Reduction of Glycosphingolipid Levels in Lipid Rafts Affects the Expression State and Function of Glycosylphosphatidylinositol-anchored Proteins but Does Not Impair Signal Transduction via the T Cell Receptor

Masakazu Nagafuku, Kazuya Kabayama, Daisuke Oka, Akiko Kato, Shizue Tani-Ichi, Yukiko Shimada, Yoshiko Ohno-Iwashita, Shou Yamasaki, Takashi Saito, Kazuya Iwabuchi, Toshiyuki Hamaoka, Jin Ichi Inokuchi, Atsushi Kosugi

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    40 Citations (Scopus)

    Abstract

    Lipid rafts are highly enriched in cholesterol and sphingolipids. In contrast to many reports that verify the importance of cholesterol among raft lipid components, studies that address the role of sphingolipids in raft organization and function are scarce. Here, we investigate the role of glycosphingolipids (GSLs) in raft structure and raft-mediated signal transduction in T lymphocytes by the usage of a specific GSL synthesis inhibitor, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP). Surface GM1 expression and the expression of GSLs in rafts were profoundly reduced by D-PDMP treatment, whereas the expression of other lipid and protein constituents, such as cholesterol, sphingomyelin, Lck, and linker for activation of T cells, was not affected. T cell receptor-mediated signal transduction induced by antigen stimulation or by antibody cross-linking was normal in D-PDMP-treated T cells. In contrast, the signal through glycosylphosphatidylinositol (GPI)-anchored proteins was clearly augmented by D-PDMP treatment. Moreover, GPI-anchored proteins became more susceptible to phosphatidylinositol-specific phospholipase C cleavage in D-PDMP-treated cells, demonsrating that GSL depletion from rafts primarily influences the expression state and function of GPI-anchored proteins. Finally, by comparing the effect of D-PDMP with that of methyl-β-cyclodextrin, we identified that compared with cholesterol depletion, GSL depletion has the opposite effect on the phosphatidylinositol-specific phospholipase C sensitivity and signaling ability of GPI-anchored proteins. These results indicate a specific role of GSLs in T cell membrane rafts that is dispensable for T cell receptor signaling but is important for the signal via GPI-anchored proteins.

    Original languageEnglish
    Pages (from-to)51920-51927
    Number of pages8
    JournalJournal of Biological Chemistry
    Volume278
    Issue number51
    DOIs
    Publication statusPublished - Dec 19 2003

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    All Science Journal Classification (ASJC) codes

    • Biochemistry
    • Molecular Biology
    • Cell Biology

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