title: T-cell receptor microclusters critical for T-cell activation are formed independently of lipid raft clustering.
abstract: We studied the function of lipid rafts in generation and signaling of T-cell receptor microclusters (TCR-MCs) and central supramolecular activation clusters (cSMACs) at immunological synapse (IS). It has been suggested that lipid raft accumulation creates a platform for recruitment of signaling molecules upon T-cell activation. However, several lipid raft probes did not accumulate at TCR-MCs or cSMACs even with costimulation and the fluorescence resonance energy transfer (FRET) between TCR or LAT and lipid raft probes was not induced at TCR-MCs under the condition of positive induction of FRET between CD3 zeta and ZAP-70. The analysis of LAT mutants revealed that raft association is essential for the membrane localization but dispensable for TCR-MC formation. Careful analysis of the accumulation of raft probes in the cell interface revealed that their accumulation occurred after cSMAC formation, probably due to membrane ruffling and/or endocytosis. These results suggest that lipid rafts control protein translocation to the membrane but are not involved in the clustering of raft-associated molecules and therefore that the lipid rafts do not serve as a platform for T-cell activation.
authors.affiliation: Laboratory for Cell Signaling, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Hashimoto-Tane
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yokosuka
authors.forename: Chitose
authors.initials: C
authors.lastname: Ishihara
authors.forename: Machie
authors.initials: M
authors.lastname: Sakuma
authors.forename: Wakana
authors.initials: W
authors.lastname: Kobayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Saito
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017252:CD3 Complex / Q000737:chemistry / Q000378:metabolism; D004705:Endocytosis; D031541:Fluorescence Resonance Energy Transfer; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D066298:In Vitro Techniques; D008213:Lymphocyte Activation / Q000276:immunology* / Q000502:physiology*; D046911:Macromolecular Substances; D021962:Membrane Microdomains / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000737:chemistry / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D017252:CD3 Complex; C121704:CD3 antigen, zeta chain; C491734:Lat protein, mouse; D046911:Macromolecular Substances; D008565:Membrane Proteins; D050505:Mutant Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; D011993:Recombinant Fusion Proteins; C402726:Sh2d2a protein, mouse; D049452:Green Fluorescent Proteins; D051746:ZAP-70 Protein-Tyrosine Kinase; C497262:Zap70 protein, mouse