Katalin
authors.initials: K
authors.lastname: Tóth
authors.affiliation: Lymphoid Malignancies Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Carolyn K
authors.initials: CK
authors.lastname: Goldman
authors.affiliation: Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Sándor
authors.initials: S
authors.lastname: Damjanovich
authors.affiliation: Lymphoid Malignancies Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Waldmann
authors.affiliation: Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bodnár
authors.affiliation: Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary. Electronic address: vamosig@med.unideb.hu.
authors.forename: György
authors.initials: G
authors.lastname: Vámosi
mesh_terms: D002460:Cell Line; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D015395:Histocompatibility Antigens Class I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D053720:Interleukin-15 Receptor alpha Subunit / Q000378:metabolism*; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism*; D009068:Movement; D066329:Protein Aggregates; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D021381:Protein Transport; D013601:T-Lymphocytes / Q000378:metabolism*
chemical_list: D015395:Histocompatibility Antigens Class I; D053720:Interleukin-15 Receptor alpha Subunit; D053645:Interleukin-2 Receptor alpha Subunit; D066329:Protein Aggregates