FAS Activation Induces Dephosphorylation of SR Proteins

Dependence on the de novo generation of ceramide and activation of protein phosphatase 1

Charles E. Chalfant, Besim Ogretmen, Sehamuddin Galadari, Bart Jan Kroesen, Benjamin J. Pettus, Yusuf A. Hannun

    Research output: Contribution to journalArticle

    Abstract

    The search for potential targets for ceramide action led to the identification of ceramide-activated protein phosphatases (CAPP). To date, two serine/threonine protein phosphatases, protein phosphatase 2A (PP2A) and protein phosphatase 1 (PP1), have been demonstrated to function as ceramide-activated protein phosphatases. In this study, we show that treatment with either anti-FAS IgM (CH-11) (150 ng/ml) or exogenous D-(e)-C6- ceramide (20 μM) induces the dephosphorylation of the PP1 substrates, serine/arginine-rich (SR) proteins, in Jurkat acute leukemia T-cells. The serine/threonine protein phosphatase inhibitor, calyculin A, but not the PP2A-specific inhibitor, okadaic acid, inhibited both FAS- and ceramide-induced dephosphorylation of SR proteins. Anti-FAS IgM treatment of Jurkat cells led to a significant increase in levels of endogenous ceramide beginning at 2 h with a maximal increase of 10-fold after 7 h. A 2-h pretreatment of Jurkat cells with fumonisin B1 (100 μM), a specific inhibitor of CoA-dependent ceramide synthase, blocked 80% of the ceramide generated and completely inhibited the dephosphorylation of SR proteins in response to anti-FAS IgM. Moreover, pretreatment of Jurkat cells with myriocin, a specific inhibitor of serine-palmitoyl transferase (the first step in de novo synthesis of ceramide), also blocked FAS-induced SR protein dephosphorylation, thus demonstrating a role for de novo ceramide. These results were further supported using A549 lung adenocarcinoma cells treated with D-(e)-C6-ceramide. Dephosphorylation of SR proteins was inhibited by fumonisin B1 and by over-expression of glucosylceramide synthase; again implicating endogenous ceramide generated de novo in regulating the dephosphorylation of SR proteins in response to FAS activation. These results establish a specific intracellular pathway involving both de novo ceramide generation and activation of PP1 to mediate the effects of FAS activation on SR proteins.

    Original languageEnglish (US)
    Pages (from-to)44848-44855
    Number of pages8
    JournalJournal of Biological Chemistry
    Volume276
    Issue number48
    DOIs
    StatePublished - Nov 30 2001

    Fingerprint

    Protein Phosphatase 1
    Ceramides
    Serine
    Arginine
    Chemical activation
    Phosphoprotein Phosphatases
    Proteins
    Jurkat Cells
    Immunoglobulin M
    Protein Phosphatase 2
    ceramide glucosyltransferase
    Cells
    Precursor T-Cell Lymphoblastic Leukemia-Lymphoma
    Okadaic Acid
    T-cells
    Coenzyme A
    Transferases

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology
    • Cell Biology

    Cite this

    FAS Activation Induces Dephosphorylation of SR Proteins : Dependence on the de novo generation of ceramide and activation of protein phosphatase 1. / Chalfant, Charles E.; Ogretmen, Besim; Galadari, Sehamuddin; Kroesen, Bart Jan; Pettus, Benjamin J.; Hannun, Yusuf A.

    In: Journal of Biological Chemistry, Vol. 276, No. 48, 30.11.2001, p. 44848-44855.

    Research output: Contribution to journalArticle

    Chalfant, Charles E. ; Ogretmen, Besim ; Galadari, Sehamuddin ; Kroesen, Bart Jan ; Pettus, Benjamin J. ; Hannun, Yusuf A. / FAS Activation Induces Dephosphorylation of SR Proteins : Dependence on the de novo generation of ceramide and activation of protein phosphatase 1. In: Journal of Biological Chemistry. 2001 ; Vol. 276, No. 48. pp. 44848-44855.
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    abstract = "The search for potential targets for ceramide action led to the identification of ceramide-activated protein phosphatases (CAPP). To date, two serine/threonine protein phosphatases, protein phosphatase 2A (PP2A) and protein phosphatase 1 (PP1), have been demonstrated to function as ceramide-activated protein phosphatases. In this study, we show that treatment with either anti-FAS IgM (CH-11) (150 ng/ml) or exogenous D-(e)-C6- ceramide (20 μM) induces the dephosphorylation of the PP1 substrates, serine/arginine-rich (SR) proteins, in Jurkat acute leukemia T-cells. The serine/threonine protein phosphatase inhibitor, calyculin A, but not the PP2A-specific inhibitor, okadaic acid, inhibited both FAS- and ceramide-induced dephosphorylation of SR proteins. Anti-FAS IgM treatment of Jurkat cells led to a significant increase in levels of endogenous ceramide beginning at 2 h with a maximal increase of 10-fold after 7 h. A 2-h pretreatment of Jurkat cells with fumonisin B1 (100 μM), a specific inhibitor of CoA-dependent ceramide synthase, blocked 80{\%} of the ceramide generated and completely inhibited the dephosphorylation of SR proteins in response to anti-FAS IgM. Moreover, pretreatment of Jurkat cells with myriocin, a specific inhibitor of serine-palmitoyl transferase (the first step in de novo synthesis of ceramide), also blocked FAS-induced SR protein dephosphorylation, thus demonstrating a role for de novo ceramide. These results were further supported using A549 lung adenocarcinoma cells treated with D-(e)-C6-ceramide. Dephosphorylation of SR proteins was inhibited by fumonisin B1 and by over-expression of glucosylceramide synthase; again implicating endogenous ceramide generated de novo in regulating the dephosphorylation of SR proteins in response to FAS activation. These results establish a specific intracellular pathway involving both de novo ceramide generation and activation of PP1 to mediate the effects of FAS activation on SR proteins.",
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    AU - Pettus, Benjamin J.

    AU - Hannun, Yusuf A.

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