Dynamic changes in the mobility of LAT in aggregated lipid rafts upon T cell activation.
Lipid rafts are known to aggregate in response to various stimuli. By way of raft aggregation after stimulation, signaling molecules in rafts accumulate and interact so that the signal received at a given membrane receptor is amplified efficiently from the site of aggregation. To elucidate the process of lipid raft aggregation during T cell activation, we analyzed the dynamic changes of a raft-associated protein, linker for activation of T cells (LAT), on T cell receptor stimulation using LAT fused to GFP (LAT-GFP). When transfectants expressing LAT-GFP were stimulated with anti-CD3-coated beads, LAT-GFP aggregated and formed patches at the area of bead contact. Photobleaching experiments using live cells revealed that LAT-GFP in patches was markedly less mobile than that in nonpatched regions. The decreased mobility in patches was dependent on raft organization supported by membrane cholesterol and signaling molecule binding sites, especially the phospholipase C gamma 1 binding site in the cytoplasmic domain of LAT. Thus, although LAT normally moves rapidly at the plasma membrane, it loses its mobility and becomes stably associated with aggregated rafts to ensure organized and sustained signal transduction required for T cell activation.
Tanimura
Natsuko
N
School of Allied Health Sciences, Faculty of Medicine, Osaka University, Suita, Japan.
Nagafuku
Masakazu
M
Minaki
Yasuko
Y
Umeda
Yukio
Y
Hayashi
Fumie
F
Sakakura
Junko
J
Kato
Akiko
A
Liddicoat
Douglas R
DR
Ogata
Masato
M
Hamaoka
Toshiyuki
T
Kosugi
Atsushi
A
D048868:Adaptor Proteins, Signal Transducing; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism; D019169:Jurkat Cells; D007700:Kinetics; D008164:Luminescent Proteins / Q000378:metabolism; D008213:Lymphocyte Activation; D008565:Membrane Proteins; D018613:Microscopy, Confocal; D051966:Phospholipase C gamma; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012190:Retroviridae / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D007527:Isoenzymes; C110810:LAT protein, human; D008164:Luminescent Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D002784:Cholesterol; D010738:Type C Phospholipases; D051966:Phospholipase C gamma