The scaffold MyD88 acts to couple protein kinase C epsilon to toll-like receptors

Amir Faisal, Adrian Thomas Saurin, Bernard Gregory, Brian Foxwell, Peter J. Parker

    Research output: Contribution to journalArticle

    40 Citations (Scopus)

    Abstract

    Mice lacking protein kinase C epsilon(PKC epsilon) are hypersensitive to both Gram-positive and Gram-negative bacterial infections; however, the mechanism of PKC epsilon coupling to the Toll-like receptors (TLRs), responsible for pathogen detection, is poorly understood. Here we sought to investigate the mechanism of PKC epsilon involvement in TLR signaling and found that PKC epsilon is recruited to TLR4 and phosphorylated on two recently identified sites in response to lipopolysaccharide (LPS) stimulation. Phosphorylation at both of these sites (Ser-346 and Ser-368) resulted in PKC epsilon binding to 14-3-3 beta. LPS-induced PKC epsilon phosphorylation, 14-3-3 beta binding, and recruitment to TLR4 were all dependent on expression of the scaffold protein MyD88. In mouse embryo fibroblasts and activated macrophages from MyD88 knock-out mice, LPS-stimulated PKC epsilon phosphorylation was reduced compared with wild type cells. Acute knockdown of MyD88 in LPS-responsive 293 cells also resulted in complete loss of Ser-346 phosphorylation and TLR4/PKC epsilon association. By contrast, MyD88 overexpression in 293 cells resulted in constitutive phosphorylation of PKC epsilon. A general role for MyD88 was evidenced by the finding that phosphorylation of PKC epsilon was induced by the activation of all TLRs tested that signal through MyD88 (i.e. all except TLR3) both in RAW cells and in primary human macrophages. Functionally, it is established that phosphorylation of PKC epsilon at these two sites is required for TLR4- and TLR2-induced NF kappa B reporter activation and I kappa B degradation in reconstituted PKC epsilon(-/-) cells. This study therefore identifies the scaffold protein MyD88 as the link coupling TLRs to PKC epsilon recruitment, phosphorylation, and downstream signaling.

    Original languageEnglish
    Pages (from-to)18591-18600
    Number of pages10
    JournalJournal of Biological Chemistry
    Volume283
    Issue number27
    DOIs
    Publication statusPublished - 4 Jul 2008

    Keywords

    • REGULATORY FACTOR-3
    • NF-KAPPA-B
    • LIPOPOLYSACCHARIDE
    • PHOSPHORYLATION
    • ZETA
    • CELLS
    • PKC-EPSILON
    • MACROPHAGE ACTIVATION
    • ALPHA
    • SIGNALING PATHWAY

    Cite this

    Faisal, Amir ; Saurin, Adrian Thomas ; Gregory, Bernard ; Foxwell, Brian ; Parker, Peter J. / The scaffold MyD88 acts to couple protein kinase C epsilon to toll-like receptors. In: Journal of Biological Chemistry. 2008 ; Vol. 283, No. 27. pp. 18591-18600.
    @article{ff1bd2066dfc4a4691011ce3a524ee95,
    title = "The scaffold MyD88 acts to couple protein kinase C epsilon to toll-like receptors",
    abstract = "Mice lacking protein kinase C epsilon(PKC epsilon) are hypersensitive to both Gram-positive and Gram-negative bacterial infections; however, the mechanism of PKC epsilon coupling to the Toll-like receptors (TLRs), responsible for pathogen detection, is poorly understood. Here we sought to investigate the mechanism of PKC epsilon involvement in TLR signaling and found that PKC epsilon is recruited to TLR4 and phosphorylated on two recently identified sites in response to lipopolysaccharide (LPS) stimulation. Phosphorylation at both of these sites (Ser-346 and Ser-368) resulted in PKC epsilon binding to 14-3-3 beta. LPS-induced PKC epsilon phosphorylation, 14-3-3 beta binding, and recruitment to TLR4 were all dependent on expression of the scaffold protein MyD88. In mouse embryo fibroblasts and activated macrophages from MyD88 knock-out mice, LPS-stimulated PKC epsilon phosphorylation was reduced compared with wild type cells. Acute knockdown of MyD88 in LPS-responsive 293 cells also resulted in complete loss of Ser-346 phosphorylation and TLR4/PKC epsilon association. By contrast, MyD88 overexpression in 293 cells resulted in constitutive phosphorylation of PKC epsilon. A general role for MyD88 was evidenced by the finding that phosphorylation of PKC epsilon was induced by the activation of all TLRs tested that signal through MyD88 (i.e. all except TLR3) both in RAW cells and in primary human macrophages. Functionally, it is established that phosphorylation of PKC epsilon at these two sites is required for TLR4- and TLR2-induced NF kappa B reporter activation and I kappa B degradation in reconstituted PKC epsilon(-/-) cells. This study therefore identifies the scaffold protein MyD88 as the link coupling TLRs to PKC epsilon recruitment, phosphorylation, and downstream signaling.",
    keywords = "REGULATORY FACTOR-3, NF-KAPPA-B, LIPOPOLYSACCHARIDE, PHOSPHORYLATION, ZETA, CELLS, PKC-EPSILON, MACROPHAGE ACTIVATION, ALPHA, SIGNALING PATHWAY",
    author = "Amir Faisal and Saurin, {Adrian Thomas} and Bernard Gregory and Brian Foxwell and Parker, {Peter J.}",
    year = "2008",
    month = "7",
    day = "4",
    doi = "10.1074/jbc.M710330200",
    language = "English",
    volume = "283",
    pages = "18591--18600",
    journal = "Journal of Biological Chemistry",
    issn = "0021-9258",
    publisher = "American Society for Biochemistry and Molecular Biology",
    number = "27",

    }

    The scaffold MyD88 acts to couple protein kinase C epsilon to toll-like receptors. / Faisal, Amir; Saurin, Adrian Thomas; Gregory, Bernard; Foxwell, Brian; Parker, Peter J.

    In: Journal of Biological Chemistry, Vol. 283, No. 27, 04.07.2008, p. 18591-18600.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - The scaffold MyD88 acts to couple protein kinase C epsilon to toll-like receptors

    AU - Faisal, Amir

    AU - Saurin, Adrian Thomas

    AU - Gregory, Bernard

    AU - Foxwell, Brian

    AU - Parker, Peter J.

    PY - 2008/7/4

    Y1 - 2008/7/4

    N2 - Mice lacking protein kinase C epsilon(PKC epsilon) are hypersensitive to both Gram-positive and Gram-negative bacterial infections; however, the mechanism of PKC epsilon coupling to the Toll-like receptors (TLRs), responsible for pathogen detection, is poorly understood. Here we sought to investigate the mechanism of PKC epsilon involvement in TLR signaling and found that PKC epsilon is recruited to TLR4 and phosphorylated on two recently identified sites in response to lipopolysaccharide (LPS) stimulation. Phosphorylation at both of these sites (Ser-346 and Ser-368) resulted in PKC epsilon binding to 14-3-3 beta. LPS-induced PKC epsilon phosphorylation, 14-3-3 beta binding, and recruitment to TLR4 were all dependent on expression of the scaffold protein MyD88. In mouse embryo fibroblasts and activated macrophages from MyD88 knock-out mice, LPS-stimulated PKC epsilon phosphorylation was reduced compared with wild type cells. Acute knockdown of MyD88 in LPS-responsive 293 cells also resulted in complete loss of Ser-346 phosphorylation and TLR4/PKC epsilon association. By contrast, MyD88 overexpression in 293 cells resulted in constitutive phosphorylation of PKC epsilon. A general role for MyD88 was evidenced by the finding that phosphorylation of PKC epsilon was induced by the activation of all TLRs tested that signal through MyD88 (i.e. all except TLR3) both in RAW cells and in primary human macrophages. Functionally, it is established that phosphorylation of PKC epsilon at these two sites is required for TLR4- and TLR2-induced NF kappa B reporter activation and I kappa B degradation in reconstituted PKC epsilon(-/-) cells. This study therefore identifies the scaffold protein MyD88 as the link coupling TLRs to PKC epsilon recruitment, phosphorylation, and downstream signaling.

    AB - Mice lacking protein kinase C epsilon(PKC epsilon) are hypersensitive to both Gram-positive and Gram-negative bacterial infections; however, the mechanism of PKC epsilon coupling to the Toll-like receptors (TLRs), responsible for pathogen detection, is poorly understood. Here we sought to investigate the mechanism of PKC epsilon involvement in TLR signaling and found that PKC epsilon is recruited to TLR4 and phosphorylated on two recently identified sites in response to lipopolysaccharide (LPS) stimulation. Phosphorylation at both of these sites (Ser-346 and Ser-368) resulted in PKC epsilon binding to 14-3-3 beta. LPS-induced PKC epsilon phosphorylation, 14-3-3 beta binding, and recruitment to TLR4 were all dependent on expression of the scaffold protein MyD88. In mouse embryo fibroblasts and activated macrophages from MyD88 knock-out mice, LPS-stimulated PKC epsilon phosphorylation was reduced compared with wild type cells. Acute knockdown of MyD88 in LPS-responsive 293 cells also resulted in complete loss of Ser-346 phosphorylation and TLR4/PKC epsilon association. By contrast, MyD88 overexpression in 293 cells resulted in constitutive phosphorylation of PKC epsilon. A general role for MyD88 was evidenced by the finding that phosphorylation of PKC epsilon was induced by the activation of all TLRs tested that signal through MyD88 (i.e. all except TLR3) both in RAW cells and in primary human macrophages. Functionally, it is established that phosphorylation of PKC epsilon at these two sites is required for TLR4- and TLR2-induced NF kappa B reporter activation and I kappa B degradation in reconstituted PKC epsilon(-/-) cells. This study therefore identifies the scaffold protein MyD88 as the link coupling TLRs to PKC epsilon recruitment, phosphorylation, and downstream signaling.

    KW - REGULATORY FACTOR-3

    KW - NF-KAPPA-B

    KW - LIPOPOLYSACCHARIDE

    KW - PHOSPHORYLATION

    KW - ZETA

    KW - CELLS

    KW - PKC-EPSILON

    KW - MACROPHAGE ACTIVATION

    KW - ALPHA

    KW - SIGNALING PATHWAY

    U2 - 10.1074/jbc.M710330200

    DO - 10.1074/jbc.M710330200

    M3 - Article

    VL - 283

    SP - 18591

    EP - 18600

    JO - Journal of Biological Chemistry

    JF - Journal of Biological Chemistry

    SN - 0021-9258

    IS - 27

    ER -